Polybrominated diphenyl ethers, polychlorinated biphenyls, and persistent pesticides in serum from the national health and nutrition examination survey: 2003-2008.

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and persistent pesticides have been measured in pooled samples representative of the general noninstitutionalized population of the United States. The pools were made from individual sera from the National Health and Nutrition Examination Survey (NHANES) during 2005/06 and 2007/08. The pooled concentrations have been contrasted to NHANES 2003/04 individual measurements to evaluate changes in concentration over time and within survey period differences among age groups, race/ethnicity groups (Mexican American, non-Hispanic Black, non-Hispanic White), and sex. The arithmetic mean serum concentrations of several PCB congeners decreased from NHANES 2003/04 through 2007/08. Larger percentage reductions were seen for younger subjects (12-19 years) compared with older subjects (≥60 years). For example, the arithmetic mean concentration of 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153) was 36% lower in 12-19 year old adolescents when comparing NHANES 2007/08 with 2003/04; while for subjects over the age of 60 a 14% lower concentration was seen, although, the 95% confidence intervals overlapped. Similarly, the arithmetic mean serum concentrations of tri- to hexaBDEs were lower in NHANES 2007/08 than in 2003/04; however, most confidence intervals of the arithmetic means overlapped. These findings suggest that a reduction in PBDE serum concentrations cannot yet be detected following the discontinuation of pentaBDE in 2004.

Polybrominated diphenyl ethers, 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) concentrations in sera collected in 2009 from Texas children.

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) have been measured in surplus serum collected in 2009 from a convenience sample of 300 Texas children (boys and girls) in the birth to 13 years of age range. Serum concentrations of traditional persistent organic pollutants such as 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153) and p,p'-DDE did not change consistently with age. By contrast, serum concentrations of tetra-, penta-, and hexa-BDEs were lowest in the youngest children (birth to two year old) and increased 3.0 to 7.9 times, depending on the analyte, for children in the >4 to 6 years of age group. From the apex concentration to the 10 to 13 years of age group, concentrations decreased significantly except for 2,2',4,4',5,5'-hexabromodiphenyl ether (PBDE-153), which also had a longer apex concentration of >4 to 8 years of age. This concentration trend for PBDE-153 is most likely due to a longer half-life of PBDE-153 than of other PBDE congeners. The observed PBDEs concentration patterns by age may be related, at least in part, to ingestion of residential dust containing PBDEs through hand-to-mouth behavior among toddlers, preschoolers, and kindergarteners. Further studies to characterize young children's exposure to PBDEs are warranted and, in particular, to determine the lifestyle factors that may contribute to such exposures.

Milk and serum standard reference materials for monitoring organic contaminants in human samples.

Four new Standard Reference Materials (SRMs) have been developed to assist in the quality assurance of chemical contaminant measurements required for human biomonitoring studies, SRM 1953 Organic Contaminants in Non-Fortified Human Milk, SRM 1954 Organic Contaminants in Fortified Human Milk, SRM 1957 Organic Contaminants in Non-Fortified Human Serum, and SRM 1958 Organic Contaminants in Fortified Human Serum. These materials were developed as part of a collaboration between the National Institute of Standards and Technology (NIST) and the Centers for Disease Control and Prevention (CDC) with both agencies contributing data used in the certification of mass fraction values for a wide range of organic contaminants including polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, polybrominated diphenyl ether (PBDE) congeners, and polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners. The certified mass fractions of the organic contaminants in unfortified samples, SRM 1953 and SRM 1957, ranged from 12 ng/kg to 2200 ng/kg with the exception of 4,4'-DDE in SRM 1953 at 7400 ng/kg with expanded uncertainties generally <14 %. This agreement suggests that there were no significant biases existing among the multiple methods used for analysis.

Plasma dioxin levels and cause-specific mortality in an occupational cohort of workers exposed to chlorophenoxy herbicides, chlorophenols and contaminants.

BACKGROUND: We recently reported increased risks for all cancers and urinary cancers in workers exposed to chlorophenoxy herbicides using data from the Dutch herbicide cohort study. These risks could not be linked to the qualitative exposure proxies available. Here, we re-investigate exposure-response relationships using a (semi)quantitative measure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure. METHODS: Plasma TCDD levels of 187 workers were used to develop a predictive model for TCDD exposure. Cox proportional hazards model was used to investigate associations between time-varying TCDD exposure and cause-specific mortality. Sensitivity analyses were performed to assess the impact of key assumptions in exposure assessment. RESULTS: Predicted TCDD levels were associated with mortality from all causes (HR 1.08; 95% CI 1.03 to 1.13), ischaemic heart disease (IHD; HR 1.19; 95% CI 1.08 to 1.32) and non-Hodgkin's lymphoma (NHL; HR 1.36; 95% CI 1.06 to 1.74). No relationships were found between TCDD exposure and mortality from all cancers, respiratory or urinary cancers, which were previously linked to qualitative proxies of TCDD exposure in this cohort. Sensitivity analyses showed that results were relatively robust to slight changes in exposure estimation. CONCLUSIONS: Modelled TCDD exposure does not explain the previously reported increased risks for cancer mortality in this cohort except for a possible association with NHL. A small increase in ischaemic heart disease was observed, however we cannot exclude that this finding was due to residual confounding. Although risk estimates for some of the rarer outcomes were still rather imprecise, we do not expect more precise estimates from longer follow-up of this cohort due to the long time-span since last exposure to TCDD.

t(14;18) Translocations in Dioxin-Exposed Workers.

OBJECTIVE: To determine if occupational exposure to dioxins is associated with an increased frequency of t(14;18) translocations. METHODS: A cross-sectional analysis of serum dioxin levels and t(14;18) frequencies in peripheral blood mononuclear cells in 218 former chemical plant workers and 150 population controls. RESULTS: The workers had significantly higher geometric mean serum levels of 2,3,7,8-TCDD (26.2 vs 2.5 ppt) and TEQ (73.8 vs 17.7 ppt) than controls. There were no significant differences in the prevalence or frequency of t(14;18) translocations in the workers compared to controls. Among former workers with current or past chloracne who were t(14;18) positive, the frequency of translocations significantly increased with quartiles of 2,3,7,8-TCDD and TEQ. CONCLUSION: Chloracne appears to modulate the association between dioxin exposure and increased frequency of t(14;18) translocations.

Dioxin and polychlorinated biphenyl concentrations in mother's serum and the timing of pubertal onset in sons.

BACKGROUND: Animal studies have demonstrated that timing of pubertal onset can be altered by prenatal exposure to dioxins or polychlorinated biphenyls (PCBs), but studies of human populations have been quite limited. METHODS: We assessed the association between maternal serum concentrations of dioxins and PCBs and the sons' age of pubertal onset in a prospective cohort of 489 mother-son pairs from Chapaevsk, Russia, a town contaminated with these chemicals during past industrial activity. The boys were recruited at ages 8 to 9 years, and 4 years of annual follow-up data were included in the analysis. Serum samples were collected at enrollment from both mothers and sons for measurement of dioxin and PCB concentrations using high-resolution mass spectrometry. The sons' pubertal onset--defined as pubertal stage 2 or higher for genitalia (G) or pubic hair (P), or testicular volume >3 mL--was assessed annually by the same physician. RESULTS: In multivariate Cox models, elevated maternal serum PCBs were associated with earlier pubertal onset defined by stage G2 or higher (4th quartile hazard ratio = 1.7 [95% confidence interval = 1.1- 2.5]), but not for stage P2 or higher or for testicular volume >3 mL. Maternal serum concentrations of dioxin toxic equivalents were not consistently associated with the sons' pubertal onset, although a dose-related delay in pubertal onset (only for G2 or higher) was seen among boys who breast-fed for 6 months or more. CONCLUSIONS: Maternal PCB serum concentrations measured 8 or 9 years after sons' births--which may reflect sons' prenatal and early-life exposures--were associated with acceleration in some, but not all, measures of pubertal onset.

Partition of environmental chemicals between maternal and fetal blood and tissues.

Passage of environmental chemicals across the placenta has important toxicological consequences, as well as for choosing samples for analysis and for interpreting the results. To obtain systematic data, we collected in 2000 maternal and cord blood, cord tissue, placenta, and milk in connection with births in the Faroe Islands, where exposures to marine contaminants is increased. In 15 sample sets, we measured a total of 87 environmental chemicals, almost all of which were detected both in maternal and fetal tissues. The maternal serum lipid-based concentrations of organohalogen compounds averaged 1.7 times those of cord serum, 2.8 times those of cord tissue and placenta, and 0.7 those of milk. For organohalogen compounds detectable in all matrices, a high degree of correlation between concentrations in maternal serum and the other tissues investigated was generally observed (r(2) > 0.5). Greater degree of chlorination resulted in lower transfer from maternal serum into milk. Concentrations of pentachlorbenzene, γ-hexachlorocyclohexane, and several polychlorinated biphenyl congeners with low chlorination were higher in fetal samples and showed poor correlation with maternal levels. Perfluorinated compounds occurred in lower concentrations in cord serum than in maternal serum. Cadmium, lead, mercury, and selenium were all detected in fetal samples, but only mercury showed close correlations among concentrations in different matrices. Although the environmental chemicals examined pass through the placenta and are excreted into milk, partitions between maternal and fetal samples are not uniform.

Dioxin exposure, from infancy through puberty, produces endocrine disruption and affects human semen quality.

BACKGROUND: Environmental toxicants are allegedly involved in decreasing semen quality in recent decades; however, definitive proof is not yet available. In 1976 an accident exposed residents in Seveso, Italy, to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). OBJECTIVE: The purpose of this study was to investigate reproductive hormones and sperm quality in exposed males. METHODS: We studied 135 males exposed to TCDD at three age groups, infancy/prepuberty (1-9 years), puberty (10-17 years), and adulthood (18-26 years), and 184 healthy male comparisons using 1976 serum TCDD levels and semen quality and reproductive hormones from samples collected 22 years later. RESULTS: Relative to comparisons, 71 men (mean age at exposure, 6.2 years; median serum TCDD, 210 ppt) at 22-31 years of age showed reductions in sperm concentration (53.6 vs. 72.5 million/mL; p = 0.025); percent progressive motility (33.2% vs. 40.8%; p < 0.001); total motile sperm count (44.2 vs. 77.5 x 10(6); p = 0.018); estradiol (76.2 vs. 95.9 pmol/L; p = 0.001); and an increase in follicle-stimulating hormone (FSH; 3.58 vs. 2.98 IU/L; p = 0.055). Forty-four men (mean age at exposure, 13.2 years; median serum TCDD, 164 ppt) at 32-39 years of age showed increased total sperm count (272 vs. 191.9 x 10(6); p = 0.042), total motile sperm count (105 vs. 64.9 x10(6); p = 0.036), FSH (4.1 vs. 3.2 UI/L; p = 0.038), and reduced estradiol (74.4 vs. 92.9 pmol/L; p < 0.001). No effects were observed in 20 men, 40-47 years of age, who were exposed to TCDD (median, 123 ppt) as adults (mean age at exposure, 21.5 years). CONCLUSIONS: Exposure to TCDD in infancy reduces sperm concentration and motility, and an opposite effect is seen with exposure during puberty. Exposure in either period leads to permanent reduction of estradiol and increased FSH. These effects are permanent and occur at TCDD concentrations < 68 ppt, which is within one order of magnitude of those in the industrialized world in the 1970s and 1980s and may be responsible at least in part for the reported decrease in sperm quality, especially in younger men.

Total TEQ reference range (PCDDs, PCDFs, cPCBs, mono-PCBs) for the US population 2001-2002.

We report reference ranges for the total toxic equivalency (TEQ) and TEQ sub-fractions of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), coplanar biphenyls (cPCBs), and mono-ortho-substituted biphenyls (mPCBs) in a statistically designed sampling of the US population in 2001-2002. The TEQ and TEQ sub-fractions have been stratified by age, sex, and race/ethnicity. The TEQ levels are lower using the 2005 toxic equivalency factors (TEFs) compared to using the 1998 TEF values, principally due to the much lower 2005 TEF values assigned to the mPCBs. Mexican Americans (MA) have significantly lower TEQ levels than both non-Hispanic whites (NHW) and non-Hispanic blacks (NHB). Using the 1998 or 2005 TEF values, males and females have nearly the same distribution of TEQ sub-fractions. We found a significant increase in TEQ levels with age for males, females, and NHW. About 80-90% of the total TEQ can be estimated by using seven congeners, namely 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, PCB-126, PCB-118, and PCB-156. We also measured geometric mean TEQ levels in pooled samples from the US population. The geometric mean TEQ levels also increase with age. In the youngest age group (12-19 years), the TEQ levels were higher in males than in females while females had higher TEQ levels than males in all older age groups. In the pools, as age increases the percent contribution of the PCDD TEQ levels increases while the percent contribution of the PCDF TEQ levels decreases for all race/ethnicity and sex strata.

Geometric mean estimation from pooled samples.

Biomonitoring for environmental chemicals presents various challenges due to the expense of measuring some compounds and the fact that in some samples the levels of many compounds may be below the limit of detection (LOD) of the measuring instrument. Even though various statistical methods have been developed to address issues associated with data being censored because results were below the LOD, the expense of measuring many compounds in large numbers of subjects remains a challenge. One solution to these challenges is to use pooled samples. There are many problems associated with the use of pooled samples as compared with individual samples, but using pooled samples can sometimes reduce the number of analytical measurements needed. Also, because pooled samples often have larger sample volumes, using pooled samples can result in lower LODs and thereby decrease the likelihood that results will be censored. However, many data sets obtained from environmental measurements have been shown to have a log-normal distribution, so using pooled samples presents a new problem: The measured value for a pooled sample is comparable to an arithmetic average of log-normal results and thus represents a biased estimate of the central tendency of the samples making up the pool. In this paper, we present a method for correcting the bias associated with using data from pooled samples with a log-normal distribution. We use simulation experiments to demonstrate how well the bias-correction method performs. We also present estimates for levels of PCB 153 and p,p'-DDE using data from pooled samples from the 2001 to 2002 National Health and Nutrition Examination Surveys.

Calculation of serum "total lipid" concentrations for the adjustment of persistent organohalogen toxicant measurements in human samples.

Persistent organohalogen toxicants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin or polychlorinated biphenyls measured in human serum are often expressed on a lipid weight basis, most commonly by dividing the toxicants' concentration by the weight of total lipids in the sample. Therefore, the manner in which this lipid adjustment is calculated may influence the final reported result. Gravimetric total lipid assays have been used, but they are time-consuming and sometimes may be ill-defined. Consequently, alternative methods using enzymatic assays have been developed based on summing the individual lipid species measured. Recent reports, however, have suggested that significantly different total lipid results may be obtained when using alternative formulae in a summation approach. In this report, we summarize the results obtained from lipid measurements of nearly 900 samples made as part of a study of a group of older American men (mean age 62 years), and we compare our total lipid estimates obtained by using both our standard and "short" formula (the latter based on total cholesterol and triglycerides only) with results obtained using the recently proposed alternative formulae. Our findings indicate that both our long and short formulae provide similar estimates of serum total lipid concentrations, and that differences observed in lipid estimates when using the newer alternative summation methods may reflect differences in how the term "total lipid" is defined, especially with regard to the need to include the contribution of the weight of the cholesterol ester fatty acids in the calculation.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in the serum of US Air Force veterans in 2002.

We measured levels of PCDDs, PCDFs, non-ortho, and mono-ortho substituted PCBs in 106 US Air Force Vietnam veterans, participants of the Air Force Health Study (AFHS) who attended the final medical examination in 2002. Twelve veterans were Ranch Hands involved in aerial spraying of herbicides in Vietnam (1962-1971), and 94 were Comparisons who flew transport missions in Southeast Asia (SEA) during the same time period. These veterans had no previous 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) measurement because they had not attended any of the previous AFHS examinations, or their previous measurements were missing or not valid. The mean TCDD levels in 2002 were 1.7 pg/g lipid in Comparisons and 5.5 pg/g lipid in Ranch Hands. The mean PCDD toxic equivalent - TEQ (1997) in Comparisons was 12.6 pg/g lipid, 5.4 pg/g lipid for PCDFs, 5.2 pg/g lipid for non-ortho PCBs, and 9.4 pg/g lipid for mono-ortho PCBs, with a total mean TEQ (1997) of 32.6 pg/g lipid. Corresponding mean TEQs in Ranch Hands were 15.5 pg/g lipid for PCDDs, 4.6 pg/g lipid for PCDFs, 2.2 pg/g lipid for non-ortho PCBs, and 9.3 pg/g lipid for mono-ortho PCBs, yielding the total mean TEQ (1997) of 31.6pg/g lipid. Using the re-evaluated 2005 WHO TEFs, the total mean TEQs (2005) decreased by about 28% in both Comparisons and Ranch Hands, to 23.6 pg/g lipid and 22.8 pg/g lipid, respectively. This was mainly due to changes of TEFs for the group of mono-ortho PCBs, which decreased the mono-ortho PCBs TEQs by almost 90% in both Ranch Hands and Comparisons.

Percentile estimation using variable censored data.

Much progress has been made in recent years to address the estimation of summary statistics, using data that are subject to censoring of results that fall below the limit of detection (LOD) for the measuring instrument. Truncated data methods (e.g., Tobit regression) and multiple-imputation are two approaches for analyzing data results that are below the LOD. To apply these methods requires an assumption about the underlying distribution of the data. Because the log-normal distribution has been shown to fit many data sets obtained from environmental measurements, the common practice is to assume that measurements of environmental factors can be described by log-normal distributions. This article describes methods for obtaining estimates of percentiles and their associated confidence intervals when the results are log-normal and a fraction of the results are below the LOD. We present limited simulations to demonstrate the bias of the proposed estimates and the coverage probability of their associated confidence intervals. Estimation methods are used to generate summary statistics for 2,3,7,8-tetrachloro dibenzo-p-dioxin (2,3,7,8-TCDD) using data from a 2001 background exposure study in which PCDDs/PCDFs/cPCBs in human blood serum were measured in a Louisiana population. Because the congener measurements used in this study were subject to variable LODs, we also present simulation results to demonstrate the effect of variable LODs on the multiple-imputation process.

Exposures among pregnant women near the World Trade Center site on 11 September 2001.

We have characterized environmental exposures among 187 women who were pregnant, were at or near the World Trade Center (WTC) on or soon after 11 September 2001, and are enrolled in a prospective cohort study of health effects. Exposures were assessed by estimating time spent in five zones around the WTC and by developing an exposure index (EI) based on plume reconstruction modeling. The daily reconstructed dust levels were correlated with levels of particulate matter < or = 2.5 microm in aerodynamic diameter (PM2.5; r = 0.68) or PM10 (r = 0.73-0.93) reported from 26 September through 8 October 2001 at four of six sites near the WTC whose data we examined. Biomarkers were measured in a subset. Most (71%) of these women were located within eight blocks of the WTC at 0900 hr on 11 September, and 12 women were in one of the two WTC towers. Daily EIs were determined to be highest immediately after 11 September and became much lower but remained highly variable over the next 4 weeks. The weekly summary EI was associated strongly with women's perception of air quality from week 2 to week 4 after the collapse (p < 0.0001). The highest levels of polycyclic aromatic hydrocarbon-deoxyribonucleic acid (PAH-DNA) adducts were seen among women whose blood was collected sooner after 11 September, but levels showed no significant associations with EI or other potential WTC exposure sources. Lead and cobalt in urine were weakly correlated with sigmaEI, but not among samples collected closest to 11 September. Plasma OC levels were low. The median polychlorinated biphenyl level (sum of congeners 118, 138, 153, 180) was 84 ng/g lipid and had a nonsignificant positive association with sigmaEI (p > 0.05). 1,2,3,4,6,7,8-Heptachlorodibenzodioxin levels (median, 30 pg/g lipid) were similar to levels reported in WTC-exposed firefighters but were not associated with EI. This report indicates intense bystander exposure after the WTC collapse and provides information about nonoccupational exposures among a vulnerable population of pregnant women.

Concentrations of environmental chemicals associated with neurodevelopmental effects in U.S. population.

Humans are exposed to many environmental chemicals, some of which can potentially affect neurodevelopment. Fetuses, infants, and young children are the most susceptible to the effects of these chemicals. As part of the National Health and Examination Survey, 1999-2000, the Centers for Disease Control and Prevention analyzed biological samples for many of these chemicals in a representative sampling of the U.S. population. Concentration data of selected metals, persistent organic pollutants, organophosphorus and carbamate insecticides, and cotinine are presented. For example, the 95th percentile estimates for serum total PCBs (whole weight) in the population aged 20 years and older is about 2.7 ng/g. The 95th percentile estimates for serum dioxin total toxic equivalence in the U.S. population aged 20 years and older is between 40 and 50 pg/g lipid basis. In general, human levels of these chemicals are decreasing over time in the U.S. population. This reflects the effects of legislation, industry efforts, and changes in lifestyle/activity patterns in the U.S. population. These data will continue to be collected in 2-year cycles and thus allow changes in human levels to be followed.

Predictors of serum dioxin levels among adolescent boys in Chapaevsk, Russia: a cross-sectional pilot study.

BACKGROUND: Toxicological studies and limited human studies have demonstrated associations between exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) and adverse developmental and reproductive health effects. Given that children may be particularly susceptible to reproductive and developmental effects of organochlorines, and the paucity of information available regarding childhood exposures to dioxins in particular, we undertook a pilot study to describe the distribution of, and identify potential predictors of exposure to, dioxin-like compounds and dioxins among adolescent boys in Chapaevsk, Russia. The pilot study was also designed to guide the development of a large prospective cohort study on the relationship of exposure to PCDDs, PCDFs, and PCBs with growth and pubertal development in peri-pubertal Chapaevsk boys. METHODS: 221 boys age 14 to 17 participated in the pilot study. Each of the boys, with his mother, was asked to complete a nurse-administered detailed questionnaire on medical history, diet, and lifestyle. The diet questions were used to measure the current and lifetime consumption of locally grown or raised foods. Blood samples from 30 of these boys were sent to the Centers for Disease Control and Prevention (CDC) for analysis of dioxins, furans and PCBs. RESULTS: The median (25th, 75th percentile) concentrations for total PCDDs, PCDFs and coplanar PCBs were 95.8 pg/g lipids (40.9, 144), 33.9 pg/g lipids (20.4, 61.8), and 120 pg/g lipids (77.6, 157), respectively. For WHO-TEQs, the median (25th, 75th percentile) for total PCDDs, PCDFs, and coplanar PCBs were 0.29 (0.1, 9.14), 7.98 (5.27, 12.3), and 7.39 (4.51, 11.9), respectively. Although TCDD was largely non-detectable, two boys had high TCDD levels (17.9 and 21.7 pg/g lipid). Higher serum levels of sum of dioxin-like compounds and sum of dioxin TEQs were positively associated with increased age, consumption of fish, local meats other than chicken, PCB 118, and inversely with weeks of gestation. CONCLUSION: The total TEQs among Chapaevsk adolescents were higher than most values previously reported in non-occupationally exposed populations of comparable or even older ages. Dietary consumption of local foods, as well as age and weeks of gestation, predicted dioxin exposure in this population.

Dioxin-Like TEQ of women from the Seveso, Italy area by ID-HRGC/HRMS and CALUX.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are widespread environmental contaminants that exist as complex mixtures and are frequently detected at part-per-trillion (ppt) levels in humans. Using isotope dilution high-resolution gas chromatography/ high-resolution mass spectrometry (HRGC/HRMS), we measure the PCDDs, PCDFs, and PCBs in serum of a population of 78 women residing in an area near Seveso, Italy where a TCDD explosion occurred in 1976 and where furniture is manufactured. The average total dioxin-like toxic equivalents (TEQ) of these women was 25.3 ppt, lipid-adjusted, comparable to other parts of Europe. TCDD levels, however, were higher among the few women who resided in the exposed area in 1976. We examined the possibility of using the CALUX (chemical-activated luciferase gene expression) bioassay to estimate total TEQ in a small volume of plasma from this population. A total of 32 archived plasma specimens were selected for CALUX bioassay, based on the distribution of Total TEQ by HRGC/HRMS. The CALUX bioassay was performed blind to HRGC/HRMS results with 2 ml plasma per replicate analysis. Of 32 samples, 10 were below detection limits in the CALUX bioassay. For the 32 samples, the CALUX-TEQ averaged 25.4 ppt, lipid-adjusted (range: 0-127.6) and was not significantly different from the HRGC/HRMS Total TEQ average of 31.2 ppt, lipid-adjusted (range: 12.7-88.3) (t = 0.88, P = 0.38), however, the two measures were not significantly correlated (R(s) = 0.04, P=0.82). More validation of the CALUX bioassay with larger sample volume is needed before application as an exposure measure in large-scale epidemiologic studies of health effects of dioxin-like compounds.

Serum PCB concentrations in residents of Calcasieu and Lafayette Parishes, Louisiana with comparison to the U.S. population.

In 2002, a cross-sectional study designed to compare the serum dioxin toxic equivalent concentrations (TEQ) of a population-based sample of Calcasieu Parish, Louisiana residents, to Lafayette Parish was conducted. The mono-ortho polychlorinated biphenyls (PCBs) were measured in order to calculate the TEQ. We compared the sum of lipid adjusted serum concentrations of 27 PCB congeners (total PCBs) in residents of these two parishes and also by their demographic characteristics. The geometric means (GM) [standard errors (SE)] of the concentrations (ngg(-1) lipids) of total PCBs in participants from Calcasieu Parish and Lafayette Parish were 154 (11.8) and 168.6 (20.8) (T-test p=0.54), respectively. Various percentiles of the distribution of serum total PCB concentrations were similar in the two parishes. After adjusting by age and race in the ANCOVA regression model, the adjusted GM for the lipid adjusted total PCBs was statistically higher in the residents in Lafayette than in Calcasieu Parish regardless of age or race (P=0.007). The adjusted GM of lipid adjusted total PCBs for African Americans was significantly higher than for Whites (p<0.001). Serum total PCB levels in residents of both parishes increased linearly with age (P<0.001). The congener profiles were similar in residents of both parishes. We also compared the GMs of a sum of 8 PCBs in Calcasieu and Lafayette Parish residents to those from a representative sample of the U.S. general population in 2001-2002 and they were not significantly different between parishes or between the parish data and the U.S. general population.

Relationship of serum TCDD concentrations and age at exposure of female residents of Seveso, Italy.

In 1976, a chemical plant explosion near Seveso, Italy, resulted in the highest known exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in residential populations. In 1996, we initiated the Seveso Women's Health Study (SWHS), a historical cohort study of females who were 40 years old at the time of explosion and residents of the most heavily contaminated areas, zones A and B. Serum samples collected near the time of the explosion were analyzed for TCDD. We also analyzed pooled serum samples collected in 1976 from females who resided in zone non-ABR, the "unexposed" zone, to assess concurrent background exposures to other dioxins, furans, and coplanar polychlorinated biphenyls (PCBs). The median lipid-adjusted TCDD level for residents of zones A and B combined was 56 ppt (range = 2.5-56,000 ppt). Zone A residents had 5-fold higher TCDD levels (n = 67, median = 272 ppt) than did zone B residents (n = 814, median = 47 ppt). The youngest children had the highest TCDD levels, which decreased with age at explosion until approximately 13 years of age and were constant thereafter. Therefore, children living in zones A and B received a disproportionately higher exposure to TCDD as a result of the explosion. Zone of residence and age were the strongest predictors of TCDD level. Chloracne, nearby animal mortality, location (outdoors vs. indoors) at the time of explosion, and consumption of homegrown food were also related to serum TCDD levels. The serum pools from zone non-ABR residents had an average TCDD concentration of 20.2 ppt, and average total toxic equivalent (TEQ) concentration of 100.4 ppt. Therefore, background exposure to dioxins, furans, and PCBs unrelated to the explosion may have been substantial. As a consequence, previous SWHS studies that considered only TCDD exposure may have underestimated health effects due to total TEQ concentrations.

Biomonitoring of chemical exposure among New York City firefighters responding to the World Trade Center fire and collapse.

The collapse of the World Trade Center (WTC) on 11 September 2001 exposed New York City firefighters to smoke and dust of unprecedented magnitude and duration. The chemicals and the concentrations produced from any fire are difficult to predict, but estimates of internal dose exposures can be assessed by the biological monitoring of blood and urine. We analyzed blood and urine specimens obtained from 321 firefighters responding to the WTC fires and collapse for 110 potentially fire-related chemicals. Controls consisted of 47 firefighters not present at the WTC. Sampling occurred 3 weeks after 11 September, while fires were still burning. When reference or background ranges were available, most chemical concentrations were found to be generally low and not outside these ranges. Compared with controls, the exposed firefighters showed significant differences in adjusted geometric means for six of the chemicals and significantly greater detection rates for an additional three. Arrival time was a significant predictor variable for four chemicals. Special Operations Command firefighters (n = 95), compared with other responding WTC firefighters (n = 226), had differences in concentrations or detection rate for 14 of the chemicals. Values for the Special Operations Command firefighters were also significantly different from the control group values for these same chemicals and for two additional chemicals. Generally, the chemical concentrations in the other firefighter group were not different from those of controls. Biomonitoring was used to characterize firefighter exposure at the WTC disaster. Although some of the chemicals analyzed showed statistically significant differences, these differences were generally small.