[Time serial changes in the concentrations of the etiological agents of fetal Yusho--PCDDs and PCDFs].

We determined polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in 6 preserved umbilical cords of fetal Yusho patients and in 11 preserved umbilical cords of Yusho suspected persons who were born to mothers with Yusho from 1970 to 2002, which were Yusho group. As a control, we also analyzed PCDFs and PCDDs in 15 preserved umbilical cords of babies who were born to healthy mothers, which was healthy group, in the same period of time. As a result, 2,3,4,7,8-pentachlorodibenzofuran and 1,2,3,4,7,8-hexachlorodibenzofuran, true causal agents of fetal Yusho, were only determined in the umbilical cords of fetal Yusho patients, except for one umbilical cords of Yusho suspected persons. Decreasing rate in concentrations of PCDFs and PCDDs seemed to greater in Yusho group than in healthy group during this period of time. Therefore, we considered due to high exposure to PCDFs some drug metabolizing enzymes such as aryl hydrocarbon hydroxylase were induced and the excretion of PCDFs and PCDDs were enhanced from the bodies of Yusho group. In order to clarify this hypothesis, further more detail researches are required.