Toxaphene and other chlorinated compounds in human milk from northern and southern Canada: a comparison.

Human milk from residents of northern Canada (Keewatin) was compared to that in national surveys of southern Canada with respect to residues of toxaphene, PCBs, PCDD/PCDFs, chlordane, and several other persistent organic compounds. Concentrations of toxaphene were approximately ten-fold higher in specimens from Keewatin than from the south. Toxaphene concentrations in samples from the Great Lakes Basin collected in 1992 were not significantly (p < 0.05) different from those of the rest of Canada; however they were significantly (p < 0.05) lower than concentrations reported in a 1986 survey. Hexachlorobenzene, trans nonachlor and oxychlordane were three to five times higher in concentration in the Keewtin samples than in samples reported in the 1992 national survey. Total PCB congeners, DDTs, PCDD/PCDFs, and other chlorinated compounds were not significantly higher in northern samples.