US flag signifying that this is a United States Federal Government website   Official website of the Department of Homeland Security

Homeland Security

Chemical Attack: The Danger

Immediate Impact to Human Health

Facts about Industrial Chemicals

  • Industrialized countries produce, transport, and store large quantities of chemicals, some of which are toxic.
  • In 1984, a release from a tank of methyl isocyanate at the Union Carbide plant in Bhopal, India killed more than 3,800 people and injured 170,000.
  • Environmental laws enacted in 1986 and 1990 were aimed at reducing risk of accidental releases.
  • The overall safety record of the chemical and transportation industries is very good, and recent engineering and other advances have improved it further.

Acutely toxic chemicals can cause injury or fatalities if they are inhaled or absorbed by the skin. The harm that chemicals can cause depends on:

  1. their degree of toxicity 
  2. the concentration of the chemical, 
  3. the route of exposure, and
  4. the duration of the exposure.

The symptoms of exposure to most toxic chemicals would appear in minutes to hours. Different chemicals have different effects on the body. Table 1 shows the health effects for some chemical weapons. Some of the most toxic industrial chemicals can produce similar types of health effects at high concentrations. Table 2 shows lethal concentrations for some chemical weapons and industrial chemicals.

The Area Affected

In an open-air environment, the area affected would depend upon such factors as the type and amount of the chemical agent, means of dispersal, local topography, and local weather conditions. With highly toxic chemicals, lethal or immediately life-threatening results could be seen close to where the agent is released where the concentration is highest, while severe to moderate symptoms could be seen at some distance from the event. A toxic cloud would spread roughly with the speed and direction of the wind, but the concentration of the chemical would be greatly diminished at distances far from the source. With a release in a closed space, a volatile chemical will disperse to fill the space. The smaller the space, the greater the concentration of the chemical.

Exposure Through Contaminated Food

Chemical agents can make foods highly toxic, sometimes without changing the appearance or taste of the foods. Butter, oils, fatty meats, and fish absorb nerve agents so readily that removing them is virtually impossible. Foods in bottles, cans, or wrappings are not affected by agent vapor and can be salvaged following decontamination. The food supply is vulnerable to intentional contamination by toxins such as botulinum toxin.

Exposure Through Contaminated Water

Toxic chemicals could be used to contaminate the drinking water distribution system. Surface water sources in the area of a chemical release could become contaminated, but dying fish or aquatic life might warn of the release before human use. Deep ground water reservoirs and protected water storage tanks are regarded as safe sources of drinking water following a vapor release of chemical agents. There are methods of treating large volumes of potentially contaminated water for emergency drinking.

Last Published Date: August 9, 2012
Back to Top