DDT was banned or restricted in industrialised countries in the 1970s but in many countries it is still widely used against malaria-transmitting mosquitoes. The concentrations to which human beings are exposed during mosquito control are thought to have no serious toxic effects, and the benefits of the reduction in malaria are substantial. The metabolite DDE has previously been linked to preterm births in small but inconclusive studies.
Basing a study on the US Collaborative Perinatal Project, Matthew Longnecker and colleagues from the National Institute of Environmental Health Sciences, USA, selected a subset of more than 44 000 eligible children born between 1959 and 1966 and measured the DDE concentration in their mothers' blood samples stored during pregnancy. Complete data were available for 2380 children, of whom 361 were born preterm (before 37 weeks' gestation) and 221 were small-for-gestational age (were in the lowest 10% weight for each week of pregnancy).
The average maternal DDE concentration was 25 μg per litre, much higher than current US concentrations. The risk of preterm birth or babies small for gestational age rose with increasing concentrations of blood DDE.
Matthew Longnecker comments: "Our findings suggest that DDT use increases preterm births, and, by inference, infant mortality. Benefits of vector control with DDT might need to be reassessed in the context of this adverse effect on human beings and the availability of alternative methods of vector management."
Contact: Dr Matthew P Longnecker, Epidemiology Branch, National Institute of Environmental Health Sciences, P O Box 12233 MDA3-05, Research Triangle Park, NC 27709, USA; T) +1 919 541 5118; F) +1 919 541 2511; E) email@example.com
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