Rachel Carson’s book, “Silent Spring” was the impetus in banning DDT. She claimed, among other allegations, that it caused the thinning of the egg shells of Eagles. Since it was banned, the bald eagle has been removed from the endangered list, so it is obvious that the eagle population has increased. However, it is also claimed that the ban has caused millions of deaths as it was an effective cure for malaria, and that the rise in the eagle population was caused, not by the DDT ban, but by laws prohibiting their shooting. http://www.foxnews.com/story/2006/07/06/bald-eagle-ddt-myth-still-flying-high.html http://www.wsj.com/articles/SB116727843118861313
There has been talk of returning DDT to the arsenal, but under very stringent usage conditions. It’s highly effective against bedbugs, for example, when very little else is.
The problem was that DDT was safe for humans, and thus thought to be safe all around except for bugs, and thus dumped in megatonne quantities rather than being used with any selectivity. Very few ag chemicals are allowed to be used that way now; adding DDT to the list under good controls would not have the effect it had in the 1950s/60s. Or need not.
The Willamette Valley here in Oregon is thick with these Bald Eagles in winter. They’re the primary scavenger once the Turkey Vultures migrate south for the winter. However, as I understand the matter, the Columbia River Valley is all but devoid of Bald Eagles, whatever is reducing their populations is still leaching out into the water. I have no idea if it’s DDT or not.
DDT was never banned for pest control, only agriculture. If anything, not using DDT for agriculture slowed down the development of mosquitoes’ resistance and saved lives. The notion that environmentalists (or even Rachel Carson personally – she never argued that DDT should be banned) are responsible for millions of malaria death is nothing but base slander.
It’s also been thoroughly debunked, here and elsewhere. DDT was never banned in Africa, where people die from malaria…nor would US law have significant effect there.
Mosquito-control authorities generally reserve DDT for emergencies; otherwise malarial mosquitoes would quickly evolve resistance and make it useless anyway.
I guess the question would be is ingestion of 50 ppm of DDT for 6 months a realistic scenario on which to have relevant data? What is considered to be significantly thinner? I have had duck eggs before, and the shells are definitely thicker than a chicken egg.
Or is this another case of skewing data to fit an agenda in the vein of feeding lab rats 5 million times the normal exposure of a random chemical in order to claim it as a carcinogen?
DDT stopped being used to kill mosquitoes because over time (only 7-10 years due to insects’ short breeding cycle and tendency to produce many offspring) the DDT-resistant mosquitoes were the only ones left in those areas. It was basically natural selection. Once DDT stopped killing mosquitoes it was abandoned.