ABSTRACT
The occupational exposure limit (OEL) has been the cornerstone of occupational hygiene risk assessment and risk management, and forms an important component in the control of occupational disease and the setting of policies on occupational health. The OEL has its basis in the toxicological concepts of a threshold of effect for exposure to chemicals and a relationship between dose and response. Substances presumed to have carcinogenic potential for humans are those for which there is sufficient evidence to establish a causal relationship between human exposure and the development of cancer. Exposure standards are concentrations in air which can be expressed as a mass per unit volume, such as milligrams of substance per cubic metre of air or parts per million. Synergism and potentiation occur when exposure to two or more contaminants results in an adverse reaction more severe than would be expected from the sum of the individual exposures.
