Effects of concentration reduction and partial replacement of paraquat by diquat on human toxicity: a clinical survey.

Paraquat poisoning was studied in 174 patients over a 12-month period when a new, low concentration paraquat product (4.5% w/v paraquat ion mixed with 4.5% w/v diquat ion; 63 cases) replaced the original high concentration paraquat product (20% w/v paraquat ion only; 111 cases). In both groups approximately 60% of the patients died from circulatory failure accompanied by multiple organ failure within a week of ingesting the products. However, a remarkable reduction in late deaths from respiratory failure was noted in the new product group (17.1% vs 6.3%). This was reflected in this group's improved survival (23.4% vs 34.9%). The improvement in survival seems to be attributable to the dilution of paraquat with diquat which seems to have a different toxicological profile to paraquat.