In 1972, on the basis of data on toxicity to fish and migrating birds (but not to humans), the Environmental Protection Agency banned virtually all uses of the pesticide DDT, an inexpensive and effective pesticide once widely deployed to kill disease-carrying insects. (How ironic that regulators banned DDT largely for its toxicity to birds, for now it's unavailable to combat a mosquito-borne disease that killing birds by the hundreds of thousands!)All those people who freak out at the thought that anyone should cast doubt on evolution might want to question whether we should have this almost religious faith in the evils of DDT when there is plenty of science out there to show that it can be used, without endangering the environment, to protect people from diseases that are killing so very many. Can we at least have a new study to look at evidence collected since 1972?
Allowing green politics to trump science, regulators also cited the possibility that DDT posed a cancer risk for humans, an assertion based on studies in mice that were fed extremely high doses of the pesticide. The validity of extrapolating these high-dose animal studies to minuscule exposures in humans was, and remains, in doubt.
Not only did government regulators underplay scientific evidence of the effectiveness and relative safety of DDT, they also failed to appreciate the distinction between its large-scale use in agriculture and more limited application for controlling carriers of human disease. Although DDT is a (modestly) toxic substance, there is a big difference between applying large amounts of it in the environment — as American farmers did before it was banned — and applying it carefully and sparingly to fight mosquitoes and other disease-carrying insects. A basic principle of toxicology is that the dose makes the poison.
The regulators who banned DDT also failed to take into consideration the inadequacy of alternatives. Because it persists after spraying, DDT works far better than many pesticides now in use, some of which are toxic to fish and other aquatic organisms. Also, the need to spray other insecticides repeatedly — especially in marshlands and forests, where mosquitoes tend to breed — drives up costs and depletes public coffers. Pyrethroid pesticides, the most common alternative to DDT, are inactivated within an hour or two.
The spraying of any pesticides — let alone DDT — has been greeted by near-hysterical resistance from environmental activists, who have attacked the killing of mosquitoes as "disrupting the food chain." New York's Green-party literature declares that "These diseases only kill the old and people whose health is already poor."
Since the banning of DDT, insect-borne diseases such as malaria and dengue — and now West Nile virus — have been on the rise. The World Health Organization estimates that malaria kills about a million people annually, and that there are between 300 million and 500 million new cases each year.
UPDATE: Apparently I wasn't clear in my point relating to evolution. What I was trying to point out is that these are both scientific questions. The reason people scoff at Intelligent Design is, I believe, due to the lack of scientific evidence. Most people feel that the theory of evolution has been proven using evidence. I'm with them but science is not my subject. However, I've seen several reports now casting doubt on the science that was used to ban DDT in the 1970s. So, using the same interest in scientific study, I feel that it would not be out of place to have new studies on the efficacy of DDT in killing disease-bearing mosquitos versus the problems that DDT purportedly causes.