Set for ban, DDT lingers in battle against malaria

Few poisons have ridden such a roller coaster through environmental history as DDT.

Once hailed as a miracle pesticide, DDT is outlawed as one of a "Dirty Dozen" chemicals as of Monday even as it stays in use as a controversial spray against malaria-spreading mosquitoes.

The man who discovered its power to kill insects won a Nobel Prize in 1948, while shock at its damage to wildlife awoke a global environmental movement in the 1960s.

Into the 21st century, countries including South Africa and Ethiopia still swear by DDT to combat malaria, which kills a million people a year. They say there is scant evidence that DDT is carcinogenic for humans.

"There is still a role for DDT," said Jim Willis, head of the U.N. Environment Program (UNEP) chemicals division, estimating that about 25 countries will use DDT under exemptions from the DDT pesticide ban.

DDT is one of 12 industrial chemicals to be outlawed under the U.N.'s 2001 Stockholm Convention on Persistent Organic Pollutants (POPs), which formally comes into force on Monday after ratification by 50 states.

Although harmful to humans, DDT can substantially reduce the rate of malaria, which kills one African child every 30 seconds, according to U.N. estimates. The disease burdens health budgets and curbs economic growth.

Best known by its initials, dichloro-diphenyl-trichloromethylmethane can suppress the immune system and is infamous for threatening bird populations by thinning eggshells.

NO HEALTH DAMAGE?

"We have seen no conclusive evidence that it (spraying) has any impact on human health. We put very small quantities of DDT on the wall," said Devanand Moonasar, national malaria program manager of South Africa's National Department of Health.

"We spray only under the eaves and also inside the houses of traditional mud structures," he said, adding that spraying was normally done from August to October when mosquitoes are worst.

Still, workers use full protective clothing for spraying, and U.N. warnings about DDT and the rest of the "Dirty Dozen" POPs are stark.

"Of all the pollutants released into the environment every year by human activity, POPS are the most dangerous," said UNEP chief Klaus Toepfer, adding that the world should hunt for alternatives to DDT to control malaria.

DDT and other POPs including dioxins or pesticides like aldrin or chlordane are found worldwide but build into highest concentrations in the fatty tissues of people in the Arctic and in animals from polar bears to seals.

In the heavily industrialized Northern Hemisphere, the chemicals are swept north by ocean currents and winds and end up lodging in fatty tissues in the apparently pristine Arctic.

"There is a conflict between the interests of the people in the Arctic and those who are living in areas where DDT is used," said Lars-Otto Reiersen, head of the Arctic Monitoring and Assessment Program.