Toxicology of paraquat and related bipyridyls: Biochemical, clinical and therapeutic aspects

Bipyridylium Quanternary ammonium compounds have a good safety record in agriculture since they were introduced in the early 1960s as herbicides. However, they, and particularly paraquat (PQ) and diquat (DQ), are responsible for many poisonings due to the accidental or deliberate ingestion of commercial products containing them. Human toxicity of bipyridyls is characterized by local irritant effects and by systemic manifestations which vary according to the compound. In paraquat poisonings, which are the most common, there is transient impairment of liver and kidney function and typical pathological lesions of the lungs characterized by progressive cellular proliferation, which in most cases lead to death because of respiratory insufficiency. An overview of the toxicology of these compounds is presented.