
When the author was faced to give her novel an appropriate title that partially dealt with the toxicity of chemicals used in everyday life and agriculture, namely chlorpyrifos (pronunciation: klôrˈpirəˌfäs), she sought a title with the first letter “C” and ended up with an appropriate alliteration that includes idiom “canary in the coal mine”–Choir of Cloistered Canaries. On all fronts, this chemical is not safe; it can affect the nervous system–health harms (e.g., neurological development and Parkinson’s disease claims). See pp. 79-86. (Image caption: Astrocyles surrounding capillaries in brain (Artwork by Ben Brahim Mohammed))
Chlorpyrifos is a broad-spectrum organophosphate insecticide used on crops and sometimes insects/pests in structure, which can affect the nervous system by disrupting acetylcholinesterase (AChE) that functions to rapidly break down the neurotransmitter acetylcholine, thus terminating nerve signals and allowing precise control of muscle and nerve activity. Like nicotine, it delivers, by breaking the blood-brain barrier (BBB) undetected. The health risk is high and higher with exposure to its spray and dust. It requires proper handling; however, the manufacturer fails to state in the warning label that use is subject to drift damage. Drift damage refers to harm caused to plants, crops, or even vehicles when chlorpyrifos are carried away from their intended target by wind (particle drift) or evaporation (vapor drift) and land on non-target areas.
Moreover, when it comes to carefully handling chlorpyrifos, it is hard to avoid breathing the spray or dust. Often the agricultural workers handling the product are not provided with appropriate PPE respirators and the like. Even children, food, and water sources are not to be exposed to chlorpyrifos, but they are exposed.
This insecticide is produced by several global agrochemical companies. While regulatory restrictions have reduced its use in some regions, it remains in production in others, and several manufacturers continue to supply it. While the science is clear and present about its health effects, it has not been banned as one would think and hope.
Key Manufacturers
Corteva Agriscience (formerly Dow AgroSciences) – Based in Indianapolis, Indiana, USA, Corteva is a major legacy producer of chlorpyrifos, historically marketed under brands like Lorsban™ and Dursban. It continues to supply in regions where the product is approved, focusing on pest control for crops such as corn, soybeans, and fruit trees (Chemical Research Insight org.)

Dow Chemical Company – The original developer of chlorpyrifos, Dow AgroSciences was part of DowDuPont before the spin-off. It has phased out production in many markets but maintains a global supply chain in approved regions chemicalresearchinsight.com+1.
Gharda Chemicals Limited – An Indian manufacturer producing technical-grade chlorpyrifos and formulations, serving both domestic and international markets. It emphasizes cost-effective production and R&D to meet demand in price-sensitive regions chemicalresearchinsight.com.
Nanjing Redsun – A leading Chinese agrochemical company with significant chlorpyrifos production capacity. It is a key supplier in Asia and exports globally, especially as Western production declines chemicalresearchinsight.com.
Sumitomo Chemical Co., Ltd. – A Japanese chemical giant with crop protection products in its portfolio, including chlorpyrifos in various formulations Discovery.
BASF – Produces chlorpyrifos in multiple formulations for different crops and pests, aligning chemical management practices www.cnagrochem.com.
Syngenta – Involved in producing chlorpyrifos formulations as part of its integrated pest management solutions www.cnagrochem.com.
UPL Limited – An Indian multinational with growing presence in chlorpyrifos production, offering pest management solutions tailored to local farming needs www.cnagrochem.com.
Guangxi Tianyuan Biochemistry Co., Ltd. – A Chinese agrochemical producer offering chlorpyrifos and other pesticides Discovery.
Other providers in the United States–Adama Agriculture Solutions (Raleigh, NC), Bayer Crop Science (St. Louis, MO), FMC Corporation (Philadelphia, PA), Gowan Corporation LLC (Yuma, AZ), Nufarm Limited (Chicago, IL),
Table 1. Chlorpyrifos uses currently allowed by U.S. States
| Use Site | State |
|---|---|
| Alfalfa | AZ, CO, IA, ID, IL, KS, MI, MN, MO, MT, ND, NE, NM, NV, OK, OR, SD, TX, UT, WA, WI, WY |
| Apple | AL, DC, DE, GA, ID, IN, KY, MD, MI, NJ, NY, OH, OR, PA, TN, VA, VT, WA, WV |
| Asparagus | MI |
| Cherry (tart) | MI |
| Citrus | AL, FL, GA, NC, SC, TX |
| Cotton | AL, FL, GA, NC, SC, VA |
| Peach | AL, DC, DE, FL, GA, MD, MI, NC, NJ, NY, OH, PA, SC, TX, VA, VT, WV |
| Soybean | AL, CO, FL, GA, IA, IL, IN, KS, KY, MN, MO, MT, NC, ND, NE, NM, OH, OK, PA, SC, SD, TN, TX, VA, WI, WV, WY |
| Strawberry | OR |
| Sugar beet | IA, ID, IL, MI, MN, ND, OR, WA, WI |
| Wheat (Spring) | CO, KS, MO, MT, ND, NE, SD, WY |
| Wheat (Winter) | CO, IA, KS, MN, MO, MT, ND, NE, OK, SD, TX, WY |
It should be noted that, where individual States (e.g., NY, MD, OR) have enacted State-level statutes banning organophosphates, State law supersedes Federal allowances.
It should also be noted that the commercial synthesis of chlorpyrifos relies on coupling two key precursor chemicals–(1) O.O-diethyl phosphorochloridothloate (DETC) and (2) 3,5,6-trichloro-2-pyridinol (TCPy).
Legal Challenges

In the United States, there have been lawsuits involving chlorpyrifos, including cases alleging health harms. Beyond private tort litigation, there haven been legal challenges on EPA regulations involving chlorpyrifos. The main EPA-regulation legal challenge that directly affected chlorpyrifos tolerances was in the U.S. Court of Appeals for the Eighth Circuit. In brief, (1) Final rule (2021) revoked all chlorpyrifos food/feed tolerances; (2) a chlorpyrifos registrant and grower groups challenged that action; (3) the U.S. court remanded the matter back to EPA for further proceedings on November 2, 2023 whereby EPA’s tolerances were reinstated on December 28, 2023; (5) then EPA approved the amended labels and reflected the reinstatement in subsequent rulemaking with additional steps.
EPA rulemaking process is described as ongoing with an expended amended proposed interim decision planned for 2026. The agency approved amended labels reflecting voluntary cancellation and geographic/use restrictions discussed in earlier review documents. In addition, EPA issued a proposed rule relating to tolerance changes and reopened the public comment period with submissions handled through the relevant docket on regulations.gov )approved amended labels reflecting voluntary cancellation and geographic/use restrictions discussed in earlier review documents (EPA-HQ-OPP-2024-0431). As of this posting (Aug 5, 2026), EPA’s proposed chlorpyrifos tolerance-related rule is in the post-comment phase, with public comments no longer accepted.
EPA has issued a final action reinstating chlorpyrifos food/feed tolerances after the court case, via an EPA Federal Register technical correction dated Feb. 5, 2024: Chlorpyrifos tolerances are currently in effect for the retained/registered food and feed uses, consistent with product labels.

The first time chorpyrifos was banned was under the Obama Administration. The second time, it was banned by the Biden Administration on February 28, 2022, to keep insects from damaging the nation’s crops as it was also toxic to plants. The chemical is still widely deployed as an agricultural pesticide in other countries, and it continues to be used as an insecticide in U.S. homes (e.g., in enclosed roach traps) and in nonfood settings such as golf courses and decorative-plant nurseries.
The twice-elected Trump Administration has reinstated use of chlorpyrifos in the United States. Chlorpyrifos was first marketed in 1965 by Dow Chemical as a presumed safer replacement for the banned insecticide DDT (dichlorodiphenyltrichloroethane)–eventually becoming one of several such “regrettable substitutions.” However, money talks and used to lobby the Executive and Legislative Branches of the United States. “The Global Chlorpyrifos Market was valued at USD 512.5 Million in 2021 and is projected to reach USD 601.4 Million by 2028, growing at a Compound Annual Growth Rate (CAGR) of 2.3% during the forecast period (2022–2028). This growth is being driven by the persistent need for effective pest control in agriculture, though the market is also navigating significant regulatory challenges and a global shift towards safer alternatives” (Chemical Insight Review). The argument to continue the use of this toxic chemical is that it is needed by global agriculture due to rising food demand.
In the United States, EPA has retained 11 crops as noted above–alfalfa, apple, asparagus, cherry (tart), citrus, cotton, peach, soybean, strawberry, sugar beets, and wheat (spring and winter). Yet, the negative consequences remain due to exposure to this toxic chemicals–they include depression, skin irritation, hormonal disturbances, immunologic abnormalities, rapid muscle shrinkage and nervous system effects. Chronic chlorpyrifos exposure is characterized by light-headedness, tachycardia (abnormally rapid heart rate), paresthesia (tingling) and an increased risk of various cancers, whereas acute exposure can cause seizures, coma and death. Young children and in utero are subject to health risks such as developmental problems and lower IQ. In humans and other mammals, chlorpyrifos toxicity is mainly due to its ability to cause accumulation of the neurotransmitter (chemical messenger) acetylcholine in the nervous system.
In summary, the list of health risks is not something to sneeze at. Studies have shown some of these risks: prostate cancer, lung cancer, breast cancer, multiple myeloma and leukemia, respiratory problems (asthma, wheeze, allergies), retinal degeneration, longer menstrual cycles and missed periods, diabetes, and the list goes on and on and on. Just like the nicotine manufacturers, they know the high health risks, for they do conduct research studies as did the Seven Dwarfs of Nicotine (CEOs) industry who testified before the U.S. Congress that “nicotine was not addictie” in 1994!






