Association between bisphenol A and abnormal free thyroxine level in men

Abstract

Bisphenol A (BPA) is a chemical that is used in a variety of consumer products, and exposure to BPA is widespread among the general population. Recent studies have suggested that BPA may affect the thyroid and related pathways. However, human studies are still limited. The aim of this study was to determine the relationship between BPA exposure and thyroid function. We obtained survey data and blood samples from The Thai National Health Examination Survey IV 2009, a nationally representative cross-sectional survey using a multistage, stratified sampling of the Thai population. A total of 2,340 subjects aged 18-94 years were sampled for the present study. Serum BPA, TSH, FT4, and related covariates were measured. BPA was log-transformed prior to analysis. BPA was detected in 52.8 % of serum samples with a median concentration of 0.33 (range 0-66.91) ng/mL. We excluded subjects who tested positive for thyroid autoantibody and then stratified the remaining subjects by gender; the analysis showed a significantly negative correlation between serum BPA and FT4 levels in males (r = -0.14, P < 0.001). In contrast, no association was observed in females. BPA was not associated with TSH in either gender. This gender-related discrepancy is possibly related to androgen-related differences in the metabolism of BPA. Our preliminary results provide evidence of a negative association between BPA and FT4 levels. Additional detailed studies are needed to investigate the temporal relationship and potential public health implications of such an association.

The Association of Serum Bisphenol A with Thyroid Autoimmunity

“…Antibodies against these xenobiotics have been demonstrated in a number of studies [11,12]. There have been studies showing that BPA acts as a thyroid receptor antagonist [13] and can increase serum free T4 [6]. In the present study, serum BPA was found to be associated with certain aspects of thyroid autoimmunity, in that there was a relationship between serum BPA and TPOAb or TgAb but not TRAb.…”

“…In the U.S. National Health and Nutrition Examination Survey (NHANES), BPA and triclosan were shown to be likely to negatively affect human immune function, as assessed by serum cytomegalovirus antibody and allergy or hay fever diagnosis [5]. We previously reported a negative association between serum BPA and serum thyroxine (T4) in males with positive serum thyroid antibodies [6] which is in agreement with a recent study in U.S. adults which suggested an inverse relationship between urinary BPA and total T4 [7]. Moreover, we have also demonstrated that estradiol is associated with thyroid autoimmunity in males [8].…”

A round robin approach to the analysis of bisphenol a (BPA) in human blood samples

“…More than forty published studies have reported low concentrations of BPA in human blood and serum samples (reviewed in [29], see also [44-63]). In spite of the relative consistency in BPA concentrations reported, these studies have been criticized that the uBPA measured in human serum could be the result of contamination and/or that BPA-G, the major metabolite found in blood, could be deconjugated by the extraction processes used [42,69-72].…”

“…In the past decade, more than three dozen studies have examined samples collected from pregnant women, non-pregnant adults, and fetal umbilical cords to evaluate the extent to which BPA may be present in blood or serum (reviewed in [11,29], see also [44-63]). Although a few studies used ELISA to measure BPA, the majority used analytical chemistry methods, and although most examined a limited number of human subjects compared to the studies examining urine, a few large studies have been published [32,64,65].…”

Occupation and Thyroid Cancer

“…In addition, cashiers are exposed to high levels of bisphenol A (BPA), an endocrine disrupting chemical that has been linked to an increased risk of breast cancer, prostate cancer and other malignancies (44, 45). While there has been no direct link between BPA and thyroid cancer, studies have shown that BPA exposure can alter thyroid hormone levels (46, 47). However, retail salespersons refer to those who sell merchandise such as furniture, motor vehicles, appliances, or apparel to consumers (cashiers not included) according to 2010 SOC code; emission of low-frequency electromagnetic fields from jobs requiring equipment and BPA exposure from receipts may not explain these association.…”