Health risk assessment
(Mission "A320" according to standard NFX 31-620-2 of December 2021)
Health Risk Assessment (HRA) or Analysis of Health Issues (AES) formerly known as EQRS, EDR and ESR, is an essential step in characterizing the health risk incurred by current or future users of a site in relation to a source of pollution identified in one or more media (soil, groundwater, soil air, ambient air, etc.).Historical and regulatory context
The concept of risk assessment was introduced in 1983 by the US National Academy of Sciences (the National Research Council - NRC). In response to the growing deterioration in the environmental situation, French regulations concerning polluted sites and soils were introduced in the 1990s, and have continued to evolve ever since.
On April 3, 1996, a circular introduced the first methodological tools, including the Simplified Risk Assessment (ESR). The simplified risk assessment is a method for classifying sites into three distinct categories (sites that can be treated as commonplace, sites to be monitored, sites requiring in-depth investigation).
On December 10, 1999, a circular introduced the Detailed Risk Assessment (DRA), enabling risks to be identified and rehabilitation objectives to be defined that are compatible with the site's uses.
In February 2007, a national methodology for polluted sites and soils was published, setting out new approaches to the management and redevelopment of polluted sites and soils. The new tools proposed include :
- Quantitative Health Risk Assessment (QHRA), which is an update of the detailed risk assessment;
- Residual Risk Analysis (RRA);
- Management Plan (MP);
- Interpretation of the State of the Environment (IEM).
In April 2017, the national methodology for polluted sites and soils was updated, notably taking into account existing regulatory or management values, and introducing situation analysis values. In this context, the Quantitative Health Risk Assessment (QHRA) is renamed Health Risk Assessment (HRA) or Health Stakes Analysis (HSA).
Principle of Health Risk Assessment (HRA) or Health Issues Analysis (HIA)
The main objectives of a health risk assessment are to :
- Quantify the risks to human health generated by pollution present on the study site in relation to its current or future use;
- Assess whether these risks are compatible with the current or planned use of the study site.
A health risk assessment is a structured analysis method and a decision-making tool for assessing the need, when quantified health risk levels are unacceptable, to plan a remediation strategy for the study site (e.g., by drawing up a management plan) or to implement corrective actions to limit or even eliminate the risks incurred by current or future site users. The purpose of the health risk assessment is to present explicit information on which to base risk management decisions for the site under study.
Prerequisites for drawing up a Health Risk Assessment (HRA) or Health Issues Analysis (HIA)
When harmful substances are detected during field investigations, notably as part of a pollution diagnosis, the concentrations measured for certain environments and substances can be directly compared with regulatory or management values, enabling a direct decision to be taken on their health compatibility with the use in question. In the absence of management or regulatory values, only the preparation of a health risk assessment can determine in a transparent manner whether or not the substances detected are likely to induce an excess health risk.
The prerequisites for the preparation of a health risk assessment are :
- Field investigations (missions A200 to A260) providing input data on one or more media (soil, water, soil air, etc.) and in particular the pollution source(s) to be studied;
- A good knowledge of the use under consideration, in order to determine the various scenarios and exposure routes, and to have sufficiently precise input parameters to minimize bias in the interpretation of the results.
Steps in the Health Risk Assessment (HRA) or Health Issues Analysis (HIA) process
The health risk assessment method comprises four stages:
1. Identifying the hazard potential of sources
This stage consists of drawing up a list of substances detected in the environment(s) under investigation, and identifying the types of effects associated with these substances. This step enables us to select the substances likely to cause a harmful effect in humans, which will then be included in the health risk assessment.
2. Assessment of the dose-response relationship
This stage consists of determining the various exposure scenarios and selecting the Toxicological Reference Values (TRVs) associated with each substance selected.
3. Exposure assessment
This stage involves estimating the Daily Exposure Dose (DDE) or the Inhaled Concentration (IC) for each exposure route and for each substance selected. Where concentrations are not measured in the exposure medium, an exposure calculation model is used to estimate concentrations at the point of exposure.
4. Risk characterization
This stage involves quantifying the risk on the basis of Daily Exposure Doses (DDE), Inhaled Concentrations (IC) and Toxicological Reference Values (TRV). This enables us to conclude whether or not a health risk exists.
If risk levels are unacceptable, the site must be remediated, or simple corrective measures can be implemented to offset the excess health risk. In the case of site remediation, a Management Plan (MP) is required to determine the best possible solutions for treating the source of pollution. Once the Management Plan has been drawn up, a Residual Risk Analysis (RRA) is required to verify that the residual concentration left in place after site remediation is compatible in terms of health.
