Decision on aerosolised use of Central Nervous System-acting chemicals adopted by OPCW Conference of States Parties

The Twenty-Sixth Session of the Conference of the States Parties to the Chemical Weapons Convention (CWC) today adopted a Decision titled “Understanding Regarding the Aerosolised Use of Central Nervous System-Acting Chemicals for Law Enforcement Purposes.”

The Decision was co-sponsored by 50 OPCW Member States: Albania, Australia, Austria, Bulgaria, Canada, Colombia, Costa Rica, Croatia, Cyprus, Czech Republic, Denmark, El Salvador, Estonia, Finland, Georgia, Germany, Greece, Haiti, Honduras, Iceland, Ireland, Japan, Latvia, Liberia, Liechtenstein, Lithuania, Luxembourg, Malta, Marshall Islands, Montenegro, Netherlands, New Zealand, Niue, North Macedonia, Norway, Philippines, Poland, Portugal, Republic of Korea, Romania, San Marino, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine, United Arab Emirates, United States of America, and Vanuatu.

The Decision provides more clarity on the Conference’s understanding under the CWC on the aerosolised use of Central Nervous System (CNS)-acting chemicals for law enforcement purposes, drawing on the extensive work of the OPCW’s Scientific Advisory Board (SAB). The SAB recognised that chemicals that selectively modify CNS functions, such as the opioid fentanyl and its analogues, which are considered to be safe when used under controlled medical conditions, can have a very low safety margin when delivered as an aerosol. The SAB has noted that CNS-acting chemicals differ from Riot Control Agents (RCAs) as they act primarily on the central nervous system and their effects are not usually confined to sensory irritation of a temporary nature. The SAB therefore recognised that CNS-acting chemicals do not meet the definition of an RCA, as set out in paragraph 7 of Article II of the Convention.

The Decision requests that the Director-General task the SAB with continuing to review relevant developments in science and technology related to CNS-acting chemicals and provide updates to the Conference, as appropriate, and include in its report the topic on developments in science and technology for future Special Sessions of the Conference of the States Parties to Review the Operation of the Chemical Weapons Convention (Review Conferences).

The Decision only addresses the aerosolised use of CNS-acting chemicals in conjunction with law enforcement purposes and does not address the use of CNS-acting chemicals for other purposes not prohibited under the Convention.


The Conference of the States Parties meets annually to assess the implementation of the Chemical Weapons Convention (CWC) and to make key decisions regarding the future work of the Organisation. The Conference of the States Parties oversees the continued implementation of the Chemical Weapons Convention, the promotion of the treaty’s objectives and reviews international compliance with the treaty. The Conference is comprised of all OPCW Member States, each of which has one vote.

As the implementing body for the Chemical Weapons Convention, the OPCW, with its 193 Member States, oversees the global endeavour to permanently eliminate chemical weapons. Since the Convention’s entry into force in 1997, it is the most successful disarmament treaty eliminating an entire class of weapons of mass destruction.

Over 98% of all declared chemical weapon stockpiles have been destroyed under OPCW verification. For its extensive efforts in eliminating chemical weapons, the OPCW received the 2013 Nobel Peace Prize.

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