New York University Professors Bart Kahr and Michael D. Ward have identified a crystallized form of DDT that could lead to the development of safer and more effective pesiticides. In light of this scientific finding, the authors researched the history of this controversial chemical. Their investigation into the politics of science policy led them to a deeper appreciation of Rachel Carson, the scientist who raised concerns about the environmental safety of pesticides in her 1962 book "Silent Spring," leading to a ban on DDT in 1972. The effect of Carson's book was monumental, and although her science was rigorous, she was subsequently villified by many, who labelled her hysterical (and worse). On the heels of their promising cystallographic discovery that could result in a renewed interest in DDT, Kahr and Ward examine "how DDT science has been misrepesented by those with extra-scientific interests."
The scientific study, published in Angewandte Chemie (DOI: 10.1002/anie.201703028) in an article called, "DDT Polymorphism and the Lethality of Crystal Forms," includes authors Jingxiang Yang, a visiting scientist in the Kahr Lab from Tianjin University, NYU Chemistry crystallographer Chunhua Hu, and Ward Group doctoral student Xiaolong Zhu, as well as their colleague from the University of Nevada, Professor Qiang Zhu.
Abstract: DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), a contact insecticide with a rich and controversial history since its activity was discovered in 1939, has long been thought to be monomorphic. Herein we report the discovery and characterization of a second polymorph, designated Form II, which can be isolated as single crystals, but converts very slowly at room temperature to the form reported previously, now designated as Form I. Computations based on an evolutionary algorithm for crystal structure prediction revealed that Forms I and II are among the four lowest energy crystal structures of fifty calculated. A preliminary study of the contact insecticidal activity toward fruit flies (Drosophila melanogaster) indicates that Form II is more active, suggesting opportunities for more effective solid-state formulations that would allow reduced amounts of DDT, thereby minimizing environmental impact.
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The related essay on science policy by Yang, Ward and Kahr, called, "Abuse of Rachel Carson, and Misuse of DDT Science in the service of Environmental Deregulation," also appears in Angewandte Chemie.
Abstract: Fake news?? The contact insecticide DDT has been reappraised as a safe, life-saving compound by special interest groups committed to repealing environmental regulations. It is shown in this essay how some specific toxicological data has been misused by those aiming to disingenuously influence public policy.
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This research, both scholarly and experimental, has been picked up by NYU Research News, Wiley's Chemistry Views, Bustle Magazine, C&E News and more.
Acknowledgments: This work was supported by the National Science Foundation, NSF Materials Research Science and Engineering Center (MRSEC) program, the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through a Department of Energy Cooperative Agreement, and the China Scholarship Council.