STUDIES ON THE MAMMALIAN TOXICITY OF FENTHION.

This paper constitutes a report on mammalian toxicological investigations of fen hion, carried out as part of the WHO malaria eradication programme, and on the conclusions drawn from them. Fenthion is found to be of intermediate toxicity to the four rodent species studied. In rats the signs of poisoning develop rather slowly but persist for several days, male rats being more susceptible than females, whereas for most phosphorothionates the converse is true. The results suggest that fenthion is not simply oxidized from the P=S compound to the P=O. It has been stated that the sulfoxide and sulfone are produced before the P=S-->P=O oxidation takes place, but experiments suggest that further changes are involved. The findings are discussed in relation to the possible health hazard that might be encountered by those who have to apply fenthion as a residual spray.