Assessment of human health risk of dioxins in Japan.

The human health risk of dioxins was evaluated for four Japanese receptor groups: the general population, local residents living near a municipal solid waste incinerator, heavy fish consumers, and their infants and fetuses. In describing the risk for these groups, four endpoints, namely, cancer, reproductive dysfunction, endometriosis and neurobehavioral effect, were considered, and the incremental cancer risk and margin of exposure (MOE) corresponding to these endpoints were calculated, based on three measures of dosimetry; average daily intake, area under the curve, and body burden. The uncertainties of these risk descriptors were also evaluated by probabilistic analysis. Although the estimated risk of cancer and reproductive dysfunction were not exceptionally high in the three adult receptor groups, the MOE values for endometriosis were not sufficiently high to guarantee safety against this endpoint. Furthermore, the MOE values for neurobehavioral effects on infants and fetuses suggest that dioxins may cause a considerable risk to those of local residents and heavy fish consumers.