POLYCHLORINATED NAPHTHALENES AND OTHER ORGANOCHLORINE CONTAMINANTS INSWEDISH HUMAN-MILK, 1972-1992

The concentrations of polychlorinated naphthalenes (PCNs) were determi ned together with polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), 1,1-bis-(4-chlorophenyl)-2,2,2-trichlo ro (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 m ulticomponent analysis of organochlorine environmental contaminants wa s adapted for simultaneous analysis of PCNs. The mean recoveries of se ven chlorinated naphthalene (CN) congeners added to milk prior to extr action were 76-99%. Similar recoveries were obtained for the commercia l 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 decre ase in the concentrations of PCNs as was of the other organochlorine c ontaminants 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 fr om 100 to 39 pg/g milk fat.