The Rational Optimist (P.S.)

by Matt Ridley

The search for a widespread epidemic of cancer caused by synthetic chemicals, relentlessly and enthusiastically pursued by many scientists ever since the 1960s, has been entirely in vain. By the 1980s, a study by the epidemiologists Richard Doll and Richard Peto had concluded that age-adjusted cancer rates were falling, that cancer is caused chiefly by cigarette smoke, infection, hormonal imbalance and unbalanced diet – and that chemical pollution causes less than 2 per cent of all cases of cancer. The premise on which much of the environmental movement had grown up – that cleaning up pollution would prevent cancer – proved false. As Bruce Ames famously demonstrated in the late 1990s, cabbage has forty-nine natural pesticides in it, more than half of which are carcinogens. In drinking a single cup of coffee you encounter far more carcinogenic chemicals than in a year’s exposure to pesticide residues in food. This does not mean that coffee is dangerous, or contaminated: the carcinogens are nearly all natural chemicals found in the coffee plant and the dose is too low to cause disease, as it is in the pesticide residue. Ames says, ‘We’ve put a hundred nails in the coffin of the cancer story and it keeps coming back out.’