Estimating the half-lives of PCB congeners in former capacitor workers measured over a 28-year interval

Abstract

To date, most estimates of the half-life of polychlorinated biphenyls (PCBs) in humans have been based on relatively short follow-up periods. To address this issue, we determined the half-lives of PCB congeners of occupational origin in the serum of former capacitor workers as part of a study conducted in [2003][2004][2005][2006] F approximately 28 years after their last occupational exposure. A total of 241 persons from a source population of 6798 former capacitor workers were interviewed and asked to donate a blood sample for serum PCB congener analysis. A subgroup of 45 participants also had serum archived from 1976 and reanalyzed for the same 27 PCB congeners by the same laboratory. Our estimates of the half-lives of the congeners among these 45 persons were longer than those reported by Wolff et al. (1992), due primarily to the much longer interval between exposure and determination of serum PCB concentrations. Half-lives were significantly greater for the heavy versus light occupational congeners, for women versus men and for those with low versus high initial exposure. Current serum total PCB concentrations, expressed as the geometric mean of wet weight data, averaged 6.7 ng/g for the entire 241-person cohort, which represents a 10-fold decrease from values reported in the late 1970s, but is still nearly twice the average for persons of similar age residing in the same area, but without occupational exposure. In addition, current serum PCB concentrations remained significantly and positively associated with earlier occupational exposure, but were not associated with fresh water fish consumption. In general, the results support a consistent and long-duration trend of increased PCB body burden in this cohort of former capacitor workers compared with non-occupationally exposed individuals. The results may aid in further understanding the toxicological/epidemiological consequences of exposure to PCBs in humans.

Sex, BMI and age in addition to dietary intakes influence blood concentrations and congener profiles of dioxins and PCBs

“…On the other hand, and in line with our findings, PCB half-lives were 1.5-10 times longer in women than in men in former capacitor workers [23]. In contrast to what was found for PCDD/Fs and ndl-PCBs, neither sex nor dietary intakes were important covariates for the dl-PCBs in our study.…”

Bias in half-life estimates using log concentration regression in the presence of background exposures, and potential solutions

“…For errors that are small relative to the predicted log biomarker concentrations, the denominator is approximately equal to c 1 so E 1 k % c3 c1 , the approximation used in Eqs. (8) and (9).…”

“…(8) and (9) provide close approximations to the bias in half-life estimates from background exposures under the single compartment pharmacokinetic model for evenly spaced samples.…”

“…Equation (9) is derived for the special case in which n ¼ 2, so the calculations in Eqs. (8) and (9) are identical for the German cohort.…”

Historical reconstruction of polychlorinated biphenyl (PCB) exposures for workers in a capacitor manufacturing plant

“…For outcomes with short indication and latency periods, measurements of current exposures may serve as reasonable surrogates for exposure in the disease induction period; however, for PCBs with both short (lower chlorinated PCBs; Phillips et al 1989) and long (higher chlorinated PCBs; Seegal et al 2011;Wolff et al 1992) biological half-lives current levels can provide only limited information on historical exposures. To reflect this, the JEM was assessed for potential daily PCB exposures in each job by route of exposures, and then the historical evolutions of PCB exposures were applied using modifying era factors.…”