Terms and definitions of toxicology

Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating exposures to toxins and toxicants. There different terms which are generally used in the field of Toxicology.


Substances producing adverse biological effects of any kind. May be chemical or physical in nature. Effects may be acute or chronic.


Peptides or proteins produced by living organisms. Venoms are toxins injected by a bite or sting.


Toxins produced by organisms.


The uptake of a chemical or water into or across a tissue, such as skin.


The build-up of chemical in the organism as a result of repeated, or long term exposure.

Acute Toxicity

Adverse effects arising from a single exposure or short term exposure to a chemical.


A substance which causes an allergic reaction.


An adverse reaction which is caused by an over-stimulation of the immune system in response to a specific allergen, which is otherwise harmless and would be normally tolerated by the majority of those who come in contact with it.


A substance that is capable of causing cancer.

Chronic Toxicity

Adverse health effects arising from continuous or intermittent exposure to low concentrations of chemicals over a lifetime.


A chemical that causes irreversible alterations or destruction in living tissue at the site of contact.

Cumulative Exposure

A summation of all the exposures that have been undergone by an organism during a specified period of time.


The amount of chemical administered. It is a measure of exposure.

Dose – Response

The relationship between the dose of a chemical and the degree/severity of the resulting effect.


The study of the incidence and distribution of disease in populations.


Contact with a chemical. The most common routes are inhalation, skin contact and also by oral ingestion.


The inherent ability of a chemical to cause an adverse effect


The state in which an individual reacts following exposure to a substance with allergic effects  after having been exposed (sensitized).


A chemical causing a localized inflammatory reaction to skin or mucous membranes at the site of contact.


Lethal Concentration 50%. This is the concentration which causes death in 50% of the test population.


An alteration in the genetic material, which can be passed onto subsequent generations.


The immune process by which individuals become hypersensitive to a substance to which they are exposed. Subsequent exposure can lead to the development of an allergic response.


A chemical agent causing adverse effects in normal embryonic development without causing lethality in the fetus or maternal toxicity.

Reviewed by:
Dr. Muhammad Adnan Asghar (Ph.D.)
Chinese Academy of Sciences Fuzhou, Fujian

%d bloggers like this: