Methylsulfonyl metabolites of PCBs and DDE in human milk in Sweden, 1972-1992

A multicomponent method used for analysis of organochlorine pesticides, polychlorinated biphenyls (PCBs), naphthalenes, dibenzo-p-dioxins, and dibenzofurans was adapted for the analysis of methylsulfonyl metabolites of chlorinated biphenyls (MeSO(2)-CBs) and of p,p'-DDE (MeSO(2)-DDE) in human milk. The extraction and initial purification was made by liquid-gel partitioning. Additional purification and separation steps were achieved by adsorption and gel permeation chromatography. The mean recoveries of 23 MeSO(2)-CBs and MeSO(2)-DDE standards, added to the milk before extraction, were 80-97%. Human milk sampled in Stockholm during 1972, 1976, 1980, 1984/85, 1990, 1991, and 1992 was analyzed by GC-MS. During the time course studied, the concentrations of MeSO(2)-CBs decreased from approximately 9 to 2 ng/g lipids and of MeSO(2)-DDE from 5 to 0.4 ng/g lipids. The concentrations of MeSO(2)-CBs and MeSO(2)-DDE correlated to the levels of total PCB and p,p'-DDE, respectively. 3-MeSO(2)-DDE was the major isomer of the aryl methyl sulfones studied in the milk. PCB methyl sulfones with five and six chlorine atoms in the molecule were predominant among the PCB methyl sulfones. Generally, the concentrations of 4-MeSO(2)-CBs were higher than the corresponding 3-MeSO(2)-CB compound. The major MeSO(2)-CBs in the milk were 4-MeSO(2)-2,5,2',3',4'-pentaCB (4-87) and 4-MeSO(2)-2,3,6,2',4',5'-hexaCB (4-149).