Japan's Ministry of the Environment has put two draft changes to pesticide registration standards out for public comment: a lower water-pollution limit for the neonicotinoid thiamethoxam, and a lower aquatic-life benchmark for glyphosate. Comments run from 6 October to 4 November 2026, and any limits adopted would apply from the day the revising notice is promulgated.
The limits sit under the Agricultural Chemicals Control Act, which bars a pesticide from being made, processed or imported without registration by the agriculture minister. The environment minister sets the standards that determine whether registration must be refused on water-pollution or ecological grounds.
What would change
| Active ingredient | Proposed limit | Current limit | Standard |
|---|---|---|---|
| Thiamethoxam | 0.031 mg/L | 0.047 mg/L | Water pollution |
| Clothianidin | 0.25 mg/L | 0.25 mg/L (unchanged) | Water pollution |
| Glyphosate (as glyphosate) | 3,000 µg/L | 6,200 µg/L | Aquatic life |
| Pyroquilon | 3,300 µg/L | 3,300 µg/L (unchanged) | Aquatic life |
Thiamethoxam tightens, clothianidin stays
The water-pollution draft covers four active ingredients, two of them new to Japan and two under re-evaluation. Thiamethoxam, first registered in Japan in 2000, would go to 0.031 mg/L from 0.047 mg/L. The ministry's working papers tie that to an acceptable daily intake of 0.012 mg/kg of body weight per day, which the Food Safety Commission notified to the agriculture ministry on 10 June 2026. The limit is that intake multiplied by a 53.3 kg body weight and a 10% allocation to drinking water, divided by 2 litres a day, then truncated.
Clothianidin, the other neonicotinoid under re-evaluation, stays at 0.25 mg/L. The ministry's predicted water concentration for thiamethoxam is 0.014 mg/L, which it says does not exceed the proposed limit.
The other two ingredients, a rice, flower and turf insecticide and a vegetable fungicide, are unregistered in Japan and would receive new limits of 0.1 mg/L and 0.25 mg/L.
Glyphosate's aquatic benchmark drops
The second draft covers protection of aquatic and terrestrial life. For glyphosate, including its ammonium, isopropylamine, potassium and sodium salts, the aquatic limit would fall to 3,000 µg/L from 6,200 µg/L, expressed as glyphosate. The ministry's materials attribute the change to a lower algae-based figure. Duckweed testing gave a toxicity value of 9,210 µg/L, divided by an uncertainty factor of 3. The prior review had used an algae-based figure of 18,000 µg/L with no uncertainty factor. The ministry also now prefers tests without a marked pH drop.
The highest predicted concentration in the ministry's calculations is 23 µg/L, for the isopropylamine salt used in paddies, which it says does not exceed the limit. A bird exposure limit of 130 mg/kg of body weight is also proposed. For wild bees, no limit would be set in this first-round re-evaluation, because the product is not an insect growth regulator and its contact toxicity value is 11 µg per bee or higher.
New rice herbicide and an unchanged fungicide
A new rice herbicide, applied for on 1 October 2024 and unregistered in Japan, would get an aquatic limit of 33 µg/L and a bird limit of 170 mg/kg of body weight. Wild-bee limits of 3.9 µg per bee for adult contact, 0.59 for single oral exposure by adults and 0.60 for larval oral exposure are also proposed.
The rice fungicide pyroquilon keeps its aquatic limit of 3,300 µg/L. It would receive a new bird limit of 83 mg/kg of body weight but no wild-bee limit.
The draft notices do not give a promulgation date. Comments may be filed in Japanese through e-Gov or by post to the ministry's pesticide environmental management office.