PCBs in passaic river sediments: Some analytical considerations

Analytical results for Aroclor may contain a great deal of uncertainty if t he relative ratios of certain PCB congeners are substantially altered follo wing differential environmental degradation. Selective degradation of PCB c ongeners has been shown to occur in biological tissues, and recent studies have shown that Aroclor analyses may significantly underestimate PCB concen trations in fish. The purpose of this study is to assess whether a similar phenomenon can occur with PCB-impacted sediments. Five hundred and thirty-s even sediment samples from the Passaic River were analyzed for Aroclors and selected non-ortho (PCB #77, 126 and 169) and mono-ortho (PCB #105, 114 11 8 123, 156, 157 167 and 189) coplanar PCB congeners. Aroclors 1248 and 1254 were detected in 67 and 53% of the samples, respectively; 54 samples (appr oximately 10%) did not contain detectable levels of any Aroclors. In these 54 samples, the sum of the detected PCB congener concentrations was signifi cantly greater, on average, than the Aroclor limit of defection by approxim ately threefold. In individual samples the sum of the PCB congeners exceede d the Aroclor limit of detection by up to 36-fold. In those samples in whic h Aroclors were detected the summed PCB congener concentrations exceeded th e Aroclor 1248 and 1254 concentrations, on average, by 41 and 33%, respecti vely. Given the fact that only a fraction of the 209 PCB congeners were qua ntitated, these findings indicate that Arocolor data may significantly unde restimate total PCB concentrations in Passaic River sediments. Total PCB da ta obtained from fetal homologue analysis indicated that Aroclor results un derestimated fetal PCB mass by up to 43-fold. These findings suggest that c aution is required when comparing Aroclor sediment data from the Passaic Ri ver to total PCB sediment criteria.