Common Toxicological Terminology

The field of Toxicology is littered with terminology. Listed below are some definitions which are commonly encountered.

Acute toxicity
Adverse health effects which occur soon after a single exposure or short term exposure to a chemical.

Allergic contact dermatitis
This is an inflammatory response of the skin as a result of the immune system reacting to a specific allergen (hypersensitivity). Nickel is a common example of an allergen which will cause this type of reaction.

Carcinogen
A substance that is capable of causing cancer. Benzene is an example of a chemical carcinogen.

Chronic toxicity
This arises from intermittent or continuous exposure to low concentrations of chemical over a lifetime.

Contact dermatitis
This is an inflammatory response of the skin arising from exposure to a chemical. There are two types; irritant contact dermatitis and allergic contact dermatitis.

Corrosive
A chemical which causes destruction to living tissues upon contact – can be referred to as “chemical burns”. Concentrated acids and alkalis are examples of corrosive chemicals.

Developmental toxicology
This is the study of adverse effects arising from exposure in the developing embryo or foetus.

Dose – response
The relationship between the dose (amount of chemical administered) and the severity of the resulting effect.

Exposure
This is simply contact with a chemical. In the industrial context, the three most common routes of exposure are by skin contact, inhalation and ingestion.

Genotoxic carcinogen
These are agents that cause cancer as a result of directly interacting with DNA. Radiation is an example of a genotoxic agent.

Irritant contact dermatitis
This is a localised inflammatory response of the skin in response to a chemical irritant. Unlike allergic contact dermatitis, it does not involve the immune system. Strong acid or alkali can cause irritant effects.

LD50 (lethal dose, 50)
The statistically derived single dose that will cause 50% mortality in the test population under set test conditions.

Mutation
An alteration in the genetic material which can be passed on to subsequent generations.

Neoplasm
This is another name for a tumour.

NOAEL
“No observable adverse effect level”. This is the largest dose that does not produce any adverse effects in the test population.

Skin sensitisation
This is an abnormal allergic response to a specific allergen. Expoxy resins and biocides are examples of substances that can cause this kind of reaction.

Systemic toxicity
This pertains to affecting the body as whole, rather than a specific organ or system.

Target organ effects
Chemical induced adverse effects on specific organs or systems of the body. For example, toluene causes adverse effects on the liver, i.e. it is hepatotoxic.

Teratogen
A chemical agent which causes adverse effects in the normal embryonic development without causing lethality or maternal toxicity. Thalidamide is a well known example.

Toxicity
The capacity to cause injury to a living organism as a result of exposure.

Toxicology
The study of adverse health effects of chemical on living organisms.