Indoor air polychlorinated biphenyl concentrations in three communities along the Upper Hudson River, New York

Characterization of the Metabolic Pathways of 4-Chlorobiphenyl (PCB3) in HepG2 Cells Using the Metabolite Profiles of Its Hydroxylated Metabolites

The characterization of the metabolism of lower chlorinated PCB, such as 4-chlorobiphenyl (PCB3), is challenging because of the complex metabolite mixtures formed in vitro and in vivo. We performed parallel metabolism studies with PCB3 and its hydroxylated metabolites to characterize the metabolism of PCB3 in HepG2 cells using nontarget high-resolution mass spectrometry (Nt-HRMS). Briefly, HepG2 cells were exposed for 24 h to 10 μM PCB3 or its seven hydroxylated metabolites in DMSO or DMSO alone. Six classes of metabolites were identified with Nt-HRMS in the culture medium exposed to PCB3, including monosubstituted metabolites at the 3'-, 4'-, 3-, and 4- (1,2-shift product) positions and disubstituted metabolites at the 3',4'-position. 3',4'-Di-OH-3 (4'-chloro-3,4-dihydroxybiphenyl), which can be oxidized to a reactive and toxic PCB3 quinone, was a central metabolite that was rapidly methylated. The resulting hydroxylated-methoxylated metabolites underwent further sulfation and, to a lesser extent, glucuronidation. Metabolomic analyses revealed an altered tryptophan metabolism in HepG2 cells following PCB3 exposure. Some PCB3 metabolites were associated with alterations of endogenous metabolic pathways, including amino acid metabolism, vitamin A (retinol) metabolism, and bile acid biosynthesis. In-depth studies are needed to investigate the toxicities of PCB3 metabolites, especially the 3',4'-di-OH-3 derivatives identified in this study.

PCBs and organochlorine pesticides in indoor environments - A comparison of indoor contamination in Canada and Czech Republic

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are restricted compounds that are ubiquitously detected in the environment, including indoor matrices such as air and residential dust. We report concentrations of PCBs and selected OCPs in indoor air and dust from homes in Canada (23 homes) and Czech Republic (20 homes). Indoor air concentrations of PCBs and OCPs were ∼10 times higher than that outdoors. PCB concentrations of ∼450 ng/m³ were similar in both countries, higher in homes built before the restrictions on PCBs, and had congener profiles consistent with PCB mixtures manufactured or used in each country. All OCP air concentrations were higher in the Czech Republic than in the Canadian samples, suggesting greater indoor use of, for example, DDT and HCH. These data emphasize the persistence of these organochlorine compounds indoors and their presence in homes even decades after new usage was prohibited. Indoor levels of these legacy POPs remain at similar concentrations to compounds of current concern, such as brominated flame retardants and perfluorinated alkyl substances, emphasizing that they deserve ongoing attention in view of knowledge of PCB and OCP toxicity.

Partitioning of PCBs from air to clothing materials in a Danish apartment

Polychlorinated biphenyl (PCB) contamination of buildings continues to pose an exposure threat, even decades after their application in the form of calks and other building materials. In this research, we investigate the ability of clothing to sorb PCBs from contaminated air and thereby influence exposure. The equilibrium concentration of PCB-28 and PCB-52 was quantified for nine used clothing fabrics exposed for 56 days to air in a Danish apartment contaminated with PCBs. Fabric materials included pure materials such as cotton and polyester, or blends of polyester, cotton, viscose/rayon, and/or elastane. Air concentrations were fairly stable over the experimental period, with PCB-28 ranging from 350 to 430 ng/m³ and PCB-52 ranging from 460 to 550 ng/m³ . Mass accumulated in fabric ranged from below detection limits to 4.5 mg/g of fabric. Cotton or materials containing elastane sorbed more than polyester materials on a mass basis. Mass-normalized partition coefficients above detection limits ranged from 10^5.7 to 10^7.0  L/kg. Clothing acts as a reservoir for PCBs that extends dermal exposure, even when outside or in uncontaminated buildings.

Chamber study of PCB emissions from caulking materials and light ballasts

The emissions of polychlorinated biphenyl (PCB) congeners from thirteen caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-L environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r(2)⩾0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs.

Evaluation and guidelines for using polyurethane foam (PUF) passive air samplers in double-dome chambers to assess semi-volatile organic compounds (SVOCs) in non-industrial indoor environments

Indoor air pollution has been recognized as an important risk factor for human health, especially in areas where people tend to spend most of their time indoors. Many semi-volatile organic compounds (SVOCs) have primarily indoor sources and are present in orders of magnitude higher concentrations indoors than outdoors. Despite this, awareness of SVOCs in indoor air and assessment of the link between indoor concentrations and human health have lagged behind those of outdoor air. This is partially related to challenges associated with indoor sampling of SVOCs. Passive air samplers (PASs), which are widely accepted in established outdoor air monitoring networks, have been used to fill the knowledge gaps on indoor SVOCs distribution. However, their applicability for indoor environments and the assessment of human health risks lack sufficient experimental data. To address this issue, we performed an indoor calibration study of polyurethane foam (PUF) PAS deployed in a double-dome chamber, covering both legacy and new SVOC classes. PUF-PAS and a continuous low-volume active air sampler (AAS) were co-deployed for a calibration period of twelve weeks. Based on the results from this evaluation, PUF-PAS in a double-bowl chamber is recommended for indoor sampling and health risk assessment of gas phase SVOCs, including novel brominated flame retardants (nBFR) providing sufficient exposure time is applied. Data for particle associated SVOCs suffered from significant uncertainties caused by low level of detection and low precision in this study. A more open chamber design for indoor studies may allow for higher sampling rates (RS) and better performance for the particle associated SVOCs.

Disposition of phenolic and sulfated metabolites after inhalation exposure to 4-chlorobiphenyl (PCB3) in female rats

PCBs, such as PCB3, are air contaminants in buildings and outdoors. Metabolites of PCB3 are potential endocrine disrupting chemicals and genotoxic agents. We studied the disposition of phenolic and sulfated metabolites after acute nose-only inhalation exposure to airborne PCB3 for 2 h in female rats. Inhalation exposure was carried out in three groups. In the first group, rats exposed to an estimated dose of 26 μg/rat were euthanized at 0, 1, 2, and 4 h after exposure. Highest concentrations of phenols and sulfates were observed at 0 h, and the values were 7 ± 1 and 560 ± 60 ng/mL in serum, 213 ± 120 and 842 ± 80 ng/g in liver, 31 ± 27 and 22 ± 7 ng/g in lung, and 27 ± 6 and 3 ± 0 ng/g in brain, respectively. First-order serum clearance half-lives of 0.5 h for phenols and 1 h for sulfates were estimated. In the second group, rats exposed to an estimated dose of 35 μg/rat were transferred to metabolism cages immediately after exposure for the collection of urine and feces over 24 h. Approximately 45 ± 5% of the dose was recovered from urine and consisted mostly of sulfates; the 18 ± 5% of the dose recovered from feces was exclusively phenols. Unchanged PCB3 was detected in both urine and feces but accounted for only 5 ± 3% of the dose. Peak excretion of metabolites in both urine and feces occurred within 18 h postexposure. In the third group, three bile-cannulated rats exposed to an estimated dose of 277 μg/rat were used for bile collection. Bile was collected for 4 h immediately after 2 h exposure. Biliary metabolites consisted mostly of sulfates, some glucuronides, and lower amounts of the free phenols. Control rats in each group were exposed to clean air. Clinical serum chemistry values, serum T4 level, and urinary 8-hydroxy-2'-deoxyguanosine were similar in treated and control rats. These data show that PCB3 is rapidly metabolized to phenols and conjugated to sulfates after inhalation and that both of these metabolites are distributed to liver, lungs, and brain. The sulfates elaborated into bile are either reabsorbed or hydrolyzed in the intestine and excreted in the feces as phenols.

Evaluation of the release of dioxins and PCBs during kiln-firing of ball clay

Ball clay is known to be naturally contaminated with high levels of polychlorinated di-benzo-p-dioxins (PCDDs). This study evaluated the potential for PCDD, polychlorinated dibenzofuran (PCDF) and polychlorinated biphenyl (PCB) release during the kiln firing of ball clay in an art studio. Toxic equivalence (TEQ) were calculated using World Health Organization (WHO) 2005 toxic equivalence factors (TEF) and congener concentrations. Ten bags of commercial ball clay were found to have an average TEQ of 1,370 nanograms/kilogram (ng kg(-1)) dry weight (dw), almost exclusively due to PCDDs (99.98% of TEQ). After firing, none of the 29 dioxin-like analytes was measured above the limits of detection (LOD) in the clay samples. Air samples were taken during firings using both low-flow and high-flow air samplers. Few low-flow air samples contained measurable levels of dioxin congeners above the LOD. The mean TEQ in the high volume air samples ranged from 0.07 pg m(-3) to 0.21 pg m(-3) when firing ball clay, and was 0.11 pg m(-3) when no clay was fired. These concentrations are within the range measured in typical residences and well-controlled industrial settings. The congener profiles in the high-flow air samples differed from the unfired clay; the air samples had a considerable contribution to the TEQ from PCDFs and PCBs. Given that the TEQs of all air samples were very low and the profiles differed from the unfired clay, it is likely that the PCDDs in dry ball clay were destroyed during kiln firing. These results suggest that inhalation of volatilized dioxins during kiln firing of dry ball clay is an unlikely source of exposure for vocational and art ceramicists.

Environmental determinants of polychlorinated biphenyl concentrations in residential carpet dust

Polychlorinated biphenyls (PCBs), banned in the United Sates in the late 1970s, are still found in indoor and outdoor environments. Little is known about the determinants of PCB levels in homes. We measured concentrations of five PCB congeners (105, 138, 153, 170, and 180) in carpet dust collected between 1998 and 2000 from 1187 homes in four sites: Detroit, Iowa, Los Angeles, and Seattle. Home characteristics, occupational history, and demographic information were obtained by interview. We used a geographic information system to geocode addresses and determine distances to the nearest major road, freight route, and railroad; percentage of developed land; number of industrial facilities within 2 km of residences; and population density. Ordinal logistic regression was used to estimate the associations between the covariates of interest and the odds of PCB detection in each site separately. Total PCB levels [all congeners < maximum practical quantitation limit (MPQL) vs at least one congener ≥ MPQL to < median concentration vs at least one congener > median concentration] were positively associated with either percentage of developed land [odds ratio (OR) range 1.01-1.04 for each percentage increase] or population density (OR 1.08 for every 1000/mi(2)) in each site. The number of industrial facilities within 2 km of a home was associated with PCB concentrations; however, facility type and direction of the association varied by site. Our findings suggest that outdoor sources of PCBs may be significant determinants of indoor concentrations.

Polychlorinated biphenyls (PCBs) in indoor air and in serum among older residents of upper Hudson River communities

A study was conducted to evaluate the association between PCBs in residential indoor air and in the serum of older, long time residents of three upper Hudson River communities. Samples of indoor air and of serum were collected from 170 persons 55 to 74 years of age, and analyzed for PCBs using glass capillary gas chromatography. After adjusting for age, BMI, cigarette smoking, and Hudson River fish consumption with multiple linear regression analysis, the results indicated statistically significant associations between concentrations in indoor air and serum for PCB-28, a lightly chlorinated congener common in air that accumulates in serum, and PCB-105. Duration of exposure was an important factor, since among persons who had lived in their home for 39 years or more, 11 of the 12 most commonly detected congeners were significantly correlated, as was their sum (∑ PCB). Significant associations between indoor air and serum PCB concentrations also were more likely when collected in cooler months and if the two samples were collected within 20 d of each other. The study is among the first to indicate that PCB concentrations characteristic of residential indoor air are associated with a detectable increase in body burden.