Almost six out of 10 kale samples tainted by pesticide banned in Europe 15 years ago
By EWG Science Team
UPDATED WEDNESDAY, JUNE 11, 2025
In August 2024, the Environmental Protection Agency issued an emergency suspension of all uses of DCPA, based on significant health risks the chemical posed to farmworkers, especially pregnant people, exposed to DCPA. The DCPA manufacturer handed over new data to the EPA nearly a decade after it was requested. The records showed that at exposure levels likely experienced by farmworkers, DCPA causes reduced levels of thyroid hormone in developing rats.
Sufficient levels of thyroid hormone are essential for brain development, and reduced levels during pregnancy are known to cause low birth weight, developmental delays and other harms in humans.
Consumption of more fresh fruits and vegetables – especially leafy greens like kale – is important for a healthy diet. These foods are rich in vitamins, minerals and antioxidants that help strengthen the immune system, protect heart health and lower the risk of chronic disease. If you’d also like to reduce your exposure to pesticides, it’s helpful to know which types of produce are more likely to carry residues.
Nearly 60 percent of kale samples sold in the U.S. were contaminated with residues of a pesticide that the EPA considers a possible human carcinogen, according to EWG’s analysis of 2017 and 2018 Department of Agriculture test data. (2017 and 2018 are the most recent years for which the USDA tested kale as part of its Pesticide Data Program.)
EPA classified DCPA as a “possible carcinogen”in 1995. In 2005, under market pressure, its biggest manufacturerterminated its registration for use on several U.S. crops, including artichokes, beans and cucumbers, after studies found that its breakdown products were highly persistent in the environment and could contaminate drinking water sources.
For these reasons, in 2009 theEuropean Union banned all uses of DCPA. In 2023, the EPA released a draft risk assessment that stated DPCA shows “significant risks to human health,” especially for those who are pregnant. And in 2024, the EPA canceled all uses of the herbicide.
Other leafy greens are also widely contaminated with DCPA. More than 35 percent of collard and mustard green samples analyzed by the USDA in 2019 had detectable levels of DCPA.
Kale, other leafy greens contaminated with numerous pesticides
Leafy greens’ popularity as a health food rich in vitamins and antioxidants has soared in recent years. DCPA is far from the only pesticide used on these vegetables.
In fact, with the exception of bell and hot peppers, the USDA tests found the most pesticides on kale, collard and mustard greens, with 100 different pesticides found in leafy greens as a category.
On average, samples of leafy greens such as kale, collards and mustard greens had detectable levels of more than five different pesticides, with up to 21 different pesticides on a single sample.
And 86 percent of samples had detectable levels of two or more pesticide residues.
That’s why kale, collard and mustard greens are third on the 2025 Dirty Dozen™.
DCPA linked to cancer and other health harms
According to U.S. Geological Survey data from 2018, just under 500,000 pounds of DCPA were sprayed in the U.S., mostly in Arizona, California, Texas, Washington, and Wisconsin. Nearly 200,000 pounds are sprayed annually In California, the only state where all pesticide use must be reported. The most recent data are from 2022.
EWG-commissioned tests of kale purchased from grocery stores in 2018 found that two of eight samples had detectable levels of DCPA at concentrations comparable to the average amount reported by the USDA.
The EPA’s 1995 classification of DCPA as a possible carcinogen noted increases in liver and thyroid tumors. DCPA can also harm the lungs, liver, kidney and thyroid.
In California and Washington, concerns have grown about the capacity of the pesticide’s breakdown products to contaminate surface and groundwater. Not only can DCPA contaminate areas near its use butstudies showit can also travel long distances in the atmosphere.
In California, DCPA’s breakdown products were detected in groundwater wells above the EPA health advisory level for these contaminants, triggering potential action to restrict the use of DCPA under state law.
But Amvac, a California-based DCPA manufacturer, argued that such uses were not a concern for human health. Siding with the manufacturer, the California Office of Environmental Health Hazard disregarded the human health risks of this pesticide.
A report by the Washington Department of Agriculturerecommended a complete phaseout of DCPA in the state beginning in 2015. The latest groundwater tests, from 2019 and 2020, found DCPA breakdown products at concerning concentrations in parts of the state, and the agency is still assessing water contamination.
Source: EWG, from California Department of Pesticide Regulation and the U.S. Geological Survey's Pesticide National Synthesis Project.
DCPA can also drift into the air and homes around farms where it is sprayed. A 2019 study led by scientists at the University of California, Berkeley, School of Public Health found thatmore than 50 percent of adolescent girlsfrom farm communities in the Salinas Valley were exposed to DCPA. This is especially concerning given that the pesticide is also a suspected endocrine disruptor – a chemical that can affect hormones – and may be particularly harmful to thyroid function.
In 2014, theEPA reviewed DCPA as part of the Endocrine Disruptor Screening Program, concluding that it may interact with thyroid signaling, and requested more data from the manufacturer, Amvac, on thyroid toxicity for sensitive populations like children and the developing fetus.
Nearly a decade later, Amvac finally submitted the requested study to the EPA, which concluded that the chemical could pose serious risks to pregnant people and their offspring. The agency is still determining whether DCPA can safely be used or whether it should terminate all uses.
Other concerning pesticides on leafy greens
One of every four leafy green samples tested by the USDA contained bifenthrin and cypermethrin, two types of pyrethroid insecticides. A recent review of epidemiological studies found that metabolites of cypermethrin and some other pyrethroid insecticides detected in the urine during pregnancy were associated with adverse neurodevelopmental outcomes in children.
Previous USDA kale tests showed 30 percent of kale samples also had detectable levels of imidacloprid, a neonicotinoid insecticide banned in the EU because of harm to bees. Imidacloprid, and other neonicotinoids, have also been associated with, harm to the human nervous system and harm to the reproductive system in animal studies. But the USDA's most recent tests did not analyze kale for imidacloprid, even though it is still likely used on the crop. In an email to EWG, the USDA explained the omission was because imidacloprid was inadvertently left off the list of compounds to be tested by its lab.
Imidacloprid was detected on 30 percent of collard greens and 27 percent of mustard greens in the most recent USDA samples, from 2019
EWG’s recommendations about leafy greens
Don’t skip the leafy greens. Kale and other leafy greens are extremely nutritious vegetables, high in vitamins A and K and iron, and consumption of leafy greens is associated with reduced risk for cardiovascular disease.
As with all produce, EWG recommends choosing kale, collard and mustard greens that are organically grown when possible, and washing them (organic or not) to reduce exposure to synthetic pesticides. Other similar vegetables on the Clean 15, the fruit and vegetables that are the lowest in pesticide residues, include cabbage, asparagus and cauliflower.
We also recommend using greens in recipes with ingredients rich in vitamin C, like lemon juice, red peppers or tomatoes, since that helps the body absorb their plentiful nutrients. Incorporating leafy greens into smoothies or pasta sauces is a great way to increase overall veggie consumption.
This article was adapted and updated from the 2021 Shopper's Guide to Pesticides in Produce™.
About EWG’s Shopper’s Guide
EWG has published the Shopper’s Guide to Pesticides in Produce almost every year since 2004.
It’s a suite of materials investigating the presence of pesticides in foods and helps consumers find ways to reduce exposure to pesticides while consuming plenty of fruits and vegetables.
It includes two lists, the first is the Clean Fifteen, the conventionally grown fruits and vegetables with very low or no traces of pesticides. The second is the Dirty Dozen, or the 12 fresh non-organic fruits and vegetables with the highest pesticide residues.
Some pesticides have more data linking them to health concerns than others. These pesticides are particularly concerning for children. The brain and nervous systems, as well as other physiological systems of young children are far from fully developed and are especially sensitive to disruption and damage from industrial chemicals, including pesticides.
The presence of so many different pesticides in foods is also also concerning from a public health standpoint. When regulating pesticides, government bodies consider them only one at a time without considering the potential total body burden for consumers. There’s little available data about how multiple pesticides interact with each other in the body or how such mixtures could compound each chemical’s individual potential health harms. But the data we do have, primarily from animal studies, suggests that when chemicals are present in a mixture, they can be more toxic combined than individually.
More information
Here are more resources from EWG’s Shopper’s Guide to Pesticides in Produce:
