The Rational Optimist_ How Prosperity Evolves - Matt Ridley [139]
It is not much of an exaggeration to say that an entire generation of Westerners grew up expecting Carson’s cancer epidemic to strike them down. I was one of them: it genuinely scared me at school to know that my life would be short and sick. Influenced by Carson and her apostles I set out to do a biological project. I would walk the countryside and pick up the dying birds I found, have their cancers diagnosed, and publish. It was not a great success: I found one corpse, of a swan that had hit a power line. ‘Individuals born since 1945,’ wrote the environmentalist Paul Ehrlich in 1971, ‘and thus exposed to DDT since before birth may well have shorter life expectancies than they would if DDT had never existed. We won’t know until the first of these reach their forties and fifties.’ Later he was more specific: ‘The U.S. life expectancy will drop to forty-two years by 1980, due to cancer epidemics.’
What actually happened is that – excepting lung cancer – both cancer incidence and death rate from cancer fell steadily, reducing by 16 per cent between 1950 and 1997, with the rate of the fall accelerating after that; even lung cancer then joined the party as smoking retreated. The life expectancy of those born after 1945 broke new records. 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.’
DDT’s miraculous ability to halt epidemics of malaria and typhus, saving perhaps 500 million lives in the 1950s and 1960s (according to the US National Academy of Sciences), far outweighed any negative effect it had on human health. Ceasing to use DDT caused a resurgence of malaria in Sri Lanka, Madagascar and many other countries. Of course, DDT should have been used more carefully than it was, for although it was far less toxic to birds than previous pesticides, many of which were arsenic-based, it did have the subversive ability to accumulate in the livers of animals and wipe out populations of predators at the top of long food chains, such as eagles, falcons and otters. Replacing it with less persistent chemicals has brought otters, bald eagles and peregrine falcons bouncing back to relative abundance after an absence of several decades. Fortunately, DDT’s modern pyrethroid successors do not persist and accumulate. Moreover, sparing, targeted use of DDT against malarial mosquitoes can be done without any such threat to wildlife, for example by spraying the inside walls of houses.
Nuclear Armageddon
There were very good reasons to be a nuclear pessimist in the Cold War: the build-up of weapons, the confrontations over Berlin and Cuba, the gung-ho rhetoric of some military commanders. Given how most arms races end, it seemed only a matter of time before the Cold War turned hot, very hot. If you had said at the time that you believed that mutually assured destruction