DDT, danger vs. malaria
Nothing counters malaria like DDT, and so various countries have resumed using the pesticide—despite the fact that its long-term side effects are still unknown.
Malaria kills at least a million people a year, most of them young children and pregnant women. To date, the best means of combatting the disease is the pesticide DDT. Mosquitoes rarely develop resistance to it, there’s no bad odor, and it has no noticeable acute health effects. But because of its known adverse environmental effects and possible carcinogenicity, countries are under pressure to ban DDT, and many have switched to other means of fighting malaria. No approach has proved as effective as DDT, however.
Tom Robins, professor of environmental health sciences, wants to know how dangerous DDT is.
In South Africa’s Limpopo Province, he’s been studying male workers who spray the interiors of domiciles with DDT to ward off malaria. DDT metabolytes such as DDE have an extremely long half-life in the human body, and because DDE interferes with the action of male sex hormones, Robins thought these men might manifest decreased sperm counts, alterations to hormonal balance, and possibly changes in libido and fertility. But he and his research team found no major effects on the workers’ health.
Robins next plans to study the male offspring of women in South Africa’s KwaZulu-Natal Province, another region where homes are routinely sprayed with DDT. Because the time of greatest risk from the anti-hormonal effects of DDT is while a fetus is undergoing the process of sex differentiation, Robins will test to see whether exposure to DDT in utero leads to subsequent reproductive problems.
Noting that some countries have resumed spraying with DDT, Robins says, “No one, including me, is an advocate for DDT. But we don’t have a substitute that works nearly as well, and malaria is a huge public health problem. In the best possible world, chemical companies with supportive governments should be putting lots of effort into finding a pesticide that’s not carcinogenic, will break down fairly quickly, doesn’t have minor acute side effects, and which will and can be used as effectively as DDT.”
To learn more
- www.cdc.gov/malaria (Centers for Disease Control and Prevention)
- www.malaria.org (Malaria Foundation International)
- www.who.int/malaria (World Health Organization)
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- Between 350 and 500 million clinical episodes of malaria occur every year.
- About 60% of the cases of mala-ria worldwide and more than 80% of the malaria deaths worldwide occur in sub-Saharan Africa.
- Although malaria is both preventable and curable, a child dies of malaria every 30 seconds.
- HIV-infected people are partic-ularly susceptible.