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A chemical commonly found in plastic packaging and lining of food cans increases the risk of autism in young boys, a new study has found.
The study, published in Nature Communications, found that boys exposed in the womb to bisphenol A, or BPA as it is commonly known, are more likely to show autism symptoms by the age of two and six times more likely to be diagnosed with autism by age 11.
Autism is a neurodevelopment disorder with a wide spectrum of behavioural and cognitive changes.
The study, conducted by The Florey Institute, the largest brain research centre in the southern hemisphere, examined BPA levels in pregnant mothers and tracked the development of their children over a period of 10 years.
It revealed that higher BPA exposure is associated with a suppression of aromatase, a key enzyme in brain development, particularly in boys. The suppression is linked to an increased likelihood of autism diagnosis.
The findings were supported by experiments on mice showing that when the gene responsible for producing aromatase is deleted, the animals exhibit repetitive behaviours, a common characteristic of autism in human beings.
“Exposure to plastic chemicals during pregnancy has already been shown in some studies to be associated with subsequent autism in offspring,” professor Anne-Louise Ponsonby, one of the study’s authors, said in a statement.
“Our work is important because it demonstrates one of the biological mechanisms potentially involved. BPA can disrupt hormone-controlled male fetal brain development in several ways, including silencing a key enzyme, aromatase, that controls neurohormones and is especially important in fetal male brain development. This appears to be part of the autism puzzle.”
Professor Ponsonby said while autism arises from a combination of genetic and environmental factors, BPA exposure seems to play a contributory role, especially in boys. “This doesn’t mean BPA is the sole cause of autism,” she explained, according to The Sydney Morning Herald. “Some children may be genetically predisposed, while others might be affected by different environmental factors.”
BPA is used in the production of plastic food packaging and metal can linings. It is commonly found in items like water dispensers, food storage containers, and reusable bottles. The chemical helps make these plastics strong and clear, but it can leak out in tiny amounts, raising concerns about its impact on human health.
BPA usually gets into our body in trace amounts through eating but it can be inhaled or absorbed by the skin as well.
Previous studies have linked BPA to possible negative impact on brains and prostate glands of foetuses, infants and children. The findings relating it to autism are new.
“Autism results from a complex interaction between genes and the environment and the nature of the environmental interactions is still largely unclear,” said Dr Ian Musgrave, senior lecturer in medicine at Adelaide University.
Explaining how BPA acts in the body, Professor Ian Rae, an expert on chemicals in the environment at the University of Melbourne said: “Bisphenol A is an industrial chemical that mimics natural hormones and can disrupt their action, especially in developing babies and children.”
“BPA’s most common uses are in plastics — epoxy resins and polycarbonate — and in that form it’s quite safe. However, BPA can escape from these plastics, roam free in the environment, and enter our bodies as a trace contaminant in food.”
Concerns about BPA have led to calls for banning it. The European Union is set to ban BPA in food contact materials such as plastic packaging, coated containers, reusable bottles, water coolers, and kitchenware.
The ban will take effect at the end of 2024, pending a review by the European Parliament and the Council.
Many other harmful plastic chemicals and microplastics like PFAS have also been linked to health risks. Called “forever chemicals” due to their persistence in the environment, PFAS are used in various products, including non-stick cookware, waterproof clothing and food packaging.
Microplastics, tiny plastic particles that can contaminate food and water, have been found everywhere, from deep oceans to our food and water supplies and our internal organs.
This new study comes as the world prepares for the final round of UN negotiations in South Korea later this year to establish a global treaty on plastic pollution.
