Pesticide Profile - Carbofuran

EPA Proposes Carbofuran Withdrawal

On August 3, 2006 the U.S. Environmental Protection Agency (EPA) proposed to cancel the registration of most uses of the highly toxic pesticide carbofuran. This followed a prolonged review by EPA and several years of campaigning by ABC and partners to remove carbofuran from the market. The cancellation, once finalized will be immediately effective for the main uses of carbofuran: alfalfa, corn, cotton, cotton, potatoes, and rice. Its use will be phased out over four years for other minor uses including artichokes, chili peppers in the southwest, cucumbers, spinach for seed, sunflowers, and pine seedlings. The cancellation also applies to use on most major imported agricultural products. This means that countries wishing to export agricultural produce to the United States will not be able to use carbofuran on those crops. For more information please visit ABC's press release on carbofuran.

An important victory for birds and other wildlife had been previously won in July 2002 by a coalition of conservation groups, brought together by American Bird Conservancy (ABC), and including Defenders of Wildlife, Humane Society of the United States, National Audubon Society, Natural Resources Defense Council, Rachel Carson Council, Sierra Club, and World Wildlife Fund, plus several Louisiana-based groups. Action from these groups has prompted the Environmental Protection Agency (EPA) to revoke the authorization it had previously granted allowing use of the deadly pesticide carbofuran to control rice water weevil in Louisiana, preventing the deaths of possibly thousands of birds.

Carbofuran is among the most highly toxic pesticides known to birds. A single granule is lethal, and more than fifty species, including Bald and Golden Eagle, Eastern Bluebird, Great Horned Owl, Red-tailed Hawk, Kestrel, Northern Pintail, and Blue-winged Teal, have been documented as having died from carbofuran poisoning. The granular formulation of the pesticide was the most lethal to birds and was phased out from legal use beginning in 1991. EPA estimated that prior to cancellation of the granular formulation, up to two million birds were killed each year by carbofuran. In fact, no other substance listed under the EPA's Ecological Incident Investigation System has killed more birds, and the U.S. Fish and Wildlife Service (FWS) has stated that "There are no known conditions under which carbofuran can be used without killing migratory birds."

Environmentalists were alarmed when they became aware that EPA was considering a "Section 18 - Emergency Use" application for the granular form of the pesticide on up to 100,000 acres of rice crops in Louisiana, and were outraged when EPA issued a permit allowing 10,000 acres to be dosed with the toxic substance without alerting FWS, the public, or conservation groups.

Conservation groups quickly mobilized, and together they convinced EPA to reduce the permit from 10,000 acres to 2,500 acres, and open a public comment period before any further use was considered.

More than 6,000 public comments subsequently resulted including a letter signed by 55 conservation groups. EPA officials were impressed by the response and in a letter to the groups cited "compelling feedback from the public" as one of the primary reasons the Louisiana permit was revoked.

Quick Facts:

• Chemical name: 2,3-Dihydro-2,2-dimethyl-7-benzofuranol methylcarbamate

• Trade names: Furadan, Curater, Bay 70143, Furacarb, Rampart

• Pesticide type: insecticide

• Class: carbamate

• Mechanism of action: cholinesterase inhibitor

• Major routes of exposure: carbofuran is highly toxic through ingestion and inhalation but only moderately toxic by dermal absorption. Birds that consume insects or other prey exposed to carbofuran are susceptible to secondary exposure and possible poisoning.

• U.S. Regulatory status and use: Carbofuran is a restricted use pesticide. Up to 2 million pounds of liquid carbofuran is used each year in the U.S., primarily on corn, alfalfa, rice, potato, sorghum, grapes, sunflowers, and tobacco.

• According to the Ecological Incident Investigation System, carbofuran has been responsible for more avian deaths than any other pesticide.

Background

Carbofuran is an insecticide and a nematicide, first brought on to the market in 1965. Two forms of the pesticide, granular and flowable (liquid) have been registered for use in the United States. The manufacturer of carbofuran agreed to a phase-out of most of the granular products based solely on the dangers it presented to birds, in 1994. Some granular formulations are still in use today, however flowable product accounts for most carbofuran use in the United States. In 1991, a Virginia state monitoring project documented wildlife mortalities in 10 of 11 farm sites where carbofuran was in use. Following this monitoring effort, the state of Virginia banned all granular formulation of carbofuran for sale or use in the Commonwealth. Canada has also banned the use of granular carbofuran in 1998.

Hundreds of bald eagle deaths have been linked to carbofuran. Eastern bluebirds, Northern pintails, American robins, owls, swallows, grackles, killdeer and kestrels: more than one hundred bird species have been documented as having died from carbofuran poisoning. The number of birds involved in any single incident ranges up to 2,450. Carbofuran has also killed mammals and fish. US Fish and Wildlife biologists have stated, "there are no known circumstances under which carbofuran can be used without killing birds." In 1989, US EPA estimated that 1 to 2 million birds were killed each year by carbofuran alone.

The U.S. Fish and Wildlife Service maintains that the use of carbofuran poses unreasonable hazards to birds. In 1992, it requested that the EPA cancel all registrations for carbofuran. Many prominent environmental organizations oppose the continued use of carbofuran, but its use is still sanctioned by the EPA. North American migratory birds are at risk of exposure from carbofuran while on their wintering grounds in Latin America. International attention and cooperation is needed to address pesticide use in all of the Americas to adequately protect migratory birds.

Environmental Effects

Fate

• Persistence: carbofuran is moderately persistent in soils, with a half-life from 30 to 120 days, depending on conditions. In soil, carbofuran is degraded by chemical hydrolysis and biodegradation. Carbofuran is soluble in water and is highly mobile in soils. Carbofuran has a high potential for groundwater contamination, and has been detected in aquifers and surface waters.

• Bioaccumulation: carbofuran does not accumulate in animal tissue.

Ecotoxicity

• Carbofuran is highly toxic to fish. The LC50 for bluegill sunfish is 0.24mg/L.

• Carbofuran is highly toxic to birds. Carbofuran has been documented in hundreds of avian mortality events sometimes involving large numbers of birds in each incident. Birds are susceptible to carbofuran from direct spraying, ingestion of granules or contaminated drinking water and from the consumption of contaminated prey. One granule of carbofuran is enough to kill a small songbird.

Incidents

• Tishomingo National Wildlife Refuge, Oklahoma, 1976. Approximately 500 Canada geese died after feeding in a field treated with 0.5 lbs / acre liquid carbofuran. This level of use is only one-sixth of the application rate of some crops (2.96 lbs / acre is used on grapes, 1997 average usage figures, USDA.)

• New Jersey, 1990. After carbofuran application to a fruit orchard, approximately 100 carcasses were discovered, including blue jay, American robin, and dark-eyed junco. Laboratory analyses confirmed carbofuran as the cause of death.

• Saskatchewan, Canada, 1986. Forty-five California gulls were found dead after a landowner applied liquid carbofuran to a grain field. Gulls had crops full of grasshoppers; analysis of the grasshoppers showed 4.2-7.2 ppm carbofuran.

• Linden, California, 1990. Liquid carbofuran was applied by irrigation, with exposure via puddle water. Carcasses of 30 mourning doves, 100 American robins, 200 European starlings, red-winged blackbirds and grackles, and 700-800 goldfinches, sparrows and house finches were recovered.

• Colusa, California, 1989. 1,985 dead ducks, approximately 97% northern pintails, and 3% green-winged teal were found in an area where carbofuran had been used. Carbofuran residues were found in duck and mud samples. The dead birds were not found in an agricultural field, but in an area that is routinely flown-over by airplanes moving between two local airstrips and rice fields.

• Stevens County, Oklahoma, 1985. Carcasses of 150-160 American wigeon and ten Canada geese were found in an alfalfa field treated with a flowable formulation of carbofuran.

• Yountville, California, 1990. Carcasses of one acorn woodpecker, one bushtit, one white-breasted nuthatch, one western bluebird, one American robin, one cedar waxwing, four hermit thrushes, seven yellow-rumped warblers, one chipping sparrow, one white-crowned sparrow, eleven dark-eyed juncos, nine house sparrows, three house finches, and six lesser goldfinches were reported following drip irrigation of a vineyard with a 6 lb/acre usage rate of flowable carbofuran.