Environmental Impact Methyl parathion is likely to enter the atmosphere from production of the pesticide, or its application as an insecticide. It should degrade in soil and water over the course of several months primarily by photolysis and biodegradation. The major exception is for spills, where degradation will occur only after many years. Methyl parathion metabolizes rapidly in plants and animals and is not expected to bioconcentrate in food products. Methyl parathion is rapidly degraded in soil at the low concentrations which are associated with its use as an insecticide.
Degradation increases with temperature and exposure to sunlight .
At very high concentrations such as might be associated with a spill, degradation is exceedingly slow and may be primarily due to photodegradation . Degradation appears to be more rapid in the presence of sediment and in fresh water rather than salt water . Amino methyl parathion is an observed product . The rate of degradation is a function of the presence and acclimation of microbial populations in the body of water . This might be the major degradative pathway in oligotrophic systems.