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Updated: Aug 15, 2026
Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants
Published on: March 6, 2018
In utero exposure to dioxins and polychlorinated biphenyls and its relations to thyroid function and growth hormone
Shu-Li Wang1, Pen-Hua Su, Shiang-Bin Jong
1Division of Environmental Health and Occupational Medicine, National Health Research Institutes, and Graduate Institute of Occupational Safety and Health, Kaohsiung Medical University, Kaohsiung, Taiwan. slwang@nhri.org.tw
Insights
In utero exposure to dioxins and polychlorinated biphenyls (PCBs) is linked to altered thyroid hormone feedback in newborns. Routine newborn screening for thyroid function is recommended due to widespread environmental contamination.
Area of Science:
- Environmental Health
- Endocrinology
- Neonatal Health
Background:
- Persistent organic pollutants like dioxins and polychlorinated biphenyls (PCBs) are widespread environmental contaminants.
- Transplacental exposure during pregnancy can impact fetal development and endocrine function.
- Thyroid and growth hormones are critical for neonatal development and well-being.
Purpose of the Study:
- To investigate the association between transplacental exposure to dioxins/PCBs and levels of thyroid and growth hormones in newborns.
- To assess the impact of specific dioxin and PCB congeners on neonatal endocrine parameters.
- To explore potential alterations in hypothalamic-pituitary-thyroid axis feedback mechanisms.
Main Methods:
- Recruitment of 118 pregnant women and assessment of newborns at delivery.
- Analysis of placental tissue for dioxins and PCBs using high-resolution gas chromatography and mass spectrometry.
- Measurement of neonatal thyroid hormones (T4, TSH) and growth hormones (IGF-1, IGFBP-3) in cord serum via radioimmunoassay.
Main Results:
- Insulin-like growth factor (IGF)-1, IGF-binding globulin-3, and thyroxine x thyroid-stimulating hormone (T4 x TSH) showed significant associations with placental weight and body mass index.
- Multivariate analyses revealed a significant decrease in free thyroxine (FT4) x TSH with increasing levels of non-ortho PCBs.
- Evidence suggests that in utero exposure to non-ortho PCBs may lead to significant alterations in FT4 feedback to the hypothalamus.
Conclusions:
- Transplacental exposure to non-ortho PCBs is associated with altered thyroid hormone regulation in newborns.
- The findings highlight the potential endocrine-disrupting effects of environmental dioxins and PCBs on fetal development.
- Routine screening of thyroid hormone levels and function in newborns is suggested due to the prevalence of these contaminants.
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 x thyroid-stimulating hormone (T4 x 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) x 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.
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