Coating effects on the glass adsorption of polychlorinated biphenyl (PCB) congeners.

The effects of coating materials on polychlorinated biphenyl (PCB) adsorption in aqueous solution were assessed in an attempt to minimize PCB sorption loss during sampling processes. A coating material, which enhances PCB adsorption and allows adsorbed PCBs to be readily extracted by solvents, can act as a sampling concentrator to reduce PCB losses from both adsorption and evaporation. Several coating materials were evaluated, including paraffin oil, silicone oil, dimethyldichlorosilane (Sylon-CT), Prosil 28 and polydimethylsiloxane (PDS) with viscosity 0.65, 50 (PDS 50), and 500 (PDS 500) cSt. PDS and silicone oil enhanced adsorption for all five congeners examined (IUPAC No. 28, 52, 101, 138, and 180). Sylon-CT, paraffin oil and Prosil 28 had inconsistent effects on adsorption of different congeners. Desorption of adsorbed PCBs onto all coating types was assessed. The recovery efficiency of extracting PCBs with solvents was enhanced greatly with all coatings as opposed to non-coated surfaces, with the exception of paraffin oil. Coating with silicon oil, PDS 50, and 500 resulted in virtually 100% recovery of adsorbed PCBs. It was also found that Teflon containers were poor substitutes for glass containers and failed to minimize PCB losses. Among the materials studied, the best coating that could be used as a sampling concentrator was PDS 500.

Pancreatic cancer and serum organochlorine levels.

Occupational exposure to p,p'-dichlorodiphenyltrichloroethane (DDT) has been associated with increased pancreatic cancer risk. We measured organochlorine levels in serum obtained at the study enrollment from 108 pancreatic cancer cases and 82 control subjects aged 32-85 years in the San Francisco Bay Area between 1996 and 1998. Cases were identified using rapid case-ascertainment methods; controls were frequency-matched to cases on age and sex via random digit dial and random sampling of Health Care Financing Administration lists. Serum organochlorine levels were adjusted for lipid content to account for variation in the lipid concentration in serum between subjects. Median concentrations of p,p'-dichlorodiphenyldichloroethylene (DDE, 1290 versus 1030 ng/g lipid; P = 0.05), polychlorinated biphenyls (PCBs; 330 versus 220 ng/g lipid; P<0.001), and transnonachlor (54 versus 28 ng/g lipid; P = 0.03) were significantly greater among cases than controls. A significant dose-response relationship was observed for total PCBs (P for trend <0.001). Subjects in the highest tertile of PCBs (> or =360 ng/g lipid) had an odds ratio (OR) of 4.2 [95% confidence interval (CI) = 1.8-9.4] compared to the lowest tertile. The OR of 2.1 for the highest level of p,p'-DDE (95% CI = 0.9-4.7) diminished (OR = 1.1; 95% CI = 0.4-2.8) when PCBs were included in the model. Because pancreatic cancer is characterized by cachexia, the impact of this on the serum organochlorine levels in cases is difficult to predict. One plausible effect of cachexia is bioconcentration of organochlorines in the diminished lipid pool, which would lead to a bias away from the null. To explore this, a sensitivity analysis was performed assuming a 10-40% bioconcentration of organochlorines in case samples. The OR associated with PCBs remained elevated under conditions of up to 25% bioconcentration.

Measurement of PCBs, DDE, and hexachlorobenzene in cord blood from infants born in towns adjacent to a PCB-contaminated waste site.

There are limited data on the concentrations of common contaminants--polychlorinated biphenyls (PCBs), dichlorodiphenyl dichloroethene (pp'-DDE) and hexachlorobenzene (HCB)--in umbilical cord blood. Cord blood provides the primary direct measure of prenatal exposure to these contaminants, the key determinant of PCBs' neurodevelopmental toxicities. The objective of this study was to characterize cord blood levels of PCBs, pp'-DDE, and HCB among 751 infants who were born between 1993 and 1998 to mothers residing adjacent to a PCB-contaminated harbor in New Bedford, Massachusetts, and for whom the neurodevelopmental toxicities of these compounds are being studied. We refined standard analytic methods to optimize the sensitivity and precision of trace-level PCB, p,p'-DDE, and HCB measurements in blood. Using these methods, we measured the concentrations of 51 individual PCBs, their sum (sum(PCB)), p,p'-DDE, and HCB in cord serum. With correction for background contamination, the respective mean+/-SD cord serum concentrations of sum(PCB), p,p'-DDE, and HCB were 0.54+/-0.83, 0.48+/-0.94, and 0.03+/-0.04 ng/g serum. These concentrations were generally lower than those in most of the few published studies with congener-specific measures of PCBs in cord blood. However, for less-chlorinated PCB congeners (e.g., congeners 99 and 118), study samples had concentrations comparable to those in other populations, including groups at risk for high dietary PCB exposure. Of note, the contaminated harbor sediment has a relatively high proportion of less-chlorinated PCB congeners. Thus, although the sum(PCB) in study infants was not higher than concentrations in infants studied elsewhere, the relative predominance of less-chlorinated congeners was generally consistent with the characteristics of the contaminated site.