Fenitrothion

Fenitrothion (IUPAC name: O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate) is a phosphorothioate (organophosphate) insecticide that is inexpensive and widely used worldwide. Trade names include Sumithion, a 94.2% solution of fenitrothion. Fenitrothion at sublethal doses affected the motor movement of marsupials, and at acute dose levels it reduced the energy of birds. In chronic (low) dose tests, unexpectedly only the lowest concentration (0.011 microgram/liter) of fenitrothion depressed the growth of an algae, though all of the chronic dose levels used were toxic in other ways to the algae. Just half of fenitrothion's minimally effective dose altered the thyroid structure of a freshwater murrel (the snakehead fish). Cases of non-specific encephalopathy and fatty visceral changes (Reye's syndrome) in children living in the vicinity of fenitrothion-spraying operations invoked the research described latterly in Science, and originally in The Lancet: 2-day-old mice were dosed topically for 11 days with fenitrothion, amongst other substances. After a further 2 days a sublethal dose of encephalomyocarditis virus was injected subcutaneously in known titre. Mortality-rates in the 10-day period after virus injection 4-9% in fenitrothion groups, and 0% in corn-oil controls. Fatty changes were noted in liver and kidney in the insecticide-virus groups. The encephalopathy showed no specific central-nervous system lesion, but death followed a sequence of paralysis and convulsions.