An Investigation of Homes with High Concentrations of PCDDs, PCDFs, and/or Dioxin-Like PCBs in House Dust

As part of the University of Michigan Dioxin Exposure Study, the 29 congeners of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls that have World Health Organization consensus toxic equivalency factors were measured in house dust from 764 homes using a population-based sampling design over selected regions in five Michigan counties. Twenty homes had a total toxic equivalency in house dust that was more than 2.5 standard deviations above the mean (i.e., defined to be outliers). This follow-up investigation describes the outlier house dust measurements and corresponding soil measurements and explores possible sources of these toxins in house dust. The congener distributions in the house dust outliers varied and were dominated (i.e., >50% of the total toxic equivalency) by either polychlorinated dibenzo-p-dioxins (n = 9), polychlorinated dibenzofurans (n = 1), or dioxin-like polychlorinated biphenyls (n = 9). Likely sources of contamination of house ...