Correlations among human plasma levels of dioxin-like compounds and polychlorinated biphenyls (PCBs) and implications for epidemiologic studies

In studies of the potential health effects of background-level exposure to organochlorine compounds (e.g., polychlorinated biphenyls, polychlorinated dibenzodioxins, and polychlorinated dibenzofurans), investigators have ofte n measured either polychlorinated biphenyls or polychlorinated dibenzodioxi ns/polychlorinated dibenzofurans-but not both. We measured polychlorinated biphenyls (including specific non-, mono-, and di-ortho congeners) and spec ific polychlorinated dibenzodioxins/dibenzofurans among 63 Canadian blood d onors. Levels of these compounds were, in general, fairly correlated. For e xample, Pearson's correlation coefficient between log total polychlorinated biphenyl and log total polychlorinated dibenzodioxins was .52. These resul ts suggest that in epidemiologic studies of health effects of background-le vel exposures to these compounds, the quantitative dose-response relation o bserved for a given compound (or class of compounds acting through a simila r mechanism) may easily be miscalibrated or confounded.