Science by headline

As a review of studies into Bisphenol A shows, the interpretation of scientific evidence is often at odds with the initial overreaction.

Back in the 1950s, when the plastics industry was in full bloom, the chemical Bisphenol A, or BPA, came into common use to harden some plastics, and in compounds that line food cans.

But in recent years BPA has become anathema, after scientific reports said it can mimic oestrogen and may be linked to a range of human ailments. These studies triggered a stampede: Canada declared the additive toxic; France will ban it from food packaging; a Swedish minister wants to ban it entirely. Some activists say it is even risky to handle shop receipts, often printed on BPA-treated paper.

But now the negative findings have all been cast into doubt, not to say into the rubbish bin, by a US government toxicologist's review of previous studies on this additive: it turns out that fully 1,000 times the normal exposure would be needed to cause the health damage trumpeted by alarmists.

The World Health Organisation, the EU's Food Safety Authority and a Japanese agency all concur: there is little or no risk in normal exposure. And a separate study says BPS, a replacement for BPA, may be worse.

The phrase "new study says" often makes headlines, but the essence of science is careful review, results that are consistent each time a test is done and prudence in interpreting results. There's no denying that some chemicals are indeed toxic, and the food supply must be protected. But hysteria and overreaction are never any help.