Freshwater environment

Exposure assessment tool

While analytical data derived from environmental monitoring programs are perceived as being highly credible, they can only be obtained if a chemical substance has already been released to the environment1. However, to follow the concept of the precautionary principle, environmental fate modelling is the method of choice to predict the concentration of chemical substances (e.g. a surfactant) before they are placed on the market.

Fate models estimate the Predicted Environmental Concentration [PEC] of a surfactant based on various kinds of information. This includes the amount of the chemical substance under consideration as well as their physico-chemical properties and the release pattern. In addition, the various processes which determine the environmental fate (biodegradation, phase transfer processes as adsorption, etc.) need to be considered as well.

Based on such information, a concentration close to a point source PEClocal (e.g. the discharge of a wastewater treatment plant ) as well as the regional background concentration (PECregional) can be estimated. In addition to generic estimation, geo-referenced fate models make predictions based on realistic environmental data including the hydrological data of the receiving surface waters. Since the input parameters can be easily changed, these models can make predictions by taking the spatial and temporal variance into account. Therefore, they can serve as a tool for the planning and steering of environmental monitoring programs based on analytical measurement in relevant environmental compartments2.


Monitoring and Modelling of Industrial Organic Chemicals, with Particular Reference to Aquatic Risk Assessment, ECETOC Technical Report No. 76, ECETOC, 1999
Technical Guidance Document on Risk Assessment, Part II, European Chemical Bureau, 2003