Determination of PCB metabolites in Canadian human milk

Chlorinated biphenyl methylsulfones and biphenylols were determined in samples of human milk from Canadian donors. Fifty samples containing an average of 10.8 ng g−1 (w/w) of total PCBs were found to contain an average of 68 pg g−1 of chlorinated biphenyl methylsulfone. The major congeners were 3-methylsulfonyl-2,2′,4′,5,5′ pentachlorobiphenyl, 4-methylsulfonyl-2,2′,3′,4′,5,-pentachlorobiphenyl and 4-methylsulfonyl-2,2′,3′,5,5′,6′-hexachlorobiphenyl. Twelve of these samples were analyzed for five chlorinated biphenylols and the 4-methoxy2,2′,3,4′,5,5′,6-heptachlorobiphenylol congener was detected in all at an average concentration of 1.9 pg g−1. The chlorinated biphenylols appear to be minor residual metabolites in human milk from the general population. The fifty samples with an average of 8.4 ng gʹ of p,pʹ-DDE also contained an average of 16.5 pg g−1 of the corresponding methylsulfone. Both the total PCB methylsulfone and p,p′ DOE methylsulfone were correlated with total PCB and p,p′ DOE contents, respectively.