Risk assessment

The aim of risk assessment is to determine the risk (here: the likelihood of damage to health) that accompanies specific hazardous substances or activities as quantitatively as possible. To give an example, risk assessment facilitates the determination of the risk of cancer further to exposure to chemicals in the workplace. The risk assessment process can be divided into four steps:

1. Risk/hazard identification
Use of laboratory, animal or epidemiological tests or case studies to identify the human health issues that can be caused by exposure to a specific substance.

2. Estimation of exposure
As precise data as possible is gathered on the extent to which a person or section of the population is exposed to a specific substance. Data is ideally to include precise indications of the duration, cumulative and average extent of exposure and exposure peaks.

3. Exposure-response relationships
Quantitative relationships between exposure and response can be identified on the basis of animal and epidemiological studies which deliver information on the levels of exposure at which specific effects on health are detected or do not occur. There is a fundamental difference to be made between substances for which a threshold value can be determined (i.e. a level of exposure beneath which no effects (e.g. irritation or liver damage) occur) and substances which even have an adverse effect on health at low levels of concentration. The latter group includes many carcinogenic substances.

4. Risk characterization
Following on from the first three steps, the risk assessment process concludes with an attempt to determine the level of likelihood of a person or section of the population exhibiting a specific health-related effect further to a defined level of exposure. It is to be noted that the level of likelihood calculated is also subject to the uncertainties of the first three steps, and in the case of carcinogenic substances in particular can rarely be determined on a definitive basis. In instances where it is possible to define threshold values, the risk linked to exposure beneath those values is essentially to be rated as zero.

Further information:
Detailed information on this topic is available from the websites of national-level authorities and institutes which carry out risk assessments and disseminate the results thereof.

• www.epa.gov/risk
• www.hse.gov.uk/risk