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

64例（男38例，女26例）先天性甲状腺功能减退或克汀病筛查阳性新生儿血清TSH、fT_3、fT_4浓度分别为35.4±49.7 μIU/ml、3.07±0.89 pg/ml和1.09±0.32 ng/dl。在108例（男58例，女50例）阴性新生儿中，血清浓度分别为8.56±5.62 μIU/ml、3.60±0.84 pg/ml和2.46±0.67 ng/dl。阳性新生儿TSH浓度明显高于阴性新生儿，fT_3、fT_4浓度低于阴性新生儿。污染水平(平均值±标准差与克汀病,新生儿:正常新生儿)有机氯化合物的母乳样本采集后4周内分娩如下:二恶英(TEQ-pg / g); 0.52±0.40:0.28±0.15,多氯联苯(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,氯丹(ng / g); 1.6±1.7:0.76±0.68和六氯苯(ng / g); 0.30±0.22:0.17±0.18。根据这些分析结果，母乳中除六氯环己烷外的其他有机氯化合物的浓度在先天性甲状腺功能减退症新生儿的母亲中明显高于正常新生儿的母亲。因此，本研究表明，在日本，较高的产前多次暴露于此类有机氯化合物可能导致先天性甲状腺功能减退。

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.