A new study, published online on October 11, 2019, in the Journal of the American Chemical Society, explores the chemistry as well as the complicated and alarming history of DFDT (image), a fast-acting insecticide. The open-access article is titled “Manipulating Solid Forms of Contact Insecticides for Infectious Disease Prevention.” "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," said Bart Kahr, PhD, Professor of Chemistry at New York University (NYU) and one of the study's senior authors. Dr. Kahr and fellow NYU Chemistry Professor Michael Ward, PhD, study the growth of crystals, which two years ago led them to discover a new crystal form of the notorious insecticide DDT. DDT is known for its detrimental effect on the environment and wildlife. But the new form developed by Dr. Kahr and Dr. Ward was found to be more effective against insects--and in smaller amounts, potentially minimizing its environmental impact. In continuing to explore the crystal structure of insecticides, the research team began studying fluorinated forms of DDT, swapping out chlorine atoms for fluorine. They prepared two solid forms of the compound--a monofluoro and a difluoro analog--and tested them on fruit flies and mosquitoes, including mosquito species that carry malaria, yellow fever, Dengue, and Zika. The solid forms of fluorinated DDT killed insects more quickly than did DDT; the difluoro analog, known as DFDT, killed mosquitoes two to four times faster. "Speed thwarts the development of resistance," said Dr. Ward, a senior author on the study. "Insecticide crystals kill mosquitoes when they are absorbed through the pads of their feet.
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