Tuesday, November 10, 2009

Health

Chemical Agents

By U.S. Department of Health and Human Services

Posted 3/29/06

Basic Facts

This section discusses four major types of chemical agents, grouped according to how they affect the human body:

Other categories of chemicals include:

For more information on these other chemical categories visit www.bt.cdc.gov.

Chemical agents can come in the form of poisonous gases, liquids, or solids.
These agents are usually fast acting and toxic to people, animals, or plants. (Note: A major exception is mustard agents, for which symptoms appear several hours after exposure.)
Poisoning by chemicals is not contagious. However, if residual chemical agents or vapors are on the skin, clothing, or hair or in biologic fluids (such as vomit), others can be exposed and affected. Once the agent is removed (e.g., by removing clothing and showering), the illness caused by a chemical agent cannot be spread.

Assessing the Risk

Because certain chemical agents are used in industry and household products, they are highly available.
After an outdoor release, the dangers associated with many chemical agents decrease over time because the chemical gets diluted as it spreads over a given area.
Terrorists could be minimally skilled to launch a limited chemical attack. A more widespread attack would require more expertise.
How lethal an attack is depends on several factors, including amount and type of agent used, route of exposure, time elapsed before decontamination, and access to medical care.

Chemical Agents as Weapons

Sufficient quantities must be used for chemical weapons to be effective.
Weather factors have an impact on the effectiveness of an open-air release. These factors include:
Temperature
Wind speed and direction
Humidity and air stability
Chemical agents are typically more deadly in confined or crowded areas, such as buildings, subways, or battlefields, where evacuation options are limited.
Chemical agents can be deployed in five ways:
Spraying the chemical with wet or dry aerosol sprayers (e.g., crop dusters, handheld spraying devices)
Using a heat source to vaporize the chemical for release
Using an explosive device to disperse the chemical
Pouring the chemical on a specific site (e.g., building floor, sidewalk, subway platform)
Contamination of food, water, or pharmaceuticals (such as the 1982 intentional contamination of acetaminophen products with cyanide)

Identifying an Attack

A chemical release may result in environmental clues, including:
Dead plants, animals, or insects
Pungent odor
Unusual clouds, vapors, or droplets
Discoloration of surfaces
Some common immediate physical symptoms from an airborne attack may include:
Tightness in chest and difficulty breathing
Nausea and vomiting
Watery eyes and blurry vision
A chemical attack is different from a biological attack in the following ways:
It is often an easily identifiable incident (e.g., chemical release from a fire at an industrial manufacturing facility).
Signs and symptoms appear rapidly after exposure (usually within minutes).
Victims are not contagious, although rescue workers can become ill if there is still residual chemical on the patient's clothes or skin, or in biologic fluids, and they are exposed to these agents without proper personal protective equipment (e.g., gloves and masks).