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Exposure assessment


The exposure assessment consists of estimating the dose (or concentration) of the substance to which humans and the environment may be exposed. It concerns all the life-cycle of the substance, from the manufacture to the different identified uses. It entails two clear steps:

  1. Generation of exposure scenario(s) (ES) or of relevant use and exposure categories.
  2. Exposure estimation.

For substances placed on the market, the relevant exposure scenario(s) and a summary of the exposure estimation shall be included in an annex to the safety data sheet (SDS). There is a standard format for the exposure scenario(s) annexed to the SDS.

Development of exposure scenarios

Exposure scenarios describe how the substance is manufactured or used and how to control exposures of humans and the environment. It includes both the operational conditions and risk management measures implemented by the manufacturer, the importer or the downstream users. These later are the main recipients of ES and must check the compliance of their requirements with the described conditions of use.

The required level of detail for an ES may substantially vary from case to case, depending on the use of a substance, its hazardous properties and the amount of available information.

Exposure scenarios may describe the appropriate risk management measures for several individual processes or uses of a substance. In this case, they may be referred to as “Exposure Categories”.

As the chemical safety assessment (CSA) process may be iterative, a first exposure scenario is developed thanks to initial assumptions about the operating conditions and risk management measures. The first assessment is based on available hazard information and on the exposure estimation corresponding to the initial scenario. If the initial risk characterisation indicates that risks are not adequately controlled, the assessment must be refined by iteration. Additional hazard information, an alteration of the operational conditions or of risk management measures or a more precise exposure estimation may be necessary to reach an adequate risk control. The scenario obtained after the last iteration, namely the “final exposure scenario”, shall be included in the chemical safety report (CSR).

Exposure estimation

The exposure estimation, carried out for each developed scenario and described in the CSR, entails the three following elements:

  1. Emission estimation
    The emissions during all the life-cycle of the substance as such and as part of articles shall be considered, including those due to the waste stage. This estimation shall be performed under the assumption that the risk management measures and operational conditions described in the exposure scenario have been implemented.
  2. Assessment of chemical fate and pathways
    Possible degradation, transformation or reaction processes shall be characterized. Besides, environmental fate and distribution shall be estimated.
  3. Estimation of exposure levels
    Exposure levels shall be estimated for all human populations (workers, consumers and humans indirectly exposed via the environment) and environmental spheres liable to exposure. Each exposure route shall be addressed (inhalation, oral, dermal and combined). Such estimations shall take account of spatial and temporal variations in the exposure pattern.

If measured exposure data are available and representative, they shall be specially considered. But appropriate models or relevant monitoring data from analogous substances may also help to the exposure assessment.



Prévention du risque chimique, France, 2007, 2011
This document is provided for information only and under no circumstances constitutes legal advice. The only authentic legal reference is the text of the REACH regulation (Regulation (EC) n° 1907/2006).