"We can't say for certain whether it increases the risk of cancer ... ... [but] the fact that we can generate the carcinogenic form in living cells is quite a concern."
Professor Lay said the latency period for chromium-induced cancer was often more than 20 years. "Chromium supplements have only been widely taken for the last couple of decades," he said. "If there are problems, they'd only be starting to emerge."
Hexavalent chromium (VI) is classified as carcinogenic to humans by the International Agency for Research on Cancer. It was the contaminant in the drinking water of the Californian town of Hinkley, linked to a spate of illnesses and made notorious by the film Erin Brockovich.