Chemical Profile: Chlorpyrifos

Chemical Profile Chlorpyrifos MADE SAFE Blog

Why It Matters

Chlorpyrifos belongs to a class of pesticides linked to neurotoxicity in children and cancer in farmworkers, as well as harm to terrestrial and aquatic life. In 2021, the EPA issued a final ruling banning the use of chlorpyrifos on food crops. Although this ban took full effect in 2022, consumers are still at risk of exposure as chlorpyrifos is still permitted for non-food use, such as in recreational spaces and on crops like cotton.

What Is It?

Chlorpyrifos belongs to a class of pesticides known as organophosphates. Organophosphates were developed as nerve gas [6] by Nazi Germany, when a scientist working on pesticides accidentally discovered [1] one pesticide formulation’s neurotoxicity.

In March of 2017, the EPA was required to make a decision on the proposed ban (dating back to 2007) of chlorpyrifos.[4] However, despite a 2016 EPA report linking chlorpyrifos to a number of health impacts (see below), the agency refused the ban.

Chemical Profile Chlorpyrifos Infographic MADE SAFE Blog

The decision baffled organizations and the public; it is extremely uncommon for the head of the EPA to stand against the agency’s own scientists. A coalition of organizations joined together to ask judges in the 9th Circuit Court of Appeals to overturn the decision. Only very recently, in August of 2021, did the EPA issue a final rule revoking all “tolerances” for the permitted amount of chlorpyrifos for use on food – a big win for the health of both farmworkers and consumers.

Where It's Found

Chlorpyrifos is a dangerous pesticide that was used in the U.S. and worldwide on staple crops like corn, wheat, soy, apples, citrus, and more before its final ban for food use in 2022. It is still allowed for non-food applications and is widely used in recreational spaces like parks and golf courses, as well as on crops such as cotton and wood (i.e. lumber, Christmas trees, etc.). [11] Chlorpyrifos is also found in home treatments for pests such as cockroaches and termites, and is sometimes found in pet flea and tick collars, as well as tick deterrents used on cattle. [10]

The Health Concern

Starting in the late ’90s, certain chlorpyrifos-containing products, like some lawn care and insect sprays, were phased out because of associated health impacts. [7]  However, chlorpyrifos was still allowed for use on foods and on crops used as ingredients in personal care products, among other uses.

In 2016, the EPA issued a report that found evidence of issues with cognitive development in exposed children, including links to attention difficulties, autism, intelligence declines, problems with the working memory, and increased odds of tremors. [8]

The report also found that the levels of chlorpyrifos that enter our bodies through everyday exposure are of concern. [8]  Because we’re already over-exposed from food, there is no safe level of chlorpyrifos in our drinking water.

In addition, the pesticide may be associated with cancer in farmworkers [3] who handle pesticides, Parkinson’s disease [9] from background exposure to organophosphates, and negative health effects in birds, aquatic animals, honeybees, and wildlife. [5]

Farmers and farmworkers, the people who harvest and grow our food, are even more severely exposed to chlorpyrifos than the general public. Rural farming communities are also at an increased risk for exposure. One study found organophosphate pesticides in the blood and urine of almost 9 out of 10 babies born in rural communities. The majority of their moms had increased levels of exposure, too. [2]

How to Avoid It

  • Take your shoes off when you enter your home. Pesticide residue can be tracked into the home through shoes worn outside, and chlorpyrifos is still allowed for non-food uses.
  • Contact your local town officials to determine whether parks or other public spaces have been treated with chlorpyrifos or other toxic pesticide applications. If so, consider ways to request a change in practice at the town level.
  • Choose organic cotton. Cotton is commonly sprayed with chlorpyrifos. Swap out linens like bedding and clothes for organic MADE SAFE Certified products (chlorpyrifos is not permitted in MADE SAFE Certified products).
  • Avoid in-home and lawn pesticide treatments that utilize toxic pesticides / insecticides such as chlorpyrifos.
  • Skip flea and tick collars containing chlorpyrifos and other toxic pesticides.
  • Shop organic. Although chlorpyrifos is no longer allowed for use on foods, other high-risk pesticides are still permitted. Wash conventional fruits and vegetables diligently. Learn which plants and vegetables are most likely to have the most pesticide residues to help you determine which foods are an organic-must if you need to prioritize which to buy organic.


[1] Chemical & Engineering News. (2016). The Nazi origins of deadly nerve gases. Accessed January 31, 2023.

[2] Huen, K., Bradman, A., Harley, K., Yousefi, P., Barr, D.B., Eskenazi, B., Holland, N. (2012). Organophosphate pesticide levels in blood and urine of women and newborns living in an agricultural community. Environmental Research. 117: 8-16.

[3] Lee, W.J., Blair, A., Hoppin, J.A., Lubin, J.H., Rusiecki, J.A., Sandler, D.P., Dosemeci, M., Alavanja, M.C.R. (2004). Cancer incidence among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study. Journal of the National Cancer Institute. 96(23): 1781-1789.

[4] Lipton, E. (2018). Court Orders EPA to Ban Chlorpyrifos, Pesticide Tied to Children’s Health Problems. The New York Times. Accessed February 1, 2023.

[5] Minnesota Department of Agriculture. (n.d.). Chlorpyrifos – General Information. Accessed February 1, 2023.

[6] The Guardian. (2013). Sarin: the deadly history of the nerve agent used in Syria. Accessed January 31, 2023.

[7] United States Environmental Protection Agency (EPA). (2022). Chlorpyrifos. Accessed January 31, 2023.

[8] United States Environmental Protection Agency (EPA). (2022). Updated Human Health Risk Analyses for Chlorpyrifos. Accessed January 31, 2023.

[9] Wang, A., Cockburn, M., Ly, T.T., Bronstein, J.M., Ritz, B. (2014). The association between ambient exposure to organophosphates and Parkinson’s disease risk. Occupational & Environmental Medicine. 71(4): 275-281.

[10] Centers for Disease Control and Prevention. (2011, October 24). ToxFAQs for Chlorpyrifos. Agency for Toxic Substances and Disease Registry (ATSDR). Accessed April 13, 2023.

[11] Dean, A., Hodgson, E., Pilcher, C. (2022). Updates on Chlorpyrifos uses in 2022. Iowa State University | Integrated Crop Management. Accessed April 25, 2023.

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