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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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Tobacco denial and pesticide alarm

Rachel Carson and Al Gore relied on a tobacco denier

I have an article in the Spectator drawing attention to the curious fact that Rachel Carson's Silent Spring owed much to a passionate tobacco denier. It's behind a paywall, but there it is with the sources as links. Hat tip Ron Bailey.


Rachel Carson's Silent Spring, published 50 years ago this month, effectively marked the birth of the modern environmental movement. "Silent Spring came as a cry in the wilderness, a deeply felt, thoroughly researched, and brilliantly written argument that changed the course of history," wrote Al Gore in his introduction to the 1994 edition.

Mr Gore reprised this theme on his website earlier this year, proudly comparing Carson's call to arms over pesticides to his own campaigning on the issue of climate change. He frequently compares the resistance he meets, and Carson met, to that which impeded the battle to establish the link between cancer and cigarette smoking. He accuses industry of "sowing doubt [about global warming] even more effectively than the tobacco companies before them."

The tobacco companies, said Mr Gore last year, "succeeded in delaying the implementation of the surgeon general's report for 40 years - 40 years! In every one of those 40 years the average number of Americans killed by cigarettes each year exceeded the total number of Americans killed in all of World War II: 450,000 per year. My sister was one of them. … It was evil, evil, evil."

Mr Gore may not be aware of a startling irony here. Carson's mentor and the source for much of her case that synthetic pesticides, and DDT in particular, were devastating bird life and causing widespread cancer in people, was himself a fervent denier of the link between tobacco smoking and lung cancer.

His name was Wilhelm Hueper. An immigrant to the United States from Germany (who shook off an embarrassing but brief enthusiasm for Nazism that led him to seek a job back in Hitler's Germany) he became the first director of the environmental cancer section of the US National Cancer Institute. There he single-mindedly pursued the idea that cancer was on the increase and that the cause was largely synthetic chemicals in the environment.

He encountered resistance, however, and not just from the chemical industry. Medical scientists were growing convinced that the rise of lung cancer was being caused by a rise in smoking. Hueper would have none of it. Here he is writing a paper called "Lung Cancers and their Causes" in 1955 in CA, a cancer journal for clinicians: "Industrial or industry-related atmospheric pollutants are to a great part responsible for the causation of lung cancer…cigarette smoking is not a major factor in the causation of lung cancer."

In her book, Carson refers to the work of Hueper throughout and made it clear he was her most important source. Describing a disease in trout, she wrote: "Dr. Hueper has described this epidemic as a serious warning that greatly increased attention must be given to controlling the number and variety of environmental carcinogens. 'If such preventive measures are not taken,' says Dr. Hueper, 'the stage will be set at a progressive rate for the future occurrence of a similar disaster to the human population.' "

The Hueper-Carson warning - that an epidemic of cancer caused by chemicals in the environment was on the way - caused one of the first eco-scares to go mainstream. The ecologist Paul Ehrlich, writing in Ramparts magazine in 1970, said that as a result of chemical pesticides, life expectancy in the United States would drop to 42 years by 1980 due to cancer epidemics. This was a widespread view. To this day many people think that pesticides causes much cancer.

Yet cancer death rates, corrected for average age of the population, are falling steadily. In the 1980s, a definitive study by Sir Richard Doll and Sir Richard Peto concluded that whereas 30% of Americans' cancer was caused by smoking, pollution caused at most a mere 5%. In 1996, the National Academy of Sciences concluded that levels of both synthetic and natural carcinogens are "so low that they are unlikely to pose an appreciable cancer risk".

Rachel Carson herself had a mastectomy and radiation therapy for breast cancer while writing Silent Spring and she died within two years of its publication at the age of 56. In his 1994 foreword, Al Gore hints that she might have been a victim of the chemicals she criticized: "Ironically, new research points strongly to a link between this disease and exposure to toxic chemicals. So in a sense, Carson was literally writing for her life."

Yet the evidence that DDT, the chemical that Carson's book is all about, can cause breast cancer doe not exist. After several studies, experts concluded that "weakly estrogenic organochlorine compounds such as PCBs, DDT, and DDE are not a cause of breast cancer."

When environmentalists attack a climate sceptic these days, they often accuse him or her of being the kind of person who would have denied the role of smoking in cancer. Tobacco denial "was transported whole cloth into the climate debate," said Al Gore in Aspen last year, citing the book Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming by Naomi Oreskes and Erik M. Conway. Oreskes herself, apparently unaware of Carson's reliance on a tobacco denier for much of her argument, told a Yale seminar she was "stunned to discover myself how much the scientific evidence confirmed Rachel Carson's precautionary approach".

In any case, the charge that climate scepticism goes with tobacco denial is false. The best example that Oreskes has produced is a 1994 paper written by the climate sceptic Fred Singer challenging some statistics about passive smoking. Yet Singer does not deny that smoking causes cancer, has served on the advisory board of an anti-smoking organization and dislikes passive smoking.

To conclude from this history that climate alarmists have more in common with tobacco deniers than climate sceptics do would be simply to repeat Mr Gore's and Ms Oreskes's egregious mistake. The true lesson is that arguments should be discussed on their merits, not tarred by tenuous association.