As I understand that quote, you claimed that the article was wrong when it claimed that “For Carson, et al., the dosage level of DDT was irrelevant”. You also made other claims, but this is the particular claim I’m considering.
The Carson quote sez:
The individual exposed to DDT, for example, is almost certain to be exposed to other liver-damaging hydrocarbons, which are so widely used as solvents, paint removers, degreasing agents, dry-cleaning fluids, and anaesthetics. What then can be a ‘safe dose’ of DDT?
Carson is saying no dose is safe, so dose is irrelevant to safety.