What happens to permethrin in the environment?
• The typical half-life of permethrin in soil is 30 days (7). Permethrin breaks down more rapidly in soil with higher levels of organic matter (humus) (1). See box on half-life. • Permethrin has an extremely low potential to move in soil. It is unlikely to contaminate groundwater because it binds tightly to soil particles (4). In water and on soil surfaces, permethrin is degraded by sunlight (1). • The average half-life of permethrin on foliage is 10 days (1). Half-life is the time required for half of the compound to degrade. 1 half-life = 50% degraded 2 half-lives = 75% degraded 3 half-lives = 87% degraded 4 half-lives = 94% degraded 5 half-lives = 97% degraded Remember that the amount of chemical remaining after a half-life will always depend on the amount of the chemical originally applied.
