Pesticide residues in human milk, Alberta, Canada--1966-70, 1977-78.

Organochlorine pesticide residues were determined in human milk of residents of Alberta, Canada, during 1966-70 and 1977-78. Levels of polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs), and some common organophosphorus pesticides were also monitored during 1977-78. Average residue levels were generally lower in 1977-78 samples, whereas the percent incidence of residues was generally lower in 1966-70 samples. beta-BHC was found in all 1977-78 samples, but was not detected in 1966-70 samples. PCBs were detected in all but two of the 1977-78 samples. Average levels of p,p'-DDT and is metabolites were substantially lower during the second period than during the first. Large increases in the average levels and percent incidences of heptachlor epoxide and o,p'-DDT have been attributed to refinements in both cleanup and gas chromatographic analysis. Although no PBBs or organophosphorus pesticides were detected in 1977-78 samples, an unidentified hydrocarbon similar to dicofol was found in all samples of that period. No correlation between donor age groups and average pesticide residue levels could be inferred.