Mefenacet メフェナセット
Stop cell division (soil-applied herbicides): Stop the roots and shoots of newly sprouted weeds from growing. Applied to the soil of paddies and fields.
In Japan
- Registration
- Its registration as a pesticide expired on September 30, 2024 (first registered October 28, 1986). It can no longer be used as a pesticide in Japan.
- ADI (acceptable daily intake)
- 0.007 mg per kg of body weight per day
- ARfD (acute reference dose)
- not evaluated
- Evaluation
- Food Safety Commission of Japan, March 13, 2008
ADI: the amount considered to have no effect on health even if eaten every day for a lifetime. ARfD: the amount considered to have no effect on health when eaten at one time (within 24 hours). Both are set by the Food Safety Commission of Japan, mainly from animal studies.
In Japan's national residue testing (fiscal 2024)
| Produce | Detected / tested | Detection rate | Over the limit |
|---|---|---|---|
| Domestic | 1 / 4,562 | 0.0% | 0 |
| Imported | 0 / 819 | 0.0% | 0 |
Found in domestic foods: carrot (max. 0.01 ppm)
Tests are counted as pesticide × sample. Any detection counts as “detected” — it does not mean the limit was exceeded. For pesticides outside the top 20, figures are summed from the food-by-food tables of the full report.
Evaluations abroad
- WHO acute toxicity class
- U (Unlikely to present acute hazard in normal use), LD50 >5000 mg/kgBased on the toxicity of the undiluted active ingredient given once, mainly to rats by mouth (LD50 = the dose that kills half; the smaller, the stronger the acute toxicity). It is not an assessment of the safety of residues in food.
- EU
- Not approved in the EU
- IARC (carcinogenicity)
- No matching entry in the IARC list (not evaluated or out of scope, including Group 3)
Related explainers
Sources
- FAMIC (Food and Agricultural Materials Inspection Center), pesticide registration information (as of Sept. 30, 2026) (Japanese)
- Food Safety Commission of Japan, risk assessment report on Mefenacet (March 13, 2008) (Japanese)
- MHLW, results of pesticide residue testing in foods, fiscal 2024 (Japanese)
- WHO Recommended Classification of Pesticides by Hazard 2019
- EU Pesticides Database (Mefenacet)
Last checked 2026-10-01. Registrations and evaluations change over time. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.