Plastic-hardening chemical makes men soft

Regular contact with high levels of bisphenol A (BPA), a compound commonly found in plastic food and drink containers, appears to cause erectile dysfunction and other sexual performance problems in men.

The finding, reported in the Washington Post, is likely to add fuel to the controversy over whether exposure to normal lower levels is harmful to humans and encourage campaigners calling for an outright ban.

According to the new study, male workers in four Chinese factories making BPA or using it reported an average fourfold increase in erectile dysfunction, a sevenfold increase in ejaculation difficulty and a fourfold decrease in sexual drive when compared to controls.

BPA is found in thousands of everyday products, such as the plastic lining of drinks cans. It is used in hard plastic bottles including some baby bottles, although some manufacturers voluntarily removed it from baby bottles sold in the US earlier this year.

More than 93 per cent of Americans have traces of the chemical in their urine and various studies have shown BPA can cause harm to animal reproductive systems, from early sexual maturity to low sperm count. The compound behaves like the hormone oestrogen, and is thought to disrupt hormonal processes.

However animals metabolise the compound more slowly than humans and the evidence base has been interpreted differently by different public health bodies.

Last August the US Food and Drug Administration (FDA) released a draft report stating it was safe at the typical exposure levels from food and drink packaging.

This was contradicted by the National Toxicology Program, which advises the FDA, and by the FDA's own Science Board. The administration is currently undertaking a new review.

The research is the first to show regular exposure to high levels of BPA in the workplace over long periods can have adverse effects on sexual function in men.

But how worried should we be? The levels of the chemical found in the urine of the Chinese workers in the study were around 50 times higher than normal.

Study leader De-Kun Li, a reproductive epidemiologist at US healthcare provider and insurer Kaiser Permanente's research institute in Oakland, California, acknowledged that his findings in BPA exposed workers could not be extrapolated to the general population.