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Links to other informative articles: Chemicals—Friend and Foe? A Flood of Man-Made Chemicals Chemicals-Friend and Foe? How Toxic Is Your Home? For a Healthier, Safer Home Who Will Clean Up Our Earth? Organophosphate Pesticides in Food
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| Pesticides are widely used in producing food.
The term pesticide includes ingredients used in products, such as
insecticides, fungicides, rodenticides, insect repellants, weed killers,
antimicrobials, and swimming pool chemicals, which are designed to prevent,
destroy, repel, or reduce pests. Before a pesticide may be sold in the
United States, EPA evaluates the proposed pesticide thoroughly to ensure
that it will not harm human health or the environment. Pesticides that pass
this evaluation are granted a license or "registration" that
permits their sale and use according to requirements set by EPA to protect
human health and the environment under the Federal Insecticide, Fungicide,
and Rodenticide Act and the Federal Food, Drug, and Cosmetic Act, both of
which were amended by the Food Quality Protection Act of 1996.
The Environmental Protection Agency is reviewing all existing tolerances (see box--What is a Tolerance?) for pesticides used on food crops to ensure that they meet current safety standards. The standard for pesticide safety is based on the requirements of the Food Quality Protection Act of 1996. A group of about 40 pesticides called organophosphates will be among the first to be reevaluated. To learn more about the requirements of the Food Quality Protection Act, contact EPA's Office of Pesticide Programs (see "For More Information" at the end of this fact sheet). FQPA requires EPA to reassess all tolerances established before August 3, 1996. EPA must give those pesticides that appear to pose the greatest risk the highest priority. EPA has placed the organophosphates in the highest priority group. |
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EPA must complete the tolerance reassessment by August 2006. There are 469 pesticide active ingredients or high-hazard inert ingredients with food use tolerances; approximately 9,700 tolerances were in effect at the passage of FQPA.
| EPA published its schedule for completing
tolerance reassessment in the Federal
Register on August 4, 1997. EPA divided the pesticides into three groups
(see box). These groupings provide the framework for the scheduling of the
pesticides for reassessment.
The law requires EPA to complete one-third of the tolerance reassessments by August 1999. Organophosphates are among the chemicals that will be reassessed earliest. In addition, EPA will complete reassessment early for some older pesticides for which the reregistration eligibility process was nearly complete. After those are completed, tolerances will be reviewed for the remaining pesticides from the first group, then the second and third groups in turn. |
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EPA's process of setting food use tolerances is described in a fact sheet, "Setting Tolerances for Pesticide Residues in Foods" (publication number 735-F-99-003). Tolerance reassessment follows the same basic process.
EPA has placed the organophosphates in the first group
of tolerances to be reassessed for several reasons:
Organophosphates account for about half (by amount sold) of all insecticides used in the U.S. In addition to major crops such as cotton, corn, and wheat, they are used on many important minor crops. Some also are used for mosquito control to protect public health against diseases such as malaria, dengue fever, and encephalitis. |
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Approximately 60 million pounds of organophosphates are applied to approximately 60 million acres of U.S. agricultural crops annually. Nonagricultural uses account for about 17 million pounds per year. (See box.)
The wide use of organophosphates is based on several factors:
Most organophosphates are insecticides. See the box at the end of this fact sheet for a list of organophosphate pesticides.
Organophosphates were developed during the early 19th century, but their effects on insects, which are similar to their effects on humans, were discovered in 1932. Some are very poisonous (they were used in World War II as nerve agents). However, they usually are not persistent in the environment.
Organophosphates affect the nervous system by reducing the ability of cholinesterase, an enzyme, to function properly in regulating a neurotransmitter called acetylcholine. Acetylcholine helps transfer nerve impulses from a nerve cell to a muscle cell or another nerve cell. If acetylcholine is not properly controlled by cholinesterase, the nerve impulses or neurons remain active longer than they should, overstimulating the nerves and muscles and causing symptoms such as weakness or paralysis of the muscles.
Because organophosphates have a wide variety of uses, there are many opportunities for exposure.
EPA considers these and other possible exposures when reviewing information on a pesticide.
Toxicity tests are conducted on animals, which are exposed to the test chemical by different routes, including oral, dermal, and inhalation. The toxicity tests are designed to explore a wide spectrum of effects that may occur (e.g., birth defects, cancer, changes in fertility or ability to reproduce, neurotoxicity, harmful effects to the kidney or liver, etc.) and to determine the dose at which such effects may occur. Some effects may appear quickly (e.g., unsteady gait). Other effects generally appear only after years of exposure (e.g, liver damage).
Organophosphates must undergo studies to determine behavioral effects and physiological effects on the nervous system. Specifically, EPA evaluates organophosphates for their ability to harm motor activity, learning and memory, reflexes and sensory ability, and cell development and structure.
While the acute effects of organophosphates are well documented and generally understood to cause acute cholinesterase inhibition, the chronic effects are less certain. Some studies suggest that at certain dose levels there may be long-term consequences of repeated acute exposures to these pesticides. Chronic toxicity must be evaluated on a case-by-case basis; these effects are difficult to generalize.
An important aspect of the human health risk assessment is whether workers
may be exposed to harmful effects of pesticides. EPA includes provisions for
protection of workers in its registration or reregistration of a pesticide.
Please see our fact sheet, "Assessing
Health Risks from Pesticides," publication number 735-F-99-002, for
more information on human health risk assessment.
ENVIRONMENTAL EFFECTS OF ORGANOPHOSPHATESOrganophosphates could cause contamination of water and injury to plants or animals that were not the targets of the pesticide application. For example, honey bees can be killed by pesticide applications, as can insects that are being used to help control pests. Animals living near an area where pesticides are used can be affected, too. EPA looks at the potential for contamination of water through runoff or seepage into groundwater, as well as the effects on other plants and animals when registering or reviewing pesticides. Problems in these areas might be addressed by restrictions on where and how a pesticide is applied. Please see our fact sheet, "Protecting Wildlife from Pesticide Risks," publication number 735-F-98-006, for more information on ecological risk assessment. CONCLUSIONEPA is reassessing pesticide tolerances based on sound science and is using a transparent regulatory process. EPA is committed to ensuring that appropriate transition mechanisms are in place to reduce risk without jeopardizing our nation's agriculture and its farm communities and to consulting with interested parties. Each risk assessment and risk management document is subject to public scrutiny and comment. All documents are placed in the public docket and are available on the Internet. At the end of the process, there may be significant changes in the uses of some of these pesticides. Changes will be made in such a way that the farmers who grow our food continue to have access to appropriate pest management techniques, while increasing the safety of our food supply. |
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