Support Open Letter to EPA and Bayer Corp.:

Fenthion, an organophosphate pesticide which was once used to kill birds, is now being used to control mosquitoes in Florida. Millions of migratory and resident birds that use Florida's unique ecosystems are at severe risk of lethal poisoning. Hundreds of dead birds have been killed throughout Florida, victims of fenthion exposure. Fenthion is extremely toxic to all avian species and other animals, including freshwater and marine fish, invertebrates and amphibians. It also poses human health questions. With equally effective, less-toxic alternatives available, American Bird Conservancy and its partners are urging the U.S. Environmental Protection Agency (EPA) to cancel fenthion use.

There are many alternatives available, used by other Florida counties and other states, and it is time to halt the use of fenthion. The U.S. Environmental Protection Agency is currently reviewing the registration of fenthion. ABC aims to pressure EPA, Bayer (the manufacturer of fenthion), and local Florida authorities into halting fenthion use. You can help apply this pressure by sending an e-mail to those concerned requesting that all uses of fenthion be immediately halted.

Florida is the only state in the U.S. to use fenthion. All other states use effective but less toxic solutions to mosquito problems. Millions of acres are sprayed year-round in Florida, in sensitive wildlife areas and suburban neighborhoods. Florida is home to a vast array of resident and
migrating bird species, which are at risk each time fenthion is used. Field biologists working in Florida have reported dead sanderlings, dunlin, black skimmers, and a piping plover from areas where fenthion had been sprayed for mosquito control.

Fenthion is toxic in the very small doses, whether it is inhaled, ingested in food or water, or absorbed through the skin. Birds are far more sensitive to fenthion than other vertebrates. Fenthion is so toxic that hundreds of birds of sixteen species were killed in twelve separate incidents when it was sprayed at a rate of only 2/3 of an ounce per acre. Not only shorebirds, but more than 80 species of songbird could be at risk from fenthion.

The EPA has documented thousands of bird kills attributed to fenthion. In one instance where fenthion was sprayed for mosquito control, an estimated 5,000 to 25,000 birds of 37 species were killed, of which migrating warblers and thrushes were found in greatest numbers.

Fenthion, like DDT, accumulates in the fat tissue of animals and can be passed on through the food chain to concentrate in top-level consumers. When rain washes residues into streams, marshes or estuaries, aquatic species are killed, including fish, shrimp, crabs, and amphibians. According to the EPA, fenthion can cause "nausea, dizziness, confusion, and at very high exposures (e.g. accidents or major spills), respiratory paralysis and death" in humans.

Fenthion has been identified as a carcinogen in mice, after a two-year National Institute of Health study found that tumors occurred at a rate significantly higher in the fenthion treated group than in the control group. Fenthion is readily absorbed through the skin and, although application methods are engineered to reduce deposition of pesticide droplets near areas where humans might contact the chemical, studies have shown that unacceptable levels of residue are found in areas where humans are likely to be exposed. Cumulative exposure may be of concern, since fenthion is stored in body fat. One study has indicated that a single dose of fenthion may have prolonged action, perhaps as a result of it being sequestered in fat and released later for metabolism (U.S. Public Health Service, Hazardous Substance Data Bank, 1995). The EPA is currently evaluating exposure in children, who are most likely to contact fenthion on lawns and in the household.

According to the EPA:
The acute dietary (single, severe exposure in food) risk of fenthion exceeds the EPA's level of concern for the general U.S. population and all subgroups, including infants and children. Acute risks to the various population subgroups were 340-800% of the "acute population adjusted dose" (aPAD), which is the dose at which an individual could be exposed on any given day with no adverse health effects expected - a value of 100% or less does not exceed the agencies level of concern. The most highly exposed subgroup of the population is children aged 1-6 years. This dietary risk comes primarily from exposure to fenthion residues in beef meat and fat. Milk is not considered a major factor to acute risk.

Similarly the chronic dietary (long-term, low level exposure in food) risk of fenthion also exceeds the EPA's level of concern for the general U.S. population. Again, the most highly exposed subgroup was children aged 1-6 years, with an cPAD (chronic population adjusted dose) of 270%.
The only population subgroup that fell below the agencies level of concern was infants. The EPA states that the likelyhood of drinking water contamination from fenthion is very low with the notable exception of mosquitocide use. There is the possibility for this use to result in surface water (reservoirs) contamination through drift (airborne particles of pesticide carried by the air from the original site of application).

According to the EPA risk assessment, there are no risks to adults from residential applications but the risk to toddlers exceeds the level of concern for two days after treatment at the standard application rate, and for eight days at the maximum (aerial) application rate. Data from national poison control centers between the years 1985-1992 reveal 417 cases of non-occupational exposure (i.e. exposure to the general public) to fenthion.