Maternal Urinary Bisphenol A during Pregnancy and Maternal and Neonatal Thyroid Function in the CHAMACOS Study

Abstract

Background: Bisphenol A (BPA) is widely used in the manufacture of polycarbonate plastic bottles, food and beverage can linings, thermal receipts, and dental sealants. Animal and human studies suggest that BPA may disrupt thyroid function. Although thyroid hormones play a determinant role in human growth and brain development, no studies have investigated relations between BPA exposure and thyroid function in pregnant women or neonates.Objective: Our goal was to evaluate whether exposure to BPA during pregnancy is related to thyroid hormone levels in pregnant women and neonates.Methods: We measured BPA concentration in urine samples collected during the first and second half of pregnancy in 476 women participating in the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We also measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in women during pregnancy, and TSH in neonates.Results: Associations between the average of the two BPA measurements and maternal thyroid hormone levels were not statistically significant. Of the two BPA measurements, only the one taken closest in time to the TH measurement was significantly associated with a reduction in total T4 (β = –0.13 µg/dL per log2 unit; 95% CI: –0.25, 0.00). The average of the maternal BPA concentrations was associated with reduced TSH in boys (–9.9% per log2 unit; 95% CI: –15.9%, –3.5%) but not in girls. Among boys, the relation was stronger when BPA was measured in the third trimester of pregnancy and decreased with time between BPA and TH measurements.Conclusion: Results suggest that exposure to BPA during pregnancy is related to reduced total T4 in pregnant women and decreased TSH in male neonates. Findings may have implications for fetal and neonatal development.

Bisphenol A – Application, sources of exposure and potential risks in infants, children and pregnant women

“…Proper functioning of thyroid hormones during this period (in utero and in early childhood) is essential for normal neurological development, hence the group at the highest risk are pregnant women and infants [111,112]. Despite this, no research is accessible that could confirm this relationship [112].…”

“…Proper functioning of thyroid hormones during this period (in utero and in early childhood) is essential for normal neurological development, hence the group at the highest risk are pregnant women and infants [111,112]. Despite this, no research is accessible that could confirm this relationship [112]. Chevrier et al (2013) conducted a study on 476 women participating in the CHAMACOS project to see whether exposure to BPA during pregnancy and after birth has an impact on the functioning of the thyroid gland [112].…”

“…Despite this, no research is accessible that could confirm this relationship [112]. Chevrier et al (2013) conducted a study on 476 women participating in the CHAMACOS project to see whether exposure to BPA during pregnancy and after birth has an impact on the functioning of the thyroid gland [112]. Concentrations of TSH (thyroid-stimulating hormone) in newborns and TSH, free thyroxine (T4) and total T4 levels in pregnant women were determined.…”

The Neuroendocrine and Neurodevelopmental Effects of Endocrine Disrupting Chemicals

“…Chevrier ve ark.nın yaptığı bir çalışmada, BPA maruziyetinin gebe kadın-larda azalmış toplam tiroksin (T4) ve yenidoğan erkek bebeklerde azalmış tiroid stimmüle edici hormon (TSH) ile ilişkisi olduğu bulunmuştur. 76 Bununla birlikte, prenatal BPA ve ftalat maruziyetinin IQ puanlarında düşme ile ilişkisi olduğunu gösteren çalışmalar da mevcuttur. 77,78 SONUÇ EBK'lerin etkileri doz, temas zamanı, temas süresi ve maruz kalınan kimyasal maddeye bağlı olarak önemli ölçüde değişiklik gösterebilmektedir.…”

The Impact of Toxins on the Developing Brain

“…Lead disrupts neurotransmission, synaptogenesis, and synaptic trimming (101,104,110). Dichlorodiphenyl trichloroethane (DDT), PCBs, polybrominated diphenyl ethers (PBDEs), phthalates, and bisphenol A appear to act-at least in part-by disrupting estrogenic or thyroid hormones (17,28,27,74). Another potential mechanism by which toxins may impact brain development is through epigenomic alterations-heritable alterations in gene expression that do not entail changes in the DNA sequence (5).…”