In April 11, 1997 in Japan, the press released that the Ministry
of Health and Welfare of Japan revealed the results of the survey of the MSW incinerators. Of the 1,150 MSW incinerators surveyed, dioxin emissions from 72 were above 80 ng international toxic equivalents TEQ/m3, which was set as the standard for taking urgent countermeasure against dioxin emissions from the MSW incinerators by Environmental Agency of Japan. This finding strongly motivated us to investigate whether or not adverse reproductive outcomes cluster in the vicinity of these MSW incinerators with high dioxin emission levels.