A PASSIONATE argument has been raging between environmentalists and malariologists over the use of DDT for malaria control around the world. The unintended victims of this spurious debate are the hapless poor people in Third World countries. To treat this massive global public health problem with the usual environmental and conservation passions for snail darter and spotted owl is to be oblivious to the suffering of 300 million to 500 million people who come down with malaria every year and of which about 2.5 million, including a disproportionate number of children, do not survive.
Malaria is an ancient disease. Charaka and Sushrutha of ancient India wrote about high fever caused by mosquito bites. The South American aborigines of Peru and Ecuador treated malaria fever with tincture made from the quinine-rich bark of cinchona trees. Our own city of Toledo was built over mosquito-infested swamps along the Maumee River. The malarial parasite was identified in 1880 by French army surgeon Alphonse Leveran. His discovery earned him the Nobel Prize in 1907.
In the past century malaria has been treated rather successfully with a variety of medication, but treating malaria in a patient is not the same as controlling or eradicating malaria through the elimination of mosquitoes. Though DDT had been around for some time, its insecticidal properties were not identified until 1939. Soon thereafter it was put to use in controlling the mosquito population and the results were immediate and dramatic. In parts of South Africa, for example, there was an almost total eradication of the disease. In addition, the chemical received wide acceptance as an insecticide in agriculture.
In this country, DDT was banned about 30 years ago. In 1962 environmental activist and author Rachel Carson published Silent Spring, a controversial and sensational book. In the book she blamed DDT for myriad problems, including the decreasing population of birds. Those on the other side of the fence dismissed the book as pseudo-scientific and outrageous.
The book does not make a distinction between the use of DDT in agriculture and its use for mosquito control even though there is an important difference between the two. Whereas the use in agriculture introduces tons of DDT into the environment, its use for mosquito control drastically limits its entry into the outdoors. The amount of DDT used to control insects in a cotton field would be enough to control mosquitoes in a small country.
That aside, is there any scientific evidence about the harmful effects of DDT on humans? There are just a few animal studies hinting at such a possibility.
DDT has been found in mothers' milk, is known to cause thinning of eggshells, and has the potential of causing endocrine disruption in small animals. But there has not been a convincing scientific study linking DDT to human illness for more than half a century. Very few chemicals have received as much scrutiny and still there is no convincing epidemiological or toxicological evidence to banish it.
So what all this has to do with us here in the United States? Simply put, DDT cannot be used when U.S. aid money is used for malaria control. Because of this restriction, malaria is on the upswing. There are other agents that are effective against mosquitoes but they are very expensive and beyond the reach of poor countries. There is as yet no vaccine against the disease.
Since the introduction of DDT for malaria control in the 1940s an estimated 500 million lives had been saved. Even if you are a fast reader, in the time that it took you to read this column another 30 children have died of malaria around the world. But the controversy and the debate go on.
Dr. S. Amjad Hussain is a Toledo surgeon whose column appears every other week in The Blade. E-mail: firstname.lastname@example.org