August 26, 2010

expert reaction to research into bisphenol A to be published in Environmental Health Perspectives

The paper shows a possible association between exposure to bisphenol-A, a chemical widely used in food and drinks packaging, and hormonal changes in men.

Prof Richard Sharpe, MRC Human Reproductive Sciences Unit at the University of Edinburgh, said:

“Most concerns about bisphenol A have centred on its developmental effects but, in view of its intrinsic (weak) oestrogenic activity there has also been concern about what effects it might have in adults. Experimental studies in animals have produced equivocal effects, although the best designed studies have shown minimal/no effects.

“The study by Galloway is in human adults and has looked at the association between current exposure to bisphenol A and the blood levels of testosterone and oestradiol (the male and female sex steroids, respectively). It shows a small but significant positive association in men between bisphenol A exposure and testosterone levels, after taking into account other potentially confounding factors. The study is well executed and the findings are accurately and carefully discussed. The explanation for this association is not obvious and the authors discuss several possibilities.

“The bottom line is that even if the association in this study is showing ’cause and effect’, i.e. that bisphenol A somehow causes an increase in testosterone levels in adult men, the changes are small and do not result in hormone levels moving outside of the (wide) normal range for adult men. The change in testosterone levels due to BPA (if there was direct cause and effect) is far less than occurs naturally in men according to the time of day (levels are highest in early morning). There is therefore no reason to suppose that the observed change presents a health risk to the men, although, as the authors correctly state, it will be important to identify the mechanism behind the association (including whether it is cause and effect or related to some other unidentified factor) and thus remove uncertainty.

“It is reassuring that bisphenol A was not associated with oestradiol levels in either men or women.”

Prof David Coggon, Professor of Occupational and Environmental Medicine, University of Southampton, said:

“The authors report a positive correlation between bisphenol A and testosterone levels, but only in men. This is an interesting observation, but it could simply be a chance finding, and therefore it needs to be independently replicated. If it is confirmed then further research will be required to understand the biochemical mechanisms underlying the relationship and its significance for health.”

Daily Bisphenol A Excretion and Associations with Sex Hormone Concentrations: Results from the InCHIANTI Adult Population Study, Galloway et al., published in Environmental Health Perspectives on Thursday 26th August 2010.