The results were based on a study on more than 30,000 people. It found that the general population’s exposure to the chemical was too low to have any toxic effects.
Experts have claimed that range of human disorders including diabetes and obesity, linked to BPA, could have been instigated by the food itself instead of the plastic wrapping.
BPA has been used to make hard plastics since the sixties but has caused alarm in recent years as it can leach into foods and drinks and has the potential to mimic oestrogen if it ends up at high enough levels in the blood, according to some experts.
In 2012 the US Food and Drug Administration prevented the use of BPA in baby bottles.
‘Western diseases’
Richard Sharpe, of the Medical Research Council’s Centre for Reproductive Health at the University of Edinburgh, said a long list of studies had shown human exposure to BPA, measured in urine, is associated with a growing number of what he calls “western diseases” such as obesity, type 2 diabetes, liver dysfunction and cardiovascular and metabolic diseases.
In a statement ahead of a talk at the annual meeting of the American Association for the Advancement of Science in Boston, Sharpe said exposure to BPA had also been associated with adverse reproductive changes, an increased risk of polycystic ovarian disease and reduced semen quality and blood testosterone levels. Though high levels of BPA have been found in people with these conditions, he said, no causal link has been found between the chemical and any disease.
Sharpe said no scientific studies had yet showed that BPA exposure caused disorders. “If this association was due to cause and effect, it would mean that bisphenol A was incredibly potent and toxic, and this does not agree with published studies,” he wrote. “This possibility therefore seems illogical.”
An alternative hypothesis, he said, was that there could be a different, causal element that is associated both with the human disorders and with exposure to bisphenol A.
Fast food
He said a factor was a modern western diet because he knew that such a diet was associated with all the disorders mentioned above.
He added: “Moreover, we already know that 95% of human exposure to bisphenol A is dietary – it comes from foods and drinks that we ingest.” Sharpe said that if he was correct it would mean that the poor fast-food western diet would be the cause of the diseases and also, coincidentally, the increased levels of BPA in unhealthy people.
Sharpe said it would not be right to assume that his explanation was correct without further testing but said the attraction of his idea was that it fitted with the available facts, unlike the idea that BPA caused the disorders.
In contrast, another study has found that BPA is harming brain and nerve cell growth in babies. The study, based on rats and human neurons grown in the laboratory, found female nerve cells more susceptible to BPA than male neurons. This might explain why certain neurodevelopmental disorders in humans are more common in females, such as Rett syndrome, a severe form of autism found only in girls, the scientists said.
“Our study found that BPA may impair the development of the central nervous system, and raises the question as to whether exposure could predispose animals and humans to neurodevelopmental disorders,” said Wolfgang Liedtke of Duke University Medical Centre in Durham, North Carolina.
“Our findings improve our understanding of how environmental exposure to BPA can affect the regulation of the Kcc2 gene. However, we expect future studies to focus on what targets aside from Kcc2 are affected by BPA,” said Professor Liedtke, who led the study published in the Proceedings of the National Academy of Sciences.
