Legal Update: Thailand’s Hazardous Substance Act – Amendment Highlights and Compliance Guidance

We published a newsletter regarding Thailand’s Hazardous Substance Act – Amendment Highlights and Compliance Guidance. To view PDF version, please click the following link.

→Legal Update: Thailand’s Hazardous Substance Act – Amendment Highlights and Compliance Guidance

Legal Update: Thailand’s Hazardous Substance Act – Amendment Highlights and Compliance Guidance

22 September 2025
OAL Thailand Office

As of July 7, 2025, Thailand’s Hazardous Substance Act (“HSA”) has been updated via its Eighth Edition Hazardous Substance List, which became effective immediately upon its announcement. Certain cyanide compounds now require a stricter permit regime, and specific persistent organic pollutants are newly banned.
This newsletter outlines the updated Hazardous Substance List and provides guidance for businesses handling these chemicals to ensure prompt and effective compliance.

1. Overview of Thailand’s Hazardous Substance Act

Enacted in 1992, the HSA regulates the manufacture, import, export, possession (including transportation) of chemicals hazardous to health or the environment. It is administered by the Ministry of Industry in coordination with several other ministries.

In addition to regulating hazardous substances, the HSA imposes specific duties on producers, importers, carriers, re-importers, re-exporters, and any persons in possession of hazardous substances. It also establishes civil liability for any damage arising from such possession.
Under the HSA, producers, importers, wholesalers, transit operators, re-importers, re-exporters, retailers, intermediaries, and any parties involved in any stage of the distribution chain—from production through to the point of the harmful incident—may be held jointly liable for any resulting tort. This liability also extends to employers, principals, hirers, or business owners, where the tortious act is committed by their representatives or employees in the course of business operations.

While the standard statute of limitations for tort claims in Thailand is one year[1] from the date the injured party becomes aware of the tort and the identity of the person responsible, the HSA extends this period to three years for torts arising from hazardous substances, reflecting the potentially severe and latent nature of the harm involved.
Thailand classifies hazardous substances into four categories based on hazard severity:

Each business must identify which category its chemicals fall into and comply with the relevant procedures, including notifying, monthly report, safety measure and safety officer arrangement.

2. Eighth Edition Hazardous Substance List: Major Amendments

2.1 Reclassification of Cyanide Compounds (Type 1 → Type 3)

Previously subject only to notification, the following cyanide compounds have been upgraded to Type 3. From the enforcement date, any manufacture, import, export, or possession (including transportation) of these chemicals requires an official permit:

• Gold(I) cyanide (CAS 506-65-0)
• Gold sodium cyanide (CAS 15280-09-8)
• Gold potassium cyanide (CAS 13967-50-5)
• Copper(I) cyanide (CAS 544-92-3)
• Copper(II) cyanide (CAS 14763-77-0)
• Propionitrile (ethyl cyanide) (CAS 107-12-0)

Action Required: Businesses handling these substances must submit permit applications by August 6, 2025 (within 30 days of enforcement). 

2.2 New Prohibition of Persistent Organic Pollutants (Type 4)

Three persistent organic pollutants are now designated as Type 4 (prohibited). Manufacture, import, export, and possession (including transportation) are banned:

• Dicofol (CAS 115-32-2) – upgraded from Type 3 to Type 4
• Pentachlorobenzene (CAS 608-93-5) – newly listed Type 4
• Hexachlorobutadiene (CAS 87-68-3) – newly listed Type 4

Action Required: Businesses handling these substances shall stop using these substances and follow the orders to dispose or return to the relevant authority that will be issued  in the near future by January 2026 (within 180 days of enforcement).

3. Penalties

• Handling Type 3 substances without permission is subject to a maximum fine of 200,000 THB, imprisonment up to 2 years, or both.
• Handling Type 4 substances without permission is subject to a maximum fine of 1,000,000 THB, imprisonment up to 10 years, or both.
• If the substance is a toxic chemical or a substance used for the production of toxic chemicals listed in the Chemical Weapons Convention, an offender who is a Thai national shall be punished even if the offence is committed outside Thailand.

4. Recommended Compliance Steps

1. Inventory Review: Identify all chemicals in use, manufacture, import, or storage that appear on the new Eighth Edition list.
2. Regulatory Planning: For Type 3 substances, prepare and submit permit applications by the deadline. For Type 4 substances, stop using these substances immediately, develop and execute the plan for disposal or return to meet the order of the relevant authority which will be issued within 180 days from the effective of this new Hazardous Substance List.
3. Supply-Chain Communication: Notify suppliers and downstream customers of these changes to ensure end-to-end compliance.

Additionally, a ministerial regulation to standardize and digitize Type 3 permit procedures will take effect on September 17, 2025. Businesses should prepare for that upcoming procedural shift as well.
Given the complexity and potential penalties for non-compliance, companies are advised to consult legal or regulatory experts for detailed guidance.

—–

[1] This is subject to an absolute limit of 10 years from the date the tort occurred.