[Preliminary Report] Pesticide Residues in Fast-Food French Fries 2026
Published October 27, 2026
Introduction
News about potato imports has been moving quickly. Recent reports suggest that Japan may lift its ban on imports of fresh potatoes for eating from the United States within a year, which surprised us. We wonder whether the aim is to push this through before the topic spreads widely in Japan.
We could not simply stand by. After discussing it with our staff, we used a small part of the donations we have already received to carry out a preliminary survey of French fries sold at fast-food chains that are believed to use U.S.-grown potatoes.
As in our earlier surveys, chlorpropham, a sprout suppressant, was detected again. Of the three products, the MOS Burger French fries showed the highest value.
This is a first (preliminary) report. We plan to add more detailed explanations and background later. Thank you for your understanding.
Samples and Analytical Method
We tested three products: "Mac French Fries, S size" from McDonald's, "French Fries, S size" from KFC (Kentucky Fried Chicken), and "French Fries, S size" from MOS Burger. All were purchased on October 15, 2026.
The samples were analyzed by GC/MS for 252 pesticide compounds. The limit of quantification (LOQ) is 0.01 ppm. For details of the analytical methods, please see the Analyses & Fees page (Japanese) and the individual method pages.
The origin information for the potatoes used in the fries, taken from each company's website and similar sources, is shown in Table 1.
Results
The results are shown below. Concentrations of detected pesticides are given in ppm.
Table 1. Pesticide residues in fast-food French fries, 2026 [preliminary]
| No. | Photo | Sample | Origin information (from company websites, etc.) |
Result (ppm) | |
|---|---|---|---|---|---|
| S1 |  |
McDonald's Purchased: 2026.10.15 |
USA, Canada, Argentina |
Chlorpropham | 0.022 |
| S2 |  |
KFC (Kentucky Fried Chicken) Purchased: 2026.10.15 |
USA, Belgium, Netherlands, China, others |
Not detected | |
| S3 |  |
MOS Burger Purchased: 2026.10.15 |
USA, Canada | Chlorpropham | 1.839 |
Discussion
- Chlorpropham, a sprout suppressant, was detected in two of the three products (McDonald's Mac French Fries and MOS Burger French Fries). No other pesticides were detected in this analysis.
- Even after taking processing factors into account, the detected values are below Japan's maximum residue limit (MRL) for chlorpropham in potatoes under the Food Sanitation Act, 30 ppm (link, Japanese), so they are not violations. Still, the results show that chlorpropham, used as a sprout suppressant, can be found even in this familiar side dish at fast-food restaurants.
- Chlorpropham is not approved for use on potatoes in Japan. Its detection is therefore considered to indicate that the raw material includes imported potatoes.
- According to information on the companies' websites and elsewhere, McDonald's lists its fries' origin as "USA, Canada, Argentina"; KFC as "USA, Belgium, Netherlands, China, others"; and MOS Burger as "USA, Canada". Nothing was detected in the KFC fries, which may mean that the potatoes in the product we purchased were not from the United States.
- This survey is based on a single purchase at each chain (one sample each), and the origin information does not necessarily describe the raw materials actually used in these products. The presence or absence of detection and the detected values apply only to the samples tested.
- In a 2005 survey, we also detected chlorpropham in French fries from hamburger restaurants (PDF, Japanese). In our 2025 survey of potato chips and similar snacks, it was also detected in products made from imported potatoes (link, Japanese).
- The Nouminren Food Analysis Center plans to continue testing products thought to use imported potatoes. Surveys require funds for testing and for running our instruments. We would greatly appreciate your support.
Related Links
Support Our Work
This survey was carried out using part of the donations we have received so far. To continue testing imported potatoes, we ask for your support. You can donate through our Congrant page.
Congrant: Nouminren Food Analysis Center, Analysis Support Donations (Japanese)
About the Nouminren Food Analysis Center
The Nouminren Food Analysis Center was founded in 1996 with donations from many farmers and consumers, a background that is unusual even worldwide for an analytical laboratory. Because it was established through donations, it works independently, free from the influence of companies or government.
Since our founding in 1996, our survey activities have been funded by donations. Frankly, our finances are tight. To continue working from the standpoint of consumers and farmers, we depend on your support.
We are recruiting "Analysis Center Supporter" members. You can become a supporter member with an annual fee of 5,000 yen or more per unit. Please help sustain our work.