The concentrations of polychlorinated naphthalenes (PCNs) were determined together with polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), 1,1-bis-(4-chlorophenyl)-2,2,2-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) in milk, sampled in the course of 1972-92 from mothers living in Stockholm. A previously developed method for multicomponent analysis of organochlorine environmental contaminants was adapted for simultaneous analysis of PCNs. The mean recoveries of seven chlorinated naphthalene (CN) congeners added to milk prior to extraction were 76-99%. Similar recoveries were obtained for the commercial PCN product Halowax 1014. The pattern of PCNs in milk differed to a great extent from that in the commercial PCN products. The dominating congeners in breast milk were 1,2,3,5,7-pentachloronaphthalene (CN-52), 1,2,3,4,6,7- and/or 1,2,3,5,6,7-hexachloronaphthalene (CN-66/ CN-67) and one unidentified tetrachloronaphthalene. There was a notable decrease in the concentrations of PCNs as was of the other organochlorine contaminants in milk from 1972 to 1992. During this time period the sum of CN congeners decreased from 3,081 to 483 pg/g milk fat and the sum of toxic equivalents of dioxin and dioxin-like compounds decreased from 100 to 39 pg/g milk fat.

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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 (MeSO2-CBs) and of p,p'-DDE (MeSO2-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 MeSO2-CBs and MeSO2-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 MeSO2-CBs decreased from approximately 9 to 2 ng/g lipids and of MeSO2-DDE from 5 to 0.4 ng/g lipids. The concentrations of MeSO2-CBs and MeSO2-DDE correlated to the levels of total PCB and p,p'-DDE, respectively. 3-MeSO2-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-MeSO2-CBs were higher than the corresponding 3-MeSO2-CB compound. The major MeSO2-CBs in the milk were 4-MeSO2-2,5,2',3',4'-pentaCB (4-87) and 4-MeSO2-2,3,6,2',4',5'-hexaCB (4-149).

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