Rotenone and the Environment
Rotenone does not persist in the environment so there is no long-term accumulation in water, soil, plants, or animals. Rotenone breaks down naturally with exposure to light and high temperatures. Even in cold temperatures, rotenone does not last longer than a few weeks to a few months. Because it breaks down so quickly, its environmental significance does not extend far beyond the treatment duration. Rotenone has low mobility in soil. It travels less than one inch through most soils with the exception of sand, where it can penetrate up to three inches. Because rotenone degrades quickly and does not leach far into underlying sediment, it does not impact groundwater supplies.
Rotenone is lethal to organisms with gills, so aquatic invertebrates such as insects and zooplankton, tadpoles, and other fish can be killed along with the target fish species. These impacts can be mitigated by timing rotenone treatments during the fall or winter when aquatic insect populations are low and no tadpoles are present. Populations of aquatic invertebrate species that are affected generally recover within the next breeding season. Most freshwater clams and snails have more resistance to rotenone than fish and will survive rotenone treatments. Plants, birds, adult amphibians, and mammals are not affected by rotenone because they lack that rapid absorption route that fish experience because of their gills. Further, most warm-blooded animals have natural enzymes that breakdown rotenone before it ever enters their blood streams.