Renewed concerns over a chemical used in the manufacture of hard plastic bottles are making headlines after Chinese men working in a factory who received very high doses of the chemical bisphenol A, or BPA, reported high rates of sexual problems.

In a recent study, financed by the National Institute of Occupational Safety and Health in the U.S., researchers say heavy exposure to BPA while on the job was linked to impotence and lower sexual desire and satisfaction, adding to concerns about the chemical’s effects on consumers.

BPA is a chemical widely used in a variety of consumer products, including some hard plastic bottles and metal food or beverage cans. Several manufacturers of baby bottles have indicated that they have stopped using the chemical. According to estimates, about 90 per cent of the U.S. population has detectable levels of the chemical in the urine.

Scientists have expressed concern that BPA exposure may harm the reproductive and nervous systems as well as promote prostate and breast cancers. A preliminary study conducted last year reported a link between BPA and possible risk for heart disease and diabetes.

According to the researchers in the recent study, the Chinese men were exposed to BPA levels that were about 50 times higher than those faced by typical American men. Furthermore, the researchers indicated there was no indication that typical doses would have the same effects.

For the study, researchers studied 164 male factory workers in China who were exposed to high levels of BPA while on the job and compared the results with those of 386 Chinese men in the same town but who either worked at other factories or were married to factory workers. The researchers measured BPA exposure through air sampling and interviewed the workers about their sexual activity.

The researchers found that men with high BPA exposure were about four times more likely to report trouble achieving erections as those men who worked at other factories, about seven times more likely to say they had difficulty ejaculating, and about four times more likely to report low sex drive or low sexual satisfaction.

According to the researchers, the workers were probably exposed to the chemical not only through inhalation and skin contamination but also by swallowing the BPA powder that contaminated their food.

Last year the Food and Drug Administration in the U.S. concluded that trace amounts of BPA that leached out of bottles and food containers was not dangerous. After this latest study, however, the FDA is reviewing its stance after criticism from its scientific advisers.