Risk assessment provides an objective, technical evaluation of the likelihood of unacceptable
impacts to human health and the environment. The purpose is to assess the need for protective measures,
since a specific risk assessment is a precondition for any such protective measures.
Risk assessment can be regarded as a pre-decision, decision support method. Its position in the process
can be summarised as follows:
1. Observation of pollution (risk identification)
2. Site Investigation (risk assessment)
3. Engineering intervention (risk mitigation), if necessary
Likewise the practices of other countries, Hungarian risk assessment method has a gradual structure
because of cost-effectiveness and feasibility. In case of gradual (progressive and iterative)
risk assessment the chosen strategy depends on the degree of knowledge, application requirements,
and the complexity of the problem.
The structure of the Hungarian risk assessment method is:
1. Comparative or qualitative risk assessment: which, in case of more contaminated areas
- gives information about the priorities by using relative scores (description and evaluation of
each contaminated area, pollution increasing and reducing factors).
2. Quantitative, general risk assessment: made for standardised exposure conditions
following the principle of ‘fit for use’ (i.e. corresponding to the existing or planned land use)
and ignores several specific local features of the environment.
3. If necessary, quantitative, area-specific risk assessment: concrete local exposure
and pollutant movement data have to be used for the determination of an area specific Remediation
limit value of pollution. Calculations should consider the source of pollution – transport route
– exposure gate – receptor relations.
During risk assessments, points of adequacy should be used to avoid the determinative role of a
large distance between the source of pollution and the receptors. At the selection of the points of
adequacy the criteria is:
- pollution should not spread from one contaminated agent over another element of the environment,
- the spreading of contamination must be limited (pollution of uncontaminated agents is not allowed).
The state of pollution has to be identified to gain important consequences from the pollution’s
movement dynamics. In case of a stable/diminishing source of pollution regular monitoring can be
sufficient, while for a spreading/growing source engineering intervention is needed. When the
contamination is growing or probably growing, or when the calculated risk is higher for the receptor
than tolerable, a “remediation limit value of pollution” (D) has to be defined for the source, which
stops its future growth and protects the receptor.
Risk assessment starts with the setting up of a so-called risk model. During the preliminary stage,
the possible elements of risk (source of pollution, potential spreading and exposure pathways,
potential receptors) are being determined. The consecutive stages of risk assessment should exclude
all irrelevant or insignificant risk factors. The risk model always has to contain all types of risk
elements. Accurate establishment and iterative improvement of the theoretical risk model is the
basis of risk-based interventions.
Three basic pollution cases can be distinguished, when discussing the effect on human and ecological,
and real or potential receptors:
- only the geological medium is polluted;
- only the groundwater is polluted;
- both the geological medium and the groundwater are polluted.
When the human health is assessed, based on exposition, land use and the characteristic of the receptor,
the dose (ÁND) of one unit weight and time has to be determined of the forecasted environmental concentration
(PEC). Its result has to be compared to the toxicological reference value and the determined ecotoxicological
concentration (PNEC) harmless to human health.
Following any engineering intervention and remediation, a new survey is required to check whether
the concentration of all potential pollutants are lower than the limit value of pollution. If so,
there is no need for any further actions (risk assessment, monitoring, intervention).
Source (in Hungarian):