FAQs

What is chlorpyrifos?
How and when was chlorpyrifos discovered?
How does chlorpyrifos function?
Has chlorpyrifos been researched and tested?
Where is chlorpyrifos labeled for use?
How is chlorpyrifos used?
What happens to chlorpyrifos in the environment?
Why was chlorpyrifos reviewed under the US Food Quality Protection Act (FQPA)?
Is Dow AgroSciences decision to globally phase out non-agricultural uses of chlorpyrifos an admission that residential use of chlorpyrifos is dangerous?
If it's not safe for residential use why should we spray it on our food?
I'm concerned about chlorpyrifos residues in my drinking water. How do I know chlorpyrifos will not be found in my drinking water?
What happens when people come in contact with chlorpyrifos?
What kind of clinical symptoms are associated with overexposure of organophosphate insecticides?
What should I do if I think I've been overexposed to chlorpyrifos?
There has been a chlorpyrifos spill. What should I do?
Does chlorpyrifos cause cancer?

What is chlorpyrifos?

corn Chlorpyrifos, a member of the organophosphate family, is the active ingredient in a wide range of agricultural pest products, including Lorsban* and Dursban* insecticides. Unless controlled, these insect pests cause billions of dollars of damage each year. Agricultural formulations are used extensively to minimize insect damage to corn, cotton, wheat, alfalfa, sugarbeets, peanuts, tree fruits, nut crops, and many vegetables.

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How and when was chlorpyrifos discovered?

Chlorpyrifos was first discovered by The Dow Chemical Company in 1962. Synthetic research with phosphorus-containing insecticides began in 1947. The most promising of this series was designated as Dowco* 179. The broad-spectrum insecticidal properties of this compound, later designated "chlorpyrifos," indicated that it possessed commercial potential. In the forty years since the discovery of chlorpyrifos, its broad-spectrum insecticidal activity has been put to use against a wide variety of insect pests through a number of commercialized products.

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How does chlorpyrifos function?

Chlorpyrifos is a member of the organophosphate family. Like other organophosphates, its insecticidal action is due to the inhibition of the enzyme acetylcholinesterase resulting in the accumulation of the neurotransmitter, acetylcholine, at nerve endings. This results in excessive transmission of nerve impulses, which causes mortality in the target pest.

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Has chlorpyrifos been researched and tested?

Chlorpyrifos, the active ingredient in Dursban and Lorsban insecticides, has been widely used and extensively studied for three decades, and manufacturers continue to update those tests with new technology each year. More than 3,600 studies and reports have been conducted examining the uses and impacts of chlorpyrifos on human health and the environment. No other pest control product has been researched more thoroughly.

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Where is chlorpyrifos labeled for use?

field Currently, chlorpyrifos is labeled for use in 98 countries around the world. Most developed nations in the world count chlorpyrifos in their insect-fighting arsenal. There are hundreds of labels in use worldwide, with over two dozen different formulations (i.e. granular, sprayable liquid), chlorpyrifos can be used most effectively by delivering the product in the best possible manner to the needed area.

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How is chlorpyrifos used?

The efficacy of chlorpyrifos has been tested under both laboratory and field conditions using a variety of formulations. The chemical is effective primarily at contact but may also kill target pests through ingestion and by vapor action. Chlorpyrifos has generally exhibited short residual activity on plant foliage, but it can be effective for several weeks in turfgrass thatch. In addition, chlorpyrifos has been shown to be effective for up to several months to years in soil, depending on the rate applied.

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What happens to chlorpyrifos in the environment?

Based on extensive research and environmental safety assessments, the fate of chlorpyrifos in the environment is well understood. It is a degradable molecule and breaks down in the environment when exposed to microorganisms, chemical reactions and sunlight. Chlorpyrifos does not readily move from the site of application once dry.

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Why was chlorpyrifos reviewed under the US Food Quality Protection Act (FQPA)?

Since the passage of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) amendments in 1988, the US EPA has been conducting a comprehensive review of older pesticides (those initially registered before November 1, 1984) to consider their health and environmental effects and to make decisions about their future use. EPA examines health and safety data for these pesticide active ingredients and determines whether they are eligible for reregistration. To be "eligible," a pesticide must have a substantially complete database and must not cause unreasonable risks to human health or the environment when used in accordance with its approved label directions and precautions.

FIFRA as amended in 1996 by the Food Quality Protection Act (FQPA) requires that all pesticides meet new safety standards. EPA must be able to conclude with "reasonable certainty" that "no harm" will come to infants, children, or other sensitive individuals exposed to pesticides. All pesticide exposures — from food, drinking water, and home and garden use — must be considered in determining allowable levels of pesticides in food. The cumulative effects of pesticides and other compounds with common mechanisms of toxicity also must be considered.

Since chlorpyrifos was originally registered before 1984, reregistration was required under these regulations.

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Is Dow AgroSciences decision to globally phase out non-agricultural uses of chlorpyrifos an admission that residential use of chlorpyrifos is dangerous?

No. Labeled uses of chlorpyrifos – both for agriculture and nonagricultural uses – rest on four decades of experience in use, health surveillance of manufacturing workers and applicators, and more that 3,600 studies and reports examining human health and environmental impacts. Both agricultural and nonagricultural uses of these products have been thoroughly evaluated and have received approvals from the World Health Organization (WHO), Food and Agriculture Organization (FAO) of the United Nations, and from regulators in a wide range of developed nations including the United Kingdom and Australia.

Dow AgroSciences has made a voluntary decision to gradually phase out non-agricultural uses of chlorpyrifos including residential uses because, as regulation and product support costs increase, we no longer have commercial rationale to remain in these markets.

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If it's not safe for residential use why should we spray it on our food?

Our confidence in the data supporting labeled uses of chlorpyrifos remains unchanged. This decision is not about the safety of residential uses of chlorpyrifos. It’s about the size and profitability of our non-agricultural chlorpyrifos business and the insufficiency of revenues from that business to sustain new research required for ongoing regulatory review. Labeled uses of chlorpyrifos – both for agriculture and nonagricultural applications – rest on four decades of experience in use, health surveillance of manufacturing workers and applicators, and more than 3,600 studies and reports examining human health and environmental impacts. Both agricultural and nonagricultural uses of these products have been thoroughly evaluated and have received approval from the World Health Organization (WHO), Food and Agriculture Organization (FAO) of the United Nations, and regulators in a wide range of developed nations, including the United Kingdom and Australia.

In July 2005, the European Union approved the continued use of chlorpyrifos as a crop protection product following a stringent and exacting review by the leading EU scientific and government experts.

The EU’s decision was in line with the United States Environmental Protection Agency, which registered agricultural uses of the product in 2001. The World Health Organization favorably evaluated all labeled uses in 1999.

Farmers, technical advisors and agronomists favor products containing chlorpyrifos because they are effective, cost-competitive and have a broad spectrum of activity against many insect pests when compared to alternative products. Additionally, chlorpyrifos is often a preferred choice for integrated pest management programs and as a replacement for persistent organochlorine and high toxicity insecticides.

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I'm concerned about chlorpyrifos residues in my drinking water. How do I know chlorpyrifos will not be found in my drinking water?

sprinklers Drinking water exposure to pesticides can occur through ground water and surface water contamination. According to the United States Environmental Protection Agency (US EPA), the available environmental fate data suggest that chlorpyrifos has a low potential to leach to groundwater in measurable quantities from most typical agricultural uses. For acute risk, the potential drinking water exposure derived from either ground or surface water is not of concern.

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What happens when people come in contact with chlorpyrifos?

It depends on the level of exposure. Based on studies that were conducted to evaluate potential exposure to labeled uses of chlorpyrifos, consumer exposure would be far too low to inhibit acetylcholinesterase, the target enzyme for its insecticidal activity. Gross exposure to chlorpyrifos, which would involve an intentional act or serious misuse of the product, could result in the inhibition of acetylcholinesterase enzyme and, possibly, clinical symptoms. Always read the product label carefully and follow instructions when using products containing chlorpyrifos.

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What kind of clinical symptoms are associated with overexposure of organophosphate insecticides?

Signs and symptoms of organophosphate insecticide poisoning in humans may be headache, dizziness, incoordination, muscle twitching, tremors, nausea, abdominal cramps, diarrhea, sweating, pinpoint pupils, blurred vision, salivation, tearing, excessive urination and tightness in the chest. In extreme cases (e.g., suicide attempts), exposure to organophosphate insecticides can result in respiratory paralysis and death.

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What should I do if I think I've been overexposed to chlorpyrifos?

field If you think you have been overexposed to chlorpyrifos or have additional health questions regarding this molecule, consult your country's Material Safety Data Sheet (MSDS) as it will have local numbers and information. Within the United States, please call the U.S. Emergency Response line at 1-800-992-5994.

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There has been a chlorpyrifos spill. What should I do?

If there has been a chlorpyrifos spill, or you have additional environmental questions regarding this molecule, consult your country's Material Safety Data Sheet (MSDS) as it will have local numbers and information.

Within the United States, please call the U.S. Emergency Response line at 1-800-992-5994.

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Does chlorpyrifos cause cancer?

Chlorpyrifos shows no indication of causing cancer. Animal testing shows that chlorpyrifos is not harmful to DNA. Tests required by the United States Environmental Protection Agency (US EPA) for carcinogenic, mutagenic and teratogenic activities were all negative. Chlorpyrifos is not listed by the US EPA as a human carcinogen.

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The conclusions that are contained within this chlorpyrifos.com web site relating to toxicological and/or environmental properties and effects are based on research and studies conducted by Dow AgroSciences or third parties. All such conclusions and findings are considered to be the opinions of Dow AgroSciences. Data substantiating these conclusions are available upon request.