Risk Evaluation for the Incidence of Congenital Hypothyroidism in Prenatal Multiple Exposure to Toxic Chemical Compounds

血清浓度（平均值±S.D.）先天性甲减或克汀病筛查阳性新生儿64例（男38例，女26例），TSH、fT_3、fT_4分别为35.4±49.7 μIU/ml、3.07± 0.89pg/ml、1.09± 0.32ng/dl。108例（男58例，女50例）筛查阴性新生儿，血清中的浓度分别为8.56±5.62 μIU/ml、3.60±0.84 pg/ml和2.46 ± 0.67 ng/dl。TSH阳性组新生儿的TSH浓度明显高于阴性组，fT_3和fT_4则明显低于阴性组。患有克汀病的新生儿：在产后4周内采集的母乳样品中，有机氯化合物的检出率分别为：二恶英（TEQ-pg/g）：0.52±0.40：0.28± 0.15，PCBs（ng/g）：2.6±2.：滴滴涕：滴滴涕（1.5± 1.3 ng/g）;六六六：六六六（7.2±6.8 ng/g）;滴滴涕：六六六（2.7± 3.4 ng/g）;六六六：六六六（1.6±1.7 ng/g）;六六六：六六六（0.30±0.22 ng/g）。根据这些分析结果，母乳中有机氯化合物（HCH除外）的浓度在生下先天性甲状腺功能减退症新生儿的母亲中明显高于生下正常新生儿的母亲，因此，本研究表明，在日本，产前多次接触此类有机氯化合物可能会导致先天性甲状腺功能减退症。

Serum concentrations (Mean±S.D.) of TSH, fT_3 and fT_4, respectively, were 35.4±49.7 μIU/ml, 3.07±0.89 pg/ml and 1.09±0.32 ng/dl in 64 (male:38,female:26) positive neonates in the mass-screening for congenital hypothyroidism or cretinism. In 108 (male:58,female:50) negative neonates in this mass-screening, the respective serum concentrations were 8.56±5.62 μIU/ml, 3.60±0.84 pg/ml and 2.46 ± 0.67 ng/dl. Concentrations of TSH were significantly higher in the positive neonates than in the negative neonates, and those of fT_3 and fT_4 lower in the former ones than in the latter ones.Contamination levels (Mean±S.D., neonates with cretinism : normal neonates) of the organochlorine compounds in the breast milk samples which were collected within 4 weeks after childbirth were as follows: Dioxins (TEQ-pg/g);0.52±0.40:0.28±0.15,PCBs (ng/g);2.6±2.:1.5±1.3,DDT (ng/g) ;7.2±6.8:3.7±3.7,HCH (ng/g);2.7±3.4:1.3±1.2,Chlordane (ng/g);1.6±1.7:0.76±0.68 and HCB (ng/g);0.30±0.22:0.17±0.18. According to these analytical results, concentrations of the organochlorine compounds except HCH in the breast milk were significantly higher in the mothers who gave birth to neonates with congenital hypothyroidism than in those who gave birth to normal neonates.Consequently, this study suggests higher prenatal multiple exposures to such organochlorine compounds may cause congenital hypothyroidism in Japan.