With Zika, Time to Bring Back DDT
The Zika virus is spreading by mosquitos northward through Latin America, possibly correlated with birth defects such as microcephaly in infants. Stories and photos of their abnormally small skulls are making headlines. The World Health Organization reports that four million people could be infected by the end of 2016.
On Monday, the WHO is meeting to decide how to address the crisis. The international body should recommend that the ban on DDT should be reversed, in order to kill the mosquitoes that carry Zika and malaria, a protistan parasite that has no cure.
Zika is in the news, but it is dwarfed by malaria. About 300 million to 600 million people suffer each year from malaria, and it kills about 1 million annually, 90 percent in sub-Saharan Africa. We have the means to reduce Zika and malaria—and we are not using it.
Under the Global Malaria Eradication Program, which started in 1955, DDT was used to kill the mosquitoes that carried the parasite, and malaria was practically eliminated. Some countries such as Sri Lanka, which started using DDT in the late 1940s, saw profound improvements. Reported cases fell from nearly 3 million a year to just 17 cases in 1963. In Venezuela, cases fell from over 8 million in 1943 to 800 in 1958. India saw a dramatic drop from 75 million cases a year to 75,000 in 1961.
This changed with the publication of Rachel Carson’s 1962 book, Silent Spring, which claimed that DDT was hazardous. After lengthy hearings between August 1971 and March 1972, Judge Edmund Sweeney, the EPA hearing examiner, decided that there was insufficient evidence to ban DDT and that its benefits outweighed any adverse effects. Yet, two months afterwards, then-EPA Administrator William D. Ruckelshaus overruled him and banned DDT effective December 31, 1972.
Other countries followed, and DDT was banned in 2001 for agriculture by the Stockholm Convention on Persistent Organic Pollutants. This was a big win for the mosquitoes, but a big loss for people who lived in Latin America, Asia, and Africa.
Carson claimed that DDT, because it is fat soluble, accumulated in the fatty tissues of animals and humans as the compound moved through the food chain, causing cancer and other genetic damage. Carson’s concerns and the EPA action halted the program in its tracks, and malaria deaths started to rise again, reaching 600,000 in 1970, 900,000 in 1990 and over 1,000,000 in 1997—back to pre-DDT levels.
Some continue to say that DDT is harmful, but others say that DDT was banned in vain. There remains no compelling evidence that the chemical has produced any ill public health effects. According to an article in the British medical journal The Lancet by Professor A.G. Smith of Leicester University,
“The early toxicological information on DDT was reassuring; it seemed that acute risks to health were small. If the huge amounts of DDT used are taken into account, the safety record for human beings is extremely good. In the 1940s many people were deliberately exposed to high concentrations of DDT thorough dusting programmes or impregnation of clothes, without any apparent ill effect…In summary, DDT can cause toxicological effects but the effects on human beings at likely exposure are very slight.”
Even though nothing is as cheap and effective as DDT, it is not a cure-all for malaria. But a study by the Uniformed Services University of the Health Sciences concluded that spraying huts in Africa with DDT reduces the number of mosquitoes by 97 percent compared with huts sprayed with an alternative pesticide. Those mosquitoes that do enter the huts are less likely to bite.
By forbidding DDT and relying on more expensive, less effective methods of prevention, we are causing immense hardship. Small environmental losses are inferior to saving thousands of human lives and potentially increasing economic growth in developing nations.
We do not yet have data on the economic effects of the Zika virus, but we know that countries with a high incidence of malaria can suffer a 1.3 percent annual loss of economic growth. According to a Harvard/WHO study, sub-Saharan Africa’s GDP could be $100 billion greater if malaria had been eliminated 35 years ago.
Rachel Carson died in 1964, but the legacy of Silent Spring and its recommended ban on DDT live with us today. Millions are suffering from malaria and countless others are contracting the Zika virus as a result of the DDT ban. They were never given the choice of living with DDT or dying without it. The World Health Organization should recognize that DDT has benefits, and encourage its use in combating today’s diseases.