Letter: In defence of the pesticide DDT

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The Independent Online
Sir: I was intrigued by the correspondence initiated by Jules Pretty (24 June) on the safety of the pesticide DDT. Despite the elaborate procedures devised over the past four decades for evaluating the safety of pesticides and other substances by testing on experimental animals, it is still not possible to be absolutely certain about the safety of any given chemical in human populations.

However, as one who has studied the biological effects of DDT for half a century and was a member of the Joint WHO/FAO Committee on Pesticides which, a few years ago, decided that DDT was safe to recommend for continued use worldwide, I must refute some of the spurious allegations made in this correspondence.

DDT was the agent that prevented an epidemic of typhus in Europe in the Second World War, and consequently saved millions of lives and untold misery among the countless displaced persons in the Forties. Subsequently, DDT was found to be the safest agent to give newborn babies for the treatment of drug-induced, life-threatening neonatal jaundice, and its use in the suppression of malaria and other vector-borne diseases doubled the life expectancy of man in many tropical countries.

The explanation of this paradox is that scientists in the Fifties, seeking the identity of the chemical that adversely affected wildlife, made a crucial mistake and identified DDT as the culprit. A refinement of the analytical techniques used (gas liquid chromatography - mass spectrometry) revealed that other chemicals, pollutants such as the dioxins and polychlorinated biphenyls, were the true culprits. These latter pollutants have been found to be carcinogens and are among some of the most toxic substances known to man.

I certainly hope that Jules Pretty and I are correct in our views on the safety of DDT, for we all have substantial amounts of DDT locked up in our body fat, and the polar ice-caps have additional stores that are being slowly released into the environment. So despite the ban imposed on the use of DDT as a pesticide in countries such as the United States, that can afford the more expensive (but certainly no safer) new, commercial pesticides, we will all continue to be exposed to DDT for centuries, due to its chemical stability and long life, and its indiscriminate and excessive use in the Forties.

Yours faithfully,

DENNIS V. PARKE

Emeritus Professor of

Biochemistry

University of Surrey, Guildford

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