What is a
Why is it important?
What is risk management?
of risk assessment
What are RA tiers?
Risk assessment is one method in a much broader field of risk management. Risk
assessment is a process that does not result in a fixed final answer. It is
impossible to determine the true magnitude and extent of any actual
contamination at a site.
Research on the effects of chemicals on microbes, plants, animals and humans
is patchy at best and confounded by factors such as:
- Variations in individual and species tolerances to the effects of
- Environmental conditions and processes affecting the properties of the
contaminant such as partitioning, transformation, degradation, temperature,
pH, organic material, etc;
- Uncertainty in extrapolating study data between species (e.g. using the
outcome of animal testing to predict the effect on people) and within
species (e.g. using the effects on a specific group of workers such as
miners to predict the effect on other groups of people such as children);
- Large information gaps about the effects of contaminant mixtures that
might have synergistic, magnifying or other effects.
- Large information gaps about the specific mechanisms and processes
affecting functions and organs within the body, how these interact, and how
they might be affected by a contaminant.
Our understanding of the interactions between affected individual people,
plants and animals within a population, populations within a community, and
communities within habitats and ecosystems is extremely limited.
As a result, generally the best you can hope for is to determine some basic
information about the risks posed by the site. These include:
- Whether there are contaminants present at a site and which contaminants
are present (although determining all the compounds potentially present
where more than one chemical has been released is unlikely to be
- Whether these contaminants are likely to have been contained on-site or
might be moving off-site;
- What media the contamination has affected including water, soil, air or
- Whether these contaminants might possibly be having an effect on microbes,
plants, animals or humans; and
- What type of effect that might be.
However, by making informed, careful, and well-documented decisions through a
systematic evaluation process, your ability to gauge the relative impact of a
contaminant on receptors can be greatly enhanced, and the possibility of
underestimating or overlooking adverse effects can be reduced.