Polychlorinated biphenyls (PCBs) are synthetic chemicals, manufactured in volume from about 1929 to the 1970s. Environmental contamination by PCBs has been documented in various substances, including human tissue. PCBs have been measured in human tissue by a variety of analytical methods. PCB levels have been reported as an approximation of total PCB content expressed in terms of a commercial mixture, by identification and quantification of chromatographic peaks, or by qualitative and quantitative characterization of specific congeners. Until recently, the coplanar mono-ortho- and di-ortho substituted PCBs, which are especially toxic and present in significant concentration in humans from industrial countries, had not been measured in human tissues. Examples of various types of commonly used analyses are presented in general population subjects and in persons who experienced special exposure. In this paper, the usefulness of PCB blood determinations following potential exposure is demonstrated, and their application in health studies is illustrated from a number of case studies. Coplanar PCB, mono-ortho-substituted and di-ortho-substituted PCB levels in human blood are presented and compared with polychlorinated dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in the U.S. population. Dioxin toxic equivalents for the two groups of chemicals are calculated and compared. It is found that mono-ortho-substituted and, to a lesser extent, coplanar PCBs, contribute substantially to dioxin toxic equivalents (TEq) in blood from U.S. adults. Because of substantial PCB contribution to dioxin toxic equivalents, total dioxinlike toxicity can only be determined if dioxins, dibenzofurans, and dioxinlike PCBs are measured.(ABSTRACT TRUNCATED AT 400 WORDS)

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A total of 412 breast milk samples from women in all provinces of Canada were analysed for polychlorinated biphenyls, eight chlorinated benzenes, 2,3-dichloronaphthalene, Mirex, alpha, beta, gamma and delta hexachlorocyclohexane, alpha and gamma chlordane, oxychlordane, transnonachlor, p,p'-DDT and some analogues, heptachlor epoxide, dieldrin and octachlorostyrene. No delta-hexachlorocyclohexane, heptachlor or aldrin were found in any of the samples, while median levels of the 1,2,4- and 1,3,5-trichlorobenzene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzenes, gamma chlordane, o,p'-DDT and octachlorostyrene were all less than the minimum detectable level (MDL). All other compounds were present at median levels ranging from < 0.1 to 7.2 ng/g whole milk, but did not occur in all samples. Di to tetrachlorobenzenes, except 1,2,4-trichlorobenzene, 2,3-dichloronaphthalene and alpha-chlordane were observed in < 50% of the samples. From 1967 to 1986 a steady decline of hexachlorobenzene, gamma-hexachlorocyclohexane, DDTs, heptachlor epoxide and dieldrin was observed in Canadian breast milk. In addition, a decrease in some chlorinated benzenes, gamma-hexachlorocyclohexane and PCBs was also observed between 1982 and 1986. Levels of oxychlordane and trans-nonachlor remained constant. Canadian breast milk contamination appears to be one of the lowest among the industrialized nations. Regional and provincial differences in residue levels appeared minimal, although more often samples from Quebec and British Columbia had higher levels of some contaminants, such as oxychlordane, than samples from other provinces. No relationship was found between maternal age and residue levels, but some contaminants, such as PCBs, were significantly higher in the milk of mothers who breastfed their first child as compared to multiparous mothers. Breast milk residue levels were not related to fish consumption.