Concentrations of Persistent Organic Pollutants in California Children's Whole Blood and Residential Dust.

We evaluated relationships between persistent organic pollutant (POP) levels in the blood of children with leukemia and POP levels in dust from their household vacuum cleaners. Blood and dust were collected from participants of the California Childhood Leukemia Study at various intervals from 1999 to 2007 and analyzed for two polybrominated diphenyl ethers (PBDEs), two polychlorinated biphenyls (PCBs), and two organochlorine pesticides using gas chromatography-mass spectrometry. Due to small blood sample volumes (100 µL), dichlorodiphenyldichloroethylene (DDE) and BDE-153 were the only analytes with detection frequencies above 70%. For each analyte, depending on its detection frequency, a multivariable linear or logistic regression model was used to evaluate the relationship between POP levels in blood and dust, adjusting for child's age, ethnicity, and breastfeeding duration; mother's country of origin; household annual income; and blood sampling date. In linear regression, concentrations of BDE-153 in blood and dust were positively associated; whereas, DDE concentrations in blood were positively associated with breastfeeding, maternal birth outside the U.S., and Hispanic ethnicity, but not with corresponding dust-DDE concentrations. The probability of PCB-153 detection in a child's blood was marginally associated with dust-PCB-153 concentrations (p = 0.08) in logistic regression and significantly associated with breastfeeding. Our findings suggest that dust ingestion is a source of children's exposure to certain POPs.

Concentrations of persistent organic pollutants in California women's serum and residential dust.

BACKGROUND: Humans are exposed to persistent organic pollutants (POPs) through various routes, including consumption of contaminated food and accidental ingestion of settled dust. OBJECTIVES: We aimed to identify key routes of exposure to organochlorine pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in California women of reproductive age. METHODS: Blood was collected from 48 mothers participating in the California Childhood Leukemia Study from 2006 to 2007 and analyzed for POPs using gas chromatography-mass spectrometry. Multivariable linear regression models of natural-log transformed serum concentrations were used to identify determinants of exposure from available questionnaire information on dietary habits, reproductive history, and demographic characteristics, as well as vacuum cleaner dust-POP levels. RESULTS: After adjusting for blood lipid levels, age, body mass index, cumulative lactation, and sampling date, serum concentrations of multiple major PCBs were positively associated with fish consumption, but not dust-PCB levels. After adjusting for blood lipid levels, Hispanic ethnicity, country of origin, and household annual income, serum concentrations of multiple major PBDEs were positively associated with dust-PBDE levels. CONCLUSIONS: Our findings suggest that the relative contribution of specific exposure routes to total POP intake varies by chemical class, with dust being a relatively important source of PBDEs and diet being a relatively important source of PCBs.

Levels of non-polybrominated diphenyl ether brominated flame retardants in residential house dust samples and fire station dust samples in California.

Eleven novel brominated flame retardants (NBFRs) were analyzed in dust samples from California homes as a part of the Northern California Childhood Leukemia Study (NCCLS) and from the living quarters of California fire stations as a part of the Firefighter Occupational Exposure (FOX) study using high resolution gas chromatography/mass spectrometry. The eleven NBFRs were α- and ß-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (α- and ß-DBE-DBCH), 2-bromoallyl 2,3,6-tribromophenylether (BATE), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), 2,3-dibromopropyl 2,4,6-tribromophenyl ether (TBP-DBPE), hexabromobenzene (HBB), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP), and decabromodiphenylethane (DBDPE). Six of the seven NBFRs that are produced in relatively small quantities (i.e., α-, ß-DBE-DBCH, BATE, PBEB, PBT, TBP-DBPE) were measured close to or below the limit of quantitation (0.64 ng/g) in both the NCCLS and FOX samples, and the seventh, HBB, was measured at median concentrations of 1.85 ng/g and 9.40 ng/g in the NCCLS and FOX samples, respectively. The remaining four NBFRs, EH-TBB, BEH-TEBP, BTBPE, and DBDPE, are produced in higher quantities, and were detected at median concentrations of 337 ng/g, 186 ng/g, 22.3 ng/g, and 82.8 ng/g, respectively in the NCCLS samples, and at median concentrations of 2687 ng/g, 2076 ng/g, 28.4 ng/g, and 161 ng/g, respectively, in the FOX samples. Concentrations of NBFRs in the NCCLS and FOX dust samples were several times lower than concentrations of PBDEs previously measured in the same samples. Concentrations of NBFRs in the NCCLS and FOX dust samples were generally comparable to concentrations of NBFRs in other studies of house dust from the US and Canada.

Polychlorinated biphenyls in residential dust: sources of variability.

We characterized the variability in concentrations of polychlorinated biphenyls (PCBs) measured in residential dust. Vacuum cleaner samples were collected from 289 homes in the California Childhood Leukemia Study during two sampling rounds from 2001 to 2010 and 15 PCBs were measured by high resolution gas chromatography-mass spectrometry. Median concentrations of the most abundant PCBs (i.e., PCBs 28, 52, 101, 105, 118, 138, 153, and 180) ranged from 1.0-5.8 ng per g of dust in the first sampling round and from 0.8-3.4 ng/g in the second sampling round. For each of these eight PCBs, we used a random-effects model to apportion total variation into regional variability (6-11%), intraregional between-home variability (27-56%), within-home variability over time (18-52%), and within-sample variability (9-16%). In mixed-effects models, differences in PCB concentrations between homes were explained by home age, with older homes having higher PCB levels. Differences in PCB concentrations within homes were explained by decreasing time trends. Estimated half-lives ranged from 5-18 years, indicating that PCBs are removed very slowly from the indoor environment. Our findings suggest that it may be feasible to use residential dust for retrospective assessment of PCB exposures in studies of children's health.

Polybrominated diphenyl ethers in residential dust: sources of variability.

We characterized the sources of variability for polybrominated diphenyl ethers (PBDEs) in residential dust and provided guidance for investigators who plan to use residential dust to assess exposure to PBDEs. We collected repeat dust samples from 292 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 to 2007 and during 2010) using household vacuum cleaners and measured 22 PBDEs using high resolution gas chromatography-high resolution mass spectrometry. Median concentrations for individual PBDEs ranged from <0.1-2500ng per g of dust. For each of eight representative PBDEs, we used a random-effects model to apportion total variance into regional variability (0-11%), intra-regional between-household variability (17-50%), within-household variability over time (38-74%), and within-sample variability (0-23%) and we used a mixed-effects model to identify determinants of PBDE levels. Regional differences in PBDE dust levels were associated with residential characteristics that differed by region, including the presence of furniture with exposed or crumbling foam and the recent installation of carpets in the residence. Intra-regional differences between households were associated with neighborhood urban density, racial and ethnic characteristics, and to a lesser extent, income. For some PBDEs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PBDE exposures in studies of children's health (e.g., the Northern California Childhood Leukemia Study).

Dichlorodiphenyltrichloroethane (DDT), DDT metabolites and pregnancy outcomes.

Organochlorine pesticides (OCPs) are persistent endocrine disruptors. OCPs cross the placenta; this prenatal exposure has been associated with adverse pregnancy outcomes. We investigated associations between prenatal exposure to OCPs and gestational age and birth weight in 600 infants born between 1960 and 1963. The primary OCP was 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT), its primary metabolite, 1,1'-dichloro-2,2'-bis(p-chlorophenyl)ethylene (p,p'-DDE) and the contaminant, 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)-ethane (o,p'-DDT). Regression analysis indicated that for each natural log unit increase in p,p'-DDT, birth weight increased by 274 g (95% CI: 122, 425) when controlling for p,p'-DDE and o,p'-DDT. At a given level of p,p'-DDT exposure, o,p'-DDT and p,p'-DDE were associated with decreased birth weight. p,p'-DDE was negatively associated with length of gestation, controlling for p,p'-DDT and o,p'-DDT. These findings suggest opposing associations between exposure to p,p'-DDT and p,p'-DDE and birth weight. We did not find evidence to support mediation by maternal thyroid hormone status nor that the association differed by sex.

Prenatal polychlorinated biphenyl exposure is associated with decreased gestational length but not birth weight: archived samples from the Child Health and Development Studies pregnancy cohort.

BACKGROUND: Polychlorinated biphenyls (PCBs), known endocrine disruptors, were banned in 1979 but persist in the environment. Previous studies are inconsistent regarding prenatal exposure to PCBs and pregnancy outcomes. We investigated associations between prenatal exposure to PCBs and gestational length and birth weight. METHODS: In a sample of 600 infants (born between 1960 and 1963) randomly selected from Child Health and Development Studies participants followed through adolescence we measured 11 PCB congeners in maternal post partum sera (within three days of delivery). Length of gestation was computed from the reported first day of the last menstrual period (LMP) and delivery date. Linear regression was used to estimate associations between PCB exposure and gestational age and birth weight, adjusting for potential confounders. PCBs were grouped according to hypothesized biological action (1b (sum of weak phenobarbital inducers), 2b (sum of limited dioxin activity), and 3 (sum of CYP1A and CYP2b inducers)) or degree of ortho- substitution (mono, di, tri). Secondary analyses examined associations between total PCB exposure and exposure to individual congeners. RESULTS: Each unit increase in mono-ortho substituted PCBs was associated with a 0.30 week decrease (95% confidence interval (CI) -0.59, -0.016), corresponding to a 2.1 (95% CI -4.13, -0.11) day decrease in length of gestation. Similar associations were estimated for di-ortho substituted PCBs, (1.4 day decrease; (95% CI -2.9, 0.1)) and group 3 PCBs (0.84 day decrease; (95% CI -1.8, 0.11). We found similar associations in congener specific analyses and for the sum of congeners. CONCLUSIONS: Our study provides new evidence that PCB exposure shortens length of gestation in humans. This may have public health implications for population exposures.