Japan amends the Deleterious Substances List under PDSCA

On 25 July 2025, Japan’s Ministry of Health, Labour and Welfare (MHLW) published draft ordinance for amending the Poisonous and Deleterious Substances List on the country’s e-Gov Public Comment Portal. Fenazaquin has been proposed to get added, whereas formulations containing sodium chlorate or sodium bicarbonate scheduled to get removed from the list.

Poisonous and Deleterious Substances List

The Poisonous and Deleterious Substances List under Japan's Poisonous and Deleterious Substances Control Act (PDSCA) classifies chemicals based on their toxicity and health risks, categorizing them as "poisonous" or "deleterious." These substances are regulated for safe handling, storage, and transportation to prevent accidents and ensure public safety. Updated regularly by Japan's MHLW, new substances are added based on scientific evidence. The regulations include safety procedures such as labelling, record-keeping, and reporting to minimize health and environmental risks. Currently there are 587 entries present on the list.

Key Insights from the Draft Ordinance

Draft ordinance proposes the following amendments to the list of Deleterious Substances:

• 4-[2-(4-tert-Butylphenyl)ethoxy]quinazoline (Fenazaquin) (CAS: 120928-09-8) and its preparations (except from those with a concentration ≤19.4%) have been designated as a new deleterious substance.
• Taking a formulation off the list: Made with sodium bicarbonate (27–37%) (CAS: 144-55-8) and sodium chlorate (47.5–52.5%) (CAS: 7775-09–9), except powdered versions.

It was determined that fenazaquin posed a significant risk of acute toxicity upon exposure, supporting its designation as a deleterious substance. On the other hand, it was found that the sodium chlorate/sodium bicarbonate formulation had far lower toxicity, which justified its removal from the list.

Obligations for the Stakeholders

Manufacturers, importers, and distributors of the Poisonous and Deleterious Substances must register their substances with the MHLW and comply with Safety Data Sheets (SDS) and Labelling regulations.

Comment Period and Enforcement Dates

Stakeholders are requested to comment on the draft till 24 August 2025. Final ordinance will be published in late October 2025. Enforcement is scheduled to be from 1 November 2025 (Except for delisting of entries which will come into effect on the same day of ordinance publication).