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Classification of toxic agents
Transcript of Classification of toxic agents
Classification of toxic agents Merey Makhanova
Jour 122R Toxicity is the degree to which a substance can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity).
A central concept of toxicology is that effects are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, lending cross-species analysis problematic. Toxicity The skull and crossbones is a common symbol for toxicity. Types of toxicity
There are generally three types of toxic entities; chemical, biological, and physical:
Physical toxicants Chemical toxicants include inorganic substances such as lead, mercury, asbestos, hydrofluoric acid, and chlorine gas, organic compounds such as methyl alcohol, most medications, and poisons from living things. Biological toxicants include bacteria and viruses that can induce disease in living organisms. Biological toxicity can be difficult to measure because the "threshold dose" may be a single organism. Theoretically one virus, bacterium or worm can reproduce to cause a serious infection. However, in a host with an intact immune system the inherent toxicity of the organism is balanced by the host's ability to fight back; the effective toxicity is then a combination of both parts of the relationship. A similar situation is also present with other types of toxic agents. Physical toxicants are substances that, due to their physical nature, interfere with biological processes. Examples include coal dust and asbestos fibers, both of which can ultimately be fatal if inhaled Another type of classification is: 1. Heavy Metals
Metals differ from other toxic substances in that they are neither created nor destroyed by
humans. Their use by humans plays an important role in determining their potential for health effects. Their effect on health could occur through at least two mechanisms: first, by increasing the presence of heavy metals in air, water, soil, and food, and second, by changing the structure of the chemical.
2. Solvents and Vapors
Nearly everyone is exposed to solvents. Occupational exposures can range from the use of “white-out” by administrative personnel, to the use of chemicals by technicians in a nail salon. When a solvent evaporates, the vapors may also pose a threat to the exposed population. 3. Radiation
Radiation is the release and propagation of energy in space or through a material medium
in the form of waves, the transfer of heat or light by waves of energy, or the stream of
particles from a nuclear reactor. Pesticides
The EPA defines pesticide as any substance or mixture of substances intended to prevent, destroy, repel, or mitigate any pest. Pesticides may also be described as any physical, chemical, or biological agent that will kill an undesirable plant or animal pest. Subcategories of Toxic Substance Classifications
All of these substances may also be further classified according to their:
# Effect on target organs (liver, kidney, hematopoietic system),
# Use (pesticide, solvent, food additive),
# Source of the agent (animal and plant toxins),
# Effects (cancer mutation, liver injury),
# Physical state (gas, dust, liquid),
# Labeling requirements (explosive, flammable, oxidizer),
# Chemistry (aromatic amine, halogenated hydrocarbon), or
# Poisoning potential (extremely toxic, very toxic, slightly toxic) All chemicals (or any chemical) may be poisonous at a given dose and through a particular route. For example, breathing too much pure oxygen, drinking excessive amounts of water, or eating too much salt can cause poisoning or death. Thank you for your attention!!!