The scientific debate over the safety of bisphenol A (BPA) continues with German safety authorities concluding that findings of two major studies do not show the chemical is hazardous. But new research from the US suggests human sperm may be harmed by exposure to the substance.
The statement by the German Federal Institute for Risk Assessment (BfR) is the latest in a string of opinions delivered by regulatory bodies that backs the view that BPA does not pose a risk to human health at permitted doses. Meanwhile, new research from a team at Michigan University suggested that exposure to BPA could damage male sperm.
BPA is a substance used in polycarbonate plastics and the epoxy resin linings of food cans. Its safety for use as a food contact material is the topic of fierce debate.
Germany dismisses Stump study
The BfR said that studies by Stump et al and Ryan et al provided no indications for adverse health effects on neurological development and behaviour.
The body said the Stump study was conducted according to the required regulatory standard test design on rats.
“The results obtained with these testing conditions did not provide any indications of adverse effects on neurological and behavioural development in the off-spring”, said the BfR.
When examining the effects of low dose exposure, the agency said the study failed to find any indications of these through evaluating the dietary administration of the substance.
In March, the Danish Government announced a ban on BPA in food contact materials for children aged three and under based on the findings of the research by Stump et al.
The BfR was also dismissive of the Ryan study findings relating to oestrogen-sensitive endpoints, - describing the matter as “a pivotal issue in the scientific debate”. The body declared “the results revealed no adverse effects in the low-dosage range on behaviour and the development of female rat offspring whose dams were treated with bisphenol A during gestation and lactation.”
To underline their point the German risk officials said that in contrast, female offspring from dams treated under the same conditions with the chemical ethinyl estradiol showed “irreversible abnormal behaviour, impaired fertility and malformations of the external genitalia”.
BPA damages male fertility?
A new study from the US has suggested that urinary BPA concentrations could be related to a fall in sperm quality and concentration. But the researchers from the University of Michigan School of Public Health stressed that the results were preliminary and that further study was necessary.
Lead researcher assistant professor John Meeker and Russ Hauser, the Frederick Lee Hisaw Professor of Reproductive Physiology at Harvard School of Public Health recruited 190 men through a fertility clinic. All gave spot urine samples and sperm samples on the same day. Subsequently, 78 of the men gave one or two additional urine samples a month apart. Researchers detected BPA in 89 per cent of the urine samples. Researchers measured sperm concentration, sperm motility, sperm shape and DNA damage in the sperm cell.
"We found that if we compare somebody in the top quartile of exposure with the lowest quartile of exposure, sperm concentration was on average about 23 percent lower in men with the highest BPA," said Meeker said.
The study also suggested a 10 percent increase in sperm DNA damage.
"Much of the focus for BPA is on the exposures in utero or in early life, which is of course extremely important, but this suggests exposure may also be a concern for adults,"
He added that further work was needed due to the study's relatively small sample size and design.