Fig. 1Chemicals can interfere with thyroid hormone action at several points. (A) The pituitary gland and hypothalamus regulate thyroid hormone synthesis through thyroid-stimulating hormone (TSH) release. (B) Thyroid hormone is synthesized in the thyroid gland. If TSH stimulates thyrocytes, iodine uptake via the sodium iodide symporter (NIS), thyroglobulin (Tg) production, and oxidation by thyroid peroxidase (TPO) occur. (C) Thyroid hormone is carried on binding proteins such as thyroxine-binding globulin (TBG) and transthyretin (TTR). (D) Thyroid hormone is metabolized in the liver by deiodinase (DIO), UDP-glucuronosyltransferase (UGT), or sulfotransferase (SULT) and eliminated in bile. (E) Thyroid hormone binds to the thyroid hormone receptor (TR) in target cells and activates thyroid hormone signaling pathways. T4, thyroxine; T3, triiodothyronine.
Fig. 2Structure of thyroid hormone and bisphenols. (A) Triiodothyronine, (B) bisphenol A, (C) bisphenol F, and (D) bisphenol S.
Table 1Previous Studies of BPA Exposure and Thyroid Measures in the General Population
Study |
Country |
Population |
No. |
Specimen |
BPA concentration, ng/mL |
Thyroid measures |
Association |
Meeker et al. (2011) [5] |
USA |
Aged ≥20 yr |
1,346 |
Urine |
GM 2.5 (95% CI, 2.3–2.7) |
Total/free T4, total/ free T3, TSH |
Total T4↓ |
Park et al. (2017) [6] |
Korea |
Aged ≥20 yr |
6,003 |
Urine |
GM 1.13 (95% CI, 1.06–1.20) |
Total T4, total T3, TSH |
TSH↓ |
Sriphrapradang et al. (2013) [7] |
Thailand |
Aged 18–94 yr |
2,340 |
Serum |
Median 0.33 (min 0–max 66.91) |
Free T4, TSH |
Free T4↓ (men) |
Wang et al. (2013) [8] |
China |
Aged ≥40 yr |
3,394 |
Urine |
Median 0.81 (IQR, 0.47–1.43) |
Free T4, free T3, TSH |
Free T3↑ TSH↓ |
Andrianou et al. (2016) [9] |
Cyprus, Romania |
Adult women |
212 |
Urine |
Median 2.258 (IQR, 1,100–4,611) |
Free T4, TSH, thyroid nodules |
TSH↑, thyroid nodule↓ |
Geens et al. (2015) [10] |
Belgium |
Case-control (obese and lean) |
194 |
Urine |
Median 1.7 |
Free T4, TSH |
TSH↑ (lean) |
Meeker et al. (2010) [11] |
USA |
Men (infertility clinic) |
167 |
Urine |
Median 1.3 (IQR, 0.7–2.4) |
Free T4, total T3, TSH |
TSH↑ |
Zhou et al. (2017) [55] |
China |
Case-control |
178 |
Urine |
Median 4.18 (IQR, 1.74–7.01) |
Thyroid cancer, nodular goiter |
Thyroid cancer↑, nodular goiter↑ |
Li et al. (2019) [56] |
China |
Case-control, women ≥18 yr |
1,416 |
Urine |
Median 1.35 (IQR, 0.83–2.34) |
Thyroid nodule |
Thyroid nodule↑ |
Table 2Previous Research on Maternal BPA Exposure and Thyroid Measures in Newborns
Study |
Country |
No. (newborn) |
BPA specimen |
BPA concentration |
Thyroid specimen |
Thyroid measures |
Association |
Chevrier et al. (2013) [16] |
USA |
364 |
Maternal urine in the first and second half of pregnancy |
GM 1.3 μg/g Cr |
Blood spots after birth |
TSH |
TSH↓ (boys) |
Romano et al. (2015) [17] |
USA |
249 |
Maternal urine at 26 weeks of gestation |
GM 2.3 μg/g Cr (95% CI, 2.1–2.5) |
Cord blood |
Total/free T4, total/free T3, TSH |
TSH↓ (girls) |
Minatoya et al. (2017) [19] |
Japan |
283 |
Cord blood |
GM 0.051 ng/mL (IQR, <LOD–0.076) |
Cord blood |
Free T4, TSH |
None |
Sanlidag et al. (2018) [20] |
Cyprus |
88 |
Cord blood |
Mean 4.934 ng/mL |
Cord blood |
Free T4, TSH |
None |
Brucker-Davis et al. (2011) [21] |
France |
84 |
Cord blood |
Median 0.9 ng/mL |
(IQR, 0.2–3.3) Cord blood |
Free T4, free T3, TSH |
None |