GC/MS analysis of PCB congeners in blood of the harbor seal Phoca vitulina from San Francisco Bay

Here we report a validated technique for quantifying up to 20 specific PCB congeners in 1–2 g samples of whole blood with a detection limit below 1 ng/g (ppb) wet weight. Specimens were analyzed from 14 harbor seals sampled in south San Francisco Bay, California during 1991–1992. Ratios of specific congeners to PCB-153, and other aspects of congener pattern, agreed with published values for PCBʹs detected in seal blood. PCB-153 constituted 30 percent of our ΣPCB values. The mean ΣPCB concentration for the San Francisco Bay seals was 50 ppb, about three times the average level reported for blood of captive seals fed exclusively on fish from the Balticʹs PCB-contaminated Dutch Wadden Sea. Such experimental populations have exhibited depressed reproductive success and impaired immune function. These findings support concerns about the ecological effects of PCB contamination in San Francisco Bay.