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On May 14, 2026, Thailand's Department of Industrial Works (DIW), operating under the Ministry of Industry, opened a public consultation on a draft amendment regarding the List of Hazardous Substances. The DIW intends to consolidate and update the categorization of chemicals controlled under the Chemical Weapons Convention (CWC), thereby aligning Thailand's national regulatory framework with its international obligations.
Background
This regulatory development stems from international updates made by the Organisation for the Prohibition of Chemical Weapons (OPCW). On November 27, 2019, the OPCW approved the addition of four new chemical entries to Schedule 1 of the CWC Annex on Chemicals, which officially took effect internationally in June 2020. In response, Thailand's National Authority for the CWC (under the DIW) approved the designation of these newly added chemicals as Type 4 Hazardous Substances under the Hazardous Substance Act B.E. 2535 (1992). Previously, CWC-controlled substances were scattered across different regulatory lists (such as List 5.1 and List 5.5), which occasionally complicated regulatory oversight and industry compliance. The partial amendment aims to ensure the clarity and specificity of the classification of CWC-controlled chemicals under the HSA, thereby facilitating effective supervision and oversight in accordance with the above-mentioned laws and conventions.
Proposed Updates
The draft amendment proposes a significant restructuring of the categorization of CWC-controlled substances. The key changes include:
Establishment of a Dedicated Sub-list: "List 5.5" will be revamped to serve as the exclusive, consolidated category for all substances controlled under the Chemical Weapons Convention.
Relocation of Existing Substances: 43 CWC-related chemicals currently listed under List 5.1 will be moved to the new List 5.5. This administrative move aims to improve regulatory clarity without altering the existing control status of these substances.
Expansion of the Sub-list: A total of 1,378 chemical names will be listed in the updated List 5.5, aligning the total number of controlled CAS numbers with the OPCW Handbook on Chemicals 2024.
Addition of 4 New Hazardous Substances: The draft amendment proposes to incorporate the following four new Schedule 1 CWC entries (comprising three chemical groups and one specific substance, covering 144 CAS numbers) as Type 4 Hazardous Substances.
P-alkyl (H or ≤C10, incl. cycloalkyl) N-(1-(dialkyl(≤C10, incl. cycloalkyl) amino))alkylidene(H or ≤C10, incl. cycloalkyl) phosphonamidic fluorides and corresponding alkylated or protonated salts
O-alkyl (H or ≤C10, incl. cycloalkyl) N-(1-(dialkyl(≤C10, incl. cycloalkyl)amino))alkylidene(H or ≤C10, incl. cycloalkyl) phosphoramidofluoridates and corresponding alkylated or protonated salts
Methyl-(bis(diethylamino)methylene)phosphonamidofluoridate (CAS No. 2387496-14-0)
Carbamates (quaternaries and bisquaternaries of dimethylcarbamoyloxypyridines)
Once adopted, these newly added Schedule 1 chemicals under CWC will be strictly regulated as Type 4 Hazardous Substances, meaning their production, import, export, or possession is prohibited under HSA.
To ensure industry stakeholders and the public have the opportunity to review and provide input on these changes, the DIW has established a one-month public consultation period. The consultation runs from May 15, 2026, to June 15, 2026. Chemical industry professionals are encouraged to study the draft and submit their feedback through the central legal system portal (www.law.go.th), the official DIW website (www.diw.go.th), or the DIW's official Facebook page before the June 15 deadline.
