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Chlorine is only the beginning of a spectrum of instant asymmetrical chemical weapons


A chemical weapon (CW) in the hands of an asymmetrical attacker or terrorist will generally not be 'WMD-scale,' certainly not in the context used in connection with Iraq under Saddam Hussein and OIF, but it will be a chemical weapon nonetheless. (Under current (but not future) means of delivery, the most likely "WMD chemical event" will be the placing of conventional explosives in an existing chemical plant.)

We must recalibrate our definition of a chemical weapon in order to understand how a terrorist can add chemical leverage to their attacks, likely using one or more items (mixtures greatly complicate defensive responses) drawn from local industrial chemical and pesticide stocks. In conflict situations where hazmat protection greatly complicates combat operations and/or local infrastructure is inept or unprepared to deal with chemical events, a simple chemical additive (even a benign additive if the defenders momentarily believe it to be a chemical additive) can be a significant force multiplier - directly against combat formations and indirectly against domestic public opinion.

The increasing use of industrial chlorine in Iraq is very good technique, so long in coming but so quickly emulated. There are many industrial chemicals that are far more toxic than chlorine. The plastics, fire retardant and semiconductor industries are examples of industrial production containing highly toxic, generally commercially available and invariably unprotected, either at the industrial supplier or on the consumers' facility.

Many common toxic industrial chemicals could be used as weapons. What they lack in toxicity is made up by the large quantities commonly available and accessible. During WWI, the Germans used common chlorine gas as a weapon by simply opening containers and allowing the chemical to drift downwind into enemy forces. Chlorine and phosgene gases are industrial chemicals that are regularly transported in bulk road and rail shipments. Saboteurs could easily target commercial containers and rupture them to release the gases. The effects of chlorine and phosgene are similar to those of mustard agent. Chlorine and other chemical spills from trucks and railcars are not uncommon; terrorists would simply need to select targets and timing to maximize the effects on the public. Trucks and railcars are notoriously vulnerable targets to which little attention has been directed.

How to Handle a Chlorine Bomb is a good introduction to addressing a chlorine release, although its pertinent recommendations will be harder to implement in a combat environment. Copies of the Emergency Response Guidebook (ERG2004), a first responder guide to "(1) quickly identifying the specific or generic classification of the material(s) involved in the incident, and (2) protecting themselves and the general public during this initial response phase of the incident" should be on their way to Iraq along with the NIOSH Pocket Guide to Chemical Hazards.

Many retardants are precursors to organophosphates - nerve agents. It is only a matter of time before asymmetricals talk to an industrial hazardous materials specialist, consult the standard industrial toxicology handbooks (many in the end list), leaf through MSDS (Material Safety Data Sheet) listings, or remember Bhopal where an accidental release of methyl isocyanate, a key ingredient to resins, killed thousands and incapacitated thousands more, often critically. Methyl isocyanate is often sold in 55 gallon drums as an industrial staple. From Plastics: Overview, a warning note to artists likely to handle unfamiliar compounds:

Isocyanates are extremely toxic by inhalation, causing bronchitis, bronchospasm, chemical pneumonia, and severe acute and chronic asthma at very low concentrations, even in people without a prior history of allergies.  They also cause severe eye irritation.  Methyl isocyanate was the chemical that killed over 2500 people in Bhopal, India when released into the atmosphere several years ago.

The degree of hazard depends on the volatility of the diisocyanate and its physical form.  TDI (toluene diisocyanate) is the most volatile and the most hazardous.  MDI (diphenyl methane diisocyanate) is less volatile and, less hazardous than TDI.  Polymeric isocyanates usually contain about 50% MDI.  If heated or sprayed, any isocyanate is extremely hazardous.  Note that isocyanates cannot be detected by odor until the concentration is many times higher than recommended levels.

The NIOSH Pocket Guide to Chemical Hazards contains a datum for Immediately Dangerous to Life or Health Concentrations (IDLH) that defines a "threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment." While its original purpose was to "ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment," it can be used by an attacker as a selection criteria.

The semiconductor industry has for decades been accorded a free ride by the lay populace as a green industry far removed from rustbelt smokestacks. Nothing could be farther from the truth as the industry is swollen with toxic processing agents, notably gases. To show how easy this is to find, search on "gases in processing semiconductors." One click will get you to Database of the Thermophysical Properties of Gases Used in the Semiconductor Industry, and one more will get you to the Index of Semiconductor Process Gases. While not an issue in Iraq, the semiconductor sector is a good example of a WMD-class event in place that only needs conventional explosives to release. Any reasonably industrialized state has materials in situ that are at risk of exploitation by terrorists.

It can get worse. There are many chemicals and formulations that share the ability of organophosphate nerve agents to kill by inhibiting the enzyme that controls the nervous system's ability to communicate. From NERVE AGENTS, PESTICIDES, AND CHOLINESTERASE INHIBITION, which I recommend as a readable introduction to a usually technical subject:

What is Cholinesterase Inhibition?

Let's take a look inside the human body. The human body, as well as other animals, contain electrical switching centers called 'synapses'. The body manufactures a chemical called 'acetylcholine' which turns on the switches and another enzyme called 'acetylcholinesterase' which breaks down the acetylcholine and turns off the switches. All this happens very fast. This is how the brain signals information throughout the body, to control respiration, muscle action, digestion, and other life functions.

Certain chemicals can throw this out of balance. A cholinesterase inhibiting chemical (nerve agents and some pesticides) interferes with the enzyme that breaks down the acetylcholine and excessive acetylcholine builds up at the synapses. There is nothing to switch off the synapses as acetylcholine builds up. Electrical impulses fire away continuously. Repeated and unchecked firing of electrical signals causes uncontrolled and rapid twitching of muscles, paralyzed breathing, convulsions, and in extreme cases, death.

Any chemical that can bind, or inhibit, cholinesterase (e.g. acetylcholinesterase) making it unable to breakdown acetylcholine is called a "cholinesterase inhibitor", or an "anticholinesterase agent". The nerve agents (chemical warfare agents) are the most potent. Certain pesticides can also show some degree of cholinesterase inhibition. The pesticides that can result in cholinesterase inhibition fall into broad classifications of either (1) organophosphates or organophorphorous pesticides, (2) carbamate pesticides, or (3) pesticides based on chlorinated derivatives of nicotine. There are also many pesticides on the market that do not inhibit cholinesterase.

The offending chemical can be ingested, absorbed through the skin or eyes, or inhaled. The amount of chemical required to kill a human being can be as little as one drop of agent VX applied on the skin. On the other hand, some of the pesticides, which possess cholinesterase inhibition are of low enough toxicity that it would be difficult for a person to poison himself.

Look, for example, at the Material Safety Data Sheet (MSDS) (also here) for SEVIN 80WSP CARBARYL INSECTICIDE and its nerve agent capacities if misused. Contrast that to Chlorine or Methyl isocyanate.

Regardless of the source or scale of attack, chemical weapon attributes can be described as:

  • Chemical weapons (CW) are relatively inexpensive to produce.
  • CW can affect opposing forces without damaging infrastructure.
  • CW can be psychologically devastating.
  • Blister agents create casualties requiring attention and inhibiting force efficiency.
  • Defensive measures can be taken to negate the effect of CW.
  • Donning of protective gear reduces combat efficiency of troops.
  • Key to employment is dissemination and dispersion of agents.
  • CW are highly susceptible to environmental effects (temperature, winds).
  • Offensive use of CW complicates command and control and logistics problems.

The Chemical Weapons Convention (CWC) is clearly inclusive in its interpretation of what constitutes a chemical weapon. It certainly includes any agent or combination of agents that an asymmetrical attacker would employ:

[All] toxic chemicals and their precursors, except when used for purposes permitted by the CWC in specified quantities, are chemical weapons. Toxic chemicals are defined as "any chemical which through its chemical action on life processes can cause death, temporary incapacitation or permanent harm to humans or animals." Precursors are chemicals involved in production stages for toxic chemicals.

Determining whether genuinely dual-use chemicals are chemical weapons is more difficult. For example, chemicals such as chlorine, phosgene and hydrogen cyanide (AC) - all of which were used during World War I as chemical weapons - are also key ingredients in numerous commercial products. To make the determination, toxic dual-use chemicals are subjected to the so-called general purpose criterion...

According to the general purpose criterion, a toxic or precursor chemical may be defined as a chemical weapon depending on its intended purpose. [A] toxic or precursor chemical is defined as a chemical weapon unless it has been developed, produced, stockpiled or used for purposes not prohibited by the Convention. The definition thus includes any chemical intended for chemical weapons purposes, regardless of whether it is specifically listed in the [CWC]...

Chemicals intended for purposes other than these are considered chemical weapons. A basic component of the general purpose criterion is the principle of consistency. A toxic chemical held by a State Party and in agreement with this principle will not only be produced, stockpiled or used for a legitimate purpose, but also will be of a type and quantity appropriate for that purpose.

Terrorists will be able to overcome the historical limitations of employing chemical weapons, in the near term, doing so by incorporating 'found' industrial materials:

Chemical weapons have a relatively small area of influence and quickly disperse into the air or settle to the ground. When combined with explosives to increase dispersion the active chemicals are often destroyed or degraded by the explosive blast. Terrorist groups have extensive experience with conventional explosives and gain little advantage from chemical weaponry... It's simply impractical for terrorists to secretly obtain, transport and disperse the large quantities of chemicals required to attain a significant result...

As soon as the asymmetricals talk to a blasting expert, as opposed to a demolition expert, they will be taught about low brisance explosives (where brisance is a measurement of the rapidity that an explosive achieves its maximum overpressure and velocity) for bursting chemical stocks; Low brisance explosives are used to heave and fracture rock strata rather than pulverize the strata as would a high brisance explosive (C4, Semtex and other military explosives).

In the near to medium term, terrorists will not have to start from ground zero, building, weaponizing and deploying CW on a WMD scale. They will learn to include industrial chemicals, pesticides and some herbicides in pointed tactical engagements combined with other attack vectors that will complicate defensive response.

Iraq Rebels Expected to Use More Chlorine Gas in Attacks
New York Times
February 23, 2007

How to Handle a Chlorine Bomb
Kris Alexander
Danger Room
Friday, February 23, 2007

Militants Using Chemical Bombs in Iraq
New York Times
February 21, 2007

Plastics: Overview
by Michael McCann, Ph.D, C.I.H and Angela Babin, M.S.

NIOSH Pocket Guide to Chemical Hazards
NIOSH Publication No. 2005-149
National Institute for Occupational Safety and Health (NIOSH)
September 2005

Deriving Toxicity Values for Organophosphate Nerve Agents: A Position Paper in Support of the Procedures and Rationale for Deriving Oral RfDs for Chemical Warfare Nerve Agents
Young, Robert A.; Opresko, Dennis M.; Watson, Annetta P.; Ross, Robert H.; King, Joe; Choudhury, Harlal
Human and Ecological Risk Assessment
Volume 5, Number 3, June 1999, pp. 589-634(46)

Jeff Slotnick
Security Driver

Terrorists, WMD, and the US Army Reserve
Parameters, Autumn 1997, pp. 98-118

Creating an explosion: The theory and practice of detonation and solid chemical explosives
J A Burgess and G Hooper
Physics in Technology 8 257-265

Toxic Substances
Agency for Toxic Substances and Disease Registry (ATSDR)
US Department of Health and Human Services

Database of the Thermophysical Properties of Gases Used in the Semiconductor Industry
NIST Standard Reference Database 134
National Institute of Standards and Technology

Index of Semiconductor Process Gases
NIST Standard Reference Database 134
National Institute of Standards and Technology

Thermophysical Properties of Gases Used in Semiconductor Processing
J.J. Hurly, K.A. Gillis, and M.R. Moldover
NIST - Physical and Chemical Properties Division

by John S. Nordin, Ph.D.
The First Responder
Tuesday, June 17, 2003

Handbook of Chemicals and Gases for the Semiconductor Industry
Wiley InterScience
March 2002

Emergency Response Guidebook (ERG2004)
US Department of Transportation, Transport Canada, and the Secretariat of Communications and Transportation of Mexico (SCT)


ChemINDEX (ChemFinder professional)

Expert Consulting and Expert Witness Services

Britney's Guide to Semiconductor Physics
written and designed by Carl Hepburn, post-grad student, at University of Essex

Chemical, Biological, Radiological and Nuclear (CBRN) Weapons
Weapons of Mass Destruction
Global Focus
Open Source Intelligence

What Is A Chemical Weapon?
FactSheet 4
Organisation for the Prohibition of Chemical Weapons (OPCW)
Last revised: 25 July 2000

Monitoring Chemicals With Possible Chemical Weapons Applications
FactSheet 7
Organisation for the Prohibition of Chemical Weapons (OPCW)
Last revised: 25 July 2000

Gordon Housworth

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