DDT in A Nutshell

DDT History and The Latest Science
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First synthesized in 1874 and discovered as an insecticide in 1939, the compound was first used in the 1940s. It helped combat typhus in the Second World War, and its discoverer Paul Müller was awarded the 1948 Nobel Prize in Physiology and Medicine. By the 1960s, DDT was shown to harm the reproductive systems of both fish and birds. Its metabolite, DDE, thinned the egg shells of certain species such as the bald eagle and the brown pelican. This image has an empty alt attribute; its file name is 1200px-pp-dichlorodiphenyldichloroethene.svg_.png

DDE, also a conjugated molecule, is even more resistant to biodegradation than DDT; it bioaccumulates, and by the end of the decade DDE was showing up in human breast milk. It has been shown that DDT and its metabolites may have adverse effects on various organs/tissues of mammals including nervous, liver, kidney, reproductive, endocrine, and immune systems. The EPA in US banned the insecticide in 1972, and eventually osprey and bald eagle populations recovered. Evidence from some tropical countries that continued to use DDT showed that correct and timely use of indoor spraying can reduce malaria transmission by up to 90%. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1570869/ ; Columbia Encyclopedia
“Using more than 200 mother-daughter granddaughter triads, Cohn’s team found that the granddaughters of those in the top third of DDT exposure during pregnancy had 2.6 times the odds of developing an unhealthy BMI(body mass index). They were also more than twice as likely to have started their periods before age 11. Both factors, Cohn says, are known to raise the risk of later developing breast cancer and cardiovascular disease. These results, published in Cancer Epidemiology, Biomarkers, and Prevention, mark the first human evidence that DDT’s health threats span three generations.”
-Scientific American July 2021
“Laboratory studies, including one by Cohn in 2019, have shown that DDT and other EDCs (endocrine disrupting chemicals) can lead to effects across generations via epigenetic changes, which alter how genes turn on and off. Cohn is also investigating the multigenerational effects of other endocrine disruptors, including BPA and polyfluorinated compounds.” https://www.nature.com/articles/190364a0

What Dubious Sources Have Said About DDT

” The half-life of DDT is about 10 years.
So, there is little question that DDT, or one of its metabolites that could be found in virtually all of us in the 1970s should be present even now.
But does this make it harmful?
There is no legitimate worry about human toxicity of DDT. Sixty percent of Americans weren’t even alive in 1972 when DDT was banned, but people think it must have been banned because it was toxic…. It is instead a rather benign chemical that you could eat and never know the difference.” -Josh Bloom of ACSH (https://www.acsh.org/news/2016/02/11/how-poisonous-is-ddt)
ACSH is a group that is notorious for printing views that are controversial but favorable to certain industries. They then solicit them for donations, creating a major conflict of interest. In this case, their strategy is to downplay environmental concerns about pesticides. If not outright vilify her, they often nitpick on Rachel Carson, whose concerns about the impact on songbirds turned out to be incorrect even though the egg-shell thinning in other species was real. Their main beef with her is that she awakened an environmental movement which was inconvenient to their sponsors. They also blame environmentalists for malarial deaths when in fact the DDT ban was only part of the story that caused malaria to come back. Some mosquito populations had developed resistance to DDT as far back as the late 50s and early 1960s .

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