Risk Assessment

Evaluating Risks

In general, risk assessment is a process designed to evaluate the potential relationship that may exist between exposure to particular agents and the particular effects.

Steps in A Risk Assessment

Risk assessment is a process that comprises four basic steps:

  • Hazard Identification
  • Exposure Assessment
  • Dose Response Assessment
  • Risk Characterization

Hazard Identification

Important aspects of hazard identification include:

  • A complete description of the pollutant/irritant and its potential to affect human health adversely at some level of exposure.
  • An understanding of the number of people who are potentially exposed.
  • The background levels of exposure in the environment.
  • The nature of the health effect of interest.
  • The level of exposure thought to be associated with an increased risk of the health effect.
  • Other exposures that potentially contribute to the development of the health outcome should also be highlighted.

Exposure Assessment

The exposure assessment is the measurement of exposure to the pollutant/irritant, which will require air sampling, collection of samples and analysis of the different components.  It is essential that other factors which may influence the exposure are understood and clearly identified.

Dose-Response Assessment

The information gathered in the steps outlined above is used to estimate the dose from the exposure, and to model the dose-response relationship. Effort is focused on identification of a threshold exposure below which no health effects are observed/reported, this threshold is now known as the No Observed Adverse Effect Level (NOAEL).  Once the NOAEL has been determined, uncertainty factor are applied to reduce the level still further to take consideration of variabilities in responses among the population.  Thus, the NOAEL becomes the Lowest Observed Adverse Effect Level (LOAEL).  Further uncertainty factors may be applied to reduce the NOAEL because of uncertainty in the collected data.

Risk Characterization

The relationship between exposure and response is used to characterize the risks within a population.

Author - Armitage; copyright 2007


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