Under normal conditions of use, chlorpyrifos products are expected to have minimal effects on wildlife even though toxicity can be shown to some species in laboratory tests. Assessment of the safety of chlorpyrifos for wildlife and potential risks that might be associated with its use has been the subject of a number of investigations, including those using both predictive and observational approaches.
Predictive assessments of potential wildlife impact compare levels of sensitivity under laboratory conditions with modeled or measured concentrations of chlorpyrifos in the environment. The route of exposure, duration of exposure and magnitude of exposure are all considered as well as the proportion of an animal population that might actually be impacted.
Observational assessments of potential wildlife impact involve collecting information on wildlife populations under actual field conditions where chlorpyrifos products are being used. Monitoring data on wildlife population growth, mortalities, reproduction and behavior may be collected. In general, such field investigations have shown limited or no acute impacts to a variety of species including birds, mammals, reptiles and amphibians. Where impacts have been observed in a sensitive aquatic system, following a spill for example, recovery of aquatic invertebrate and fish populations has been generally rapid since chlorpyrifos residues quickly decline due to degradation and sediment binding.
“Pesticides: Environmental Effects - Ecological Risk Assessments”, U.S. EPA
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