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Quick test keeps tabs on sex-change danger

点击量:   时间:2019-03-07 05:10:02

By Ian Sample GENDER-bending chemicals in food could soon be screened out using a cheap new test developed by researchers in Britain. They have already found substances in tea, fruit and vegetables that bind to the same human receptors as female hormones. A host of natural and synthetic substances mimic the behaviour of the female sex hormone oestrogen. These chemicals have been linked to sex changes in fish and reptiles, increasing levels of breast and testicular cancer in people, and even changes in the wiring of the brain (New Scientist, 18 July 1998, p 4). Although tests for oestrogenic substances do exist, they are expensive and mostly laborious. But Heather Lee of the Institute of Food Research in Norwich has found an easier way. “It’s useful for screening food, not just for the chemicals we know are oestrogenic but for chemicals we don’t know about that have the same effect,” she says. The test relies on making the oestrogenic substances in food compete with the hormone itself for human oestrogen receptors in tiny plastic wells. The greater the concentration of an oestrogenic substance in the food, the more receptors it is likely to bind to. Lee and her colleagues use a coloured enzyme to measure how much of the real hormone—rather than the oestrogenic substances in the food—has bound to the receptors. The lighter the colour, the less added oestrogen has bound and therefore the more oestrogenic substance is in the food. Lee admits that the test is unable to distinguish between those chemicals that simply block the oestrogen receptor and those that cause an oestrogenic response. “Some chemicals can bind to the oestrogen receptor but don’t stimulate oestrogen responsive genes,” agrees Gerald LeBlanc,