Nearly all potato samples contain pesticide not approved for use in the EU
WEDNESDAY, JUNE 11, 2025
Potatoes – the most consumed vegetable in the U.S. – join this year’s Dirty Dozen™ in twelfth place. The reason: high concentrations of chlorpropham, a plant growth regulator banned in the European Union due to health concerns.
From 2022 to 2023, the Department of Agriculture collected and tested more than 1,000 samples of potatoes. They washed and scrubbed the samples, then tested for pesticide residues. Ninety percent of the samples contained residues of chlorpropham.
The average concentration across all samples was nearly three parts per million – high concentrations relative to most other pesticides detected across produce. And the concentrations are twice the level that the Environmental Protection Agency used in its most recent assessment of chlorpropham from 2017.
The chemical was detected on 90% of U.S. potato samples. Since 1990, chlorpropham has mostly been used on potatoes in the U.S. to prevent them from sprouting during storage.
In 2019, the EU rolled back its approval of chlorpropham. That decision followed a 2017 risk assessment finding that people, especially children, eating potatoes and other foods sprayed with chlorpropham may be exposed to the chemical – and its breakdown product 3-chloroaniline – at levels above those regulators consider won’t cause any health harms. The assessment also emphasized more data were needed to assess the potential endocrine disrupting effects of chlorpropham.
Chlorpropham potential health harms
Both U.S. and European regulators identified changes in blood cells and harm to the thyroid as the primary toxicological effects associated with exposure to chlorpropham in animal studies submitted to agencies in the U.S. and EU by pesticide companies.
Peer-reviewed studies also suggest chlorpropham may have hormone-disrupting properties, though more research is needed.
The 2017 assessment by the European Food Safety Authority, or EFSA, as well as peer-reviewed studies have noted that potato storage and processing, like boiling, roasting or frying, can decrease chlorpropham levels in potatoes.
EFSA also raised concerns about the degradation of chlorpropham into 3-chloroaniline, a breakdown product structurally similar to the cancer-causing compound 4-chloroaniline.
And the EPA’s assessment indicated 3-chloroaniline can form in fried potatoes. EFSA found that health risks associated with 3-chloroanaline exposure exceeded the risks associated with chlorpropham, and requested more data on 3-chloroaniline formation.
The EPA also found that children were the most exposed to chlorpropham of any age group, though these levels did not exceed the agency’s level of concern. Toxic chemical exposures can be especially harmful to children, whose bodies are still developing and who consume more food per measurement of body weight than adults.
Exposure to chlorpropham
Despite the prevalence of chlorpropham on potatoes, and the high consumption rates in the U.S., there are no studies assessing the effects of chlorpropham exposure in people.
A study of over 2,000 people from five EU countries, before chlorpropham was phased out in the EU, identified chlorpropham as the most frequently detected pesticide in human urine samples, with higher concentrations observed in children than in adults.
Organic potatoes do not allow the use of chlorpropham. But USDA tests of 28 organic samples of potatoes found residues on 12, likely due to cross-contamination during storage with non-organic potatoes. The average concentration on organic samples was 0.196 parts per million.
Exposure to chlorpropham was lower in individuals from the Netherlands and Switzerland who reported eating a lot of organic fruits and vegetables.
What about sweet potatoes?
Unlike white potatoes, non-organic sweet potatoes are not sprayed with chlorpropham. And sweet potatoes rank only two spots off the Clean Fifteen in EWG’s full list of fruit and vegetable rankings, meaning that sweet potatoes are a cleaner alternative to potatoes.
Just under 60% of sweet potato samples tested by the USDA contained any pesticides residues, compared to the 94% of samples for potatoes. The overall pesticide toxicity was also lower for sweet potatoes than for potatoes.
Consumption of sweet potatoes has been increasing in the U.S., according to USDA data.
Reducing your exposure
Consumption of fresh fruits and vegetables is important for a healthy diet. They 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 like to reduce pesticide exposure, there are simple steps you can take, without giving up potatoes.
EWG recommends continuing to eat potatoes, as well as other fruits and vegetables. Consider choosing sweet potatoes or if white potatoes are a favorite food, consider choosing organic when possible, to minimize exposure to chlorpropham. While organic potatoes still tested positive for chlorpropham because of cross contamination, the levels were much lower in concentration than conventional potatoes.
Make sure to wash all produce with water before consuming to help reduce pesticide levels as well as bacteria. Peeling potatoes can also reduce chlorpropham levels, but may also reduce the nutritional value.
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:
