Comparability and Precision of Serum PCB Measurements

Abstract

The 95% prediction interval for single measurements of serum "Aroclor" reported by a reputable commercial analyst was found to be approximately +/- 42%. The geometric mean serum PCB levels in a population of capacitor workers who had formerly had direct exposure to the commercial PCBs--Aroclors 1016, 1242, and 1254-were found to be alternatively reportable as 1905 ppb minimum initial PCBs (as calculated from most persistent peaks present); 1093 ppb non-overlapping analytical "Aroclor" levels (as calculated by the conventional sum-of-the-peak-heights method); 303 ppb total PCBs actually present; or 19 ppb "human PCB" (as calculated by the NHMP procedure). The broad spread in reportable values was relatable to the PCB isomer distribution and clearance patterns in the occupationally exposed population.

Effects of PCB exposure on biochemical and hematological findings in capacitor workers.

“…We have shown elsewhere that the minimum initial concentrations of Aroclors 1016 plus 1242 required to account for the most persistent LPCB peaks were about 7.5 times the residual LPCB levels (27). Thus, the minimal LPCB uptake by the study population may be estimated as 15 g (2.5-92 g).…”

“…The latter are now more commonly described in terms of values for LPCB ("lower PCBs," i.e., all isomers having gas chromatographic retention times on silicone less than that of DDE, which comes in the middle of the pentachlorobiphenyl range), and HPCB ("higher PCBs," i.e., those with retention times > DDE) with the sum of LPCB and HPCB representing the total PCB present (TPCB). We have shown elsewhere (27) …”

“…The observed distributions of PCB isomer peaks in the capacitor workers' chromatograms are also described elsewhere (27) Because of the differences in PCB composition between the serum samples and the standards, such values overstate the amounts of PCB actually present. The latter are now more commonly described in terms of values for LPCB ("lower PCBs," i.e., all isomers having gas chromatographic retention times on silicone less than that of DDE, which comes in the middle of the pentachlorobiphenyl range), and HPCB ("higher PCBs," i.e., those with retention times > DDE) with the sum of LPCB and HPCB representing the total PCB present (TPCB).…”

“…The mean serum HPCB level in 1976 was estimated mers (27,34,35) resulting either from exposures to to be 8 ppm (2-34 ppm), corresponding to a mean body Aroclor 1242 (which contained a few percent of the lower (Table 3). We have shown elsewhere that the minimum initial concentrations of Aroclors 1016 plus 1242 required to account for the most persistent LPCB peaks were about 7.5 times the residual LPCB levels (27).…”

“…The chest X-rays were read by a local radiologist (R. C. Batt) who coded the findings according to the ILO/UC criteria (CRC/NIOSH (M) 2 (27).…”