The US Environmental Protection Agency (EPA) has concluded that currently approved uses of fenthion, an organophosphate pesticide, pose unreasonable risks to human health and the environment. EPA said it would seek public comment of what measures should be taken to lessen risks posed by the pesticide, which is primarily used in Florida to combat mosquitoes. Fenthion is very highly toxic to birds and highly toxic to marine invertebrated. Its use has been implicated in several bird kill incidents, including recent bird kills on Marco Island, Florida, which are currently under investigation by the US Fish and Wildlife Service.
„There is reason for the EPA to be concerned about fenthion,“ said Carey Pope, a toxicologist who worked for the Defense Department.
„It tends to hang in longer than other pesticides.“ Linda Farley from the American Bird Conservancy states that the U.S. Fish and Wildlife report documents the deaths of at least 16 species of birds caused by fenthion, including the Piping Plover.
Fenthion can also cause cholinesterase inhibition in humans; that is, it can overstimulate the nervous system causing nausea, dizziness, and at high exposures respiratory paralysis and death. EPA toxicologist William Boyes is reviewing a Japanese study that found a high rate of myopia (nearsightedness) in people exposed to fenthion. Another study, by fenthion manufacturer Bayer Corporation, indicates that rats that were given high doses of fenthion over a period of two years had eye problems as well. „A conservative approach is what is toxic to animals is hurtful to humans,“ Boyes said.
Bayer Corporation of Kansas City, Mo., maintains the pesticide is safe when used in accordance with label instructions. Bayer has said the pesticide does not pose a threat to birds or other wildlife when it is used properly. Organophosphates made by Bayer include azinphos-methyl, fenamiphos, isofenphos, tribufos and fenthion.
EPA said its decision is „interim“ because the agency still must assess the cumulative risks of multiple organophosphate pesticides. After that assessment – which could be completed this year – additional risk mitigation measures may be required on organophosphates that share a common mechanism of toxicity, EPA said.
Sources: Chemical Market Reporter, American Birding Conservancy, Article by Laura Linden (San Francisco)