One of the world's most widely used chemicals, a key constituent of plastic food and drink containers, has been linked for the first time with increased rates of heart disease and diabetes in adults.
Bisphenol A (BPA) is one of the 10 most common chemicals produced worldwide and gives plastic its rigidity, durability and light weight. Researchers now fear that tiny amounts which leach out of plastic containers into food and drink may cause harm to health.
A team of British toxicologists analysed findings from an American survey of 1,455 adults and showed that the 25 per cent with the highest levels of the chemical were more than twice as likely to have heart disease and/or diabetes compared with the 25 per cent with the lowest levels. They also had higher levels of liver enzymes indicative of metabolic abnormalities.
Yesterday, the scientists from the Peninsula Medical School in Exeter and the University of Iowa presented their findings to a panel of the US Food and Drug Administrationwhich is hearing evidence on the risks of BPA.
Ninety per cent of the population were exposed to BPA, which is ubiquitous in products such as CD cases and dental sealants, the researchers said. Vast quantities were buried in landfill sites which could potentially have leached into drinking water and was also present in the air around manufacturing facilities.
Iain Lang, an epidemiologist from Peninsula Medical School and lead author of the study, said: "This is something everyone is exposed to. It is the first ever study in a large human population. But this is a single scientific study and we would not want to leap to conclusions on the basis of it."
Critics said there could be a more "commonsense" explanation for the findings – that people who consumed a lot of canned drinks would increase their risk of heart disease and diabetes from the sugar, incidentally exposing themselves to higher levels of BPA from the can. Younger people showed the highest levels of BPA, lending support to the hypothesis.
Asked if the consumption of sugar in canned drinks could explain the findings, Dr Lang said: "It is possible... [but] we have done all we can to exclude that possibility."
The study is published in The Journal of the American Medical Association, which carries an editorial calling for further regulation of BPA in the wake of the findings. The authors of the editorial have made extensive studies of BPA and have called for curbs on its use in the past. Dr Lang said: "The editorialists are more bullish than us. A single study is not enough to justify a change in policy."
The findings show that those with the highest levels of BPA, measured in their urine, had exposure to about 35 micrograms a day, compared with 20 micrograms a day for those with the lowest exposure. These levels are at least 100 times below the level currently regarded as "safe" in the US and Europe of more than 3,000 micrograms per day.
Professor Richard Sharpe, of the Medical Research Council's Human Reproductive Sciences Unit at the University of Edinburgh, said the study showed an association, not a causal link, between BPA and heart disease and diabetes, and it was too easy to jump to the "obvious scary conclusion". Professor Sharpe added: "There may be an altogether more commonsense (although still scary) explanation... that if you drink lots of sugary canned drinks you will over time increase your risk of cardiovascular disease and diabetes (I think we already suspect this) and incidentally you will be exposed to more BPA (from the can lining). Our present understanding, and this study, do not allow us to choose between these two explanations."
A spokeswoman for the Chemical Industries Association said the European Food Safety Authority had reviewed the use of BPA in products in contact with food and drink this year and found it to be safe: "This new study will be subject to the same scrutiny to see if further research is required."
The UK Food Standards Agency said it would "continue to closely monitor scientific reports about the health effects of BPA".
Popular plastic building block
Bisphenol A is a chemical building block, mainly used to make polycarbonate plastic and epoxy resins. It was first created in a laboratory by the German scientist Thomas Zincke in 1905, and is now one of the most extensively tested materials in use today, after becoming increasingly popular throughout the 20th century. Polycarbonate plastic – which has been widely manufactured in the US since 1957 – is light, tough and heat resistant, and is used in many everyday products including CDs, DVDs, electronic equipment and food and drink containers. Epoxy resins are chemically resistant, adhesive and can be easily moulded, and are often used as protective coatings for electronic circuit boards inside electrical equipment, but are also widely used to line metal cans and tins to protect the food or drink stored inside.