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BPA Linked to Hormonal Effects in Men
  Bisphenol A
Bisphenol A (BPA) is a chemical used to make polycarbonate plastic. Polycarbonate plastic is used to make hard plastic items, such as baby bottles,
MedPage Today
Published: August 25, 2010
Action Points
* Explain to interested patients that increased exposure to bisphenol A (BPA), common to food and drink packaging, predicted higher testosterone levels in men, suggesting the chemical effects endocrine changes in men.
* Note that exposure to bisphenol A occurs primarily through dietary means, although dental sealants, dermal exposure, and inhalation of household dust.
Increased exposure to a chemical common to food and drink packaging predicted higher testosterone levels in men, suggesting the chemical bisphenol A (BPA) effects endocrine changes in men, data from a cohort study showed.
In multivariable-adjusted models, higher daily excretion of BPA had a significant association with higher total testosterone concentrations (P=0.044 to P=0.004), investigators reported in Environmental Health Perspectives.
BPA excretion was not associated with other serum parameters in men and had no associations with serum outcomes in women.
"These results are important because they provide a first report in a large-scale human population of associations between elevated exposure to BPA and alterations in circulating hormone levels," Tamara Galloway, PhD, of the University of Exeter in England, and colleagues noted in the discussion of their findings.
BPA has a history of suspicion regarding its possible effects on the human endocrine system. Exposure occurs primarily through dietary means, although dental sealants, dermal exposure, and inhalation of household dust also may contribute to total daily exposure, the researchers noted.
Population studies have shown that more than 90% of people have detectable urinary levels of BPA metabolites.
Studies of the health effects of BPA generally have focused on estrogenic activity, including evidence of estrogen agonism and androgen antagonism. Additionally, BPA has been linked to thyroid dysregulation, altered pancreatic beta-cell function, and obesity.
On the basis of experimental evidence, Galloway and colleagues hypothesized that higher urinary BPA would be associated with adverse effects in humans. They had previously reported a correlation between BPA exposure and cardiovascular disease and diabetes and replicated the findings in a sample of participants in the National Health and Nutrition Evaluation Survey (Epidemiology 2008; 19: S379, PLoS One 2010; 5: e8673).
Following publication of studies showing a link between BPA and levels of reproductive hormones, the investigators evaluated BPA urinary excretion and sex hormone levels among participants in an ongoing cohort study in Italy. In contrast to previous studies of such associations, Galloway and colleagues based their findings on 24-hour urine collections to determine daily excretion rates for BPA.
The study involved a random sample of about 715 adults 20 to 74. Each participant provided a 24-hour urine sample, which was evaluated by liquid chromatography mass spectrometry to determine BPA concentrations.
The principal outcomes were serum concentrations of total testosterone and 17 beta-estradiol.
The geometric mean urinary BPA concentration was 3.59 ng/mL, and daily excretion averaged 5.63 g. Higher excretion was associated with male sex, younger age, greater waist circumference (P=0.013), and weight (P=0.003).
In models adjusted for age, sex, and study site, women had significantly lower BPA excretion compared with men (P<0.001). Older age was associated with significantly lower excretion (P<0.001).
In fully adjusted models, BPA excretion had a significant association with total testosterone (P=0.004) but not 17 beta-estradiol.
Further analysis did show a significant association between BPA excretion and sex hormone binding globulin in premenopausal women (P=0.004).
The authors acknowledged several limitations of the study, including the need for validation in other independent populations, use of a single 24-hour BPA excretion rate, and the cross-sectional nature of the study.
Co-authors Cathryn Money and Paul McCormack are employees of AstraZeneca.
Primary source: Environmental Health Perspectives
Source reference:
Galloway T et al "Daily bisphenol A excretion and ssociations with sex hormone concentrations: results from the InCHIANTI adult population study" Environ Health Perspect 2010; DOI:10.1289/ehp.1002367.
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