Since the 1930s it has been known that BPA can mimic the female sex hormone, oestrogen. The effects on fertility and reproduction and the endocrine (hormonal) system have been subject to much scientific debate, linked to reports of so-called “low-dose effects” of BPA observed in tests using rodents. EFSA recently published an opinion on this issue as part of the wider review of the European Union’s strategy on the regulation of endocrine active substances.
In February 2012, following further consideration of new scientific studies, experts on EFSA’s CEF Panel decided to undertake a full re-evaluation of the human risks associated with exposure to BPA through the diet, also taking into consideration the contribution of non-dietary sources of exposure to BPA.
EFSA’s scientific experts provisionally concluded that for all population groups considered diet is the major source of exposure to BPA in the European Union. In 2010, EFSA set a TDI of 50 μg/kg bw/d. Since 2010, new robust studies have become available which have allowed EFSA to better assess how the chemical behaves in various animal species compared to humans. Based on new kinetic data it was possible to convert the dose that causes the adverse effect in mice into an oral equivalent dose for humans of 113 µg/kg bw/d. The next step involved applying an uncertainty factor to derive a TDI. EFSA noted the default uncertainty factor of 4 connected to kinetics differences between animal species was already accounted for in the calculation for converting the animal dose into a human equivalent dose. Thus, the remaining component of the default uncertainty factor of 25 that accounts for:
(i) difference in toxicity between animals and humans, and
(ii) between sensitivities in humans was applied to the equivalent human dose of 113 µg/kg bw/d to derive the proposed temporary TDI (t-TDI) of 5 µg/kg bw/d, which is 10-fold lower than that in 2010.
The t-TDI reflects the current uncertainties surrounding effects of BPA on the reproductive, nervous, immune, metabolic and cardiovascular systems, as well as in the development of cancer. While an association between BPA and these latter effects is not considered likely at present, EFSA concludes they may be of potential concern for human health and they add to the overall uncertainty about the risks of the substance. EFSA proposes that the TDI remains a temporary one pending the outcome of research from the US National Toxicology Program (NTP) which will address many of the current uncertainties about these potential health effects of BPA.
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