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Shu-Li Wang,¹ Pen-Hua Su,² Shiang-Bin Jong,³ Yueliang L. Guo,⁴ Wei-Ling Chou,¹ and Olaf Päpke⁵

¹Division of Environmental Health and Occupational Medicine, National Health Research Institutes, and Graduate Institute of Occupational Safety and Health, Kaohsiung Medical University, Kaohsiung, Taiwan; ²Institute of Medicine, Chung Shan Medical University, and Department of Pediatrics, Chung Shan Medical University Hospital, Taichung, Taiwan; ³Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; ⁴Department of Occupational and Environmental Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan; ⁵ERGO Research Laboratory, Hamburg, Germany

Abstract
The aim of this study is to examine the association between transplacental exposure to dioxins/polychlorinated biphenyls (PCBs) and thyroid and growth hormones in newborns. We recruited 118 pregnant women, between 25 and 34 years of age, at the obstetric clinic. Personal data collected included reproductive and medical histories and physical factors. Clinicians gathered placental and umbilical cord serum upon delivery and carefully scored the 118 newborns, making both structural and functional assessments. We analyzed placentas for 17 polychlorinated dibenzo-p-dioxins and dibenzofurans and 12 dioxin-like PCB congeners with the World Health Organization-defined toxic equivalent factors, and six indicator PCBs by high-resolution gas chromatography and high-resolution mass spectrometry. We analyzed thyroid and growth hormones from cord serum using radioimmunoassay. Insulin-like growth factor (IGF) -1, IGF-binding globulin-3, and thyroxine thyroid-stimulating hormone (T₄ TSH) were significantly associated with increased placental weight and Quetelet index (in kilograms per square meter ; correlation coefficient r = 0.2-0.3 ; p < 0.05) . Multivariate analyses showed independently and significantly decreased free T₄ (FT₄) TSH with increasing non-ortho PCBs (r = -0.2 ; p < 0.05) . We suggest that significant FT₄ feedback alterations to the hypothalamus result from in utero exposure to non-ortho PCBs. Considering the vast existence of bioaccumulated dioxins and PCBs and the resultant body burden in modern society, we suggest routine screening of both thyroid hormone levels and thyroid function in newborns. Key words: dioxins, infant, placenta, prenatal exposure delayed effects, thyroid hormones. Environ Health Perspect 113:1645-1650 (2005) . doi:10.1289/ehp.7994 available via http://dx.doi.org/ [Online 27 June 2005]

Address correspondence to S.-L. Wang, No. 35, Keyan Rd., Zhunan Town, Miaoli County 350, Taiwan. Telephone: 886-935-285848. Fax: 886-7-316 2725. E-mail: slwang@nhri.org.tw

We are grateful to L.-Y. Lin for placenta gathering, C.-N. Huang for providing endocrinology documents, H.-Y. Yu for specimen collections, and K.-H. Chang for final statistical assistance.

The study was performed under grants from the National Health Research Institutes (EO-091-PP-01 and EO-092-PP-05) , Taiwan.

The scientific content of the manuscript has been reviewed and approved for publication by the Division of Environmental Health and Occupational Medicine (DEHOM) of the National Health Research Institutes (NHRI) . Approval for publication does not necessarily signify that the content reflects the view and policies of the DEHOM/NHRI, or condemnation or endorsement and recommendation for use on this issue presented.

The authors declare they have no competing financial interests.

Received 4 February 2005 ; accepted 27 June 2005.