Two lawsuits have recently been filed in California state courts against Corteva Inc. (“Corteva”), the corporation which manufactures the pesticide chlorpyrifos. The plaintiffs in Avila v. Corteva Inc., No. 20C-0311 (Cal. Super. Ct., October 27, 2020) and Calderon de Cerda v. Corteva Inc., No. 20C-0250 (Cal. Super. Ct., September 16, 2020) are agricultural workers who live and work in Kings County, California. In each case, the plaintiffs are suing on behalf of their minor children, alleging that chlorpyrifos caused their children’s neurological injuries and that Corteva is at fault as the manufacturer of chlorpyrifos. According to the plaintiffs, Corteva either knew or should have known about the risks posed by chlorpyrifos, and continued to manufacture an unreasonably dangerous product while failing to warn consumers. Additionally, the plaintiffs allege that the city which supplied drinking water to their households negligently allowed chlorpyrifos to contaminate that water.


Both of the California lawsuits have been brought against Corteva, which was previously known as Dow Agrosciences, LLC (“Dow Agrosciences”). During the 2000s, Dow Agrosciences held the federal registration for, and was the primary seller of, Lorsban, the trade name used by Dow Agrosciences to market chlorpyrifos. Dow Chemical Company (“Dow Chemical”) is both the parent company of Dow Agrosciences, and the manufacturer of Lorsban. All three companies are named in the lawsuit, and are collectively referred to as “Dow.”

Chlorpyrifos was first patented by Dow Chemical in 1966. It was first registered under the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”) in 1965 for use in the United States. Chlorpyrifos is primarily used to control foliage and soil-borne insect pests on a variety of crops including corn, soybeans, fruit and nut trees, and a variety of row crops. Until the year 2000, chlorpyrifos was also approved for residential uses.

Because chlorpyrifos is a type of chemical known as a phosphorothioate organophosphate, it will metabolize into its oxon form within the body of an organism. Chlorpyrifos oxon (“oxon”) is considered to be about 1000 times more toxic than chlorpyrifos, and is a neurotoxin that can be harmful to humans. Although oxon was included as a pesticide in the 1966 chlorpyrifos patent, it has never been registered for use as a pesticide or presented for registration. However, the effectiveness of chlorpyrifos as an insecticide depends on its transformation into oxon. According to Dow, this transformation depends on the target insect’s biological ability to convert chlorpyrifos into oxon after ingestion.

The plaintiffs, on the other hand, state that chlorpyrifos is unstable in the environment and will convert to oxon when mixed with water that contains chlorine or bromide, and when exposed to sunlight. According to the plaintiffs, the practical effect of spraying chlorpyrifos in agricultural areas is an application of the unregistered oxon. The plaintiffs also claim that Dow is aware that spraying chlorpyrifos results in an application of oxon, and has known so for decades.

Claims Brought Against Dow

In both complaints, three claims were brought against Dow: negligence, failure to warn, and design defect. All three are state law claims. The following arguments all come directly from the plaintiffs’ complaints. Because Corteva has yet to file its answer, there are currently no counter-arguments to discuss.


According to the plaintiffs, Dow negligently failed “to test for certain specific harms or to appreciate and take appropriate measures to protect from those harms associated with chlorpyrifos.” In other words, the plaintiffs claim that Dow violated the law by failing to discover the risks associated with using chlorpyrifos, or to protect the public from those risks.

The plaintiffs assert that during the 1980s, the need to assess the exposure of children to chlorpyrifos was well known. According to both complaints, researchers with the California Department of Food and Agriculture’s Worker Health and Safety Branch flagged chlorpyrifos as a potential risk to children during the 1980s and in 1990. Yet Dow did nothing at that time to examine the exposure of children to chlorpyrifos. In 1991, the Environmental Protection Agency (“EPA”) issued a standardized protocol for testing the degree to which a substance was poisonous to developing nervous systems. However, Dow did not begin such testing until 1995 after an independent study suggested that chlorpyrifos had a high level of developmental neurotoxicity.

The plaintiffs claim that if Dow had taken the steps that a reasonably careful manufacturer would have taken, it would have conducted additional tests, reported the results, and adopted the necessary protective measures such as removing Lorsban from the market entirely or issuing stricter directions for use. Instead, Dow acted negligently by not testing chlorpyrifos for harm to neurological development, ultimately leading to the neurological injuries sustained by the children represented in the California lawsuits.

Failure to Warn

Under their failure to warn claims, the plaintiffs assert that Dow had a duty under California law to know the expected uses of its chlorpyrifos products and to ensure that those products were safe for those reasonably expected uses. The plaintiffs allege that by the time the children at the center of these lawsuits were born in the early 2000s, Dow knew or should have known that Lorsban was not safe for its reasonably expected uses because its labeling lacked warnings necessary to render it safe for use.

According to the plaintiffs, the warnings that would have been necessary to make Lorsban safe would have included warnings that chlorpyrifos transforms into oxon after being introduced to chlorinated water; that chlorpyrifos and oxon were known to be hazardous to the developing nervous systems of animals; and that extra care was required when spraying Lorsban near structures that contained children or pregnant women. Had Dow appropriately labeled Lorsban, the plaintiffs argue that they would not have been injured.

Design Defect

As the manufacturer and seller of Lorsban in the United States, Dow had a duty under California law to ensure that its Lorsban products were safely designed for its reasonably expected uses. In other words, Dow had a duty to ensure that the way its Lorsban products were designed rendered them safe for their intended purpose. According to the plaintiffs, Dow’s Lorsban products were defectively designed in two ways. First, they were more dangerous than the ordinary customer or end user would reasonably expect. Second, they contained ingredients – chlorpyrifos and oxon – that rendered the products unreasonably dangerous when safer ingredients were available.

The plaintiffs claim that the Lorsban products were more dangerous than any reasonable consumer would expect because chlorpyrifos and oxon were highly toxic to developing nervous systems, caused developmental issues from repeated low-dose exposures, and become more toxic when mixed with chlorinated water. Although these hazards were known or should have been known to Dow by 2002. Ordinary consumers would have had no way of knowing about the hazards posed by Lorsban, which therefore made Lorsban more dangerous than the ordinary consumer would expect. According to the plaintiffs, the defective design of Lorsban lead to the injuries sustained by the children.

Other Claims

In addition to bringing claims against Dow and Corteva, the plaintiffs have also brought claims against the City of Avenal (“City”), where both families reside. Under California law, utilities that provide drinking water for human consumption have a duty to ensure that water is “wholesome, potable, [and] in no way harmful or dangerous to human health.” According to the plaintiffs, the City violated this duty by negligently allowing chlorpyrifos to enter the drinking water provided to the families.

The plaintiffs allege that the City failed to exercise reasonable care to ensure safe drinking water in two ways. First, the City allowed portions of its water treatment facility open to the air which allowed drift from chlorpyrifos applications to enter the water. Second, the City failed to follow a 2002 publication from the United States Department of Agriculture which advised the City to take extra precautions against invasion of its water system by chloryrifos and oxon.

According to the plaintiffs, if the City had not been negligent in its duty to provide safe drinking water, the plaintiffs would not have been injured.

Going Forward

Numerous lawsuits have been filed during the past few years against pesticide manufacturers alleging that their pesticide products have caused serious health issues in the plaintiffs. The lawsuits brought against Monsanto over its glyphosate-based pesticide, Roundup, has resulted in judgements requiring the company to pay millions of dollars, and settlements that may require the company to pay billions. Although Roundup is still available for use, the on-going lawsuits have cost a considerable amount of time and resources.

More cases are expected to be filed concerning damage allegedly caused by chlorpyrifos. However, whether these cases will impact the future availability of chlorpyrifos is hard to say. The two California cases request that the defendants pay damages for injuries allegedly caused by chlorpyrifos, but do not challenge the registration of chlorpyrifos. While it is possible that future lawsuits may challenge the chlorpyrifos registration, which could result in chlorpyrifos no longer being available for use, the two lawsuits from California are not likely to affect the availability of chlorpyrifos.


To read the complaint in Avila v. Corteva Inc., click here.

To read the complaint in Calderon de Cerda v. Corteva Inc., click here.

To read the text of FIFRA, click here.

For more National Agricultural Law Center resources on pesticides, click here.