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Draft of January 15, 2005

Best available scientific information on the effects of deposition of POPs

Executive summary This paper has been developed in support of the Review of Effectiveness and Sufficiency of the obligations set out in the POPs Protocol to the UNECE Convention on Long-Range Transboundary Air Pollution. As specified by the task force on POPs, this paper considers the best available scientific information on atmospheric transport and deposition, levels in environmental media, and the potential toxicological effects that those levels may cause. To this end information has been drawn primarily from existing reports that have previously been reviewed and accepted by a variety of international organizations (e.g. EMEP, WHO and AMAP) that have, themselves, condensed and synthesized primary sources of scientific information on the effects of pollutants. Each of the chemicals covered by the protocol share some measurable physicochemical characteristics that, combined with a high degree of environmental persistence, enable them to be carried long distances through the atmosphere. By combining an understanding of persistence and physicochemical properties, and how these influence environmental fate and transport with expert estimations of emission levels and environmental data, the atmospheric distribution of POPs can be modeled in both time and space. Based on the best estimates of emissions, simulations carried out on global, hemispheric and region scales predict that levels of atmospheric distribution and deposition of POPs should have decreased substantially over the past ten years, particularly in industrialized countries, and will continue to decrease as long as there are no new emissions. Once primary emissions of POPs have been cut off, environmental concentrations should decline according to degradation rates in various media. For more recalcitrant substances like highly chlorinated PCBs, this process could be quite slow and large environmental reservoirs, e.g. PCBs in carbon rich soils and HCHs in ocean water, could become long-term low level sources to the atmosphere and other environmental media. Atmospheric levels of POPs, measured at monitoring stations throughout the UNECE region seem to reflect the model simulations. The highest concentrations are generally measured in temperate regions, closer to the source of emissions. Among Arctic monitoring stations, higher concentrations are generally measured in the European Arctic which is strongly influenced by sources in Northern Europe, including re-emissions from environmental reservoirs. As predicted, levels are decreasing for most POPs, with the greatest decreases being observed in temperate regions. Levels of POPs in Arctic air are also showing sings of decrease though at slower rates than in temperate regions.

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In terrestrial ecosystems, levels of POPs are relatively low and do not appear to present a toxicological risk to most terrestrial mammals. Possible exceptions are top predators including wolverines and Arctic fox that scavenge in the marine food web (carrion from polar bear kills, seabird eggs, etc.). The wolverine can achieve levels of POP contamination that exceed thresholds for neurodevelopmental effects in mink, while Arctic fox feeding on marine mammal carrion can obtain POP levels on the same order as predatory marine mammals and exceed thresholds for reproductive effects. Concentrations of POPs in freshwater fish have resulted in high levels of exposure in fish eating mammals, which exceed thresholds for toxicity. Fish themselves do not generally accumulate high enough levels to cause toxicological effects, however, they can represent a significant source of POPs to those who consume them. It is strongly suspected that past population declines in Swedish mink and otter were a direct result of POPs contamination, and PCBs in particular. Temporal trends in freshwater fish have demonstrated substantial decreases since the 1970s and it appears that mink and otter populations have begun to recover as well. Population recoveries have not yet taken hold, however, in more polluted areas such as the eastern Baltic. Marine ecosystems are the most effective at biomagnifying POPs. As a result, predatory marine mammals can accumulate levels of POPs that can reach over 100 000 ng/g lipid. There is strong evidence that seal populations in areas of elevated exposure, e.g. the Baltic, have suffered immunological and reproductive effects resulting in past population declines. More recently populations appear to be recovering along with decreasing levels of POPs. While direct evidence of adverse effects is scant, a comparison of current tissue residues with toxicological thresholds suggests that adverse effects on neurological, immune and reproductive systems are probable. There is also growing evidence of effects on polar bear immune systems and potentially reproduction. These conditions presently exist despite evidence of resent declines in the levels of POPs in marine mammals. Seabirds and birds of prey can have levels of POPs that are similar to those measured in predatory marine mammals. During times of peak exposure, during the 1970s and 1980s, many raptor species were nearly driven to extinction in some areas due to reproductive effects arising from DDE pollution. The declining environmental levels of DDE and other POPs have reversed this trend and most raptor populations appear to be recovering. Current exposure levels to PCBs in particular, however, can still exceed thresholds for immune and reproductive effects. The general human population continues to be exposed to POPs as a result of long-range atmospheric transport. The primary source of POPs to humans is through the consumption of animal based foods. The four most abundant POPs in human tissues are PCBs, DDTs, HCBs and HCHs. Polychlorinated dibenzo-p-dioxins and dibenzo furans are also ubiquitous in human tissues and together with dioxin like PCBs can contribute to levels of dioxin like toxicity that regularly exceed WHO allowable daily intake (ADI) and tolerable weekly intake (TWI). Despite decreasing temporal trends in environmental levels and human exposure to POPs, estimated daily intake of PCBs still exceed reference

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levels set by the ASTDR and USEPA in some population groups. Newborns are most at risk having been exposed to POPs in-utero and then through breast milk at levels that can exceed adult exposure levels by an order of magnitude. A large proportion of women in some Arctic areas have blood PCB levels that exceed Health Canada’s level of concern and a significant proportion of Inuit women have levels that exceed the more serious action level. Among the general population, levels of exposure to POPs such as DDT, HCB, and HCHs are well below existing guidelines as a result of declining levels in the environment. Among highly exposed populations, however, such as indigenous Arctic people who consume marine mammals, levels of these POPs can still exceed existing exposure guidelines. As a direct result of consuming marine mammals, Inuit are still exposed to levels of chlordane and toxaphene that exceed guidelines established by Health Canada, ASTDR and USEPA. Among the general population, however, exposure to these POPs is relatively low. A number of POP like substances have recently been measured in remote environments for which local source do not exist. These include brominated flame retardants (PBDEs and HBCD), fluorinated organic compounds (PFOS and related compounds), chlorinated industrial chemicals (SCCPs and PCNs) and current use pesticides (endosulfan). Increasing temporal trends with doubling times of 4-5 years have been reported from some PBDE congeners and concentrations of PFOS have been measured in some species at levels higher than any POP. PBDEs and PFOS are also being measured in human tissues with increasing regularity and in the case of PBDEs, levels increased rapidly, particularly in North America. In Sweden, human PBDE levels appear to have peaked in the mid 1990s and are now in decline.

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Table of Contents

Executive summary _________________________________________________________ 1 1. Introduction _____________________________________________________________ 5 2. Atmospheric Transport and Deposition_______________________________________ 6

Modeling Atmospheric transport and depositions of POPs _________________________________ 8 Levels and Trends in air and deposition ______________________________________________ 12

3. Level and Effects in Terrestrial Ecosystems __________________________________ 13 POP-like substances in terrestrial ecosystems __________________________________________ 14

4. Levels, effects and Trends in Freshwater Aquatic Ecosystems ___________________ 14 Temporal trends of POPs in freshwater aquatic ecosystems _______________________________ 16 POP like substances in freshwater aquatic ecosystems ___________________________________ 16

5. Levels, Effects and Trends in Marine Ecosystems _____________________________ 19 Temporal Trends of POPs in the marine environment____________________________________ 23 POP-like substances in the marine environment ________________________________________ 26

6. Levels, Effects and Trends in Seabirds and Birds of Prey _______________________ 27 Temporal Trends in Seabirds and Birds of Prey ________________________________________ 29 POP like substances in seabirds and birds of prey_______________________________________ 31

7. Levels and Trends of POPs in humans and potential health risks ________________ 32 8. Conclusions_____________________________________________________________ 42 References________________________________________________________________ 44

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Glossary ADI ATSDR BaP bw CLRTAP DDE DDT EMEP HBCD HCB HCBD HCH IARC LOAEL LOEL LRTAP MRL MSC-E NOAEL NOEL PAH(s) PBDDs PBDEs PBDFs PCBs PCDDs PCDFs PCNs PCP PCTs PeCB PFOS POPs PTDI RfD SCCPs TCDD TDI TWI TEF TEQ UNECE USEPA

Acceptable daily intake Agency for Toxic Substances and Disease Registry Benzo[a]pyrene Body weight Convention on Long-range Transboundary Air Pollution 1,1-dichloro-2,2-bis (4-chlorophenyl) ethylene 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe Hexabromocyclododecane Hexachlorobenzene Hexachlorobutadiene Hexachlorocyclohexane International Agency for Research on Cancer Lowest observed adverse effect level Lowest observed effect level Long-range transboundary air pollution Minimum risk level Meteorological Synthesizing Centre – East No observed adverse effect level No observed effect level Polycyclic aromatic hydrocarbon(s) Polybrominated dibenzo-p-dioxins Polybrominated diphenylethers Polybrominated dibenzofurans Polychlorinated biphenyls Polychlorinated dibenzo-p-dioxins Polychlorinated dibenzofurans Polychlorinated naphthalenes Pentachlorophenol Polychlorinated terphenyls Pentachlorobenzene Perfluorooctanesulfonate Persistent organic pollutants Provisional tolerable daily intake Reference dose Short-chain chlorinated paraffins 2,3,7,8-tetrachlorodibenzo-p-dioxin Tolerable daily intake Tolerable weekly intake Toxic (TCDD) equivalency factor Toxic equivalent United Nations Economic Commission for Europe US Environmental Protection Agency

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1. Introduction The following paper is intended to provide a synopsis of the best available scientific information on effects of deposition of POPs in the UNECE region. It has been prepared to support the Review of Sufficiency and Effectiveness of the obligations set out in the POPs Protocol to The Convention on Long-Range Transboundary Air Pollution (LRTAP). The purpose of the review, as described by the Task Force on POPs, is “to examine whether fulfillment of the Protocol’s basic obligations (articles 3 and 4) is resulting in control, reduction or elimination of discharges, emissions and losses of persistent organic pollutants”. As specified by the Task Force on POPs, this paper considers the best available scientific information on atmospheric transport and deposition, levels in environmental media, and the potential toxicological effects that these levels may cause. Information relating to POP emissions are not discussed. The majority of the information in this paper has been drawn from existing reports that have previously been reviewed and accepted by a variety of international organizations (e.g. EMEP, WHO and AMAP) that have, themselves, condensed and synthesized primary sources of scientific information on the effects of pollutants. Where necessary, information from primary peer reviewed literature is included in an attempt to make the review as complete and as current as possible. All regions of the UN ECE are impacted by the deposition of POPs from long-range atmospheric transport. The sources of POPs include those that are regional, hemispheric and global in nature. In the more populated and industrial regions of the UN ECE, however, it can be difficult to distinguish the influence of local, and often direct inputs of POPs, from those of long-range transport (LRT). Therefore, this paper pays particular attention to the Arctic as a remote environment that receives POPs primarily from LRT. The processes involved have been comprehensively studied by the Arctic Monitoring and Assessment Programme (AMAP) over the last fifteen years making the Arctic especially informative for the sufficiency and effectiveness review. The impacts of POPs that are observed in the Arctic provide an overall measure of the effects of deposition of POPs that is synthesized from numerous LRT sources. Information from non-Arctic regions is also presented and discussed, and provides a valuable perspective relating to the influence of nearby or regional LRT sources, for example, the particular influence Northern European sources have on the Baltic.

2. Atmospheric Transport and Deposition In order for a substance to undergo long-range atmospheric transport it must first become airborne. Once airborne the substance must have the potential to travel a great distance through the atmosphere until it is finally deposited in a receiving environment. If the substance is persistent enough to endure this journey without being degraded, it may adversely impact the ecosystem into which it is deposited.

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Four basic scenarios can be used to describe how POPs are transported from their sources and moved around the globe. These processes are primarily related to environmental interactions determined by the partitioning characteristics of the substance (Table 1) (UNEP 2003). Using this conceptual approach to understanding how physicochemical characteristics govern environmental behavior of POPs, it is possible to develop models of atmospheric transport and deposition and to assess a chemical’s potential for long-range atmospheric transport. Table 1. Categorization of various organic compounds according to their transport behavior (adapted from UNEP 2003) Category Characterization Examples no hop (volatile)

Chemicals that are so volatile that they do not deposit substantially to the Earth’s surface and therefore remain in the atmosphere

Chlorofluorocarbons

multi-hop (semisoluble/ semivolatile)

Chemicals that readily shift their distribution between gas phase and condensed phase (soil, vegetation, water) in response to changes in environmental temperature and phase composition, and therefore can travel long distances in repeated cycles of evaporation and deposition.

PCBs, lighter PCDD/PCDF, HCB, toxaphene, dieldrin, chlordane, endosulphan

single-hop (non-volatile/ insoluble)

Chemicals that are non-volatile and insoluble in water and that undergo long range transport by absorption on particles and suspended solids in air and water. Once deposited these chemicals do not readily re-enter the atmospheric pathway.

Heavier PCDD/PCDF, five ring PAHs such as benzo-a-pyrene, heavy PBDEs, mirex, decachlorobiphenyl

no hop required (soluble)

Chemicals that are sufficiently water soluble to undergo long range transport mainly in the dissolved phase in oceanic or riverine transport pathways.

HCHs, PCP, atrazine, phthalates, PFOS

The substances that are currently included in the Protocol fall into the multi-hop, single hop, and no hop required categories. It will be noted that some examples are shown, that display suitable physicochemical properties that suggest the potential for LRT but that are not in the Protocol (Figure 1, Figure 2). Whether substances such as polybrominated diphenyl ethers (PBDEs), polychlorinated naphthalenes (PCNs), short-chain chlorinated paraffins (SCCPs), endosulfan, chlorinated benzenes, and perfluorinated alcohols, the environmental precursors to perfluorooctane sulfonate (PFOS), may be considered POPs in the context of the Protocol will require a comprehensive evaluation of the their characteristics as laid out in the Protocol. The present paper provides some information

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on their environmental presence for the purposes of the sufficiency and effectiveness review.

Figure 1. The characterization of several chemical compounds including POPs and POP-like substances according to partitioning characteristics (Source, F. Wania, adapted from UNEP 2003).

a0 2000 4000 6000 8000 10000

HCBD

PeCB

BDE-99

BDE-47

PCN-47

b-endosulfan

PCP

dicofol

a-endosulfan

BDE-28

Transport distance (Europe), km b 0 50 100 150 200 250 300 350 400 450

HCBD

PeCB

BDE-99

BDE-47

PCN-47

BDE-28

PCP

dicofol

a-endosulfan

b-endosulfan

Half-life in the environment (Europe), days Figure 2. Transport distance (a) and half-life in the environment (b) as predicted for 10 POP-like chemicals using the MSCE-POP model. BDE – brominated diphenyl ether, PCP – pentachlorophenol, PeCB – pentachlorinated benzene, HCBD – hexachlorobutadiene. (reprinted from EMEP 2004)

Modeling Atmospheric transport and depositions of POPs

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A variety of computer based models have been created to evaluate transport and fate of contaminants on both regional and global scales. These models vary widely in complexity and resolution. Simple models assess long range transport potential under hypothetical conditions, whereas others simulate global transport at higher spatial and temporal resolution. Regional and global atmospheric transport models use input parameters related to environmental conditions (e.g. climatic and meteorological data, topography, ground cover) along with parameters associated with a specific chemical (e.g. partitioning characteristics, atmospheric half-lives, use and emissions patterns) to predict atmospheric, transport, deposition, and fate. Some regionally based models for the UNECE region, namely North America and Eurasia, have been fairly well developed (UNEP 2003). Some of the greatest challenges these modeling efforts face relate to uncertainty in fate processes, incomplete and/or uncertain emissions data, and the lack of measured data required to ground truth simulated results. The MSCE-POP model, developed under EMEP, provides an example of a model that has been used to evaluate atmospheric transport and deposition on both a regional (EMEP region) and a hemispheric scale using official data and expert estimates of emissions. According to MSCE-POP model simulations, atmospheric levels of PCDD/Fs, certain PAHs, γ-HCH (lindane), PCB - 153, and HCB should have all experienced a decrease over Europe between 1990 and 2001. The magnitude of the decrease is estimated at 15-30% for PAHs, 50% for PCDD/Fs, 90% for lindane, and 65% for PCB-153. Atmospheric levels of HCB underwent an estimated order of magnitude decrease between the 1970s and 1990 and have since remained relatively stable. Similar corresponding declines were estimated for overall atmospheric burdens and deposition rates for all five groups of compounds (Figures 3 presents the exampleof PCB-153). The maximum deposition rates were generally predicted for eastern Europe and northwestern Europe, although these regions also recorded the greatest declines in deposition since 1990. On a hemispheric scale, the MSCE-POP model estimated that of the total mass emitted, the EMEP region exported approximately 20% of B[a]P, 40% of PCDD/Fs, 50% of PCBs, 75% of γ-HCH, and 80% of HCB out of the region. Modeled atmospheric PCB-153 transport to the Arctic illustrates how sources within the northern hemisphere all contribute to Arctic PCB pollution (Figure 4a). Contamination of the Arctic Ocean by PCB-153 is further highlighted in the modeled distribution of deposition rates to ocean surfaces (Figure 4b). The apparent preferential northward transport and accumulation of POPs , has been explored in a number of studies examining latitudinal trends in concentration and composition of POPs (Macdonald et al., 2000; Meijer et al., 2002; 2003a and b). The term cold condensation has been used to explain the temperature driven accumulation of POPs in colder high latitude environments. This notion of contaminant transport has been further developed into the concept of latitudinal fractionation, a process whereby certain components of the original mixture of substances are preferentially transported and accumulate in environmental media at higher latitudes, thus resulting in a modification of the mixture’s composition. For example, PCB congener signatures

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measured in higher latitudes are relatively enriched in lower chlorinated congeners than those measured in temperate source regions. Both of these environmental processes have been demonstrated using global latitudinal models such as the Globo-POP model developed by Wania and Mackay (2000).

Figure 3. Spatial distribution of PCB-153 depositions in the Northern Hemisphere and in the EMEP domain, 1990 (a) and 2000 (b). (reprinted from EMEP 2004)

Figure 4. A) The modeled relative contribution of atmospheric PCBs to the Arctic from various sources regions in the northern hemisphere. B) Modeled deposition of PCB-153 to marine waters of the northern hemisphere. (adapted from EMEP 2004)

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In the case of α-HCH, the Globo-POP model demonstrated how emissions in north tropical and temperate zones resulted in the accumulation of α-HCH in the Arctic Ocean (Wania 2003). The model also demonstrated how when use and environmental levels declined in the source zones, Arctic environmental conditions promoted the accumulation of α-HCH and retarded degradation. The net result of these transport and accumulation processes is increasing northward concentrations of HCHs in seawater with maxima in the Arctic (Macdonald et al. 2000). Forecasting potential future trends for PCBs Globo-POP simulations using PCB emissions data were carried out for several PCB congeners to evaluate degradation mechanisms and assess the likely rate of future declines in environmental concentrations (Wania 2003). Historically the most important degradation pathways have been, for lower chlorinated congeners, via OH-radical reactions in the atmosphere, and for more chlorinated congers, transfer to the deep sea. The model predicted that declining primary sources of PCBs would result in decreasing concentrations in seawater and air, and therefore the associated degradation processes would also become less important. Soils on the other hand would retain a large portion of the global PCB burden due to their large adsorptive capacity and slow rates of degradation and emission. It is therefore predicted that PCBs in soil will moderate the rate of global decontamination according to the slow rates of evaporation and poorly understood degradation processes therein (Ockenden et al., 2002). The MSCE-POP model was used to estimate future trends in PCB levels for major environmental compartments. The simulation assumed that primary emissions after 2000 were non-existent and that PCB redistribution between 2000 and 2010 was strictly a function of re-emission from accumulated stores in soil, vegetation and seawater. The declining trends illustrated in this forecast (Figure 5) suggest a best-case scenario of PCB loads in soil and seawater being nearly halved between 2000 and 2010. Remission fluxes and air concentrations would undergo a 65% decline over the same period of time. Given that the environmental fate of POPs is highly dependent on climate related variables such as temperature it is expected that rates of decline in polar regions would be slower than in temperate regions.

Figure 5. Calculations with assumed zero primary emission. Trends of mean PCB concentrations in the surface air layer (a), reemission flux (b), content in soil (c) and sea water (d) averaged over the EMEP grid. (reprinted from EMEP 2004)

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Levels and Trends in air and deposition Atmospheric concentrations of POPs have been monitored fairly regularly in a number of locations in the UNECE region since the early 1990s. Most notable are the air monitoring programs that have been established to monitor air quality in various regions such as the Arctic Monitoring and Assessment Program (AMAP) and the Integrated Atmospheric Deposition Network (IADN) which monitors the Great Lakes Region of North America. In Europe, EMEP has consolidated atmospheric POPs data collected in collaboration with several regional programs including AMAP, HELCOM, OSPARCOM, and MEDPOP. In general, levels of organochlorine pesticides are low throughout the Arctic and rural Great Lakes sites when compared to more urban and developed regions (AMAP 2004, UNEP 2002a). Levels of DDT related compounds from the European Arctic sites were more than twice as high as the levels in Arctic Canada. Similarly, concentrations of PCBs, PAHs and HCB in air from Ny-Ålesund and PCBs from Stórhöfdi were substantially higher than levels in Arctic Canada and the rural Great Lakes site. It is suggested that the higher concentrations measured in the European Arctic are related to near region atmospheric transport from northern Europe (AMAP 2004). Deposition rates for organochlorine pesticides to the Great Lakes in 1997 and 1998 ranged from 0.004 – 14.6 g/km2/yr (UNEP 2002a). The highest fluxes were calculated for in-use pesticides, which at the time included lindane. These fluxes were within the same range of depositional rates that the MSCE-POP model calculated for most of southern and western Europe (EMEP 2004). Depositional rates for HCB and ∑PCB ranged from 0.008 – 4.0 g/km2/yr and were generally higher in the eastern Great Lakes. These figures also seem to be in the same range as those predicted for deposition in Europe for HCB and PCB 153 using the MSCE-POP model. The sum of four PAHs was found to deposit at 0.1 – 193 g/km2/yr, which is also consistent with modeled European rates. Temporal datasets from monitoring stations such as Alert, Canada and Ny-Ålesund , Norway, which were initiated in 1993, are starting to reveal some trends (AMAP 2004). Between 1993 and 2000, the concentration of most OC pesticides, including HCHs, chlordanes, toxaphene and lower chlorinated PCBs appeared to slowly decrease at Alert. Trends were similar at Ny-Ålesund, if not more pronounced for α-HCH, and, unlike Alert concentrations of p,p′-DDE appeared to decrease. Higher chlorinated PCBs, dieldrin, α-endosulfan, p,p′-DDE and o,p′-DDT remained at fairly constant levels in Arctic air sampled at Alert and if anything, may have decreases slightly between 1993 and 1999 (Hung et al., 2005). The relatively stable levels of o,p′-DDT is thought to be indicative of lingering fresh sources. Decreasing trends were detected for most POPs in air and depositional rates measured around the Great Lakes of North America and the UK (PCBs only). Air-water flux data from the Great Lakes actually suggests that the net transfer of most POPs is now from the lakes to the atmosphere (UNEP 2002a). General trends for lindane and α-HCH indicated declining atmospheric concentrations in the Czech Republic, Ireland, and southern Norway (UNEP 2003).

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POP-like substances Several POP-like organic compounds have been measured in Arctic air, including the current use pesticides trifluralin, methoxychlor, pentachloroanisole and endosulfan. Other halogenated substances that were measured in Arctic air include polychlorinated naphthalenes, polybrominated diphenyl ethers, and short chain chlorinated paraffins. PCDD/Fs were measured in the Canadian Arctic and at Ny-Ålesund, Norway. Results for all POP like substances measured at both stations were relatively low compared to urban North American and European regions (AMAP 2004). In 2000 and 2001, PBDEs resembling the penta-formulation were measured at three rural/semi-rural sites in the UK. Mean ∑PBDE concentrations for the three sites were 2.6, 11 and 12 pg/m3 (Lee et al., 2004). Total PBDEs have also been measured in air from remote IADN monitoring stations around the Great Lakes with concentrations ranging from 5-20 pg/m3 (UNEP 2002a).

3. Level and Effects in Terrestrial Ecosystems The terrestrial environment exchanges POPs directly with the atmosphere and also through precipitation scavenging and particulate fallout. At the foundation of the terrestrial ecosystem is soil, where concentrations of POPs tend to be quite low, at least in locations that are not impacted by local sources. Terrestrial vegetation has the ability to remove POPs directly from the atmosphere and transfer it to the soil over seasonal cycles. Similarly, POPs can be taken up from the soil and incorporated into vegetable matter, thus providing a pathway to the terrestrial foodchain. Since terrestrial food chains tend to be fairly short, biomagnification is relatively minimal and POP concentrations in apex predators (e.g. wolf) are generally much lower than levels measured in marine predators. Some large scale surveys have been conducted for heavier PAHs, PCBs and PCDD/Fs which preferentially sorb to particulate matter and for which soils are a natural sink. Meijer et al. (2003a) conducted a near global scale survey of PCB concentrations in background soils and found that soil organic matter was a strong determinant in PCB concentration and that the region between 30°N and 60°N contained the highest concentrations (generally around 1 ng/g dw). As PCBs reach a global equilibrium, it is predicted that this zone may shift to Northern boreal forests where soil is rich in organic carbon and capacity to hold PCBs. Background/rural soil concentrations were also reported for PCDD/Fs in Europe, where typical levels ranged from <1 – 20 pg TEQ/g dw (UNEP 2003). Average ∑PAH16 concentrations ranged from 300-400 ng/g dw. POPs have been assessed in the lichen – caribou – wolf food chain. While POPs were found to accumulate in caribou and wolf, concentrations were still quite low. Concentrations of individual OC pesticides in caribou tend to be less than 1 ng/g dw and may be in the low single digit (1-5 ng/g dw) for total PCBs. Caribou throughout the Arctic region display fairly uniform levels of POPs although the Eurasian Arctic may have slightly higher levels (2-3 times) than the North American Arctic. This is consistent

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with modeled hemispheric patterns of atmospheric transportation and monitoring data (AMAP 2004, EMEP 2004). PCBs, HCB, DDTs, dieldrin and chlordanes were the dominant POPs in terrestrial carnivores such as fox, wolverine and wolf. As long as these predators feed within the terrestrial food chain, however, individual POPs do not appear to reach very high levels (<50 ng/g dw total PCB in liver). Given the low levels of exposure there are few cases where terrestrial mammals in the UNECE region are thought to be at risk of adverse effects from current levels of POPs. Most terrestrial mammals do not appear to exceed toxicity thresholds for PCBs (Figure 8) which are generally the most abundant POP found in terrestrial mammal tissues. Predatory birds, which can have very high levels of POPs are discussed separately (see p.29). Extremely high levels of POPs have, however, been found in coastal dwelling Arctic fox from the North American and European Arctic where concentrations in fat have been measured in the thousands of ng/g. These high concentrations, which are similar to those found in polar bears, have been attributed to feeding in marine food webs (on carion, remains of polar bear kills, and seabird eggs, etc.) (AMAP 2004). To a lesser extent, wolverines have also been found to have relatively high levels of POPs, also owing to their high trophic position. In the case of these two species, levels of exposure can exceed toxicity benchmarks for a variety of potential effects including neurological impairment in rhesus monkeys (a possible surrogate species for wolverine and other terrestrial mammals; effects studies rarely involve the actual wildlife species concerned) and in the most exposed Arctic fox, thresholds for decreased reproduction and immune suppression in mink and otter (Figure 8).

POP-like substances in terrestrial ecosystems Surface soils from rural parts of the UK and Norway displayed concentrations of ∑PBDEs with median values of 2.5 ng/g dw and 1 ng/g dw respectively (Hassanin et al., 2004). Congener patterns closely resembled the penta-BDE commercial formulation but also contained components of the more highly brominated octa-BDE formulation. A substantial amount of work has been reported on identifying POP-like substances in birds of prey which are discussed separately.

4. Levels, Effects and Trends in Freshwater Aquatic Ecosystems Freshwater aquatic environments accumulate POPs directly from the atmosphere through direct air-water exchange, precipitation and particulate fallout, however, they can also incorporate atmospheric POPs deposited in their terrestrial catchments. In general, levels of POPs in freshwater are quite low, particularly in instances where the only source of POPs is from long-range transport, as is the case for remote lakes. Rivers tend to accumulate POPs from run-off and direct input as they make their way through agricultural and industrial areas and therefore can have somewhat higher levels of POPs. There are numerous studies examining POPs in river water and associated ecosystems,

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however, given the propensity for local source influences, they will not be reviewed here unless an absence of direct pollution has been demonstrated. The concentrations of POPs in lake water that is solely influenced by long-range atmospheric transport are very low and therefore very difficult to measure. As a result there are only a few studies that have reported POPs data for remote lake water. Some of the most abundant contaminants in water of remote lakes of North America are HCHs, particularly α- and γ-HCH (lindane)(AMAP 2004). Several other POPs and organochlorine pesticides were measured in Arctic lakes including DDTs, HCB, toxaphene, PCBs, endosulfan, methoxychlor and pentachloroanisole (AMAP 1998). POPs have also been measured in water from Lake Baikal. Concentrations were reported for HCB, PCBs, HCHs, chlordanes, DDTs, toxaphenes and all were found to be within the range of levels found in Canadian Arctic lakes (UNEP 2002d). In Europe, the study of remote mountain lakes revealed measurable concentrations of PCBs, HCHs, DDTs, HCB and endosulfans that could have only resulted from atmospheric deposition. Of particular interest were relatively high concentrations of γ-HCH (lindane), which were among the highest recorded in any continental waters. Despite relatively low levels of POPs in water, freshwater fish tend to have higher concentrations of POPs than terrestrial herbivores. Within freshwater ecosystems fish can occupy several trophic levels and are thereby susceptible to biomagnification as POPs concentrate in the successive steps of the phytoplankton-zooplankton-forage fish-piscivorous fish food chain. The dominant POPs found in freshwater fish from the circumpolar Arctic were PCBs, toxaphene and DDTs (AMAP 2004). In addition to these, chlordanes, HCHs, dieldrin and HCB were also measured in Arctic fish. The highest concentrations of POPs are found in long lived predatory fish such as lake trout. Concentrations of PCBs and toxaphene in lake trout muscle from remote northern lakes can range from 10 to 100 ng/g ww but can reach into the low hundreds in particularly old fish. Concentrations of DDTs and chlordanes tend to be lower, <20 ng/g ww, and HCHs, HCBs and dieldrin in the 1-10 ng/g ww range. Mirex has been measured in a limited number of freshwater fish (landlocked char and burbot) at levels between the detection limit of 0.05 ng/g ww and 1 ng/g ww. A substantial amount of data has also been gathered for landlocked Arctic char, burbot, northern pike, and whitefish. Concentrations of ∑PCB28 in trout from alpine lakes in the Pyrenees were comparable to lower trophic level fish found in the Arctic and ranged from 2.7-7.5 ng/g ww (UNEP 2002c). Lake Baikal Omul, a local forage fish, displayed POP concentrations that were an order of magnitude higher than in similar species (eg. cisco or whitefish) from the Canadian Arctic (UNEP 2002d). While the levels of POPs that are measured in freshwater fish do not appear to present a risk of toxicological effects, levels in fish eating mammals can put them at risk. Particularly elevated levels of POPs are found in mink and otter for which fish make up a significant portion of the diet. European otters, for example, were found to have levels of PCBs ranging from 30 000 – 180 000 ng/g lipid (Smit et al., 1998). Levels of exposure in mink and otter can exceed toxicity benchmarks for PCBs (Figure 14) and it has been

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suggested that population level declines in some North American mink and European otter may be due to PCB exposure in these sensitive fish eating mammals (Bernes, 1998; Damstra et al., 2002; Smit et al., 1998), although a direct link to PCB exposure and population level declines has been hard to make. The weight of evidence, however, which includes the occurrence of more subtle effects on the reproductive systems of mink and otter, suggests that population level effects are possible. This is supported by a Swedish study that linked high concentration of PCBs during the 1970s and 80s to declining otter populations that have since recovered as PCB levels decreased in the 1990s (Roos et al., 2001). Lake Baikal seals also have elevated levels of POPs, with levels of PCBs and DDTs reaching into the tens of thousands of ng/g lipid (UNEP 2002d), also putting them at risk of adverse effects.

Temporal trends of POPs in freshwater aquatic ecosystems As is the general trend, levels of POPs in freshwater systems appear to be decreasing. This has been demonstrated in sediment cores from remote lakes that contain a preserved record of POP flux to the lake bottom and provide a convenient tool for examining historical trends. Recent trends in freshwater fish seem to mirror the historic profiles observed in sediment cores. The most complete temporal record for POPs in Arctic freshwater fish comes from a Swedish study that has been monitoring PCBs, DDT, HCB and HCH in pike since 1967 and in char since 1980 (AMAP 2004). These records show rapidly declining trends through the 1970s and 1980s with decreases slowing during the 1990s (Figure 6). The recent trends observed in the Swedish fish are consistent with trends observed in fish from the Canadian Arctic and North American Great Lakes (UNEP 2002a). While there doesn’t seem to be very much temporal trend data on freshwater fish eating mammals, the trends for fish suggest that exposure levels and therefore risk should be decreasing. Roos et al. (2001) found that levels of ∑PCBs and ∑DDTs decreased significantly (15% and 11% annual decreases respectively) between the early 1970s and mid 1990s in otters from northern Sweden, whereas only ∑PCBs were found to decrease (by 6.5% annually) in otters from southern Sweden. The decrease in otter PCB concentrations from northern Sweden was associated with an increase in the otter population. In southern Sweden, where otter PCB concentrations were still relatively high, the populations had yet to show signs of recovery. The authors propose that increasing otter populations being reported in the UK, Finland and Denmark are also likely due to decreases in PCB contamination. Other locations where levels of pollution are higher, however, such as the southwest Baltic coast, have yet to experience similar recoveries.

POP like substances in freshwater aquatic ecosystems A growing number of POP-like substances are being measured in freshwater fish from the UNECE region. These include a variety of brominated flame retardants, fluorinated surfactants, chlorinated industrial chemicals and current use pesticides.

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Salmonids from Lake Michigan displayed concentrations of total PBDEs in the range of 45-150 ng/g ww and levels seem to be increasing rapidly (UNEP 2002a). Between 1978 and 1998 lake trout from lake Ontario showed a 300-fold increase in PBDE concentrations. In the Norwegian Arctic, where BDE-47 and -99 are the dominant congeners, total PBDE concentrations in trout muscle and burbot liver were 0.10-0.36 ng/g ww and 20 ng/g ww respectively (AMAP 2004). These represent levels approximately 2-10 times lower than are typically measured for ∑PCB7.

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Figure 6. Temporal trends in levels of PCB, DDT, α-HCH, and lindane (γ-HCH) in pike muscle from lake Storvindeln, Sweden. Symbols and error bars represent geometric mean concentrations and 95% confidence intervals. Symbols without bars represent single pooled samples. Dashed horizontal lines represent the overall geometric mean level. The trend, over the entire period of sampling and in some cases the period 1990-2000, is shown by a log-linear regression line (black lines, plotted if p<0.10, two sided regression analysis). Red lines show a three-point running smoother applied to test for non-linear trend components if p<0.10. (reprinted from AMAP 2004.) Isomoers of hexabromocyclododecane (α-, β-, and γ-HBCD) were recently measured in the pelagic food web of Lake Ontario (Tomy et al., 2004). Lake trout had concentrations of ∑HBCD of 0.4-3.8 ng/g ww (whole body). The degree of biomagnification for HBCDs between trophic levels of the food web is comparable to that of p,p′-DDE and ∑PCB.

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The fluorinated surfactants perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been increasingly measured in freshwater ecosystems. These substances are not bioaccumulated like most other lipophylic compounds which accumulate in fat. Instead, perfluoroorganic substances, which are very stable polar compounds, accumulate via recycling in the entero-hepatic circulation. The commercial surfactants PFOS and PFOA are also degradation products of other fluorinated compounds (precursors). In the Great Lakes region of North America, salmon liver, herring gull plasma and mink liver have displayed PFOS concentrations of 110 ng/g, 277-453 ng/ml and 590-4900 ng/g respectively (UNEP 2002a). In a comprehensive investigation by Martin et al. (2004) a variety of fluorinated organic compounds were measured in freshwater fish from Northern Quebec. PFOS, with concentrations ranging from 5.7-50 ng/g, was the most abundant fluorinated compound measured in fish. Other fluorinated organic compounds including heptadecafluorooctanesulfonamide (FOSA) and perfluoroalkyl carboxylates (PFCAs) were also measured. The concentrations of these fluorinated organic compounds are comparable to levels of organochlorine pesticides like DDTs and chlordanes that have been measured in similar fish species from remote lakes. The chlorinated industrial compound short chain chlorinated paraffins (SCCPs) have been detected in lake Ontario water in the ng/L range and in fish at 100 ng/g ww (UNEP 2002a). In fish from remote lakes, concentrations of ∑SCCPs were 3.3 ng/g ww and 38 ng/g ww in trout muscle and burbot liver respectively (AMAP 2004). Historic profiles of ∑SCCPs were also examined in sediment cores from Arctic lakes (AMAP 2004). The profile for ∑SCCPs, displayed a sharp increase in sediment concentrations since the early 1980s and historical maxima in surface sediments (circa. 1997). Polychlorinated naphthalenes (PCNs) have been measured in Great Lakes fish at 0.02 – 31.4 ng/g ww (UNEP 2002a). The dioxin-like toxicity associated with the levels found in fish translates into TEQs of 0.007-11 pg/g ww. Trout muscle and burbot liver from northern Norway displayed PCN concentrations of 8.6-16 ng/g ww and 643 ng/g ww respectively (AMAP 2004).

5. Levels, Effects and Trends in Marine Ecosystems Marine environments are often the most impacted by POPs. Oceans and seas have large areas of surface water that effectively exchange POPs directly with the atmosphere and also receive inputs through precipitation and particulate fallout. Oceans are also the ultimate receptors of the world’s rivers that can carry a burden of POPs that were originally deposited in their broad terrestrial catchments. In the marine environment long foodchains and long-lived, fat rich wildlife can accumulate high levels of POPs. The majority of POPs that biomagnify in marine food chains are delivered to the ocean via long-range atmospheric transport. Like freshwater, seawater generally has very low levels of POPs, particularly in the open ocean where atmospheric deposition is the major source. In coastal areas or confined seas, POP levels may be influenced by riverine input and or the direct influence of

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populated coastal regions. For this reason the level of POPs in seawater often decreases with increased distance from the coast. For example dissolved phase DDT levels in continental shelf waters of the Mediterranean were 4 pg/L whereas open seawater had levels of 0.4 – 2.8 pg/L (UNEP 2002c). The POPs that have been measured in Arctic seawater include, in general order of abundance: HCHs > PCBs ≈ toxaphene > chlorobenzenes > DDTs ≈ dieldrin ≈ chlordanes (AMAP 2004). Concentrations of ∑HCHs are about 1000 pg/L in Arctic seawater, whereas PCBs and toxaphene are found in the low hundreds and high tens of pg/L. Chlorobenzenes may be found in the tens of pg/L in Arctic seawater whereas DDTs, dieldrin and chlordanes are all generally present in low (single digit) pg/L levels. Phytoplankton effectively scavenge POPs from the water column and are able to accumulate relatively high concentrations through a bioconcentration process. This represents the first step in a process of biomagnification that defines how POP concentrations in marine species can increase by orders of magnitude as they are passed up through the marine food web. For a relatively persistent bioaccumulative substance like PCB-180, trophic level biomagnification can be a factor of 10 as demonstrated in an Arctic food web (Figure 7). Predator-prey biomagnification factors can, however, be an order of magnitude higher, particularly between higher trophic level organisms (AMAP 2004). Arctic forage fish and other species that feed primarily on zooplankton may have concentrations of POPs in the low single digit ng/g range and lower for muscle. In the Baltic sea, where contaminant levels tend to be relatively high compared to the Arctic, herring, a relatively fatty fish, can have POP levels in the hundreds of ng/g lipid, particularly for PCBs, which are the most abundant POP found in fish (Strandberg et al., 1998). Other POPs measured in marine fish include include HCHs, DDTs, HCB, chlordanes, toxaphene, dieldrin, and mirex. More predatory fish may have POP concentrations in the tens of ng/g for muscle. The highest concentrations of POPs in marine fish are found in large, long-lived predatory fish such as certain species of shark, tuna and swordfish. The concentrations of POPs in Greenland shark liver are in the thousands of ng/g and comparable to levels found in marine mammals (AMAP 2004). Concentrations of POPs measured in Mediterranean tuna and swordfish livers were in the mid to high hundreds of ng/g (UNEP 2003). The toxicological impact of high POP concentrations on large predatory fish is unknown. Other marine wildlife species that feed high in the food web display similarly high concentrations of POPs (AMAP 2004, UNEP 2003). Among the highest concentrations of POPs (e.g. > 10 000 ng/g for ∑PCBs) are measured in the fat of predatory species such as killer whales and polar bears. The POPs that are routinely measured in marine mammals include, in general decreasing order of abundance: PCBs ≈ DDTs ≈ toxaphene > chlordanes > HCHs > dieldrin > HCB > mirex, where PCBs, DDTs, toxaphenes routinely and even chlordanes on occasion exceed 1000 ng/g in fat, HCHs are in the low hundreds of ng/g in fat, and dieldrin and HCB are found in the tens of ng/g in fat. Arctic fox that inhabit coastal environments and periodically consume the remains of marine

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mammals provide another example where scavenging can result in highly elevated levels of POPs. The concentration of some POP groups (eg. PCBs) in scavenging birds and Arctic fox can exceed 10 000 ng/g in fat (AMAP 2004).

Figure 7. CB-180 concentrations versus trophic level relationships for the Northwater Polynya marine food web. The top graph shows all data points and the bottom graph shows mean (±1SE) values for each species. Lines are log-lnear regressions. Trophic level based on δ15N. (Reprinted from AMAP 2004) Some examples of extremely high levels of POPs in marine mammals have been reported. Concentrations of PCBs exceeding 100 000 ng/g have been measured in the fat of transient killer whales off the coast of Alaska (AMAP 2004). In the Mediterranean sea off the coast of Italy dolphins were also reported to have PCB concentrations in excess of 100 000 ng/g in fat (UNEP 2003). Concentrations of DDTs in the same dolphins were as high as 63 500 ng/g in fat. Very few toxicological studies, from which toxicity benchmarks can be derived, have been carried out on marine mammals, although there are a few. Figure 8 provides a comparison for PCB exposure in various Arctic marine mammals to available toxicity thresholds for mammals. Contaminant levels in several species of seal, including ringed

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seal, harbour seal and grey seal, generally have levels of exposure that may put them at risk of subtle neurobehavioural effects. In regions with even higher levels of exposure, like the Baltic and Caspian Seas, and lake Baikal, there may also be concern from effects on vitamin A levels, immune function and possibly reproduction. These comparisons must be used cautiously, however, since extrapolation of toxic effects between species is problematic. Interspecies comparisons, under standard risk assessment processes usually employ a 10-fold safety factor to account for interspecies variations in toxic response. This has not been accounted for in the comparisons made here. In other words there is no built in level of conservatism. The immunotoxic reproductive effects of POPs is suspected in population declines of Baltic seals during the 1970s and 1980s (Bernes 1998). For most species of toothed whale, minke whales and some grey whales, levels of PCB exposure are high enough to suggest risks of subtle neurobehavioural effects, as well as effects on reproduction and vitamin A metabolism. For more highly exposed species, such as harbour porpoises, some resident killer whales, and all transient killer whales from Alaska, and some long-finned pilot whales from the Faroe Islands, there may also be a risk of adverse affects on immune function and reproduction. With the exception of those mentioned above, most baleen whales have levels of POPs exposure that are below thresholds for effects as they generally feed lower in the food chain than toothed whales. Concerns of adverse biological effects in polar bears have long been a concern owing to their extremely high levels of exposure to POPs. There is also concern for Arctic fox that have similar levels of POPs due to a diet that includes remnants of polar bear kills. Previous assessment of health risks to polar bears were all based on toxicity thresholds determined for other species and single contaminant toxicity and did not provide an accurate enough assessment of potential risks. Norwegian and Canadian scientists have recently teamed up to investigate POPs related effects in polar bears at Svalbard, Norway and Hudson Bay, Canada (AMAP 2004). Observations of cub survival between the more highly exposed Svalbard bears and those from Hudson Bay suggested that an unusual number of Svalbard bears were not surviving and that the female reproductive cycle at Svalbard was shorter than normal. These results, however, may be related to other factors unrelated to contaminants. In a study of Canadian bears, it was demonstrated that contaminant concentrations in polar bear milk from mothers whose cubs eventually died were consistently higher than in mothers whose cubs survived. High levels of PCB exposure were associated with lower levels of testosterone, thyroid hormone and vitamin A, although the biological significance of the altered levels was unknown. In another study high levels of PCBs were correlated with suppressed immune function, an effect that could put the health of the bears at risk. The results of these studies in combination with comparisons to established toxicity thresholds provide further evidence that polar bears throughout the Arctic are likely at risk of subtle neurobehavioral effects and alteration of vitamin A stasis. At several sites in Alaska, Canada, East Greenland, Svalbard, and Russia, exposures may be high enough to have reproductive effects. In the most highly exposed populations, near Svalbard, Frans Josef Land, and the Kara Sea there may also be risks of immune suppression.

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Figure 8. Comparison of measured tissue PCB concentrations in Arctic mammals and toxicity benchmarks measured in other mammalian species (reprinted from AMAP 2004).

Temporal Trends of POPs in the marine environment In general levels of most POPs in marine biota appear to be decreasing although there are few temporal datasets that are robust enough to clearly demonstrate declining trends. Monitoring of marine fish in the Baltic Sea has evaluated temporal trends of POPs since the 1970s (UNEP 2003). Results from this monitoring program demonstrated declining

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trends of DDTs, PCBs, HCB and HCHs in both the southern and northern regions of the Baltic. Some of the most dramatic decreases were detected in ∑DDTs where average annual decreases of 7-12% were measured in Baltic herring since the late 1960s-early 1970s.

Figure 9. Temporal trends of ∑DDTs (ng/g lw) in cod liver from a) the Baltic Proper, and b) the Kattegat; and in perch muscle from c) the Gulf of Bothnia and d) the Baltic Proper. 95% confidence intervals and log linear regression line are indicated. Reprinted from UNEP 2003. A comparison of results from mussel surveys carried out in the early 1970s and again in the late 1980s in the Mediterranean Sea has demonstrated 5-fold decreases in levels of PCBs and DDT (UNEP 2003). In contrast to the mussel results, red mullet, which are benthic fish, showed relatively stable levels of DDTs over a ten year period. It is suggested that this result reflects the greater persistence of DDTs in sediments than in the water column. While the evidence for declining levels of DDTs in the Mediterranean is fairly consistent, the evidence for PCBs is mixed. Temporal data for benthic fish from the Adriatic, fish eating birds from the coast of Italy, and Mediterranean tuna and sharks suggest that PCB levels have remained more or less constant through the 1980s and 1990s. The evidence for temporal trends in marine mammals is not as strong as it is for fish. In general, temporal datasets for marine mammals are shorter and comprise fewer data points than those of fish, and therefore trends are more difficult to assess. Among the most extensive datasets are those for ringed seal and beluga in the Canadian Arctic. At the time of the recent AMAP assessment (2004), ringed seal data from three locations, and spanning approximately 25 years (3-5 temporal data points) was available for PCBs, DDTs, HCHs, and chlordanes (Figure 10). Data for ∑PCBs and ∑DDTs at all three

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locations demonstrated significant declines of 1.5 to 5.5 fold for ∑PCBs and 2.5 to 3.3 fold for ∑DDTs. Results for ∑HCHs and ∑Chlordanes were mixed and do not suggest any clear trends. Consistent for all four substances was an increase in the proportion of the most recalcitrant components of the mixture. For example, a temporal increase in the proportion of CB-153: ∑PCB10 is suggestive of a weathered PCB mixture for which fresh sources of PCBs have diminished. This was also evident in the ratio of p,p’-DDE: ∑DDTs and to a lesser extent in the ration of oxychlordane: ∑chlordanes. By far the most dramatic shift in composition was measured in the ratio of β-HCH: ∑HCHs, which more than tripled. While ∑PCBs appeared to decrease in ringed seals, levels of dioxin-like PCBs and ∑PCDD/Fs in seals from Holman Island, the only site for which data existed, showed no discernible trends between 1981 and 2000. Where data exists for other marine mammals, eg. narwhal, beluga, pilot whale and polar bear, trends vary somewhat, however, the similarities seem dominant. Non of the POPs appear to be increasing.

Figure 10. Temporal trends in concentrations and proportions of major OC components in blubber of female ringed seal Arctic Bay, Nunavut, Canada. Arithmetic means and 95% confidence intervals are presented. (Adapted from AMAP 2004)

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POP-like substances in the marine environment Endosulfan was detectable in seawater at levels of 0.0007 – 0.009 ng/L (AMAP 2004). Concentrations of endosulfan in beluga blubber from the Canadian Arctic were found to increase by a factor of 2.1 between 1982 and 1990. Concentrations of PBDEs have been reported for ringed seal and beluga from the North American and European Arctic (AMAP 2004). Beluga blubber from the western Canadian Arctic displayed ∑PBDE concentrations of 15ng/g whereas levels in Svalbard beluga blubber were reported at 92.9 ± 56.5 ng/g. Ringed seal showed a similar spatial trend where ∑PBDE levels in blubber from northeastern Greenland (58 ± 23 ng/g ww) were an order of magnitude higher than levels in western Greenland (3.6 ± 1.1 ng/g ww) and the western Canadian Arctic (4.6 ng/g ww). Some of the highest concentrations of ∑PBDEs have been measured in long-finned pilot whales from the Faeroe Islands where levels ranged from 144 – 1620 ng/g ww (AMAP 2004). Temporal trends data for PBDEs in ringed seal and beluga reported in AMAP 2004 suggest that PBDE concentrations have increased exponentially in ringed seal and beluga since the early 1980s. Based on trends in ringed seal, it is suggested that some penta- and hexa- BDE congeners are actually doubling every four to five years (Figure 11).

Figure 11. Temporal trends of PBDEs in ringed seal and beluga from the Canadian Arctic. Reprinted from AMAP 2004. Polychlorinated naphthalenes have been measured in beluga and ringed seal from the Canadian Arctic (AMAP 2004). Concentrations of ∑PCNs in beluga blubber ranged from 40 - 384 pg/g ww which is low compared to levels of other POPs, nevertheless, PCNs contributed 11% to the overall dioxin like toxicity (TEQ) in the beluga. Ringed seal blubber had lower concentrations of ∑PCNs with levels of 29-63 pg/g ww that made a negligible contribution to the TEQ calculation. Short chain chlorinated paraffins (SCCPs) have been measured in ringed seals and beluga from the Canadian Arctic (Fisk et al., 2003). Mean ∑SCCP concentrations in ringed seal from southern Baffin Island were 89 ± 44 ng/g ww and 100 ± 27 ng/g ww for males and females respectively, while a mean concentration of 527 ± 164 ng/g ww (male and

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female) were measured Eureka in the Canadian High Arctic. Beluga from Mackenzie Bay had mean ∑SCCP concentrations of 206 ± 96 ng/g ww and beluga from the Kimmirut area had mean concentrations of 116 ± 52 and 168 ± 35 for females and males respectively. The congener pattern of SCCPs being measured in Arctic biota appears to be enriched in more volatile compounds relative to commercial mixtures and mixtures measured in biota closer to source regions, e.g. St. Lawrence River Beluga (Canada). The congener shift demonstrates latitudinal fractionation and is indicative of contamination resulting from long range atmospheric transport. Concentrations of PFOS were measured in liver and kidney of harbour porpoise, grey seal, harbour seal, white beaked dolphin and sperm whale from the North Sea (Van de Vijver et al., 2004). Concentrations ranged from less than 10 ng/g ww to 821 ng/g ww. Fluorinated organic compounds including PFOS were also measured in polar bear and ringed seal from the Canadian Arctic (Martin et al., 2004). The mean PFOS concentration in polar bear liver from Hudson Bay was 3100 ng/g, which is higher than most individual PCB congeners. Arctic fox displayed significantly lower levels of PFOS than polar bear with a mean liver concentration of 250 ng/g. Mean concentrations of ringed seal from Holman Island and Grise fjord were 16ng/g and 19ng/g respectively. The study by Martin et al. (2004) also found a suite of perfluorinated carboxylic acids to be present in marine mammal livers in the tens of ng/g.

6. Levels, Effects and Trends in Seabirds and Birds of Prey Some of the highest concentrations of POPs that are found in wildlife have been measured in seabirds and birds of prey. Various species of gull, hawk, eagle and falcon from North America and Europe all display high concentrations of POPs in eggs where mean concentrations of ∑DDTs, ∑chlordanes and ∑PCB are consistently measured in the low thousands of ng/g. These high concentrations are attributed to feeding high in the food chain on a diet that includes carrion and some species of other migratory birds, and also potentially high exposures in industrial areas along migration routes (AMAP 2004, UNEP 2003). There have been several studies of contaminant related toxic effects on wild seabirds exposed to POPs. Many of these studies have taken place on the North American Great lakes where seabirds have been exposed to relatively high levels of POPs, compared to more remote location such as the Arctic. Toxicological benchmarks arising, in large part, from these and laboratory studies are very useful for assessing risks in other avian species. Figure 12 provides a simple comparison of PCB exposure in Arctic birds and a number of toxicity benchmarks that have been determined for similar species. Clearly there are a number bird species common to the UNECE region being exposed to levels of PCBs that exceed existing thresholds of effects for other species. Among the most highly exposed, and consequently those that are most at risk, are the scavenging seabirds and birds of prey. In general, sea ducks (e.g. eiders) and alcids (e.g. guillemots,

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dovekies, murres) that feed lower in the food chain do not have levels of exposure that exceed applicable thresholds. The indication of risk gleaned from Figure 12 seems to be reflected in field studies. Such studies have demonstrated a variety of effects associated with POPs exposure including: egg shell thinning and reduced hatching success in peregrine falcons; reduced reproductive success in Alaskan bald eagles; behavioral alterations, poor body conditions of chicks, suppressed immune systems, decreased hatching success and decreased probability of adult survival in glaucous gulls; and decreased hatchling weight and vitamin-A levels in Shag (AMAP 2004). In a recent study Hario et al. (2004) examined lesser black back gull and herring gull chicks from the Gulf of Finland and Bothnian Bay. The authors found that chicks collected in 1995 had concentrations of DDE and PCBs in their livers that were several times greater than established thresholds for toxic effects (Figure 12) despite apparent temporal decreases in contaminant levels in the Baltic. Lesser black backed gull chicks that did not survive and were found to be diseased had mean liver ∑PCB levels rangeing from 4400 ng/g ww to 43 000 ng/g ww and DDE levels 1300 ng/g ww to 30 000 ng/g ww. Although the unhealthy chicks did have higher contaminant levels than chicks that survived, the study was not robust enough to establish a direct link between contaminant levels and survival rates. Another marked difference between surviving chicks and those that died was high DDE:PCB ratios in the chicks that died. It was speculated that elevated DDE exposure was occurring outside the Baltic region during migration. A comprehensive study by Helender et al. (2002) examined the productivity of Swedish white tailed sea eagles between 1964 and 1999. The study found highly significant correlations between productivity and DDE levels in eggs throughout the study period with a calculated lowest observable adverse effect level (LOAEL) of 120 ug/g lw, which converts to about 6 ug/g ww assuming 5% lipid content for healthy eagle eggs (Helender et al., 2002). Productivity was also correlated with PCB concentrations suggesting a LOAEL of 500 ug/g lw, or 25 ug/g ww in eggs. The authors concluded that the depressed rates of productivity seen in the 1970s and 1980s were due mostly to DDE. The Baltic population of white tailed sea eagles, which was nearly brought to extinction due to pollution, has since recovered and although there is still evidence of adverse effects due to both DDE and PCBs (i.e. levels in some individuals still exceed the LOAELS), the population appears to have recovered. Declining levels of DDE and PCBs since the late 1980s (Figure 13) are credited with the recovery of the Baltic population (Helender et al., 2002).

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Figure 12. Comparison of measured tissue PCB concentrations in Arctic birds and toxicity benchmarks measured in other avian species (Adapted from AMAP 2004).

Temporal Trends in Seabirds and Birds of Prey Peregrine falcons from Alaska showed significantly decreasing trends in concentrations of dieldrin, p,p′-DDE, heptachlor epoxide, oxychlordane and ∑PCBs between 1979 and 1995 (AMAP 2004). Declining trends for PCBs and DDTs were also documented in peregrine falcon eggs from northern Europe, however, dieldrin, chlordanes, and HCB did not show significant changes between 1977 and 1990. Declining levels of DDE has been attributed to the recovering populations of many raptors including the white tailed sea eagle and peregrine falcon. In one particular study looking at Arctic birds of prey, a two-fold decrease was documented for PCBs and a five-fold decrease was found in p,p′-DDE

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between 1972 and 1994 (UNEP 2003). Gannets from the United Kingdom demonstrated decreasing trends for individual PCB congeners with calculated half lives ranging from 5.4 – 10.1 years for CB-101, 118, 153 and 138 which was similar to half lives calculated for Great Lakes Herring Gulls and trends in UK air (Alcock et al., 2002).

A)

B) Figure 13. Temporal trends of ∑PCBs and ∑DDTs (ug/g lw) in A) seabird eggs from the Canadian Arctic (Reprinted from AMAP 2004) and B) white tailed sea eagles from Sweden (adapted from Helander et al. (2002)). Canadian Arctic seabird eggs have been periodically collected from the same site and archived over a period encompassing the last thirty years (AMAP 2004). Retrospective analysis of this archive has demonstrated significant declines in concentrations of ∑PCBs, ∑DDTs, and ∑CBzs in eggs of thick billed murres, black legged kittiwakes and northern fulmars. Significant decreases in concentrations of ∑CHLs, dieldrin and mirex were only evident in kittiwake eggs, not the other two species. These decreasing trends, particularly those for ∑PCBs and ∑DDTs (Figure 13), have also been reported for seabird eggs from other areas including the Baltic Sea, the Barents Sea, the Bering Sea and the Great Lakes. The only POP for which concentrations in the Canadian Arctic

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seabird eggs appeared to increase was β-HCH which, between 1975 and 1998, made up an increasing proportion of ∑HCH. Comparisons of historic and recent levels of PCDD/Fs and dioxin-like PCBs in some seabird tissues from the Canadian Arctic decreased between the mid 1970s and 1990s, however, increases were observed in others (AMAP 2004). Results of the same study also suggested that toxaphene levels in the same birds increased slightly over the same period of time. In seabird tissues from Greenland, Iceland, and the Faeroe Islands results suggest that levels of PCDD/Fs have decreased between 1989 and 2000 (AMAP 2004). The decreasing temporal trends in POP levels measured in Arctic seabirds was also reflected in herring gulls from the North American Great Lakes (UNEP 2003). While significant decreases were recorded for ∑PCBs and ∑DDTs in herring gull eggs between the 1970s and 1990s, levels of dieldrin remained relatively unchanged.

POP like substances in seabirds and birds of prey Polybrominated diphenyl ethers have recently been measured in seabird eggs collected from both the Canadian and European Arctic (AMAP 2004). Canadian seabird eggs from 1975 did not contain detectable levels of PBDEs, however, eggs from the same colony collected in 1993 and others collected in both the Canadian and European Arctic since then have displayed concentrations at the single digit ng/g level. Recent studies have identified relatively high concentrations of PBDEs and hexabromocyclododecane (HBCD) in terrestrial birds of prey. Swedish peregrine falcons were found to have ∑PBDE concentrations in the thousands of ng/g in lipids (AMAP 2004). Among the congeners measured where highly brominated congeners BDE 183 and BDE 209. Concentrations of HBCD were also measured in the thousands of ng/g lipid in some of the birds. Levels of PBDEs were somewhat lower in Norwegian golden eagles, gyrfalcons and merlins where concentrations of ∑PBDE were in the hundreds of ng/g lipid. Fluorinated organic compounds have been identified in a number of bird species from North America and Europe. In a review by Giesy and Kannan (2001) levels of PFOS with species and locations means ranging from 73 to 460 ng/g ww in liver and plasma for double crested cormorants, herring gulls, ring billed gulls, common loon, brown pelican, common cormorant and bald eagles. Kannan et al. (2002) also reported levels of PFOS in livers of Baltic white tailed sea eagles from the Germany and Poland, where in 1999 the mean concentrations was 45 ng/g ww. Polychlorinated naphthalenes were measured in Mediterranean cormorant livers in the hundreds of pg/g ww (Kannan et al., 2002) and have also been measured in Norwegian seabirds (AMAP 2004).

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7. Levels and Trends of POPs in humans and potential health risks The primary source of POPs to non-occupationally exposed humans is through diet. Due to their biomagnifying nature, the highest levels of several POPs in food items are found in animal products, particularly those with high fat content. The greatest sources of POPs to adult humans are generally, meat, dairy products, poultry and in some cases fatty fish (i.e. where they make up a significant portion of the diet). The risk of adverse health effects arising from POPs is, however, greatest during early life stages. During the most sensitive developmental stages, the fetus can be exposed to POPs at levels that have accumulated in the mother over her lifetime. Infants may subsequently be exposed to even higher levels of POPs contained in breast milk which can have levels of POPs that are several times higher than other foods. When human exposure to POPs is examined on a more regional basis in the UNECE, a few examples of relatively high exposure are evident and have been well studied. These include elevated levels of exposure due to the consumption of fish from the Great Lakes region of North America, similarly high levels of exposure due to the consumption of fatty fish from the Baltic Sea, and particularly high levels of exposure due to the consumption of marine mammals among Arctic indigenous populations. In each of these cases, particularly that of Arctic indigenous populations, the main source of POPs comes from long range atmospheric transport. It should be recognized however, that the elevated levels of POPs in the Great Lakes and the Baltic are likely due in part to direct input from local sources. In general the most abundant, and regularly measured, POPs in human tissues are (in order of abundance): PCBs, DDTs, HCB, HCHs, chlordanes and mirex. This is based on recent surveys (late 1990s) of POPs in blood from Scandinavian countries where exposure is due primarily to LRTAP and levels are considered to be indistinguishable from other European countries (Van Oostdam et al., 2004). Samples were also analyzed for dieldrin, heptachlor epoxide and toxaphene, however, levels were not reported since these POPs were only detected in 1%, 7% and 4% of samples respectively (Van Oostdam, pers. comm. 2004). Guidelines for safe levels of intake and residues in human tissues have been developed in order to protect human health from the potential adverse effects of POPs (Table 2). A comparison of recently measured levels of exposure and tissue residues to these guidelines provides a quick assessment of ongoing risks to human health that are associated with the deposition of POPs. Estimating dietary intake of POPs, however, is a fairly complicated process and data is somewhat limited.

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Table 2. Guidelines for the protection of human health. LRTAP POP Existing Guideline1

Aldrin ASTDR MRL – 0.03 ug/kg/day USEPA RfD – 0.03 ug/kg/day

Chlordane WHO ADI – 0-1 ug/kg/day ASTDR MRL – 0.6 ug/kg/day USEPA RfD – 0.06 ug/kg/day Health Canada pTDI – 0.05 ug/kg/day

Chlordecone ASTDR MRL – 0.5 ug/kg/day DDT WHO ADI – 20 ug/kg/day

WHO PTDI – 10 ug/kg/day USEPA RfD – 0.5 ug/kg/day Health Canada pTDI – 20 ug/kg/day

Dieldrin ASTDR MRL – 0.05 ug/kg/day USEPA RfD – 0.05 ug/kg/day

Dioxins/furans (PCDD/Fs) WHO TDI – 1-4 pg TEQ/kg/day ASTDR MRL – 1 pg TEQ/kg/day Health Council of Netherlands health-based exposure limit 1 pg TEQ/kg/day

Endrin ASTDR MRL – 0.3 ug/kg/day USEPA RfD – 0.3 ug/kg/day

Heptachlor WHO ADI – 0.5 ug/kg/day USEPA RfD – 0.5 ug/kg/day

Hexabromobiphenyl Hexachlorobenzene WHO ADI – 0.16 ug/kg/day (neoplastic effects)

- 0.17 ug/kg/day (non-cancer effects) ASTDR MRL – 0.05 ug/kg/day USEPA RfD – 0.8 ug/kg/day Health Canada pTDI – 0.27 ug/kg/day

Hexachlorocyclohexanes (HCHs) WHO tADI γ-HCH – 0-1 ug/kg/day ASTDR MRL α-HCH – 8 ug/kg/day

Mirex ASTDR MRL – 0.8 ug/kg/day USEPA RfD – 0.2 ug/kg/day Health Canada pTDI – 0.07 ug/kg/day

Polycyclic aromatic hydrocarbons (PAHs)

USEPA RfD Anthracene – 300 ug/kg/day Acenaphthene – 60 ug/kg/day Fluoranthene – 40 ug/kg/day Fluorine – 40 ug/kg/day Pyrene – 30 ug/kg/day

Polychlorinated biphenyls (PCB) ASTDR MRL – 0.02 ug/kg/day USEPA RfD – 0.02 ug/kg/day Health Canada pTDI – 1 ug/kg/day Health Canada level of concern 5-100 ug/L blood Health Canada action level >100 ug/L blood

Toxaphene Health Canada pTDI – 0.2 ug/kg/day 1. Guidelines drawn from reports of the Agency for Toxic Substances and Disease Registry (ASTDR) who have developed minimum risk levels (MRL). MRLs for chronic exposure are listed. Also included are United States Environmental Protection Agency Reference doses (USEPA RfD), World Health Organizations tolerable/acceptable daily intake (WHO TDI/ADI). Health Canada provisional daily intakes (pTDI) were drawn from Van Oostdam et al. (2003).

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A particularly useful review of human exposure to POPs and potential health risks is the joint WHO/Convention Task Force on the Health Aspects of Air Pollution report, Health risks of persistent organic pollutants from long-range transboundary air pollution (WHO 2004). This report reviews scientific information on various POPs, including DDT, HCB, HCHs, PAHs, heptachlor, PCDD/Fs, PCBs and polychlorinated terphenyls (PCTs). The POP-like substances, pentachlorophenol, PBDEs, polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), SCCPs, and ugilec are also reviewed. This list covers the POPs to which human exposure is most prevalent in the general population (i.e. PCBs, DDTs, HCBs, and HCHs) as well as PCDD/Fs for which concerns over toxicity are relatively high. In general, levels of other POPs (toxaphene, chlordane, aldrin, dieldrin, endrin, heptachlor, hexabromobiphenyl, mirex and chlordecone) have declined quite dramatically over the past 20-30 years and levels of exposure are quite low. This is not the case, however, among Arctic indigenous people who consume marine mammals where exposure to chlordanes and toxaphenes may still be of toxicological significance. Among adults from industrialized countries, the estimated daily intake of PCBs is 50 ng/kg body weight (WHO 2004), which is well above the 20 ng/kg body weight/day MRL and RfD set by the ASTDR and USEPA. It was also noted that adult intake of PCBs is in the same order of magnitude as the lowest observable adverse effect level (LOAEL) for subtle neurotoxic effects in infants (14 – 900 ng/kg bw/day). The risks associated with PCBs are greatest for infants who, when breastfed, experience levels of exposure that can be one to two orders of magnitude greater than adults (WHO 2004). For PCBs, the greatest risk to infants, however, appears to be from pre-natal exposure. Levels of PCB among women from Iceland, Sweden and Norway were found to exceed the Health Canada Level of Concern for PCB in maternal blood in 35%, 68% and 70% of women respectively (Figure 14, AMAP 2004). The levels of ∑PCB14 in maternal blood ranged from 175-225 ug/kg lipid, which is considered to be indistinguishable from levels measured elsewhere in Europe (Van Oostdam et al., 2004). Despite decreasing levels of PCBs in the environment, the levels of human exposure among the general population continue to present a risk of adverse health effects. The risk of effects from PCBs is even greater for populations at higher levels of exposure. These include populations that consume a large amount of fatty fish from, e.g. the Baltic sea or fish from the North American Great Lakes and those for whom marine mammals make up a significant portion of the diet. In blood surveys conducted in North America current mean PCB blood serum levels range from 0.9-1.5 ug/L in individuals that do not have a diet high in fish. For people who reported consuming Great Lakes sport fish for more than a 15-year period PCB blood serum levels were two- to four-times higher. These results suggest that high consumers of Great Lakes sport fish may have blood PCB levels above the level of concern (5 ug/L) established by Health Canada for women of childbearing age. Among Greenland Inuit of a particular community, where PCB exposure appears to be higher than in other populations, over 10% of pregnant women exceeded the Health Canada action level (100 ug/L) (AMAP 2004). This rate jumped to over 50% among non-pregnant women from the same community.

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When discussing the toxicity of PCBs, it is also relevant to consider the influence of dioxin-like toxicity and additive effects of both PCBs and dioxins (i.e. PCDDs and PCDFs). As with other POPs, humans are exposed to dioxins primarily through diet. The average intake of dioxins among adults is in the order of 1-3 pg TEQ/kg bw/day (WHO 2004). The influence of dioxin-like PCBs can actually double or triple these figures, which puts the average adult intake in the range of 2-9 pg TEQ/kg bw/day. This range of exposure exceeds most of the applicable guidelines (Table 2) for intake of dioxin like substances. On a weekly basis, the average TEQ intake (based on PCDD/Fs and dioxin like PCBs) in the general European population is estimated to be 8.4 – 21 pg/kg bw/week (UNEP 2002b). When compared to the most recent tolerable weekly intake (TWI = 14 pg TEQ/kg bw/week) set by the EU Scientific Committee on Food (SCF) it is apparent that some portion of the population is consistently exceeding the guideline. In Europe, a large amount of work has been done to characterize levels of PCBs, PCDD/Fs and dioxin-like toxicity (TEQs) in the human population (UNEP 2002b). The most important route of exposure for these compounds is considered to be diet, particularly fatty foods like dairy, meat, and poultry. In Europe and North America, however, lipid rich fish appears to be the most important source of POPs for regular consumers of fish. Fisherman from the east coast of Sweden, consuming relatively large amounts of fatty herring and salmon from the Baltic Sea, had higher levels of PCBs, DDTs and PCDD/Fs than average fish consumers. Due to enrichment of POPs in human breast milk, breast fed babies were shown to have approximately two to three-times greater daily TEQ intakes than European adults (UNEP 2002b). Based on data collected in 1993/1994, a UK study calculated mean daily TEQ intakes (combined PCDD/F and PCB) of 170 pg TEQ/kg bw/day in 2 month old babies. After 10 months this fell to 39 pg TEQ/kg bw/day, however, levels still far exceeded all guidelines. A regional survey of PCBs and PCDD/Fs in human breast milk for the European region suggested fairly large differences between countries with relatively high levels in Russia, Slovakia, Ukraine and the Netherlands and lower levels in countries like Ireland, Bulgaria and Hungary (UNEP 2003). These trends seem to be consistent with deposition estimates from the MSC-E model runs (EMEP 2004). Analysis of temporal trends among countries participating in the survey found that a concentration of dioxins in breast milk has been halved in some countries since the late 1980s (Figure 15, WHO 2004). Despite the relatively high exposures to breast fed infants, the general consensus among health authorities is that the benefits of breast feeding outweigh any risks from POPs. This is even true when it comes to the relatively high levels of exposure experienced in Inuit populations (AMAP 2003).

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Figure 14. PCB levels in blood of women of reproductive age; percentage of samples exceeding public health guidelines for levels of concern and action (Source, AMAP 2002).

Figure 15. Temporal trends in the levels of dioxins and furans in human milk in various countries participating in consecutive rounds of the WHO exposure study (adapted from WHO 2004).

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The levels of DDTs that are measured in human tissues are second in abundance to PCBs. As is the case for PCBs, human exposure to DDTs is primarily through the consumption of animal based foods. Based on dietary surveys in five countries including Finland, Netherlands, Switzerland, the UK and the USA, daily intake of DDTs were all well below the WHO ADI and even below the PTDI of 10 ug/kg bw/day (WHO 2004). Average daily intake for each of these countries during the late 1980s ranged from 0.004 ug/kg bw/day in the Netherlands (1985) to 0.05 ug/kg bw/day in the UK (1985). Given the evidence for declining levels in the environment, it is quite likely that current levels of intake are even lower. There are, however, cases where dietary intake of DDTs is relatively high, particularly among Arctic indigenous people who consume marine mammals. Dietary surveys among Inuit from Baffin Island, Canada, demonstrated levels of daily intake that approach the WHO PTDI, whereby the 95 percentile of those surveyed exceeded 13.1 ug/kg bw/day (Van Oostdam et al., 2003). Some individuals actually exceeded the ADI of 20 ug/kg bw/day. Van Oostdam et al. (2004) reported significantly higher concentrations of ∑DDTs in maternal blood among Inuit of Canada and Greenland that non-indigenous populations of Norway, Sweden and Iceland, which are considered to be similar to the rest of Europe. Levels among Greenland Inuit were more than four-times higher than levels in Norway. Among fish eating women from the Great Lakes region of North America, ∑DDTs levels were generally lower than for Inuit but higher than Norway Sweden and Iceland. In all of these cases, the ratio of DDE:DDT is relatively high (>15) indicating a weathered source of the commercial product. In some parts of Russia, however, DDE:DDT ratios have been observed at significantly lower levels (9) indicating relatively fresh sources of DDT (Van Oostdam et al., 2004). Levels of ∑DDTs in maternal blood from Russia were significantly higher than in mothers from Scandinavian countries and even higher than levels among Canadian Inuit. These results all suggest relatively recent contamination. The WHO guideline for DDT in blood plasma or serum is 200ug/L, which is not exceeded by even the most highly exposed groups. Levels of ∑DDTs in maternal blood from Greeland Inuit were approximately 7.2 ug/L.

The third most abundant compound found in human tissues, with the exception of indigenous Arctic populations, is HCB. Among Inuit and Great Lakes fish consumers, levels of ∑chlordane can exceed those of HCB. In the general population the main source of HCB is through the consumption of animal based foods. Mean daily intake for adults is 0.0004-0.0028 ug/kg bw, however, levels of exposure among breastfed infants may be <0.018-5.1 ug/kg bw/day (WHO 2004). These results suggest that intake levels among the general adult population were well below the guidelines set by the ASTDR, USEPA and WHO (Table 2). Intake among Inuit from a community on Baffin Island, however, appears to exceed all of these guidelines. Mean daily intake levels among Inuit were 0.23 ug/kg bw (Van Oostdam et al., 2003). Concentrations of HCB in maternal blood were also significantly higher among Inuit from Canada and Greenland than among mothers from Norway, Sweden and Iceland. The highest mean level was reported for Greenland (80 ug/kg lipid) whereas the lowest mean was reported for Sweden (16 ug/kg lipid).

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In total diet and market based studies, the daily intake of γ-HCH in Czechoslovakia, the Federal Republic of Germany and Netherlands in 1970 was estimated at 0.05 ug/kg bw. By 1980 the intake level had dropped to 0.0003 ug/kg bw/day (WHO 2004). The estimated daily intake of ∑HCHs in the 1980s was estimated at 0.01 ug/kg bw in the USA and 0.015 ug/kg bw in the Nertherlands (WHO 2004). Even then, over twenty years ago, levels of dietary intake were more than an order of magnitude below the WHO ADI of 1 ug/kg bw/day and the Health Canada PTDI of 0.3 ug/kg bw/day. More resent dietary intake levels for Baffin Island Inuit were estimated at a mean of 0.06 ug/kg bw/day. The Health Canada PTDI was only reached by the 95th percentile with estimated intakes of 0.36 ug/kg bw/day.

Of the HCHs commonly measured in human tissues, β-HCH is typically the most abundant because it is significantly more persistent than α- or γ-HCH. In their survey of maternal blood, Van Oostdam et al. (2004) found that Inuit from Canada and Scandinavians had relatively similar levels of β-HCH. Only Greenland Inuit had significantly higher levels of β-HCH, which at 18 ug/kg lipid, were roughly twice as high as levels measured in Canadian Inuit. The levels of β-HCH in maternal blood from Russia were 223 ug/kg lipid, which was over 10 times higher than the levels in Greenland Inuit.

The WHO report on health risks from POPs from LRTAP concludes that human exposure to heptachlor from long range transport in unlikely to result in harmful effects with the possible exception of high exposure groups such as Inuit. Although heptachlorepoxide, the primary breakdown product of heptachlor, was detected in 40% of Inuit maternal blood samples, mean levels were at or near the detection limit. Heptachlor is not generally detectable in human tissues. There does not appear to be any recent estimates of daily intake, although intake levels in the US during 1971-74 were estimated at 0.29-0.64 ug/day, or 0.005-0.01 ug/kg/day (assuming 60kg/person), which were well below the current ADI of 0.5 ug/kg/day (WHO 2004). PAHs were also examined in the WHO (2004) report, however, the report concludes that since PAHs are not effectively accumulated in biota, there is limited risk of elevated exposure from LRTAP. The majority of diet related human exposure to PAHs results from PAH formation during food preparation. While levels of ∑chlordanes are relatively low in the general population, 9.2-25 ug/kg lipid in blood among Scandinavian mothers, and levels of toxaphene are generally at or below detection limits, levels among Arctic indigenous populations that consume marine mammals are substantially higher (Van Oostdam et al., 2004). Mean maternal blood levels of ∑chlordanes were 74-106 ug/kg lipid among Canadian Inuit and 163 ug/kg lipid among Greenland Inuit. Mean dietary intake of chlordane and toxaphene among Baffin Island Inuit is estimated at 0.62 ug/kg bw/day and 3.34 ug/kg bw/day respectively (Van Oostdam et al., 2003). Both of these levels are well above the Health Canada guidelines of 0.05 ug/kg bw/day and 0.2 ug/kg bw/day for chlordane and toxaphene respectively. While dietary estimates for Greenland Inuit were not available, given the relatively high blood levels, exposure levels would also likely exceed the Health Canada guidelines. Estimates of dietary intake of chlordane among Baffin Inuit also exceed the less

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conservative reference values established by the ASTDR and USEPA, although they do not exceed the WHO ADI (Table 2). Mirex is also detected in maternal blood of circumpolar countries. Mirex was detected in 8-35% of maternal blood samples from Norway, Sweden and Iceland, whereas it was detected in over 85% of all Inuit samples. Mean concentrations of mirex in blood of Inuit from Canada and Greenland ranged from 4.7 to 8 ug/kg lipid, and from 1.1 to 1.9 in samples from Norway, Sweden and Iceland (Van Oostdam et al., 2004). As with other POPs, the elevated concentrations in Inuit is due to the consumption of marine mammals. The estimated mean dietary intake of mirex among Baffin Island Inuit is 0.01 ug/kg bw/day which is about seven times lower than the Health Canada PTDI of 0.07 ug/kg bw/day (Van Oostdam et al., 2003). It was however noted that several individuals who participated in the dietary survey did actually exceed the PTDI. Guidelines from the ASTDR and USEPA were not exceeded. An increasing volume of data is being gathered on POP-like substances in human tissues. In Europe and North America levels of PDBEs have demonstrated exponential increases in human breast milk since the 1970s (UNEP 2003, UNEP 2002b, EEA 2003). While levels of PBDEs in Swedish breast milk appear to have peaked in the mid-1990s, levels in North America continue to rise (UNEP 2002b). In a comprehensive review of global PBDE data, Hites (2004) reports that PBDE concentrations in human tissues have increased 100 times in the last 30 years, doubling every 5 years. Average concentrations of PBDEs in human fat averages ~2ng/g in Europeans but is much higher in North Americans at ~35ng/g. Peak levels in the US have been measured at levels in excess of 300 ng/g lipid. The exponential increases in PBDEs observed in human tissues is also reflected in rises reported for fish, seabirds and marine mammals in North America, Europe and the Arctic. In the Baltic region of Europe, PBDE exposure has been related to the consumption of fatty fish. In Latvia, men who consumed more than 12 meals of fish per month had levels of BDE-47 of 2.4 ng/g lipid in their blood, as opposed to 0.26 ng/g lipid in the blood of men who at a maximum of one fish meal per month (WHO 2004). The mean intake of ∑PBDEs based on a Swedish food survey was 51 ng/person/day or 1ng/kg bw/day. In Canada the estimated mean intake was similar at 44 ng/person/day. The toxic effects and benchmarks for toxicity of PBDEs are still poorly understood. Some risk assessment has been done based on a NOAEL of 44 ug/kg bw/day for hepatic effects in rats, and another NOAEL of 1.55 ug/kg bw/day for persistent behavioral effects in weanling mice. Based on two different models of current human exposure the margins of safety were considered to be unacceptably low (WHO 2004).

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Figure 16. Temporal trends of PCBs and PBDEs in Swedish breast milk. Reprinted from EEA 2003. Another class POP-like substances that has been detected in numerous environmental media since the late 1990s are fluorinated organic compounds the most commonly measured of which is perfluorooctanesulfonate (PFOS). In recent years PFOS has been measured in human blood and liver with increasing frequency. In an extensive survey of US blood, Olsen et al. (2003) analyzed 645 samples from blood donors in a number of US cities. Concentrations of PFOS in serum ranged from <4.3 ug/L to 1656 ug/L with a mean of 34.9 ug/L. Serum PFOS levels between different cities were very similar and authors concluded that the average concentration in non-occupationally exposed adults ranged from 30 to 40 ug/L and that 95% of the US population would have levels below 100 ug/L. This is consistent with the results of Kannan et al. (2004) who measured a median serum PFOS level of 31.2 ug/L in US blood donors. Kannan et al. (2004) also measured PFOS in serum from three European countries including Poland, Italy and Belgium. Levels of PFOS in serum from Poland were similar to levels in the US with mean levels in females and males of 33.3 ug/L and 55.4 ug/L respectively. Levels for men and women in Belgium were lower at 11.1 ug/L and 16.8 ug/L respectively and lower still for Italian men and women at 4.3 ug/L and 4.4 ug/L respectively. It is apparent that levels of PFOS exposure vary from country to country, however, it is not yet clear what drives these differences. The toxicological relevance of PFOS at the levels seen in human blood is also not very well understood. The levels of PFOS that have been measured in human blood are significantly higher than the levels of any POP. Short Chain Chlorinated Paraffins (SCCPs) were considered in the report by WHO (2004). These compounds have been measured in an increasing number of wildlife species including Arctic wildlife. The primary exposure route for humans is expected to be dietary, with the consumption of animal products being most important, however, to date there is very limited data on human exposure and levels in human tissues. Based on

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the best available toxicological data, the WHO recommends that daily intake of SCCPs not exceed 11 ug/kg bw/day. An EU risk assessment concluded that there was no significant risk from environmental exposure to SCCPs, however, it was noted that the worst case estimates for human exposure exceeded the WHO recommended daily intake. Polychlorinated naphthalenes (PCNs) have also been measured in numerous wildlife species throughout the UNECE region. Despite it’s ubiquitous presence in the environment, there have few estimates of human exposure. In what is reportedly the first study of it’s kind, Domingo et al. (2003) estimated dietary exposure to PCNs among the Catalan population of Spain. The authors measured PCNs in a broad range of foods and found levels of ∑PCNs ranging from 0.4-447 pg/g ww, where the lowest levels were measured in fruit and the highest in oils and fats. Mean daily intake rates were calculated for different age brackets and ranged from 0.54 ng/kg bw/day for seniors to 1.64 ng/kg bw/day for children. While the contribution to overall dioxin-like toxicity from the PCN exposure was not calculated, the authors noted another study where PCNs contributed between 2% and 57% of the overall TEQ in Great Lakes fish.

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8. Conclusions

• Based on estimated levels of emissions, model simulations indicate that atmospheric concentrations and deposition of POPs should have decreased substantially over the past ten years and will continue to decrease as long as there are no new emissions.

• Atmospheric levels of POPs, measured by monitoring stations throughout the UNECE region seem to reflect the model simulations, in that levels are decreasing for most POPs. Levels of POPs in Arctic air are also showing sings of decrease though at slower rates than in temperate regions.

• Concentrations of POPs in freshwater fish have resulted in high levels of exposure in fish eating mammals and birds, exceeding thresholds for toxicity. It is suspected that past population declines in mink and otter were a direct result of this contamination, primarily due to DDT and PCBs. As levels of POPs in freshwater ecosystems decrease, it appears that mink and otter populations have begun to recover. This has not been the case, however, it more polluted areas such as the eastern Baltic.

• Marine ecosystems are the most effective at biomagnifying POPs. As a result, predatory marine mammals can accumulate levels of POPs that can reach over 100 000 ng/g lipid. While direct evidence of adverse effects is scant, there is strong evidence that seal populations in areas of elevated exposure, e.g. the Baltic, have suffered immunological and reproductive effects that have been associated in past population declines. Most marine mammal species contain levels of POPs, PCBs in particular, that exceed toxicological benchmarks for hepatic and neurological effects, and in some cases immune effects. Such effects have been demonstrated in polar bear. These conditions presently exist despite evidence of resent declines in the levels of POPs in marine mammals.

• Seabirds and birds of prey can have levels of POPs that are similar to those measured in predatory marine mammals. During times of peak exposure, during the 1970s and 1980s, many raptor species were nearly driven to extinction due to reproductive effects arising from DDE pollution. The declining environmental levels of DDE and other POPs have reversed this trend and most raptor populations appear to be recovering. Current exposure levels, however, can still exceed thresholds for reproductive effects.

• The general human population continues to be exposed to POPs as a result of long-range atmospheric transport. The primary source of POPs to humans is through the consumption of animal based foods. The four most abundant POPs in human tissues are PCBs, DDTs, HCBs and HCHs. Polychlorinated dibenzo-p-dioxins and dibenzo furans are also ubiquitous in human tissues and together with dioxin like PCBs can contribute to levels of dioxin like toxicity that regularly exceed WHO allowable daily intake (ADI) and tolerable weekly intake (TWI). Despite decreasing temporal trends in environmental levels and human exposure to POPs, estimated daily intake of PCBs still exceed reference levels set by the ASTDR and USEPA. Newborns, however, are clearly the most at risk having been exposed to POPs in-utero and then through breast milk at levels that can

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exceed adult exposure levels by an order of magnitude. A large proportion of women have blood PCB levels that exceed Health Canada’s level of concern and a significant proportion of Inuit women have levels that exceed the more serious action level.

• Among the general population, levels of exposure to POPs such as DDT, HCB, and HCHs are well below existing guidelines as a result of declining levels in the environment. Among highly exposed populations, however, such as indigenous Arctic people who consume marine mammals, levels of these POPs can still exceed existing exposure guidelines.

• As a direct result of consuming marine mammals, Inuit are still exposed to levels of chlordane and toxaphene that exceed guidelines established by Health Canada, ASTDR and USEPA. Among the general population, however, exposure to these POPs is relatively low.

• A number of POP like substances have recently been measured in remote environments for which local source do not exist. These include brominated flame retardants (PBDEs and HBCD), fluorinated organic compounds (PFOS and related compounds), chlorinated industrial chemicals (SCCPs and PCNs) and current use pesticides (endosulfan). Increasing temporal trends with doubling times of 4-5 years have been reported from some PBDE congeners and concentrations of PFOS have been measured in some species at levels higher than any POP. PBDEs and PFOS are also being measured in human tissues with increasing regularity and in the case of PBDEs, levels are increasing, particularly in North America.

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