Rotenone and the Environment
Rotenone can degrade rapidly in the environment so there is typically no long-term accumulation in water, soil, plants, or animals. Rotenone breaks down naturally with exposure to light and high temperatures but can persist for much longer in cold temperatures, which can be advantageous for some fishery-related applications. Rotenone travels less than an inch through most soil types with the exception of sand, where it can penetrate up to three inches. Because rotenone does not leach far into underlying sediment and binds strongly to soil organics, it does not impact groundwater supplies.
Rotenone is most lethal to organisms with gills, so aquatic invertebrates such as 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 many aquatic insect populations are low or in dormant stages and no tadpoles are present. Populations of aquatic invertebrates that are affected generally recover within a year or two. Most freshwater clams and snails have more resistance to rotenone than fish and usually survive rotenone treatments. Plants, birds, adult amphibians, and mammals are typically not affected by rotenone because they lack that rapid absorption route that fish experience because of their gills. Rotenone is poorly absorbed through the human skin and rotenone has a slow rate of gut absorption, likely reflecting its metabolism and/or rapid breakdown in the gastrointestinal tract.