London: Drinking water from plastic cups or bottles could be giving millions of Britons migraines.

Research shows that a controversial “gender-bending” chemical in synthetic packaging may trigger the attacks.

Bisphenol A (BPA) has already been linked to a range of heath problems including obesity, infertility and heart attacks.

The latest study points to BPA causing the debilitating headaches which afflict one in seven adults in Britain, the journal Toxicological Sciences reports.

The study authors urge sufferers to remove potential sources of contamination, including plastic microwave trays, bottles and office water coolers.

The University of Kansas researchers tested a group of rats, half of which were given BPA once every three days. Within half an hour those exposed to BPA became less active, steered clear of loud noise and strong light, were easily startled, and showed signs of tenderness to the head.

The rats’ brains also gave off signals of an influx of oestrogen; migraines have been linked to sudden changes in levels of the female sex hormone, which BPA mimics.

The report states: “These results imply that BPA has the ability to amplify symptoms that are used to diagnose the disorder in human patients, suggesting that exposure to BPA would increase both the incidence and prevalence of this disorder.”

Neurologist Dr Fayyaz Ahmed, of the Migraine Trust charity, said: “In most sufferers, attacks are genetically linked and the triggers only generate them in those who are predisposed. But if BPA is implicated in the genesis of migraines then this would be a milestone in headache research.”

Bisphenol A is found in a vast range of products, from car dashboards and shower curtains to till receipts and cosmetics.