Factors Affecting Toxicity:
1.Dosage :
Harmful effect of a toxic compound is largely dependent on the amount of that compound absorbed into the body.
2.Physical nature:
The physical state, e.g., whether solid, powder, orin solution will affect the dose of a poison. Coarsely crystalline arsenic trioxideis slowly absorbed and so has relatively low toxicity; finely powdered arsenic is highly toxic. Many substances are readily absorbed from oily than from aqueous solution, e.g., insecticides.
Gases > liquid > solid
3.Chemical nature:
It is important in regard to toxicity, yellow phosphorus is a most poisonous substance, its allotrope red phosphorus is inert when taken in body, it is in soluble and is excreted unchanged. Compounds containing trivalent arsenic are much more toxic than those containing the pentavalent form. Barium carbonate is intensely toxic than barium sulfate.
4.Sources of Poisons.
Under certain circumstances poisoning from a.particular compound may be enhanced or reduced. Some plant poisons are destroyed by drying or storage and hay contaminated by them is harmless (e.g., buttercups). Presence of oils in the diet will enhance the absorption and so toxicity of poison e.g., phosphorus. Accumulation of copper in the liver may be mobilized by administering molybdenum and vice versa.
5.Repeated Exposure
It is logical that several doses of a poison will be effective than a single dose. The degree of harmfulness of repeated small doses also depends on whether the poison accumulates in body and whether its effects are cumulative (e.g., carcinogen). Carcinogens are the example of such chronic toxicity.
6.Species : Toxicological effect varies greatly qualitatively and quantitatively from species to species.There are extraordinary wide variations in response to a particular poison between species.
7.Size, Age and Sex
In general, the amount of a poison required to produce toxic symptoms is related to the weight of the animals.This relationship between weight and dose may vary between species.
Very young and very old animals are usually more susceptible to poisons. There are few instances of sex difference in response to poisons in animals. For example. red squill has about twice the toxicity for female rats than for males. Female are more susceptible than males.
8.General State of Heath
Debilitated animals are more susceptible to poisons and drugs because their general resistance and detoxication mechanisms are defective. For example, hepatic or renal disease may enormously increase the susceptibility to poisons.
9.Dietary factors: A high protein factors usually increases biotransformation of Xenobiotics.
- Method of administration- Inhalation / I.V. > I.M. / S.C. > Ingestion > Skin contact
- Factors related to environment- Temperature, pressure, humidity and radiation can bring alterations on poison status.