The four riders of the modern apocalypse are chemicals (DDT, CFCs, acid rain), diseases (bird flu, swine flu, SARS, AIDS, Ebola, mad cow disease), people (population, famine), and resources (oil, metals). Matt Ridley discusses DDT first:
Silent Spring, published 50 years ago this year, was instrumental in the emergence of modern environmentalism. “Without this book, the environmental movement might have been long delayed or never have developed at all,” Al Gore wrote in his introduction to the 1994 edition. Carson’s main theme was that the use of synthetic pesticides — DDT in particular — was causing not only a massacre of wildlife but an epidemic of cancer in human beings. One of her chief inspirations and sources for the book was Wilhelm Hueper, the first director of the environmental arm of the National Cancer Institute. So obsessed was Hueper with his notion that pesticides and other synthetic chemicals were causing cancers (and that industry was covering this up) that he strenuously opposed the suggestion that tobacco-smoking take any blame. Hueper wrote in a 1955 paper called “Lung Cancers and Their Causes,” published 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 fact, of course, the link between smoking and lung cancer was found to be ironclad. But the link between modern chemicals and cancer is sketchy at best. Even DDT, which clearly does pose health risks to those unsafely exposed, has never been definitively linked to cancer. In general, cancer incidence and death rates, when corrected for the average age of the population, have been falling now for 20 years.
In the 1980s it was acid rain’s turn to be the source of apocalyptic forecasts:
In this case it was nature in the form of forests and lakes that would bear the brunt of human pollution. The issue caught fire in Germany, where a cover story in the news magazine Der Spiegel in November 1981 screamed: “THE FOREST DIES.” Not to be outdone, Stern magazine declared that a third of Germany’s forests were already dead or dying. Bernhard Ulrich, a soil scientist at the University of Göttingen, said it was already too late for the country’s forests: “They cannot be saved.” Forest death, or waldsterben, became a huge story across Europe. “The forests and lakes are dying. Already the damage may be irreversible,” journalist Fred Pearce wrote in New Scientist in 1982. It was much the same in North America: Half of all US lakes were said to be becoming dangerously acidified, and forests from Virginia to central Canada were thought to be suffering mass die-offs of trees.
Conventional wisdom has it that this fate was averted by prompt legislative action to reduce sulphur dioxide emissions from power plants. That account is largely false. There was no net loss of forest in the 1980s to reverse. In the US, a 10-year government-sponsored study involving some 700 scientists and costing about $500 million reported in 1990 that “there is no evidence of a general or unusual decline of forests in the United States and Canada due to acid rain” and “there is no case of forest decline in which acidic deposition is known to be a predominant cause.” In Germany, Heinrich Spiecker, director of the Institute for Forest Growth, was commissioned by a Finnish forestry organization to assess the health of European forests. He concluded that they were growing faster and healthier than ever and had been improving throughout the 1980s. “Since we began measuring the forest more than 100 years ago, there’s never been a higher volume of wood … than there is now,” Spiecker said. (Ironically, one of the chief ingredients of acid rain — nitrogen oxide — breaks down naturally to become nitrate, a fertilizer for trees.) As for lakes, it turned out that their rising acidity was likely caused more by reforestation than by acid rain; one study suggested that the correlation between acidity in rainwater and the pH in the lakes was very low. The story of acid rain is not of catastrophe averted but of a minor environmental nuisance somewhat abated.
1. DDT almost certainly does cause cancer. The logic presented that it doesn’t because cancer incidence and mortality have fallen over 20 years is highly faulty. Cancer has many causes, quite a few unknown, so just because cancer incidence might faul during a time period hardly means that a substance used in that period has nothing to do with cancer. It is possible, though, to reasonably suspect something of causing cancer even if the very expensive and rigerous studies to absolutely prove it have not been done. For example, substances that cause genetic mutation in cells are highly likely to increase one’s risk of cancer.
2. Cancer incidence has not fallen even when you adjust for age. Look at this age adjusted graph of childhood cancer.
While mortality has fallen slightly, incidence has increased.
Likewise this chart shows common cancer incidence for men and women (again age adjusted).
Except for lung and colon cancer in men, most cancers seem to have seen incidence increase or stay flat.