STATS ARTICLES 2010

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Once again, Europe says BPA is safe
Trevor Butterworth, October 1, 2010
Precautionary thinking continues to find evidence against the chemical too weak for any reduction or ban. European Food Safety Authority says Denmark’s temporary ban on BPA in food contact material for children under 3 not justified by statistical analysis of the data.

The European Union’s Food Safety Authority (EFSA) announced yesterday that it would take no action to reduce or ban bisphenol A, a chemical widely used in plastic and food safety applications. As EFSA notes:

“Following a detailed and comprehensive review of recent scientific literature and studies on the toxicity of bisphenol A at low doses, scientists on the European Food Safety Authority’s (EFSA) CEF[1] Panel conclude they could not identify any new evidence which would lead them to revise the current Tolerable Daily Intake.”

This decision reconfirms EFSA’s earlier 2006 risk assessment and its 2008 update, both of which, STATS has noted, were widely ignored in the American media in favor of reporting the evidence that EFSA’s experts dismissed and speculating about an industry conspiracy to suppress the truth about BPA.

What is notable about yesterday’s decision is that even though obligated to regulate chemical exposures on precautionary grounds, EFSA has continued to find that such grounds do not exist, and that the evidence that the chemical is dangerous is just not methodologically or statistically convincing.

The 21-member panel of scientific experts (a list of biographies and declaration of interests is available here) noted, for instance, that the claims about BPA inducing neurotoxic effects were not supported by a study of the available scientific literature, and that one study (Stump et al, 2009), when statistically reanalyzed, was inconclusive due to wide variability in the findings and censoring error. Denmark’s National Food Institute had imposed a temporary ban on BPA in food contact material for children aged 0 to 3 based on data from Stump indicating the possibility of learning impairment.

The panel also went through “the toxicological data published between 2007 and July 2010 mainly focusing on toxicokinetic, human and animal toxicity studies.” The panel examined these studies “with respect to quality criteria (sufficient sample size, adequacy of control procedures, inclusion of positive controls when applicable, assessment of correlation between morphological and functional changes, and consideration of litter or dam as the appropriate statistical unit) in order to assess the validity and/or applicability of the individual findings to human risk assessment.”

The panel found that studies in the toxcokinetics of BPA confirmed that studies where the chemical was administered orally had greater relevance for human risk assessment. They found that new studies on BPA in non-human primates (a more human like model for toxokinetics than rats) “further strengthen the view that BPA is eliminated faster in humans than in rodents.”

And if BPA is eliminated faster in humans than rodents, internal exposure to BPA in humans is going to be lower than internal exposure in rodents. In other words, the rodent models may overstate any risk for humans because BPA takes longer to be excreted.

Another crucial finding from the latest research is that “even human premature infants can metabolise and excrete BPA efficiently (via glucuronidation and sulfation), as supported by recent human data and data in young monkeys. The use of the standard uncertainty factor (UF) of 10 to take into account interspecies differences is therefore considered quite conservative.” The panel also concluded that “in utero exposure and exposure through lactation appear to be limited.”

The panel dismissed some epidemiological studies which “suggested some statistically significant associations of BPA exposure (urine concentrations) and health effects (coronary heart disease, reproductive disorders) in adults and behavioural changes in young girls.”

“The Panel noted that cross sectional epidemiological studies such as these can demonstrate statistical associations between BPA exposure and the presence (e.g. coronary heart disease) or absence (e.g. cancer, asthma) of health outcomes, but the inherent design of cross sectional studies does not allow establishment of a causal relationship between BPA exposure and health effects (e.g. chronic diseases). In addition, the Panel has identified some limitations in these studies, which raise further questions as to the significance of the reported findings. Therefore, the Panel could not draw any relevant conclusion for risk assessment from these studies.”

The panel dismissed studies on developmental and reproductive toxicology which claimed effects at doses lower than 5 mg/kg b.w./day for having “severe shortcomings.” These studies “were considered to be invalid.”

The panel dismissed studies suggesting a “BPA-induced enhancement of sensitivity of the mammary gland to carcinogen-induced breast tumour formation in rat offspring following lactational BPA exposure of pups” as suffering from poor design but that the findings were worthy of “further consideration.”

A summary of EFSA’s report (html) can be found here. The full report, with an addenda “minority opinion” from one panel member on certain uncertainties in the data can be found here.

 


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