Last week, scientists advising the European Union published their assessment of studies into the dangers posed by bisphenol A – one of the world’s most widely used chemicals – and produced a verdict that could be described as ‘not proven’ rather than ‘not guilty’.

After lengthy investigation, scientists at the European Food Safety Authority (EFSA) concluded that there were no grounds to change their current advice that the chemical is safe in small doses. But bisphenol A is still in the dock in the eyes of some governments and it could yet face Europe-wide restrictions.

One of the world’s most versatile chemicals, bisphenol A (BPA) is a monomer that forms sturdy, heat-resistant plastics used in scores of products – from dental sealants to drain pipes. But it is the use of BPA in food-container plastics and tins that has ignited the current controversy. Denmark, France, Canada and several US states have already banned the sale of baby bottles and food containers made with BPA, fearing the long-term effects on child development. But will the EU follow suit?

As with many chemicals, BPA pits the claims of decades of apparently safe use cited by the industry against the ‘better safe than sorry’ precautionary principle invoked by chemicals campaigners and (increasingly) some regulators. The problem is that ‘the science’ is not ready to be plucked off the shelf by governments, but remains uncertain and continues to evolve. Policymakers are left to judge the risks, weighing possible overreaction against the ‘known unknown’ effects on child development.

What is not disputed is that BPA is an endocrine disruptor – that is, it can interfere with hormones. The question is what quantities of BPA are dangerous for human health. EFSA’s current advice is that 0.05 milligrams per kilogram of human body weight (of BPA) can be ingested as the average ‘tolerable daily intake’ (TDI).

This advice was issued in 2006 and in 2008 and re-affirmed last week. The latest review looked at more than 800 studies, of which 180 were examined in-depth, and concluded that there was no new evidence to justify changing the advice on TDI.

One key piece of evidence was a well-known study on rats that triggered the Danish ban on BPA. In this study researchers had injected pregnant rats with different amounts of BPA and later tested the brain development of their new-born pups. The baby rats did not demonstrate changes in learning or memory; nevertheless, the study raised enough questions about low-level concentrations of BPA to prompt Danish authorities to introduce a BPA ban in baby bottles this year.

When EFSA looked at this study, they criticised the methodology and concluded that the results were “inconclusive” and of “limited value”. Many other studies reviewed by EFSA were also found not to meet methodological standards. Such flaws meant that the EFSA panel was unconvinced by the claims of these recent studies.

But one member of the 20-strong EFSA panel disagreed. The dissenting scientist agreed that there were methodological flaws in many studies, but argued that the studies threw up enough uncertainties to justify EFSA continuing to declare that its current dose recommendation (TDI) is temporary.

An EFSA spokesman said that the agency would continue to review new evidence, commenting, “in a sense every TDI is a temporary TDI because science is not set in stone”.

Bans stay in place

Denmark and France have both promised to keep their BPA baby-bottle bans in place. “Our ban is based on a study which, according to Danish experts, shows uncertainty about the effects of even small doses of bisphenol A on the learning ability in young rats. So I stick to the temporary Danish ban,” said Henrik Høegh, Denmark’s food minister. Chantal Jouanno, France’s environment minister, reaffirmed France’s policy, telling Le Figaro that the priority was “the protection of babies”.

Meanwhile, the Swedish Chemicals Agency is continuing to study the case for a national ban. It is carrying out its own review into BPA; its findings will be reported in March.

The European Commission is still digesting the results of what it sees as a “nuanced” EFSA study and has not ruled out legislation to ban or restrict the use of BPA, an official told European Voice.

And it is worth remembering that the EU is eyeing further action against ‘chemical cocktails’, the combined effects of chemicals everyone is exposed to in their everyday life. A little-noticed paper from environment ministers in December called for an investigation into how chemicals combine and for the Commission to come up with recommendations on how to tackle endocrine disruptors from multiple sources.

The case on BPA is far from closed.