Bisphenol-A is used to harden plastics and is found in baby bottles, CD cases, plastic knives and forks and the lining of food and drink cans.
Because the chemical mimics the female sex hormone oestrogen, scientists had long feared it would interfere with the way hormones are processed by the body.
Now U.S researchers have linked the BPA chemical to poor semen quality in humans for the first time.
They reported in the journal Fertility and Sterility that Chinese factory workers exposed to high levels of the plastics chemical had low sperm counts.
Dr De-Kun Li, at the Kaiser Permanente Division of Research in Oakland, California, said the troubling findings echoed studies in animals that linked the chemical with reproductive problems.
It follows his previous research in the same men that linked BPA exposure with sexual problems. His latest study was funded by The National Institute of Occupational Safety and Health.
Andrea Gore, a toxicology professor at the University of Texas who was not involved in the research, called it an important but preliminary study.
She said the results ‘are at least suggestive of the possibility that BPA may be one of the compounds that are causing some of these changes’ in sperm.
The study involved 130 Chinese factory employees who worked directly with materials containing BPA and 88 workers who didn’t handle it and whose exposure was similar to that of typical western men.
Low sperm counts were found in workers who had detectable levels of bisphenol-A in their urine. Poor sperm quality was two to four times more prevalent among these men than among workers whose urine showed no sign of BPA.
The lowest sperm counts were in men with the highest levels of BPA.
BPA in urine was linked with lower-quality semen even in men who didn’t work with the chemical, although their average BPA levels were much lower than in the other group.
It comes just months after Professor David Melzer from Exeter University called for an urgent review into the safety of bisphenol A (BPA ).
The leading academic also urged manufacturers to cut down on BPA in food packaging and containers.
He told a briefing at the Royal Institution in London: ‘Millions of pounds of this compound are being produced every day, but we still don’t know how it gets into humans.
‘I think small effects for large numbers of people matter and it’s reasonable that a tiny proportion of the costs of BPA should be put to human drug trial-type assessments to settle once and for all whether this compound is bio-active in humans