Both Aroclor and non-Aroclor sources of airborne polychlorinated biphenyls (PCBs) were found in residential homes. We deployed passive air samplers at 16 residences and found PCB-47, PCB-51, and PCB-68 to account for up to 50% of measured indoor ΣPCBs (2700 pg m). Although PCB-47 and PCB-51 are neurotoxins present in Aroclor mixtures (<2.5 and <0.3 wt %, respectively), we found them at much higher levels than expected for any Aroclor source. PCB-68 is not present in Aroclor mixtures. Another non-Aroclor congener, PCB-11, a byproduct of pigment manufacturing, was found inside and outside of every household and was frequently the predominate congener. We conducted direct measurements of surface emissions and identified finished cabinetry to be a major source of PCB-47, PCB-51, and PCB-68. We hypothesize that these congeners are inadvertent byproducts of polymer sealant manufacturing and produced from the decomposition of 2,4-dichlorobenzoyl peroxide used as an initiator in free-radical polymerization of polyester resins. The presence of these three compounds in polymer products, such as silicone, has been widely noted, but to our knowledge they have never been shown to be a significant environmental source of PCBs.
Polychlorinated biphenyls (PCBs) are known human carcinogens that are byproducts of pigment manufacturing and found in colorants used to tint consumer paints sold in the United States and elsewhere. PCBs have the potential to be emitted from paint containing these pigments. To quantify the gas-phase emissions of ∑PCBs, we used polyurethane foam (PUF) to capture emissions from freshly applied colorants. Some PCB emissions were detected on the PUF after one day. After six weeks, all PCBs found in the colorant were also found on the PUF. Even the fully chlorinated PCB209 was emitted from green colorant. Mono-and dichlorinated PCBs were released from the colorant at a faster rate than the higher chlorinated congeners. By the end of the experiment all the lower chlorinated congeners were absent from the colorant while more than 75% of the higher chlorinated congeners remained in the sample. The rate of PCB emissions from paint colorants is a function of the surface/air equilibrium coefficient and the presence of water accelerates the emissions. Although concentrations of PCBs in colorants are less than 285 ng g −1 , PCB emissions from colorants in paint can cause environmentally relevant concentrations of ≥500 pg m −3 within hours of painting a room.
Airborne polychlorinated biphenyl
(PCB) concentrations are higher
indoors than outdoors due to their historical use in building materials
and their presence in modern paints and surface treatments. For some
populations, including school children, PCB levels indoors result
in inhalation exposures that may be greater than or equivalent to
exposure through diet. In a school, PCB exposure may come from multiple
sources. We hypothesized that there are both Aroclor and non-Aroclor
sources within a single school and that PCB concentration and congener
profiles differ among rooms within a single building. To evaluate
this hypothesis and to identify potential localized sources, we measured
airborne PCBs in nine rooms in a school. We found that schoolroom
concentrations exceed outdoor air concentrations. Schoolroom concentrations
and congener profiles also varied from one room to another. The concentrations
were highest in the math room (35.75 ng m–3 ±
8.08) and lowest in the practice gym (1.54 ng m–3 ± 0.35). Rooms in the oldest wing of the building, originally
constructed between 1920 and 1970, had the highest concentrations.
The congener distribution patterns indicate historic use of Aroclor
1254 as well as modern sources of non-Aroclor congeners associated
with paint pigments and surface coatings. Our findings suggest this
noninvasive source identification method presents an opportunity for
targeted source testing for more cost-effective prioritization of
materials remediation in schools.
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