Monday, March 12, 2018

Novichok agent

Chemical Agents

Ian Greaves, Paul Hunt, in Responding to Terrorism: A Medical Handbook. Churchill Livingstone 2010, 233–344.

Brief description
The Novichok class of agents were reportedly developed in an attempt to circumvent the Chemical Weapons Treaty (chemical weapons are banned on the basis of chemical structure and therefore a new chemical agent is not subject to past treaties). They have reportedly been engineered to be undetectable by standard detection equipment and to defeat standard chemical protective gear. Like other nerve agents, the Novichok agents act by inhibiting the enzyme cholinesterase.

Novichok agents may be dispersed as an ultra-fine powder as opposed to a gas or a vapour.

Identifying characteristics
Novichok agents may consist of two separate ‘non-toxic’ components that, when mixed, become the active nerve agent. No further information is available.

The main route of exposure is thought to be by inhalation, although absorption may also occur via skin or mucous membrane exposure.

Novichok is reported to be 5–8 times more lethal than VX nerve agent and effects are rapid, usually within 30 seconds to 2 minutes.

Major symptoms
Symptoms are the same as those of other nerve agents... Local effects are thought to be immediate, while systemic effects may be delayed up to 18 hours.

Initial management
Initial management must concentrate upon basic life support measures and decontamination in order to remove the agent and prevent additional exposure. Clothing should be removed and the skin washed with soap and water. Contact lenses should be removed and the eyes thoroughly irrigated for at least 5–10 minutes. Supplementary oxygen should be administered as soon as possible. Airway maintenance with manual or mechanical ventilation may be required.

Specific treatment
Antidotes to nerve agent poisoning must be given immediately (see below). It should be noted that some Novichok agents have been specifically designed to be resistant to standard nerve agent antidote therapy.

Atropine repeated as required.

Novichok agents have a higher density than air and will therefore tend to collect in low-lying areas. No other information is available regarding their persistency.

Novichok agents are reported to produce more permanent injury, even following appropriate nerve agent antidote treatment.

Further information
Exposure to nerve agents may be tested for by checking blood samples for any decrease of acetylcholinesterase enzyme activity.

Appropriate PPE must be worn by members of emergency services who may be treating nerve agent casualties. Inadequate decontamination may result in secondary cases from exposure to primary cases.

Progressive symptoms suggest continued exposure which may be due to inadequate decontamination or inadequate treatment/insufficient antidote therapy.

Muscle twitching and excess secretions are the main distinguishing features between nerve agents and chemical asphyxiant agents, such as cyanide.

Future Biological and Chemical Weapons
Robert G. Darling, Erin E. Noste, in Ciottone's Disaster Medicine (Second Edition), Elsevier 2016, 489–498

Novichok (Russian for “newcomer”) refers to the alleged Russian development of a highly toxic binary nerve agent or generation of nerve agents (sometimes called “fourth-generation” agents). Only sketchy and unverifiable information is available in the unclassified literature, but the existence of these agents would demonstrate the possibility of creating new chemical compounds toxic enough to be used as chemical warfare or terrorist agents. One of the sources of unclassified information is from a dissident Russian scientist who wrote newspaper articles and published a book about the Novichok program and the types of chemical agents that were produced.

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