Ethical debate: doctoring malaria, badly: the global campaign to ban DDT.

The treaty on persistent organic pollutants—POPs—will be finalised at the United Nations Environment Programme meeting in Johannesburg, 4-9 December. One proposal is to ban DDT, still used by many countries for controlling the mosquitoes that spread malaria. It should not be banned, argue Amir Attaran and Rajendra Maharaj, specialists in malariology and also international development and law—there’s no evidence that spraying with DDT harms anyone. The issue is not straightforward, says Richard Liroff, director of the World Wildlife Fund’s alternatives to DDT project; the treaty raises a series of equity challenges.