Toxic Agents
A toxic agent is anything that can produce an adverse biological effect. It may be in the form of a chemical (e.g. cyanide), physical (e.g. radiation), or biological agent (e.g. snake venom). Toxic agents can be divided into seven categories:
- Asphyxiants
- Physical asphyxiants (CO2, methane) that deprive the lungs of oxygen, and
- Chemical asphyxiants (CO, HCN) that deprive specific cells within body tissue of oxygen.
- Irritants: Inflammation of membranes results from exposure to irritants. Other effects include redness, swelling, blistering, burning, and itching. Irritants usually act locally or topically.
- Sensitizers: Sensitizers are systemic irritants. Allergic sensitizers affect an entire system instead of producing local irritation. Often it is difficult to determine whether a reaction is merely from an irritant or the result of an allergy.
- Corrosives: Corrosives cause chemical deterioration of living tissue (i.e., acid burns).
- Carcinogens: Carcinogens are agents that cause cancer. Other non-carcinogenic chemicals may increase the number and severity of cancer tumors.
- When applied before or with the carcinogen, these chemicals are termed "co-carcinogens" (asbestos is a co-carcinogen).
- When applied after the carcinogen, they are referred to as "promoters."
- Substances carcinogenic to laboratory animals but have not been shown conclusively to cause cancer in humans are "suspect" carcinogens.
- Mutagens: Mutagens are generally a chemical or form of radiation causing changes in the genetic structure of cells. In humans, the two types of affected cells are body cells (resulting in cancer) or reproductive cells (either egg or sperm cells possibly affecting the offspring). Carcinogens are a type of mutagen, but not all mutagens are carcinogens.
- Teratogens: These hazardous substances affect the developing fetus without harming the mother.
Knowledge Check Choose the best answer for the question.
4-3. Which category of toxic agents are generally a chemical or form of radiation that causes changes in the genetic structure of cells?
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