The issue with DDT, as I understand it, was that it was massively overused.
The toxicity of DDT to humans is extremely low, regardless of what scumbags like Rachel Carson hyperventilated about.
The deaths of millions of people killed by insect borne diseases because DDT was unnecessarily banned are on the hands of her and her Leftist allies.
And I should add, even if it was massively overused for everything under the sun, its benefits STILL far outweighed the risks.
By far.
All the arguments presented by the Environmental Defense Fund responsible for getting DDT banned during the hearings in the summer of 1972 were ultimately debunked by the independent studies done by the Fish and Wildlife service.
Then EPA director, William Ruckelshaus, who never attended one of the hearings, just arbitrarily banned it. Apparently he had personal ties to the EDF.
The claim that DDT caused the thinning of birds' eggs was a lie and subsequent studies by the Fish Wild. dept. proved just the opposite. It the test studies done on pheasant and quail eggs, the birds that were fed a steady diet of DDT had a hatch rate of approx. 80% while the other test group that wasn't fed DDT only had a hatch rate of around 53%
Another lie was that DDT was responsible for the decline in the bald eagle. The reality was the loss of habitat and hunter predation on not only the eagles but all other raptors as well. In fact, Alaska offered a bounty on bald eagles between 1917 and 1953 in order to protect the salmon industry.
Junkscience has a great article at their site detailing all that happened during those hearings.