|
The Legacy of the DDT Ban, the Legacy of Rachel Carson
By Patricia Ludwig
Malaria is responsible for over one million deaths a year worldwide with most deaths occurring in children under the age of five. Approximately 40% of the world's population is at risk of contracting malaria, with the highest concentration of risk occurring in sub-Saharan Africa. The disease is not a problem for developed regions such as Europe and the United States because they eradicated it through the use of DDT in the years following World War II.
DDT is a pesticide that not only kills the mosquitoes that transmit the disease, but also irritates them so that they will not bite, and repels them. The U.S. military introduced the use of DDT for malarial control in 1944, and other countries followed. South Africa adopted DDT use in 1946, causing malaria cases in the Transvaal to decline to 10% of their 1942-43 level. DDT was so successful in attacking malaria that Dr. Paul Muller won the Nobel Prize in Medicine in 1948 for his discovery that DDT could kill the mosquitoes that carry the malaria parasite.
Silent Spring vs. DDT
Despite this success, environmentalists, fueled by Rachel Carson's 1962 publication of Silent Spring, lobbied for the banning of DDT. Their two arguments for the ban were that DDT was carcinogenic, causing an increased risk for breast cancer, and that it had a detrimental effect on beneficial insects, aquatic animals, and birds, particularly bald eagles. The carcinogenic claim was based on a study in which high doses of DDT caused increased cancer incidence rates in mice, but no correlation was found in humans. A study conducted on North Vietnamese women who had high serum concentrations of DDT found that these women did not have increased incidence of cancer.
Studies also showed that the risk of DDT to birds was not as great as environmentalists claimed. A 1966 report by the U.S. Fish and Wildlife Service found that environmental DDT residues encountered by bald eagles would not affect eagles or their eggs. A 1970 report by the Pesticides Monitoring Journal further confirmed that DDT residues were not correlated with the thinning of birds' eggshells. The studies that supported the claims of eggshell thinning were ones in which the birds were exposed to levels of DDT much greater than environmental levels and were conducted on birds with low-calcium diets. Even with this evidence, environmentalists and anti-chemical activists triumphed, and on June 14, 1972, EPA administrator William Ruckelshaus banned the use of DDT.
Effects of the Ban
The ban of DDT by the EPA caused many other countries to follow suit and discontinue use of DDT as a method for malarial control. The ban was supported by many aid agencies such as USAID, the WHO, the Norwegian Development Agency, and the Swedish Aid Agency, which contributed a large portion of public health aid to poor nations. These countries, dependent on aid, could not continue to use DDT after the ban. Many countries also stopped using DDT for fear that European countries would refuse to buy their agricultural exports. The ban on DDT thwarted progress in the eradication of malaria. In South Africa, DDT was phased out in 1996, causing malaria cases to increase from 12,500 in 1995 to 50,000 in 1999. However, cases dropped by 80% in 2000 in KwaZuluNatal, the one province in South Africa that began using DDT extensively again. Though DDT need not be used on everything as it was in the 1950s and 1960s, its judicious use is clearly effective in controlling malaria.
To replace DDT, many countries such as South Africa began using synthetic pyrethoids to kill malarial mosquitoes. The problem with these substitutes is that they are more expensive and less effective. The per structure cost of indoor spraying of DDT is 2.26 rands, whereas it is 3.81 rands for Deltametrin and 9.28 rands for Cyfluthrin, two forms of synthetic pyrethoids. In addition, A. funestrus, a malaria-transmitter mosquito that feeds almost exclusively on humans, has developed resistance to pyrethroids. In the 1950s, it had almost disappeared from South Africa. It began to reappear in the 1990s, which correlates with the removal of DDT.
Return to DDT
Since DDT is the cheapest, most effective way of preventing the transmission of malaria, its judicious use should be promoted. DDT can be safely sprayed inside people's homes, killing the mosquitoes that carry the parasite. This method avoids any possible environmental dangers to crops or wildlife. With over one million people dying every year from malaria, the benefits of DDT use far outweigh any possible adverse affects.
With the recent one-hundredth anniversary of Rachel Carson's birthday, the question arises as to whether we should celebrate her legacy. It seems inappropriate to shower her with praise because her argument in Silent Spring was based on faulty statistics and emotionally appealing anecdotes. The real legacy left behind by Silent Spring is millions of deaths from malaria that could have been prevented if health authorities had continued to use DDT as a method for killing mosquitoes carrying the disease.
With the evidence so strongly in favor of the effectiveness of DDT, this argument has a clear solution. The restrictions on DDT should be lifted in order to save the lives of millions of African children.
Patricia Ludwig is a research intern at the American Council on Science and Health (ACSH.org, HealthFactsAndFears.com).
|
