log K V.P. K - WSU FEQLfeql.wsu.edu/esrp532/ESRP532Lecture19_110804.pdfC. BETX has been problematic at LUST sites (Leaking Underground Storage Tanks), especially at local gas stations

ES/RP 532 Applied Environmental Toxicology Page 1 of 19

ESRP532 Lecture 19.doc Fall 2004

November 8, 2004

Lecture 19 Volatile Organic Compounds (VOCs) (BTEX; Chlorinated Solvents; MTBE)

I. General Comments About SourcesA. Obviously, the groups of compounds targeted for this lecture is too varied and too

numerous to cover adequately in one lecture. Thus, I will highlight some of the compoundsthat have been comparatively more studied because of known health effects (usually fromhigh dose animal testing).

B. These groups of compounds in general arise from fuel use (for ex., gasoline--BETX,benzene, ethylbenzene, toluene, xylene; a.k.a. monoaromatic hydrocarbons [HCs]),industrial precursor for synthesis of polymers (for ex., styrene, dibutyl phthalates andcongeners [to be discussed in the lecture on plasticizers], some volatile organohalogens),from water treatment processes and subsequent environmental reactions (some of thehalogenated VOCs), from natural sources (for ex. organohalogens including brominatedcompounds like methyl bromide).

C. BETX has been problematic at LUST sites (Leaking Underground Storage Tanks),especially at local gas stations.

D. A major source of VOCs in water is wastewater effluents and runoff from streets.E. One unexpected source was discovered in the early 70’s; surface water undergoing

chlorination and being held unprotected from sunlight was found to contain numerous oneand two carbon halocarbons--thus photocatalytic synthesis in the presence of humicmaterials can also produce halogenated VOCs. These groups of chemicals are calledtrihalomethanes (THMs) because most of them have a total of three halogens as eitherchlorine or bromine.

F. In an attempt to reduce air pollution in urban areas, specific localities in the U.S. wererequired by the EPA to oxygenate gasoline supplies.1. MTBE (methyl tertiary butyl ether) was the most widely used fuel oxygenate.2. Now we know that MTBE has become a ubiquitous water contaminant in areas where it

was used.G. Biosynthesis and emission, especially brominated compounds from oceans. VOCs such as

isoprene may also be emitted from vegetation. These groups are generally called biogenicVOCs.

II. Environmental ChemistryA. Physicochemical Properties

1. In the table below, you will note that most of the compounds of concern have low Koc’ sand are quite volatile, as measured by both V.P. and KH.

Compound WS(mg/L)

log Kow log Koc V.P.(mm Hg)

KH(atm.m3/mol)

benzene 1800 1.6 - 2.1 1.7 -2.0 76 - 118 5.5 x 10-3

ethylbenzene 161 3.15 2.2 9.53 8.4x10-3

toluene 490-515 2.7 - 2.8 2.1 22-40 6.7x10-3

xylene 152-200 3.0 - 3.2 2.1 -3.2 10 5 -7 x 10-3

hexachlorobenzene 0.0062 5.31 4-5 1.9x10-5 1.3x10-3

styrene 310 2.95 2.4-2.7 6.6 2.81x10-3

cresols (N) 23-30 1.95 1.3-1.7 0.13-0.31 8.7-16 x10-7

dibutyl phthalate 11.2 4.72 2.2-3.8 1.4x10-5 4.6x10-7

methyl bromide 17,500 1.2 2.1 1633 6.2x10-3

methyl chloride 6,480 0.9 4310 2.4x10-2



chloroform 8,000-9,300 1.9 - 2.0 1.6 160-245 3- 7.2 x10-3

carbon tetrachloride 800-1,160 2.8 2.4-2.6 113 2.4- 3 x10-2

formaldehyde (N) 550,000 0.4 3883 3.3x10-7

trichloroethylene 1,100-1,470 2.3 - 3.3 1.8-2.1 58 -94 9-11 x 10-3

tetrachloroethylene 150 2.6 -2.9 2.3 -2.6 20 1.5x10-2

vinyl chloride 2763 1.4 <1 2660 1.1x10-2

acrolein 208,000 -0.1 1.4 265 4.4x10-6

Benzene ethylbenzene o-xylenetoluene m-xylene p-xylene

Cl

Cl

Cl

Cl

Cl

Cl

hexachlorobenzene styrene

OH

o-cresol

HO

m-cresol

OH

p-cresol

O

O

O

O

dibutyl phthalate

H3C Br

methyl bromide

H3C Cl

methylchloride

CH

Cl

Cl

Cl

chloroform

C

Cl

Cl Cl

Cl

carbon tetrachloride

H2C O

formaldehyde

CH

Cl

Cl

Br

bromodichloromethane

CH

Cl

Br

Br

dibromochloromethane

CH

Br

Br

Br

bromoform

Trihalomethanes (THMs)

Cl

Cl

Cl

trichloroethylene Cl

Cl

Cl

Cl

tetrachloroethylene

O

acrolein

Cl

vinyl chloride

B. Fate of VOCs in water1. General Observations: (based on Wakeham, S. G. et al. 1983. Distributions and fate of

volatile organic compounds in Narragansett Bay, Rhode Island. Can. J. Fish. Aquat.Sci. 40:304-321).



a. VOCs measured in water columns along a north-south transect in Narragansett Bay,RI.1. Gas chromatograms of water extracts indicated several hundred different VOCs

in the bay.

b. Volatilization apparently is a major removal process for all VOCs. Calculationssuggested water column residence times of 150-300 h with respect to volatilization.

c. Biodegradation was important for aromatic hydrocarbons (HCs) during summer;HCs degraded in a few days;

d. Sorption onto particulate matter and eventual sedimentation was minor, except forthe higher molecular weight alkanes.

e. Observations about tetrachloroethylene (also known as perchloroethylene or Perc);1. Concentrations decreased significantly along transect (i.e., gradient evident)

a. Note the relatively higher concentrations (in ppt or ng/L) at the Fields Point(OT; F) sampling sites in the map below; these areas are outfalls for sewagetreatment facilities that discharge combined municipal, industrial, and stormwater effluents into the Providence River and upper Narragansett Bay.

b. Note that the sampling point (P) in the Providence River is just upstream ofthe sewage plant outfalls.

c. Absolute concentrations in the lower Bay were greater in winter thansummer, but levels in the upper bay tended to be a little less variable.



d. Note that in the shallower part of the bay (where depths are 4 m or less),significant concentrations of VOCs were found near the bottom of the watercolumn. Thus, the water may be fairly well mixed.

f. Observations about toluene1. Concentrations tend to be higher in winter than summer2. Concentration gradient tended to be weak, suggesting either uniform inputs

around the bay or rapid removal near the sources so as to leave a uniformdistribution

3. Aromatic hydrocarbons could have multiple input sources all around the bay; forexample, runoff of petroleum derivatives (fuel, gasoline, oil, etc.) used intransportation or at homes; perhaps spills

Perc and toluene concentration in Narragansett Bay. All residue concentrations expressed as ppt (ng/L)



2. Wakeham et al (1983) conducted mesocosm experiments to determine the fate andpersistence of volatile organic compounds in coastal seawater. Environ. Sci. Technol.17:611617.a. Experimental setup:

1. Mesocosms (5.5 m high x 1.8 m diameter) were spiked with VOCs;2. Mesocosms were outside; sampled different times of year;3. One set of tanks was sterilized with HgCl2.

b. Results:1. Volatilization appeared to be the major process removing aromatic HCs,

chlorinated C2-HC’s, and chlorinated aromatic hydrocarbons during all seasons,with biodegradation also important for aromatic hydrocarbons in summer.

2. Aliphatic hydrocarbons were quickly sorbed onto particulate matter and thusremoved from the volatile pool; biodegradation also affected alkanes.

Half-lives of Selected VOCs from the Wakeham Mesocosm Exp’t. The two summer experimentsrepresent sampling at two different times in summer, so the values for half-life are differentCompound Winter T1/2 Summer T1/2 T1/2, summer, (Sterile) T1/2, summer, (Natural)benzene 13 3.1 6.9toluene 13 1.5 7.9naphthalene 12 nd 11.3 0.8tetrachloroethylene 12 14 12.1 12.0dodecane 3.6 0.7 1.8 0.94



C. Fate in Air1. The Clean Air Act has tightened the regulations regarding ambient concentrations of a

host of “hazardous air pollutants” (HAPs); of course, VOCs make a large contributionto total HAPs.

2. EPA ambient monitoring programs have yielded information on concentrations (medianand ranges in µg/m3) as well as expected atmospheric lifetimes (lifetime measurementsshown as days;a. Categorized as <1 day, 1-5 days, and >5 days).

1. See table below (adopted from Kelly et al., 1994, Concentrations andtransformation of hazardous air pollutants, Environ. Sci. Technol. 28(8):378-387).

b. Primary reaction influencing lifetime was interaction with OH radical.

Summaries of atmospheric concentrations and atmospheric lifetimes of selected VOCsAmbient Concentration Measurements

Compound# of LocationsSampled # of Samples

Median or range(µg/m3)

Lifetime in Air(days)

benzene >140 >10,000 5.1 >5ethylbenzene 93 8723 1.1 <1toluene 131 9373 8.6 1-5o-xylene 104 8542 2.2 <1m-xylene 98 8431 4.2 <1p-xylene 102 3597 4.3 <1 to 1-5hexachlorobenzene 21 6117 0.6 <1o-cresol 3 10 1.5 <1m-cresol 2 3 nd <1p-cresol 11 62 0.20 <1dibutylphthalate 3 >13 0.5-6.0 ng/m <1methyl bromide 48 1081 nd >5methyl chloride 37 1434 1.3 >5chloroform 117 4368 0.2 >5carbon tetrachloride 131 5739 0.8 >5formaldehyde 58 1358 3.3 1-5trichloroethylene 124 4267 0.4 >5tetrachloroethylene 133 4893 1.7 >5vinyl chloride 66 1864 nd <1 to 1-5acrolein 2 12 nd <1nd = not detected

D. Fate in Soil1. Volatilization from soil is directly dependent on temperature and humidity (Shonnard

& Bell. 1993. ES&T 27:2909-2913.a. Note in the results taken from Shonnard & Bell’s paper, sinusoidal fluctuations in

soil temperature cause sinusoidal variations in volatilization flux of benzene;1. Beware that the x-axis is the reciprocal square root of time;



Benzene Flux(mg/cm 2/min)

Temperature

Elapsed Time in Experiment

1/time

6

2

20

26

oC

b. Note that when the relative humidity in a soil-column dropped to near zero, flux alsodropped off (note the break in the flux curve between points 1 and 2; remember thatin the upper graph, time is the square root of the reciprocal)

2. BETX components are biodegradable under both aerobic and anaerobic conditions;microbial cultures have been isolated which can degrade the compounds; major pathwayis via oxidative enzyme system (a.k.a. toluene dioxygenase)



OH

OH COOHCOOH

Benzene Catechol cis, cis-Muconic acid

COOHCOOHO

beta-Ketoadipic Acid

O2

CHOCOOH

OH2-hydroxy-cis,cis-Muconic Semialdehyde

O2

acetaldehyde + pyruvic acid succinic acid + acetyl-CoA

3. Leaching will occur because of the solubility of the compounds; if there is a spill or aleak where large concentrations of compounds are present, soil water (and thusgroundwater) can easily be contaminated.

III. Toxicology (mainly concentrating on human exposures and effects of BENZENE as a knownhazard)A. Toxic Effects

1. The major and most hazardous effect of benzene is probably its known carcinogenicity(there seems to be sufficient human evidence); the site of action seems to be the bonemarrow, producing acute mylogenous leukemia (ALM) or the adult form of acuteleukemia.

2. Another effect of benzene is the potential to cause multiple myeloma (tumor of bonemarrow plasma cells, which are the antibody-producing cells derived fromlymphocytes).

3. A non-neoplastic effect is aplastic anemia; benzene affects the formation of red andwhite blood cells and platelets

4. At levels of 100 ppm and significantly above, benzene can adversely affect the centralnervous system (drowsiness, lightheadedness, headache, delirium, vertigo, and narcosisleading to loss of consciousness).

B. Metabolism & Toxicodynamics (Mammalian)1. 43% of administered benzene dose was expired unmetabolized;2. 1.5% exhaled as CO2;3. 35% recovered as urinary metabolites;

a. 23% phenolb. 4.8% hydroquinonec. 2.2% catechold. 1-2% trans,trans-muconic acid



4. Metabolism to phenol and subsequent conjugations are detoxifications;5. Metabolism of phenol to hydroquinone (and to p-benzoquinone) and of benzene to

muconic acid are two pathways that are currently thought to lead to the formation oftoxic metabolites.a. Muconaldehyde causes bone marrow depression in miceb. Benzoquinone is known to form DNA adducts

O

O

C CHOOC

H

C CCOOH

H

trans, trans-Muconic Acid

OH OH

OH

OHOH

O

O

Phenol Hydroquinone

Glucuronide + Sulfate Conjugates

+

Catechol

p-Benzoquinone

Benzene

Oxepin

Benzene oxide

S N Acetyl Cysteine

C. A recent report suggests that benzene toxicity may be regulated by AhR signaling (Yoon etal. 2002; Aryl hydrocarbon receptor mediates benzene-induced hematotoxicity.Toxicological Sciences 70:150-156.)1. This hypothesis stemmed from an experiment in which AhR knock-out mice were not

affected by benzene (300 ppm inhalational exposure; hematotoxicity as the toxicologicalendpoint); AhR wildtype mice were adversely affected.

2. Metabolites of benzene (phenol and hydroquinone) given to AhR knock-out mice,however, could cause characteristic physiological affects.

D. Risk Characterization1. Estimated risk of 8 in 1 million for benzene-induced leukemia associated with breathing

1 µg/m3 (~0.4 ppb) of benzene for 70 years.2. For drinking water, the level of benzene responsible for a one in 1 million lifetime risk

has been calculated by EPA to be 0.66 ppb.E. Human Exposure to Benzene (and other VOCs)--a case of contaminants everywhere!!!

1. Chan et al. 1991. Driver exposure to volatile organic compounds, CO, ozone, and NO2,under different driving conditions. ES&T 25:964-972.

Median In-Vehicle Concentrations of Seven Target Aromatic VOCs Measured at Urban and InterstateRoutes for Each Driving Period (concentrations as µg/m3)

Urban InterstateMorning Evening Morning Evening

Benzene 11.6 15.9 10.8 9.1



Toluene 19.0 75.8 38.5 30.7Ethylbenzene 9.5 13.9 7.4 6.0m/p-Xylene 33.3 46.0 25.7 20.6o-Xylene 12.8 17.1 9.5 7.81,3,5-trimethylbenzene 5.0 7.1 3.7 3.51,2,4-trimethylbenzene 17.3 24.1 13.0 11.0

Comparisons of in-vehicle concentrations of CO and selected VOCs between three ventilation conditions(Raleigh, NC, 1988; Chan et al. 1991)



Comparison of VOC measurements in in-vehicle, car exterior, sidewalk, and fixed site for selected VOCs((Raleigh, NC, 1988; Chan et al. 1991)

2. McKone, T. E. 1987. Human exposure to volatile organic compounds in householdtap water: the indoor inhalation pathway. ES&T 21:1194-1201.a. Note that chloroform has been a concern because of studies during the 1970’s that

showed it was a liver carcinogen in mice. Chloroform (CHCl3) is one type ofdisinfection byproduct produced by chlorination of water and subsequent exposureto sunlight. These types of disinfection byproducts are called trihalomethanes(THMs). Other important species include bromodichloromethane (CHCl2Br),dibromochloromethane (CHClBr2), and bromoform (CHBr3).1. However, further biochemically based mechanistic studies showed that at high

doses it caused hepatic cellular toxicity, which was accompanied by cellularproliferation. (Larson et al. 1994. Induced cytotoxicity and cell proliferation inthe hepatocarcinogenicity of chloroform in female BC3F1 mice: comparison ofadministration by gavage in corn oil vs. ad libitum in drinking water.Fundamental and Applied Toxicology 22:90-102)a. Thus, chloroform at normal environmental concentrations should present a

very small risk of hepatocarcinogenicityb. Indeed, recently for the first time, the EPA proposed to consider a “non-

zero” water standard for chloroform on the basis that it was a thresholdcarcinogen! However, environmental advocacy groups cried foul, and theEPA seems to have backed off its “courageous” stand.



b. Other VOCs have also been found in potable water; for example trichloroethylene(TCE), which is used as a degreasing and cleaning agent by industry and drycleaners.1. TCE has been deemed carcinogenic by the EPA, although genotoxicity studies

are equivocal (some are positive, some are negative); similar results have beenobserved in carcinogenicity assays (Fan, A. M., 1988, Trichloroethylene: watercontamination and health risk assessment. Reviews of Environ. Contam. &Toxicol. 101:56-92.)a. The safety criterion for TCE in water is 5 ppb; in urban areas of California, a

number of wells have been reported to have concentrations greater than 5ppb.

b. The main concern, however, is with worker exposure.c. McKone has modeled the concentration of VOCs in the air of households (in

general) as well as specifically in the shower. Note that in McKone’s model, heassumed a 1 mg/L concentration of each VOC.

Average Air Concentrations Calculated for VOCs in Each of Three Household Compartments Using a TapWater Concentration of 1 mg/L. (The concentrations shown are in µg/L).

Shower Air Bathroom Air Household Air 1 Household Air 2Carbon tetrachloride 18 3.6 0.12 0.024Chloroform 20 3.8 0.12 0.026DBCP 93 1.8 0.80 0.020EDB 19 3.8 0.12 0.025PCE (Perc)(=tetrachloroethylene)

17 3.4 0.11 0.023

TCE(trichloroethylene)

18 3.5 0.11 0.024

For the shower, the period form 7 am to 8 am is modeled. For the bathroom, the period 7 am to 9 am ismodeled. For the household air 1, the period 7 am to 11 pm is modeled. For household air 2, theperiod 11 pm to 7 am is modeled.

d. So what does it mean?1. For TCE, the EPA and National Academy of Sciences (NAS) have set a lifetime

exposure water criteria for no more than a 1 x 10- 6 risk of excess cancer at 2.8and 4.5 ppb, respectively.

2. Potable water should not be normally be contaminated with TCE at levels higherthan the standards; for example, in sampling programs conducted in California,median levels were <2 ppb. However, some wells were very high andapproached 100 ppb.

3. Fan (1988) has presented a calculation of short term exposure (via showering ordermal and inhalation and drinking) to TCE contaminated water;a. A short term risk assessment (say for 3 months) is valuable because if a

water supply is unacceptably contaminated (for example because of aleaking underground tank or spill), than the water could be treated or analternative supply used for a short time; meanwhile people may have beenusing the water for a short while before the contamination was discovered.

b. Fan calculated that exposure to water with TCE at 3 ppm for 3 months (viashowering and bathing route), should not cause excess cancer at a risk of 1 x10-6.

c. The level of exposure considered not to cause any adverse health effects andprovide a margin of safety of 1000-fold was 0.1 mg/kg/day;



1. Note that the exposures calculated and presented by Fan based on watercontaining 3 ppm TCE are generally lower than the health standard(some are a little above).

TCE Occurrences from Random and Nonrandom Sample Sites Serving Large (>10,000 persons) andSmall (<10,000 persons) Ground Water Systems in an EPA (1984) National Survey

Type ofSystem

Type ofSamples

No. ofSamples

OccurrencesNumber

Occurrences%

Median(ppb)

Maximum(ppb)

Large Random 186 21 11.4 1.0 78Small Random 280 9 3.2 0.88 40Large Nonrandom 158 38 24.1 1.5 130Small Nonrandom 321 23 7.2 1.2 29

Comparative Daily Doses (mg/kg bw) of TCE Received by Individuals of Various Body Weights UnderVarious Exposure Conditions to Water Containing 3 ppm TCE

Body Weight70 kg 22 kg 10 kg

Drinking (oral) 0.086 0.204 0.3Showering Dermal Dermal + Inhalation Inhalation

0.0640.0830.099

0.10.129

Bathing (3 mg/L) Dermal (15 min) Dermal (5 min)

0.1540.051

0.240.08 0.08

F. Recent Concerns—Associations with adverse reproductive outcomes (e.g., spontaneousabortion) due to trihalomethanes1. Trihalomethanes (THMs) are disinfection byproducts produced from the chlorination of

drinking water, interaction of the chlorine with natural organic matter, and subsequentphotocatalytic synthesis of small molecular weight chlorine or bromine containingvolatile and semi-volatile hydrocarbons.

2. THMs include compounds like chloroform, bromoform, bromodichloromethane, andchlorodibromomethane.

3. The EPA defined regulatory limit for THMs in drinking water is 100 ppb (100 µg/L).4. Many water utilities have switched to chlorine dioxide or ozone as a disinfectant. Both

produce substantially less THMs (by up to three orders of magnitude according toRichardson (1994, Today’s Chemist at Work, vol. 3 (3), p. 29-32). However, neitherdisinfectant is stable and so chlorine or chloramine must be added to the water before itis sent through the distribution system.

5. During 1998, THMs in drinking water were in the news (once again) because ofstudies published by the CA Dept. of Health Services (CDH) (Swan et al., 1998,Epidemiology 9:126-133; Waller et al., 1998, Epidemiology 9:134-140)a. CDH researchers studied spontaneous abortions in CA women from three regions

having different water sources (I = mix of ground water and surface water; II =primarily surface water; III = primarily ground water.

b. Within each region, respondents to a survey (5,342 useable subjects) weresegregated by consumption of bottled water vs. tap water and number of glassesdrunk each day.

c. The study was prospective, so pregnancy outcomes could be followed postinterviews.



d. The study results showed the following:

Number of Women, Percentages within Each Region, and Percent with Spontaneous Abortion (SAB) inCalifornia (Swan et al. 1998)

Region I Region II Region IIIVariable N % %

SABN % %

SABN % %

SABConsumption of Bottled Water0 548 33.3 11.5 781 44.4 10.9 775 44.5 9.80.5-5.5 826 50.2 8.0 746 42.5 9.0 726 41.7 10.1≥6 271 16.5 8.1 230 13.1 10.9 239 13.7 9.2≥6 & no coldtapwater

184 11.2 6.5 149 8.5 12.8 137 7.9 11.0

Consumption of Total Tapwater0 565 34.3 8.7 457 26.0 9.4 441 25.3 10.40.5-5.5 879 53.4 8.5 1008 57.4 10.3 1000 57.4 10.0≥6 200 12.2 13.0 291 16.6 10.3 300 17.2 8.3≥6 & nobottled water

148 9.0 14.9 241 13.7 9.5 234 13.4 8.1

Consumption of Cold Tapwater0 771 46.8 8.4 619 35.2 9.7 535 30.7 11.40.5-5.5 753 45.7 8.9 955 54.4 10.4 981 56.4 9.5≥6 120 7.3 15.0 182 10.4 9.9 225 12.9 7.6≥6; no bottledwater

95 5.8 17.9 162 9.2 9.9 187 10.7 8.0

Spontaneous Abortion Rates and Odds Ratios by Water Type and Amount in Region I (Note that inRegion II and Region III, there was no trend in SAB with water source)Bottled Water Unadjusted Odds Ratio

(95% CI)_Adjusted Odds Ratio(95% CI)

0.5 – 5.5 vs. 0 0.66 (0.46-0.95) 0.68 (0.47-0.99)≥6 vs. 0 0.68 (0.41-1.13) 0.60 (0.35-1.03)≥6 and no cold tap vs 0 and≥6 cold tapTotal Tapwater0.5-5.5 vs. 0 0.98 (0.68-1.43) 1.03 (0.70-1.52)≥6 vs. 0 1.57 (0.95-2.61) 1.66 (0.99-2.78)≥6 and no cold tap vs 0 and≥6 cold tap

2.50 (1.11-5.64) 3.51 (1.43-8.63)

Cold Tapwater0.5-5.5 vs. 0 1.06 (0.74-1.52) 1.10 (0.76-1.59)≥6 vs. 0 1.92 (1.09-3.36) 2.17 (1.22-3.87)≥6 and no bottled vs 0 and≥6 bottled

3.12 (1.42-6.86) 4.58 (1.97-10.64)

Odds ratio adjusted for age, prior spontaneous abortion, race, gestational age at interview, showering,weight.

e. The abstract of the Swan et al. paper (tables illustrated above) concludes that thestudy confirms the association between cold tapwater and spontaneous abortion, that



was first seen in Region I in 1980. “If causal, the agent(s) is not ubiquitous but islikely to have been present in Region I for some time.”1. Note: Cold water was included as a separate variable because hypothetically,

letting the water sit should allow for volatilization of THMs.f. Interestingly, in the discussion, Swan et al. state:

1. “Our prior studies suggested that the relation between spontaneous abortionand tapwater was independent of chlorination by-products, since the strongestassociations were seen in the two studies conducted in areas served only byunchlorinated groundwater.” (Referring to studies published in 1992).

2. Swan et al also state in their discussion: “Nevertheless, we believe that theassociations with cold tapwater and bottled water presented here, which arespecific to Region I, cannot be explained by exposure to chlorination by-products, because the association is seen in the absence of high levels of thesechemicals.

3. The chemical concentrations (i.e., of the four main THMs) were analyzed in thecompanion paper by Waller et al. 1998. From that study they concluded that therisk was associated with specific chlorination by-products, namely ,bromodichloromethane.

% SAB and O.R. for SAB among 5144 Women Exposed to Varying Levels of Total THMs in ResidentialDrinking Water During The First Trimester of Pregnancy

Total THMs(µg/L)

Cold TapwaterGlasses/Day

% SAB N UnadjustedOdds Ratio(95% C.I.)

AdjustedOdds Ratio(95% C.I.)

<75 N/A 9.1 3,672 1.0 1.0≥75 N/A 11.4 950 1.3 (1.0-1.6) 1.2 (1.0-1.5)<75 <5 9.2 3,105 1.0 1.0≥75 <5 10.8 828 1.2 (0.9-1.5) 1.1 (0.9-1.4)<75 ≥5 8.5 565 1.0 1.0≥75 ≥5 15.7 121 2.0 (1.1-3.6) 2.0 (1.1-3.6)Low Personal THMexposure

N/A 4,988 1.0 1.0

High Personal THMExposure

N/A 121 1.8 (1.1-2.9) 1.8 (1.1-3.0)

Region I Low <75 µg/L <5 8.9 1,614 1.0 1.0 High (≥75 µg/L) ≥5 24.1 29 3.2 (1.4-7.7) 4.3 (1.8-10.6)Region II Low <75 µg/L <5 9.7 1,656 1.0 1.0 High (≥75 µg/L) ≥5 14.0 86 1.5 (0.8-2.8) 1.5 (0.8-2.9)Region III Low <75 µg/L <5 9.8 1,718 High (≥75 µg/L) ≥5 0.0 6 N/A N/A

O.R. for SAB Associated with High Personal Exposure to Individual THMsTHM All Regions All Regions * Region I Region II/IIIChloroform 0.9 (0.5-1.6) 0.6 (0.3-1.2) 1.4 (0.5-4.1) 0.8 (0.4-1.5)Bromoform 1.0 (0.5-2.0) 0.7 (0.2-2.1) 1.3 (0.4-4.5) 1.0 (0.5-2.1)Bromodichloromethane 2.0 (1.2-3.5) 3.0 (1.4-6.6) 2.1 (0.9-4.5) 2.3 (1.1-4.9)Chlorodibromomethane 1.3 (0.7-2.4) 0.8 (0.2-2.8) 1.3 (0.4-3.7) 1.4 (0.6-3.2)



* Adjusted for all covariates (gestational age at interview, maternal age at interview, cigarette smoking,history of pregnancy loss, race, employment during pregnancy plus all four individual THMs as covariatessimultaneously.

g. Note that a 1995 study by Savitz et al. (Environ. Health Perspectives 103:592-596)found no association between level of water intake, THMs, and spontaneousabortion.

h. A paper by Reif et al. (1996, Environ. Health Perspectives 104:1056-1061) madethis statement in discussing the reproductive and developmental effects ofdisinfection by-products in drinking water:1. “The epidemiologic evidence supporting associations between exposure to

water disinfection by-products and adverse pregnancy outcomes is sparse, andpositive findings should be interpreted cautiously.”

6. One pathway of loss not taken into consideration is the possibility of volatilization ofTHMs upon allowing the water to stand. Research (Batterman et al. 2000, ES&T,34:4418-4424) has shown that volatilization losses approached 75% when water wasboiled for brief period of time and reached 90% when boiled water was poured andserved. For typical adults, who drink nearly half of their water as hot beverages,volatilization will reduce ingestion of THMs by a factor of 2.

Volatilization rate constants for total THM from water at different temperatures and water columnheights (Batterman et al. 2000)

Container Water ColumnHeight (cm)

Temperature(°C )

Rate Constantk (h-1)

Tall glass 14.5 Average 4 –16 0.081Tall glass 14.5 25 0.048Tall glass 14.5 30 0.154Tall glass—half full 6.2 25 0.065Tall glass—half full 6.2 30 0.206Wide-mouth 8.5 25 0.135Wide-mouth 8.5 30 0.391Coffee mug 6.2 Average 40 – 100 1.5

IV. The Saga of MTBE (methyl tertiary-butyl ether): Creating an EnvironmentalContaminant While Trying to Fix Another Problem (Source: Hogue, 2000, Chemical &Engineering News 78[13]:6).

CH3 O C CH3

CH3

CH3A. MTBE was originally added to gasoline as an octane enhancer compound to replace alkyl

lead compounds.B. Under the 1990 mandate of the Clean Air Act to reduce ozone and thus smog formation,

MTBE was added as a fuel oxygenate, supposedly to make gasoline burn cleaner.C. Until recently, only reformulated gasoline (i.e., with MTBE added to conventional gasoline)

could be sold in ~12 urban areas with smog problems. A number of states and citiesvoluntarily chose to use reformulated gasoline.1. About 87% of reformulated gasoline uses MTBE as an oxygenate.

a. MTBE is added to a concentration of up to 15% by weight, which creates a fuel withabout 2.7% oxygen by weight (Hanson 1999, Chem. Eng. News 77(42):49).

2. Thus, the annual use of MTBE was ~4.5 billion gallons.



D. Nearly from the beginning of its use, MTBE was pegged with problems.1. A number of consumers complained about ill health, including dizziness, nausea,

irritated nose and throat, coughing, disorientation and headaches.a. However, controlled exposures in the lab did not cause an increase in putative

symptoms.E. By 1996, however, MTBE was being found in drinking-water supplies because of leaking

underground gasoline pipelines and storage tanks.1. As little as 15 ppb of MTBE can be tasted or smelled in water.2. The USGS conducted a survey of ground water contamination by MTBE around the

U.S. (Squillace et al. 1996, Preliminary assessment of the occurrence and possiblesources of MTBE in groundwater in the United States, 1993-1994. Environ. Sci.Technol. 30:1721-30.).a. Note that about 109 million people live in areas where oxygenated fuels were

mandated for use.b. About 27% of urban ground water samples had detections of MTBE at 0.2 ppb or

above.1. About 1.3% of agricultural wells had MTBE detections.

Concentration of MTBE in shallow groundwater from urban land use study areas, 1993-1994(Squillace et al. 1996)

F. MTBE has generally not been found in ground water with other components of BTEX.1. Nevertheless, research suggests that MTBE is more likely associated with gas stations

using oxygenated fuels than using “conventional” fuel. (Lince et al. 2001. Effects of



gasoline formulation on methyl tert-butyl ether (MtBE) contamination in private wellsnear gasoline stations. Environ. Sci. Technol. 35:1050-1053.)

Well Classification(Independent variableclassified by fueltype)

Numberof Wells

>1 µg/L-19 µg/L ≥20 µg/L -49 µg/L ≥50 µg/L

Combined (wellsrepresenting all gasstations)

74 14 (19%) 5 (7%) 2 (3%)

Conventional gasoline 40 6 (15%) 1 (3%) 1 (3%)

ReformulatedGas/Oxyfuel (MTBE) *

34 8 (24%) 4 (12% 1 (3%)

Control wells (upgradient of gas stations

21 1 (5%) 0 0

* RFG or reformulated gasoline will probably have MTBE (estimates of 84% use) but not all RFGwill necessarily have used MTBE.

G. It is not surprising that MTBE has been found in so many water wells; note itsphysicochemical properties:1. Water solubility: 23.2 – 54.5 g/L2. Log Kow: 0.94 – 1.163. Vapor Pressure: 249 mm Hg4. KH: 5.87 x 10-4 atm-m3/mole

H. MTBE moves in the soil as a conservative tracer (little interaction with substrate).I. MTBE has been found at ppt concentrations in the Sierra Mts., but it is noted for rapid

photodegradation that may reduce the deposition load (Schade, G. W., B. Dreyfus, and A. H.Goldstein. 2002. Atmospheric methyl tertiary butyl ether (MtBE) at a rural mountain site in California.J. Environ. Qual. 31:1088-1094.)1. However, MTBE has been measured in urban and rural precipitation in Germany

(Achten, C. and A. Puttmann W. Kolb. 2001. Methyl tert-butyl ether (MTBE) in urban and ruralprecipitation in Germany. Atmospheric Environment 35:6337-6345.)a. MTBE is detected in precipitation when ambient temperatures are lower than about

10-15°C.b. MTBE is detected in greater amounts in the first precipitation after a dry period than

after a wet period.c. Urban runoff contains MTBE.d. MTBE is detected in urban precipitation more often (86% of samples with detects)

than in rural precipitation (18% of samples with detects)J. An interesting ecotoxicological phenomenon (Cho, E.-A., A. J. Bailer, and J. T. Oris. 2003.

Effect of methyl tert-butyl ether on the bioconcentration and photo induced toxicity of fluoranthene infathead minnow larvae (Pimephales promelas). Environ. Sci. Technol. 37:1306-1310.)1. MTBE is also released directly into lakes from motorized water craft.2. Between 20 and 30% of thee fuel that enters the combustion chamber is released in the

exhaust unburned, and between 3 and 10% of MTBE is released directly into water.3. Watercraft exhaust is considered one of the most important sources of MTBE in

California lakes and reservoirs.a. Residues range from <1 µg/L to a high of 88 µg/L.

1. Use of MTBE in watercraft fuel is now forbidden in the Lake Tahoe Basin.4. Combustion of fuel in gasoline engines produces a complex mixture of PAHs.



a. In the presence of natural or simulated sunlight, PAHs are acute toxic to aquaticorganisms at concentrations that are below the PAH aqueous solubility limits (i.e.,PAHs are phototoxic).

b. Is there any interaction between MTBE and PAHs5. Fathead minnows exposed to 20 µg/L fluoranthene (FA) in the presence (40 µg/L) or

absence of MTBE (Cho et al. 2003)a. Bioconcentration of FA and depuration by fish was monitored

1. Bioconcentration of FA in the presence of MTBE increased up to 2.2 times overexposures in the absence of MTBE.

2. Survivability, when in the presence of artificial sunlight, was decreased by thepresence of MTBE.

K. Whether MTBE is carcinogenic or not is up in the air; nevertheless EPA has essentiallyruled that MTBE is “history” as far as its use in gasoline is concerned.

Documents

log K V.P. K - WSU FEQLfeql.wsu.edu/esrp532/ESRP532Lecture19_110804.pdfC. BETX has been problematic at LUST sites (Leaking Underground Storage Tanks), especially at local gas stations