Neurotoxic effects of paraquat

Paraquat is highly corrosive. It is absorbed poorly after inhalation but is extremely toxic if ingested. After paraquat ingestion, oedema, burns or ulceration may be seen in the mucosa of the mouth, oesophagus, stomach and intestines. Death usually occurs within 48 hours of ingestion of 50 mg/kg. Self-ingestion of paraquat is a serious health problem in many developing countries as it is used for suicidal attempts. It was described that 15 ml of 20% paraquat or one mouthful is a lethal dose in adults (2). An antidote for paraquat has still not been found. The World Health Organization classifies paraquat as a Class 2 moderately toxic substance but ‘Pesticide Action Network Asia & Pacific’ believes it to be in Class 1 due to its acute toxicity, delayed effects, and lack of antidote. There is a lag time between exposure and development of symptoms, early exposure is most deleterious. Unborn foetus and children are at more risk (3). In 2010, the California Environmental Protection Agency showed if exposed to lower doses even, during critical periods of childhood brain development is adversely affected.