How toxic is DDT?

Abstract

In many regions of the world, especially Europe and the USA, people have forgotten what it is like to have endemic malaria. One of the most important reasons why these regions are no longer endemic for malaria is the use of DDT (dichlorodiphenyltrichloroethane) after the 1939–45 war. When DDT was first used in Naples in January, 1944, 1·3 million civilians were dusted, and even in the midst of winter the incidence of typhus fell sharply. 1 West TF Campbell GA DDT the synthetic insecticide. Chapman and Hall Ltd, London1946 Google Scholar Subsequently, many allied troops and refugees were dusted or wore clothes impregnated with DDT to protect against vermin and typhus. Since DDT turned out to be a highly potent contact insecticide, its potential in the control of malaria was soon recognised. The spraying of houses with DDT led to striking reductions in mosquito counts indoors and, subsequently, in cases of malaria. Reports of such findings, with huge economic benefits, came from Europe, Africa, the USA, India, Sri Lanka, and South America. 2 Hayes WJ Introduction. in: Hayes WJ Laws ER Handbook of pesticide toxicology. Academic Press, San Diego1991: 1-37 Google Scholar The start of the decline, by the early 1960s, of the use of DDT in Europe and the USA, was due partly to the introduction of other insecticides but was also hastened by the recognition that DDT and its metabolite DDE (dichlorodiphenyl-dichloroethylene) persisted in the environment and might harm some species of wildlife. Much of the environmental concern arose as a result of the general use of DDT for the control of many pests and because DDT was not distinguished from other insecticides, but there has also been concern over its direct effects on human beings. DDT house spraying and re-emerging malariaGlobally, numbers of malaria cases are increasing and the rate of increase is accelerating. This pattern is illustrated by multifold increases in malaria rates since 1979 in South America1 accompanied by a rise in the proportions of populations at high to moderate risk of the disease. For example, populations at high to moderate risk more than doubled in Colombia and Peru from 1996 to 1997.2,3 Malaria is reappearing in urban areas and in countries that previously eradicated the disease (eg, urban areas of the Amazon Basin,4 South and North Korea,5 Armenia, Azerbaijan, and Tajikistan6). Full-Text PDF