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Study details version of insecticide DDT lost in aftermath of WWII

By
Brooks Hays
In the 1950s and 60s, the harmful insecticide DDT was sprayed liberally across North America forests and croplands. Photo by Forest Service/USDA
In the 1950s and 60s, the harmful insecticide DDT was sprayed liberally across North America forests and croplands. Photo by Forest Service/USDA

Oct. 14 (UPI) -- In a newly published study, scientists recounted their rediscovery of a fast-acting insecticide DFDT, the forgotten relative of the infamous pesticide DDT.

"We set out to study the growth of crystals in a little-known insecticide and uncovered its surprising history, including the impact of World War II on the choice of DDT -- and not DFDT -- as a primary insecticide in the 20th century," Bart Kahr, professor of chemistry at New York University, said in a news release.

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While studying crystal growth in the lab, scientists happened upon a new crystal form of DDT. When the researchers tested the new pesticide, they found it was more effective and faster-acting than DDT. Because the insecticide can be applied in smaller quantities, DFDT could be more eco-friendly than DDT.

Scientists created the new insecticide by fluorinating molecules of DDT, swapping out the chemical's chlorine atoms for fluorine. When the researchers exposed mosquitoes and fruit flies to the the difluoro analog of DFDT -- with molecules featuring two fluoride atoms -- the targets were killed two to four times faster.

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"Speed thwarts the development of resistance," said NYU chemistry professor Michael Ward. "Insecticide crystals kill mosquitoes when they are absorbed through the pads of their feet. Effective compounds kill insects quickly, possibly before they are able to reproduce."

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After realizing the power of their discovery, scientists surveyed historic chemistry research to see if there was a precedent for the novel insecticide. The researchers found evidence that DFDT was first created by German scientists during World War II. The German military deployed the chemical for insect control in the Soviet Union and North Africa.

In the United States, DDT became the insecticide of choice. Records suggest military officials with the Allied Forces interviewed German scientists about DFDT, but dismissed their claims that the insecticide was more effective and less toxic than DDT.

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"We were surprised to discover that at the outset DDT had a competitor which lost the race because of geopolitical and economic circumstances, not to mention its connection to the German military, and not necessarily because of scientific considerations," said Kahr. "A faster, less persistent insecticide, as is DFDT, might have changed the course of the 20th century; it forces us to imagine counterfactual science histories."

Kahr and his colleagues detailed this alternative history and their rediscovery of a long-lost insecticide in the Journal of the American Chemical Society.

In most places, DDT has been banned for decades -- outlawed for its harmful effects on the environment and wildlife. Though once sprayed indiscriminately, today, DDT is only occasionally deployed for the treatment of malaria-carrying mosquito populations.

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But with the continued prevalence of malaria and the emergence other mosquito-borne diseases, like the Zika virus, scientists and officials have begun to reconsider the use of more powerful insecticides like DDT.

In places where the renewed use of DDT makes sense, DFDT could serve as a safer and more effective alternative.

"While more research is needed to better understand the safety and environmental impact of DFDT, we, along with the World Health Organization, recognize the urgent need for new, fast insecticides," Ward said. "Not only are fast-acting insecticides critical for fighting the development of resistance, but less insecticide can be used, potentially reducing its environmental impact."

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