Toxic Substance Forms
Toxic substances can take the form of solids, liquids, gases, vapors, dusts, fumes, fibers and mists. How a substance gets into the body and what damage it causes depends on the form or the physical properties of the substance. A description of each of the forms follows.
Solid: A solid is a material that retains its form, like stone. Most solids are not hazardous since they are unlikely to be absorbed into the body, unless present as small particles such as dust.
- Example: Lead in solid form is less harmful than when ground into fine dust that can be inhaled.
Liquid: A liquid is a material that flows freely, like water. Many hazardous substances are liquids at normal temperatures. Some can damage the skin, while others can pass through the skin into the body. Liquids may also evaporate, producing vapors that can be inhaled.
- Example: Gasoline is a liquid that can irritate the skin and evaporates to form toxic vapors.
Gas: A gas consists of individual chemical molecules dispersed in the air at normal temperature and pressure. Some gases are flammable, explosive, or toxic. Colorless and odorless gases may be especially dangerous because they are hard to detect without monitoring equipment.
- Example: Carbon monoxide is a colorless, odorless gas that can cause poisoning and death.
Vapor: A vapor is the gas form of a substance that is normally a liquid at room temperature. Vapors can be inhaled into the lungs and may irritate the eyes, skin, or respiratory tract. Some are also flammable, explosive, or toxic.
- Example: Paint thinner evaporates easily and produces vapors that can cause headaches and dizziness.
Dust: A dust consists of small solid particles in the air, created when solids are crushed, ground, or disturbed. Dust can be inhaled into the respiratory system, where small particles may reach and damage the lungs.
- Example: Silica dust from cutting or drilling concrete can cause silicosis when inhaled.
Fume: A fume is made of very fine solid particles created when materials, often metals, are heated to high temperatures, evaporate, and then condense in the air. Fumes are hazardous because they are easily inhaled.
- Example: Welding metal produces fumes that can cause metal fume fever.
Fiber: A fiber is a solid particle that is much longer than it is wide. The hazard depends on the size of the fiber. Small fibers can lodge in the lungs and cause serious harm, while larger ones are usually trapped and expelled by the respiratory system.
- Example: Asbestos fibers are small enough to reach the lungs and cause diseases like asbestosis or cancer.
Mist: A mist consists of tiny liquid droplets in the air, formed by spraying, agitation, or condensation. Mists can be hazardous when inhaled or when they come into contact with the skin.
- Example: Pesticide spraying produces mists that can be inhaled by workers if proper protection is not used.
Knowledge Check Choose the best answer for the question.
3-8. Very small, fine solid particles in the air which form when solid chemicals are heated to very high temperatures, evaporate to vapor, and finally become solid again are called _____.
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