- 1. 2009Fourth National Report on Human Exposure to
Environmental Chemicals
2. Fourth National Report on Human Exposure toEnvironmental
Chemicals 2009 Department of Health and Human Services Centers for
Disease Control and Prevention 3. ContentsContents Introduction1
Whats New in this Report 2 Whats Different in this Report 3 Data
Sources and Data Analysis4 Interpretation of Report Data: Important
Factors8 Chemical and Toxicological Information9 Acrylamide
11Acrylamide hemoglobin adducts 11Glycidamide hemoglobin adducts12
Cotinine 15Cotinine15 N,N-Diethyl-meta-toluamide
(DEET)19N,N-Diethyl-meta-toluamide (DEET) 19 Disinfection
By-Products (Trihalomethanes)
22Bromodichloromethane22Dibromochloromethane (Chlorodibromomethane)
23Tribromomethane (Bromoform) 24Trichloromethane (Chloroform) 25
Environmental Phenols27Benzophenone-3
(2-Hydroxy-4-methoxybenzophenone)28Bisphenol A
(2,2-bis[4-Hydroxyphenyl] propane)304-tert-Octylphenol (4-[1,1,3,3-
Tetramethylbutyl] phenol) 34Triclosan (2,4,4-
Trichloro-2-hydroxyphenyl ether)38 Fungicides 40Pentachlorophenol
40ortho-Phenylphenol43 Herbicides 46Acetochlor47 Acetochlor
mercapturate48Alachlor50 Alachlor mercapturate51Atrazine53 Atrazine
mercapturate532,4-Dichlorophenoxyacetic Acid57Metolachlor 61
Metolachlor mercapturate 622,4,5-Trichlorophenoxyacetic Acid 64
Insecticides/Pesticides67Carbamate Insecticides67 Carbofuran 68
Carbofuranphenol 68 Propoxur 71Fourth National Report on Human
Exposure to Environmental Chemicals i 4. Contents
2-Isopropoxyphenol72 Organochlorine Pesticides 75 Aldrin and
Dieldrin 77Aldrin 77Dieldrin 79 Chlordane and
Heptachlor81Oxychlordane 81Heptachlor Epoxide 84trans-Nonachlor86
Dichlorodiphenyltrichloroethane (DDT)
89p,p-Dichlorodiphenyltrichloroethane (DDT)
89p,p-Dichlorodiphenyldichloroethene
(DDE)91o,p-Dichlorodiphenyltrichloroethane 93 Endrin97
Hexachlorobenzene100
Hexachlorocyclohexane104beta-Hexachlorocyclohexane104gamma-
Hexachlorocyclohexane (Lindane)106 Mirex109 2,4,5-Trichlorophenol
and 2,4,6-Trichlorophenol112 Organophosphorus Insecticides: Dialkyl
Phosphate Metabolites 117 Diethylphosphate (DEP) 120
Dimethylphosphate (DMP)122 Diethylthiophosphate (DETP)124
Dimethylthiophosphate (DMTP) 126 Diethyldithiophosphate (DEDTP) 128
Dimethyldithiophosphate (DMDTP)130 Organophosphorus Insecticides:
Specific Metabolites134 Chlorpyrifos,
Chlorpyrifos-methyl1353,5,6-Trichloro-2-pyridinol 135
Coumaphos1403-Chloro-7-hydroxy-4-methyl-2H-chromen-2-one/ol 141
Diazinon 1432-Isopropyl-4-methyl-6-hydroxypyrimidine143
Malathion146Malathion dicarboxylic acid 146 Methyl Parathion, Ethyl
Parathion149para-Nitrophenol149 Pirmiphos-methyl
1532-(Diethylamino)-6-methylpyrimidin-4-ol/one 154 Pyrethroid
Pesticides156 Cyfluthrin 1594-Fluoro-3-phenoxybenzoic
acid160iiFourth National Report on Human Exposure to Environmental
Chemicals 5. Contents Cyfluthrin, Cypermethrin, Permethrin
163cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic
acid163trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane
carboxylic acid165 Deltamethrin
168cis-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropane carboxylic
acid 169 Cyhalothrin, Cypermethrin, Deltamethrin, Fenpropathrin,
Permethrin, Tralomethrin 1723-Phenoxybenzoic acid 173 Metals
176Antimony176Arsenic 180 Arsenic, Total 180 Arsenic (V) Acid 182
Arsenobetaine184 Arsenocholine186 Arsenous (III) Acid187
Dimethylarsinic Acid 188 Monomethylarsonic Acid 189 Trimethylarsine
oxide190Barium193Beryllium 196Cadmium
199Cesium205Cobalt208Lead212Mercury
218Molybdenum227Platinum230Thallium233Tungsten236Uranium 239
Perchlorate243Perchlorate 243 Perfluorochemicals 247Perfluorobutane
sulfonic acid (PFBuS) 248Perfluorodecanoic acid
(PFDeA)249Perfluorododecanoic acid (PFDoA)251Perfluoroheptanoic
acid (PFHpA) 251Perfluorohexane sulfonic acid (PFHxS)
252Perfluorononanoic acid (PFNA) 252Perfluorooctanoic acid (PFOA)
253Perfluorooctane acid (PFOS) 253Perfluorooctane sulfonamide
(PFOSA) 2542-(N-Ethyl-perfluorooctane sulfonamido) acetic acid
(Et-PFOSA-AcOH) 254Fourth National Report on Human Exposure to
Environmental Chemicals iii 6. Contents2-(N-Methyl-perfluorooctane
sulfonamido) acetic acid (Me-PFOSA-AcOH) 255Perfluoroundecanoic
acid (PFUA)255 Phthalates258Benzylbutyl Phthalate262 Mono-benzyl
phthalate (MBzP)262Dibutyl Phthalates 265 Mono-isobutyl phthalate
(MiBP)265 Mono-n-butyl phthalate (MnBP) 267Dicyclohexyl Phthalate
270 Mono-cyclohexyl phthalate (MCHP)270Diethyl Phthalate272
Mono-ethyl phthalate (MEP)272Di-2-ethylhexyl Phthalate275
Mono-2-ethylhexyl phthalate (MEHP)275 Mono-(2-ethyl-5-hydroxyhexyl)
phthalate (MEHHP) 277 Mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP)
279 Mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)281Di-isononyl
Phthalate284 Mono-isononyl phthalate (MiNP)284Dimethyl Phthalate
287 Mono-methyl phthalate (MMP) 287Di-(n-octyl) Phthalate 290
Mono-(3-carboxypropyl) phthalate (MCPP) 290 Mono-n-octyl phthalate
(MOP)292 Phytoestrogens295Daidzein
296O-Desmethylangolensin298Enterodiol
300Enterolactone302Equol304Genistein306 Polybrominated Diphenyl
Ethers and 2,2,4,4,5,5-Hexabromobiphenyl
(BB-153)3112,2,4-Tribromodiphenyl ether (BDE 17)
3122,4,4-Tribromodiphenyl ether (BDE 28)
3132,2,4,4-Tetrabromodiphenyl ether (BDE
47)3142,3,4,4-Tetrabromodiphenyl ether (BDE
66)3142,2,3,4,4-Pentabromodiphenyl ether (BDE
85)3152,2,4,4,5-Pentabromodiphenyl ether (BDE
99)3152,2,4,4,6-Pentabromodiphenyl ether (BDE 100)
3162,2,4,4,5,5-Hexabromodiphenyl ether (BDE 153)
3162,2,4,4,5,6-Hexabromodiphenyl ether (BDE 154)
3172,2,3,4,4,5,6-Heptabromodiphenyl ether (BDE
183)3172,2,4,4,5,5-Hexabromobiphenyl (BB 153)318iv Fourth National
Report on Human Exposure to Environmental Chemicals 7. Contents
Polychlorinated BiphenylsNon-Dioxin-Like3212,4,4-Trichlorobiphenyl
(PCB 28) 3222,2,3,5-Tetrachlorobiphenyl (PCB
44)3262,2,4,5-Tetrachlorobiphenyl (PCB
49)3272,2,5,5-Tetrachlorobiphenyl (PCB
52)3282,3,4,4-Tetrachlorobiphenyl (PCB
66)3302,4,4,5-Tetrachlorobiphenyl (PCB 74)
3322,2,3,4,5-Pentachlorobiphenyl (PCB
87)3342,2,4,4,5-Pentachlorobiphenyl (PCB
99)3362,2,4,5,5-Pentachlorobiphenyl (PCB 101)
3382,3,3,4,6-Pentachlorobiphenyl (PCB 110)
3402,2,3,3,4,4-Hexachlorobiphenyl (PCB 128) 3422,2,3,4,4,5and
2,3,3,4,4,6-Hexachlorobiphenyl (PCB 138 &
158)3442,2,3,4,5,5-Hexachlorobiphenyl (PCB 146)
3462,2,3,4,5,6-Hexachlorobiphenyl (PCB 149)
3482,2,3,5,5,6-Hexachlorobiphenyl (PCB
151)3502,2,4,4,5,5,-Hexachlorobiphenyl (PCB
153)3522,2,3,3,4,4,5-Heptachlorobiphenyl (PCB
170)3542,2,3,3,4,5,5-Heptachlorobiphenyl (PCB
172)3562,2,3,3,4,5,6-Heptachlorobiphenyl (PCB 177)
3582,2,3,3,5,5,6-Heptachlorobiphenyl (PCB
178)3602,2,3,4,4,5,5-Heptachlorobiphenyl (PCB
180)3622,2,3,4,4,5,6-Heptachlorobiphenyl (PCB
183)3642,2,3,4,5,5,6-Heptachlorobiphenyl (PCB
187)3662,2,3,3,4,4,5,5-Octachlorobiphenyl (PCB
194)3682,2,3,3,4,4,5,6-Octachlorobiphenyl (PCB 195)
3692,2,3,3,4,4,5,6 and 2,2,3,4,4,5,5,6-Octachlorobiphenyl (PCB 196
& 203) 3702,2,3,3,4,5,5,6-Octachlorobiphenyl (PCB 199)
3712,2,3,3,4,4,5,5,6-Nonachlorobiphenyl (PCB
206)3722,2,3,3,4,4,5,5,6,6-Decachlorobiphenyl (PCB 209) 373
Dioxin-Like Chemicals377Polychlorinated Dibenzo-p-dioxins 377
1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin (HpCDD)378
1,2,3,4,7,8-Hexachlorodibenzo-p-dioxin (HxCDD) 380
1,2,3,6,7,8-Hexachlorodibenzo-p-dioxin (HxCDD) 382
1,2,3,7,8,9-Hexachlorodibenzo-p-dioxin (HxCDD) 384
1,2,3,4,6,7,8,9-Octachlorodibenzo-p-dioxin (OCDD)386
1,2,3,7,8-Pentachlorodibenzo-p-dioxin (PeCDD)388
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) 390Polychlorinated
Dibenzofurans 392 1,2,3,4,6,7,8-Heptachlorodibenzofuran (HpCDF)392
1,2,3,4,7,8,9-Heptachlorodibenzofuran (HpCDF)394
1,2,3,4,7,8-Hexachlorodibenzofuran (HxCDF) 396Fourth National
Report on Human Exposure to Environmental Chemicals v 8. Contents
1,2,3,6,7,8-Hexachlorodibenzofuran (HxCDF) 398
1,2,3,7,8,9-Hexachlorodibenzofuran (HxCDF) 400
2,3,4,6,7,8-Hexachlorodibenzofuran (HxCDF) 402
1,2,3,4,6,7,8,9-Octachlorodibenzofuran (OCDF)404
1,2,3,7,8-Pentachlorodibenzofuran (PeCDF)406
2,3,4,7,8-Pentachlorodibenzofuran (PeCDF)408
2,3,7,8-Tetrachlorodibenzofuran (TCDF) 410Coplanar Polychlorinated
Biphenyls412 3,4,4,5-Tetrachlorobiphenyl (PCB 81)412
3,3,4,4,5-Pentachlorobiphenyl (PCB 126)414
3,3,4,4,5,5-Hexachlorobiphenyl (PCB 169)416Mono-ortho-substituted
Polychlorinated Biphenyls418 2,3,3,4,4-Pentachlorobiphenyl (PCB
105)418 2,3,4,4,5-Pentachlorobiphenyl (PCB 118)420
2,3,3,4,4,5-Hexachlorobiphenyl (PCB 156) 422
2,3,3,4,4,5-Hexachlorobiphenyl (PCB 157)424
2,3,4,4,5,5-Hexachlorobiphenyl (PCB 167)426
2,3,3,4,4,5,5-Heptachlorobiphenyl (PCB 189) 428 Polycyclic Aromatic
Hydrocarbons 434Fluorene436 2-Hydroxyfluorene436
3-Hydroxyfluorene438 9-Hydroxyfluorene440Naphthalene 442
1-Hydroxynaphthalene (1-Naphthol)442 2-Hydroxynaphthalene
(2-Naphthol)444Phenanthrene447 1-Hydroxyphenanthrene447
2-Hydroxyphenanthrene449 3-Hydroxyphenanthrene451
4-Hydroxyphenanthrene453Pyrene455 1-Hydroxypyrene456 Volatile
Organic Compounds (VOCs)458Benzene 458Chlorobenzene 461
Chlorobenzene (Monochlorobenzene)461 1,2-Dichlorobenzene
(o-Dichlorobenzene)462 1,3-Dichlorobenzene (m-Dichlorobenzene)464
1,4-Dichlorobenzene
(Paradichlorobenzene)4641,2-Dibromo-3-chloropropane
(DBCP)4662,5-Dimethylfuran 468Ethylbenzene470viFourth National
Report on Human Exposure to Environmental Chemicals 9. Contents
Halogenated Solvents473Dichloromethane (Methylene chloride)
473Trichloroethene (Trichloroethylene)474Tetrachloroethene
(Perchloroethylene)475 Other Halogenated Solvents478Dibromomethane
4781,1-Dichloroethane 4791,2-Dichloroethane (Ethylene dichloride)
4801,1-Dichloroethene (Vinylidene chloride)
481cis-1,2-Dichloroethene 481trans-1,2-Dichloroethene
4821,2-Dichloropropane4821,1,1-Trichloroethane (Methyl
chloroform)4831,1,2-Trichloroethane4831,1,2,2-Tetrachloroethane484Tetrachloromethane
(Carbon tetrachloride)484 Hexachloroethane487 Methyl tert-butyl
ether (MTBE)489 Nitrobenzene492 Styrene 494 Toluene 497 Xylenes
500o-Xylene 500m- and p-Xylene501 Appendices503 Appendix A.
Procedure to Estimate Percentiles 503 Appendix B. Changes and Edits
to Results Released in the Third Report 506 Appendix C. References
for Biomonitoring Analytical Methods 507 Appendix D. Limit of
Detection Table511 Appendix E. Abbreviations 519Fourth National
Report on Human Exposure to Environmental Chemicalsvii 10.
IntroductionIntroduction Public Health Uses of the ReportThe Fourth
National Report on Human Exposure toThe overall purpose of the
Report is to provide uniqueEnvironmental Chemicals, 2009 (the
Report) provides an exposure information to scientists, physicians,
and healthongoing assessment of the exposure of the U.S.
populationofficials to help prevent exposure to some
environmentalto environmental chemicals by the use of
biomonitoring.chemicals. Specific public health uses of the
exposureThe Report is cumulative (containing all the results
frominformation in the Report areprevious Reports) and provides new
data for years 2003-2004. Data for 75 new environmental chemicals
are To determine which chemicals get into Americans andincluded for
the survey period 2003-2004. The Report at what
concentrations.website http://www.cdc.gov/exposurereport is also
the best For chemicals with a known toxicity level, to
determinesource for the most recent update of available data. the
prevalence of people with levels above those toxicity levels (e.g.,
a blood lead level greater than orIn each survey period, most
chemicals or their metabolites equal to 10 micrograms per deciliter
[ 10 g/dL]).were measured in blood, serum, and urine samples from
To establish reference values that can be used byrandom subsamples
of about 2500 participants fromphysicians and scientists to
determine whether athe National Health and Nutrition Examination
Survey person or group has an unusually high exposure. This(NHANES)
conducted by the Centers for Disease Controlinformation is
especially helpful to identify populationand Preventions (CDCs)
National Center for Healthgroups that merit further assessment of
exposureStatistics. NHANES is a series of surveys designed
tosources or health effects.collect data related to the health and
nutritional status of To assess the effectiveness of public health
efforts tothe U.S. population. The blood, serum, and urine
exposurereduce exposure of Americans to specific
chemicals.measurements presented in the Report were made by CDCs To
determine whether exposure levels are higherEnvironmental Health
Laboratory (Division of Laboratoryamong such potentially vulnerable
groups as minoritiesSciences, National Center for Environmental
Health) usingand children.mass spectrometry methods. To track, over
time, trends in levels of exposure of the population.The term
environmental chemical refers to a chemical To set priorities for
research on human health effects.compound or chemical element
present in air, water, food,soil, dust, or other environmental
media (e.g., consumerproducts). Biomonitoring is the assessment of
humanexposure to chemicals by measuring the chemicals or
theirmetabolites in such human specimens as blood or urine.
Ametabolite is a chemical alteration of the original
compoundproduced by body tissues. Blood, serum, and urine
levelsreflect the amount of a chemical that actually gets intothe
body by all routes of exposure, including ingestion,inhalation, and
dermal absorption. The measurement ofan environmental chemical in a
persons blood or urineis an indication of exposure; it does not by
itself meanthat the chemical causes disease or an adverse
effect.Research studies, separate from these data, are required
todetermine which blood or urine levels are safe and whichare
associated with disease or an adverse effect. For blood,serum, and
urine levels, the Report provides geometricmeans and percentiles of
environmental chemicals by agegroup, gender and race/ethnicity.
More in-depth statisticalanalysis, including multivariate analysis
incorporatinghealth endpoints and other predictive variables, is
beyondthe scope of this document. We encourage scientists toexamine
the data further through analysis of the raw dataavailable at
http://www.cdc.gov/nchs/nhanes.htm.Fourth National Report on Human
Exposure to Environmental Chemicals 1 11. Whats New in this
ReportWhats New in this ReportIn this Fourth Report, 75 new
chemicals are added for the 2003-2004 survey period and are listed
in Table 1. Theprocess for selection is described at
http://www.cdc.gov/exposurereport/chemical_selection.html.Table 1.
Chemicals reported for the first time in the Fourth National Report
on Human Exposure to EnvironmentalChemicals, 2009 Acrylamide
Adducts Phthalate Metabolite Acrylamide
Mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)
GlycidamidePolybrominated Diphenyl Ethers (PBDE) and Total and
Speciated Arsenic Polybrominated Biphenyl Arsenic, Total
2,2,4-Tribromodiphenyl ether (BDE 17) Arsenic (V) acid
2,4,4-Tribromodiphenyl ether (BDE 28)
Arsenobetaine2,2,4,4-Tetrabromodiphenyl ether (BDE 47)
Arsenocholine2,3,4,4-Tetrabromodiphenyl ether (BDE 66) Arsenous
(III) acid2,2,3,4,4-Pentabromodiphenyl ether (BDE 85)
Dimethylarsinic acid 2,2,4,4,5-Pentabromodiphenyl ether (BDE 99)
Monomethylarsonic acid 2,2,4,4,6-Pentabromodiphenyl ether (BDE 100)
Trimethylarsine oxide2,2,4,4,5,5-Hexabromodiphenyl ether (BDE
153)2,2,4,4,5,6-Hexabromodiphenyl ether (BDE 154) Disinfection
By-Products (Trihalomethanes) 2,2,3,4,4,5,6-Heptabromodiphenyl
ether (BDE 183) Bromodichloromethane 2,2,4,4,5,5-Hexabromobiphenyl
(BB 153) Dibromochloromethane (Chlorodibromomethane) Bromoform
(Tribromomethane)Volatile Organic Compounds (VOCs) Chloroform
(Trichloromethane)BenzeneChlorobenzene (Monochlorobenzene)
Environmental Phenols1,2-Dibromo-3-chloropropane (DBCP)
Benzophenone-3 (2-Hydroxy-4-methoxybenzophenone) Dibromomethane
Bisphenol A (2,2-bis[4-Hydroxyphenyl] propane) 1,2-Dichlorobenzene
(o-Dichlorobenzene) 4-tert-Octyl phenol
(4-[1,1,3,3-Tetramethylbutyl] phenol)1,3-Dichlorobenzene
(m-Dichlorobenzene) Triclosan (2,4,4-Trichloro-2-hydroxyphenyl
ether)1,4-Dichlorobenzene (p-Dichlorobenzene, Paradichlorobenzene)
Non-dioxin-like Polychlorinated Biphenyls1,1-Dichloroethane
2,23,5-Tetrachlorobiphenyl (PCB 44)1,2-Dichloroethane (Ethylene
dichloride) 2,24,5-Tetrachlorobiphenyl (PCB 49)1,1-Dichloroethene
(Vinylidene chloride) 2,2,3,3,4,4,5,5,6,6-Decachlorobiphenyl (PCB
209)cis-1,2-Dichloroethenetrans-1,2-Dichloroethene
PerchlorateDichloromethane (Methylene chloride)1,2-Dichloropropane
Perfluorinated Compounds 2,5-Dimethylfuran Perfluorobutane sulfonic
acid (PFBuS)Ethylbenzene Perfluorodecanoic acid (PFDeA)
Hexachloroethane Perfluorododecanoic acid (PFDoA) Methyl-tert-butyl
ether (MTBE) Perfluoroheptanoic acid (PFHpA)Nitrobenzene
Perfluorohexane sulfonic acid (PFHxS)Styrene Perfluorononanoic acid
(PFNA)1,1,2,2-Tetrachloroethane Perfluorooctane sulfonamide
(PFOSA)Tetrachloroethene Perfluorooctane sulfonic acid (PFOS)
Tetrachloromethane (Carbon tetrachloride)
2-(N-Ethyl-Perfluorooctane sulfonamido) acetic acidToluene
(Et-PFOSA-AcOH)1,1,1-Trichloroethane (Methyl chloroform)
2-(N-Methyl-perfluorooctane sulfonamido) acetic acid
1,1,2-Trichloroethane (Me-PFOSA-AcOH)Trichloroethene
(Trichloroethylene) Perfluorooctanoic acid (PFOA)m- and p-Xylene
Perfluoroundecanoic acid (PFUA)o-Xylene 2Fourth National Report on
Human Exposure to Environmental Chemicals 12. Whats Different in
this ReportWhats Different in this ReportThe Fourth Report uses a
new procedure to estimatepercentiles when the percentile estimate
falls on a valuethat is repeated multiple times (e.g., five results
that allhave the value 90.1). Percentiles for all three
NHANESsurvey periods (1999-2000, 2001-2002, 2003-2004) havebeen
re-computed by use of this improved procedure. Onlyslight
differences should be noted when one compares therecomputations to
previous releases of the Report. Detailsof this procedure are
provided in Appendix A.2003-2004 data for the organochlorine
pesticides andthe dialkyl phosphate organophosphorus
insecticidesare included in the Report. Data for other pesticides
areincluded only for 1999-2000 and 2001-2002. 2003-2004data for
these other pesticides will be provided on thiswebsite as soon as
they are available, and these data will beincluded in the next
release of the Report.Some results reported previously have been
changed orremoved due to improvements in analytical measurementor
recognition of an analytical issue (e.g., the presence ofan
interference) that produced results of inadequate quality.Affected
analytes were serum beta-hexachlorocyclohexanefor the 2001-2002
survey period; urinary 2,4-dichlorophenoland 2,5-dichlorophenol for
the 1999-2002 survey periods;and polycyclic aromatic hydrocarbons
(PAHs) for one ormore of the 1999-2002 survey periods. Explanations
foreach change are provided in Appendix B.Fourth National Report on
Human Exposure to Environmental Chemicals 3 13. Data Sources and
Data AnalysisData Sources and Data Analysis the 2003-2004 survey,
urinary mercury was measured in a random one-third subsample of
participants aged 6 yearsBlood, serum, and urine samples from
NHANESand older. Serum cotinine and acrylamide adducts were
measured in the entire NHANES sample for ages 3 yearsBiomonitoring
measurements for the Report were made in and older. Cotinine is
reported only in nonsmokers.samples from participants in NHANES.
NHANES is a seriesof surveys conducted by CDCs National Center for
Health Though most chemicals in urine were measured in aStatistics
(NCHS). NHANES is designed to collect datarandom one-third
subsample of participants aged 6 yearson the health and nutritional
status of the U.S. population. and older, there have been some
exceptions. UrinaryNHANES collects information about a wide range
of health-levels of herbicides, selected pesticides, and
metabolitesrelated behaviors, performs physical examinations, and
of organophosphate pesticides were measured in a randomcollects
samples for laboratory tests. NHANES is uniqueone-half subsample of
children aged 6-11 years in 1999 andin its ability to examine
public health issues in the U.S. 2000; in a random one-quarter
subsample of people agedpopulation, such as risk factors for
cardiovascular disease. 12-59 years in 1999; and in a random
one-third subsampleBeginning in 1999, NHANES became a continuous
survey,of people aged 12 years and older in 2000. Otherwise
insampling the U.S. population annually and releasing the2001-2002
and 2003-2004, these chemicals were measureddata in 2-year cycles.
The sampling plan follows a complex,in a random one-third subsample
of participants aged 6stratified, multistage, probability-cluster
design to select a years and older.representative sample of the
civilian, noninstitutionalizedpopulation in the United States based
on age, gender, andDioxins, furans, polychlorinated biphenyls
(PCBs), andrace/ethnicity.organochlorine pesticides were measured
in serum from a random one-third subsample of participants aged
12The NHANES protocol includes a home interview followed years and
older in 1999-2000 and 2003-2004. In 2001-by a standardized
physical examination in a mobile 2002, dioxins, furans, and
coplanar PCBs were measuredexamination center. As part of the
examination component,in a random one-third subsample of
participants aged 20blood is obtained by venipuncture from
participants aged years and older, while organochlorine pesticides
and other1 year and older, and urine specimens are collected from
PCBs were measured in a random one-third subsample ofparticipants
aged 6 years and older. Additional detailed participants aged 12
years and older.information on the design and conduct of the
NHANESsurvey is available at http://www.cdc.gov/nchs/nhanes.htm.
Chemicals in the Report were selected on the basis of scientific
data that suggested exposure in the U.S.Environmental chemicals
were measured in blood, serum, population; the seriousness of
health effects known oror urine specimens collected as part of the
examinationsuspected to result from some levels of exposure; the
needcomponent of NHANES. The participant ages for whichto assess
the effectiveness of public health actions to reducea chemical was
measured varied by chemical group.exposure to a chemical; the
availability of a biomonitoringMost of the environmental chemicals
were measured in analytical method with adequate accuracy,
precision,randomly selected subsamples within specific age groups.
sensitivity, specificity, and throughput; the
availabilityRandomization of subsample selection is built into the
of adequate blood or urine samples; and the incrementalNHANES
design before sample collection begins. Different analytical cost
to perform the biomonitoring analysis forrandom subsamples include
different participants. This the chemical. The availability of
biomonitoring methodssubsampling was needed to ensure an adequate
quantity of with adequate performance and acceptable cost was a
majorsample for analysis and to accommodate the throughput of
consideration. Details on the prioritization process forthe mass
spectrometry analytical methods.scoring nominated chemicals and the
resulting scores are available at
http://www.cdc.gov/exposurereport/chemical_Age groups and sample
sizes for each exposure measurementselection.html.are provided in
each of the data tables. Blood lead andblood cadmium were measured
in all participants aged 1 Laboratory Analysisyear and older for
all survey periods. Total blood mercurywas measured in children
aged 1-5 years and in women The blood, serum and urine exposure
measurements inaged 16-49 years in 1999-2002. Total blood mercury
and the Report were made by CDCs Environmental Healthinorganic
blood mercury were measured in all participantsLaboratory (Division
of Laboratory Sciences, Nationalaged 1 year and older in 2003-2004.
Urinary mercury wasCenter for Environmental Health). The analytical
methodsmeasured in women aged 16-49 years in 1999-2002. For used
for measuring the environmental chemicals or their 4 Fourth
National Report on Human Exposure to Environmental Chemicals 14.
Data Sources and Data Analysismetabolites in blood, serum, and
urine were based on isotopegram of creatinine (i.e., creatinine
corrected) adjust fordilution mass spectrometry, inductively
coupled plasmaurine dilution. For example, if one person has
consumedmass spectrometry, or graphite furnace atomic
absorptionmore fluids than another person, his or her urine output
isspectrometry. Laboratory measurements underwent likely higher and
the urine more dilute than that of the otherextensive quality
control and quality assurance review, person. Interpretation of
creatinine corrected results shouldincluding tolerance limits for
operational parameters, thealso recognize that creatinine
correction can also partiallymeasurement of quality control samples
in each analytical adjust for differences in lean body mass or
renal functionrun to detect unacceptable performance in accuracy or
among persons.precision, and verification of traceable calibration
materials.References for the analytical methods used to measure the
For dioxins, furans, PCBs, and organochlorine pesticides,different
chemicals are provided in Appendix C. serum levels are presented
per gram of total lipid and perwhole weight of serum. These
compounds are lipophilicData Analysis and concentrate in the bodys
lipid stores, including thelipid in serum. Serum levels reported
per gram of total lipidBecause the NHANES is a complex, stratified,
multistage,reflect the amount of these compounds that are stored
inprobability-cluster design, sample weights must be used body fat.
Serum levels per whole weight of serum are alsoto adjust for the
unequal probability of selection into the included to facilitate
comparison with studies investigatingsurvey. Sample weights also
are used to adjust for possible exposure to these chemicals and
reported levels in thesebias resulting from nonresponse and are
post-stratified units. Other mostly non-lipophilic chemicals
measured into U.S. Census Bureau estimates of the U.S. population.
serum are expressed per liter of serum (e.g., micrograms perData
were analyzed using the statistical software package liter).
Acrylamide and glycidamide adducts are expressedStatistical
Analysis System (SAS) (SAS Institute Inc.,as the picomoles per gram
of blood hemoglobin to which2002) and the statistical software
package SUDAAN the adduct is bound.(SUDAAN Release 8.0, 2001).
SUDAAN uses sampleweights and calculates variance estimates that
account forUnits of measurement are important. Results are
reportedthe complex survey design. This design does not permithere
using standard units, generally conforming to thosestraightforward
analysis of exposure levels by non-targeted most commonly used in
biomonitoring measurements.strata such as locality, state, or
region; seasons of the year; Useful unit conversions are shown in
Table 2.proximity to sources of exposure; or by use of
particularproducts. Guidelines for the analysis of NHANES data
areTable 2. Units of Measurements and Abbreviationsprovided by NCHS
at http://www.cdc.gov/nchs/nhanes/
UnitAbbreviationValuenhanes2003-2004/analytical_guidelines.htm.
literL-1 deciliter dL 10 litersThe Report presents descriptive
statistics on the blood,-3 milliliter mL10 litersserum, or urine
levels for each environmental chemical. gramgStatistics include
unadjusted geometric means and -3 milligrammg10 gramspercentiles
with confidence intervals. In each table, resultsmicrogramg-610
gramsare given for the total population as well as by age
group,nanogram ng-910 gramsgender, and race/ethnicity as defined in
NHANES. For these picogram pg-1210 gramsanalyses, race/ethnicity is
categorized based on the samplefemtogramfg-1510 gramsdesign as
Mexican American, non-Hispanic black, and non-Hispanic white. Other
racial/ethnic groups are sampled,but the proportion of the total
population represented by Geometric means: A geometric mean
provides a betterother racial/ethnic groups is not large enough to
produce estimate of central tendency for data that are
distributedvalid estimates. Other racial/ethnic groups are included
in with a long tail at the upper end of the distribution.
Thisestimates that are based on the entire population sample. type
of distribution is common in the measurement ofAge groups are as
described for each chemical in each dataenvironmental chemicals in
blood or urine. The geometrictable. Gender is coded as male or
female. mean is influenced less by high values than is the
arithmeticmean. Geometric means were calculated by taking the log
ofUnits: For chemicals measured in urine, levels areeach
concentration and then computing the weighted meanpresented two
ways: per volume of urine and per gramof those log-transformed
values using SUDAAN software.of creatinine. Urinary levels are
expressed both ways inNinety-five percent confidence intervals
around thisthe literature and used for different purposes. Levels
perFourth National Report on Human Exposure to Environmental
Chemicals5 15. Data Sources and Data Analysisweighted mean were
calculated by adding and subtracting an a conservative rule was
used for reporting percentiles: ifamount equal to the product of a
Students t-statistic and the any individual sample LOD in the
demographic group wasstandard error of the weighted mean estimate.
The degreesabove the percentile estimate, the percentile estimate
wasof freedom of the t-statistic were determined by subtracting not
reported.the number of strata from the number of primary
samplingunits (PSUs) according to the data available from theFor
chemicals measured in urine, separate tables arecomplex survey
design. The standard error was computed presented for the chemical
concentration expressed perwith SUDAANs Proc Descript (design=WR),
which usesvolume of urine (uncorrected table) and the
chemicalTaylor series linearization for variance estimation. The
concentration expressed per gram of creatinine (creatinineweighted
geometric mean and its confidence limits were corrected table).
Geometric mean and percentile calculationsthen obtained by taking
the antilogs of this weighted mean were performed separately for
each of these concentrations.and its upper and lower confidence
limits. LOD calculations were performed using the chemical
concentration expressed per volume of urine, because thisLimit of
detection: The limit of detection (LOD) is theconcentration
determines the analytical sensitivity. For thislevel at which the
measurement has a 95% probability ofreason, LOD results for urine
measurements in each databeing greater than zero (Taylor, 1987).
The LODs for eachtable and in Appendix D are in units of weight per
volumechemical and survey period are provided in each data table of
urine. In the creatinine corrected tables, a result for aand
collectively in Appendix D. Concentrations less than geometric mean
or percentile was reported as < LOD if thethe LOD were assigned
a value equal to the LOD divided corresponding geometric mean or
percentile was < LOD inby the square root of 2 for calculation
of geometric means.the table using weight per volume of urine. For
example, ifAssigning a value of the LOD divided by 2 made littlethe
50th percentile for males was < LOD in the table usingdifference
in geometric mean estimates. If the proportionweight per volume of
urine, it would also be < LOD in theof results below the LOD was
greater than 40%, geometric creatinine corrected table.means were
not calculated. For the same chemical, LODvalues may change over
time as a result of improvementsFor chemicals measured in serum
lipid, separate tables areto analytical methods. One possible
consequence is thatpresented for the chemical concentration
expressed perresults may be reported as < LOD in the 1999-2000
data volume of serum (lipid unadjusted table) and the chemicalbut
be reported as a concentration value above the LOD inconcentration
expressed per amount of lipid (lipid adjusted2001-2002 or 2003-2004
because the analytical method had table). Geometric mean and
percentile calculations wereimproved. Thus, for proper
interpretation of LODs in the performed separately for each of
these concentrations.data tables, care must be taken to use the LOD
that appliesLOD calculations were performed using the chemicalto
the survey period. Percentile estimates (see below)
thatconcentration expressed per amount of lipid, because thisare
less than the LOD for the chemical analysis are reported
concentration determines the analytical sensitivity. For thisas
< LOD.reason, LOD results for chemicals measured in each data
table and in Appendix D are in weight per amount of lipid.For most
chemicals, the LOD is constant for each In the lipid unadjusted
tables, a result for a geometric meanindividual specimen analyzed.
For dioxins, furans, PCBs, or percentile was reported as < LOD
if the correspondingorganochlorine pesticides, and a few other
pesticides, eachgeometric mean or percentile was < LOD in the
lipidindividual sample has its own LOD. These analyses have
adjusted table.an individual LOD for each sample, mostly because
thesample volume used for analysis differed for each
sample.Percentiles: Percentiles (50th, 75th, 90th, and 95th) are
givenA higher sample volume results in a lower LOD (i.e., a to
provide additional information about the shape of thebetter ability
to detect low levels). For these chemicals, the distribution.
Percentile estimates and 95% confidencemaximum LOD value is
provided in each data table and interval estimates that are less
than the limit of detection arein Appendix D. The maximum LOD was
the highest LOD indicated as
