The US Food and Drug Administration (FDA) draft assessment on the safety of Bisphenol A, also called BPA, was criticized earlier this week by a panel of experts convened by an advisory subcommittee to the agency. They said the new exposure safety level proposed by the FDA should be at least ten times lower.

BPA is used to make polycarbonate plastics, including those used in plastic baby bottles and drinking water bottles and the lining of metal food packaging. It is one of the highest production volume chemicals in the world. Two million metric tons of BPA were produced in 2003.

Some animal studies suggest there are potential health risks from BPA, especially to infants, and two months ago, a paper in the Journal of the American Medical Association, JAMA suggested there was a link between higher levels of urinary BPA and cardiovascular disease, type 2 diabetes and liver-enzyme abnormalities.

The current controversy is about what level is considered safe for consumers and whether the current safety level set by the FDA is low enough.

The FDA recently produced a draft safety document on BPA which is scheduled to be discussed by an FDA advisory panel (called the Science Board) on 31st October.

In preparation for the Science Board meeting the FDA asked the Board to convene a subcommittee of experts to review the FDA report. The subcommittee comprised two members of the current Science Board and experts drawn from academia and government agencies. They published their conclusions about the FDA draft assessment of BPA earlier this week. They said that:

  • They agreed with the FDA assessment on BPA in that children are likely to have more exposure and be more susceptible to BPA than adults because of their “food consumption patterns, metabolism, vulnerability of developing systems and other factors”. However, the FDA assessment also needs to address cumulative exposure and the differential risk to newborns, they said.

  • The FDA draft assessment is limited by the fact it did not use enough infant formula samples and relied on mean values and did not take into account variability in the samples.

  • The FDA’s scientific arguments for choosing the data to use in the assessment are not sufficiently clear and reasoned. For instance the Subcommittee did not agree with the FDA decision to exclude a large number of “non-GLP studies”. (GLP stands for “Good Laboratory Practice”.)

  • The Subcomittee would use a different standard for including studies in the assessment. This standard would allow studies judged as “adequate” by the Center for the Evaluation of Risks to Human Reproduction (CERHR). Also, several studies that concluded after the FDA draft safety report should now be included in the final assessment.

  • The FDA assessment did not adequately estimate uncertainties in BPA exposure and its effects.

  • The evidence, including that from studies that the Subcommittee thinks should be included in a safety assessment of BPA, suggests that the proposed FDA safety level of 5 mg/kg bw/day should be at least ten times lower.

  • Taking all the qualitative and quantitative factors into account, including the uncertainty calculations, there is sufficient scientific argument to conclude that the margins of safety the FDA declares to be “adequate” exposure to BPA “are in fact inadequate”.

The FDA responded by saying the agency was looking forward to the review of the subcommittee’s findings at the Science Board meeting on October 31st and said it agreed that additional research was needed. More research is already planned to address the potential low dose effects of BPA, said the FDA.

The regulatory agencies of the US, Canada, Europe and Japan all agree that “current levels of exposure to BPA through food packaging do not pose an immediate health risk to the general population, including infants and babies”, said the FDA, although out of caution, Canada is taking steps to restrict the use of BPA.

In the meantime, parents and carers who wish to use an alternative to polycarbonate plastic for their bottle-fed babies can use glass and other substitutes, or avoid heating formula in polycarbonate bottles, said the FDA.

Click here for the full report from the Science Board Subcommittee (PDF download).

Sources: FDA.

Written by: Catharine Paddock, PhD.