In mammals they exert CNS stimulatory activity similar to some insecticides. At high doses, they may cause death by ventricular fibrillation. Lower dose exposure will cause ataxia, paralysis, peripheral neuritis, and protracted coma. This dioxin derivative may produce teratogenicity, reproductive toxicity, hepatotoxicity, and a depressed immune response. It has also been associated with the development of diabetes mellitus.
Treatment is primarily supportive and symptomatic.
This post-emergent herbicide and its analogue diquat bind tightly to soil and does not leech out into the ground water, lessening the environmental impact. Mechanistically, in plants paraquat inhibits photosynthesis. It will initially produce a pulmonary toxicity characterised by a frothy pulmonary exudate. As toxicity progresses, the lungs and kidneys become fibrotic. Death is usually due to respiratory failure.