What is meaning of Toxicity?

2. Biological

This relates to the effects of viruses and bacteria. Measuring the toxicity of such compounds is more complicated because it depends on the effectiveness of the immune system of the person exposed.

3. Physical

This relates to compounds that on their own are not specifically toxic, but which can be directly responsible for potentially life threatening consequences, for example the inhalation of dust from coal and asbestos.

DEGREES OF TOXICITY

Toxicity can be defined as acute, sub-acute or chronic:

• A substance with acute toxicity is sufficient to cause harm almost immediately after exposure.Substances commonly called poisons have extreme acute toxicity;
• A substance with sub-acute toxicity will only start to show symptoms after repeated exposure in doses too small to cause an immediate acute effect; or
• A substance has chronic toxicity if its effects only appear after repeated exposure over a period of ime. Examples are substances which are carcinogenic (cancer inducing) such as benzene.