A substance often found in plastic food containers could damage the genetic material of egg cells, according to a new study by a group of US researchers. The scientists, based at the Case Western Reserve University in Cleveland, Ohio, found that the chemical bisphenol A affected the number of chromosomes in the eggs of laboratory mice. Similar problems in human eggs could lead to an increased incidence of miscarriages or chromosomal conditions such as Down syndrome, say the researchers, who published their findings in the journal Current Biology.
The team, lead by Patricia Hunt, originally set out to study the effects of ageing on the genetic material of mouse eggs. Their suspicions were aroused when the number of dividing egg cells showing chromosome disruption, usually around one per cent, shot up to 40 per cent. After investigating other possible causes, Hunt found that a detergent used to clean the cages had attacked the plastic, releasing bisphenol A. The researchers then measured the effect of different levels of exposure to the chemical, and found that even tiny amounts (20 parts per billion) caused defects in eight per cent of the eggs.
Bisphenol A is widely used in see-through plastic bottles and for lining tin cans, reports Nature. It can mimic the female hormone oestrogen, and previous animal research suggested that exposure to bisphenol A in the womb can affect prostate and testicular development. Although some studies have found no evidence that the chemical is harmful, Hunt and others would now like to see it more tightly regulated. The research paper also calls for 'extensive further study' to investigate the possibility that bisphenol A exposure increases the likelihood of genetic errors in offspring.