Progress in science, like progress everywhere, is not inevitable. Progress often requires champions or entrepreneurs to persist in overcoming obstacles. In the case of DFDT, the obstacles arise due to the drug’s association with the chemical DDT and with Nazi Germany, the first of which is unjustly reviled and the second of which is justly reviled. But DFDT should not be judged by either its relatives or its venue of origins It should be judged by its efficacy against malaria, and by its effects, if any, on the environment.
(p. D1) In postwar Allied intelligence reports examined by Dr. Ward and his colleagues, German scientists claimed their insecticide, now called DFDT, was more effective than DDT. Allied officials dismissed those assertions as fanciful, especially given the deplorable behavior of Hoechst, the German chemical manufacturer that developed the insecticide, during the war. The company had forced residents of countries occupied by Germany to work in its factories, and it tested drugs on concentration camp prisoners.
The insecticide was forgotten for decades.
Now, work by Dr. Ward and his colleagues, reported this month [Oct. 2019] in an article in the Journal of the American Chemical Society, appears to corroborate the German claims. The forgotten compound killed mosquitoes in as little as one-fourth the time as DDT.
. . .
(p. D4) Conceivably the more lethal DFDT could be used in even smaller, possibly safer doses. A new option could allow public health officials to rotate insecticides and thwart the resistance to DDT in many mosquitoes today.
“It’s exciting and desperately needed,” said Duane J. Gubler, an emeritus professor in the emerging infectious diseases program at Duke University and the National University of Singapore Graduate Medical School. He was not involved in the study.
But will anyone today risk the time and money needed to determine whether DFDT could be a safe and effective tool against malaria as well as other mosquito-borne diseases like Zika, dengue and yellow fever?
“Donors, governments, they just don’t want the backlash, even if it’s not wholly justified,” said Bart Kahr, Dr. Ward’s colleague at N.Y.U. and an author of the paper.
. . .
The N.Y.U. chemists started the research with no interest in insecticides whatsoever.
They were studying materials that crystallize in a twisted helical pattern. One of the ways to identify such molecules is to scan the internet for images of crystals made by hobbyists. DDT, they found, exhibited the characteristic pinwheel gradients of a helical crystal when illuminated with polarized light.
Jingxiang Yang, a postdoctoral researcher at N.Y.U., started growing DDT crystals and found not only the expected crystals but also more jumbled, chaotic patterns.
“There was some organized and some crazy,” Dr. Kahr said. “We didn’t expect the other stuff, and that other stuff turned out to be a different arrangement of molecules in the crystal. That form wasn’t known to science.”
That led to the next set of experiments. “Since we have two forms,” Dr. Kahr said, “it was natural to ask, which of these forms was the historical killer of insects?”
It turned out that the chaotic form of DDT is deadlier.
As they were going through early scientific data on DDT, the N.Y.U. chemists found mentions of DFDT.
The compound, difluoro-diphenyl-trichloro-ethane is the same molecule as DDT, except with fluorine atoms replacing two of the chlorines.
The Germans developed DFDT at least in part to avoid paying the licensing fees for DDT to the Swiss. It is also possible that the chemical ingredients for DFDT, although considerably more expensive at the time than those for DDT, may have been more readily available in wartime Germany.
. . .
Dr. Kahr wonders: If DFDT had displaced DDT, would the 1955 push have succeeded in bringing malaria under control before resistance set in? “What if this compound wasn’t forgotten,” he said. “What would the world be like? Science doesn’t go as linearly as the general public thinks it does.”
For the full story see:
(Note: ellipses, and bracketed month, added.)
(Note: the online version of the story was updated Oct. 22, 2019 [sic], and has the title “A Nazi Version of DDT Was Forgotten. Could It Help Fight Malaria?” Where the more detailed online version differs from the print version, the passages quoted above follow the print [sic] version.)