SOLUTIONS project output simulating the impact of chemical mixtures on a potentially affected fraction of species (msPAF) and highlighting regions where there could be significant chemical pollution pressure on freshwater species

Figure Created 22 Nov 2022 Last modified 22 Nov 2022
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This map shows a mixture toxicity metric called multi-substance Potentially Affected Fraction of species (msPAF). For individual substances, the Potentially Affected Fraction of species (PAF) is derived from the results from laboratory toxicity tests, as the fraction of the tested species that would show effects if a laboratory test would be performed with a given concentration of the chemical. To this end, the results from laboratory tests have been converted beforehand into a species sensitivity distribution (SSD). The individual PAFs are then combined into an msPAF using the dose-addition principle. For this map, toxicity tests have been used that seek to quantify the no-observed-effect concentration (NOEC). The use of this endpoint links the result to the regulatory concept of “sufficient protection” of aquatic ecosystems. The above has been applied to the simulated concentrations of 1,785 chemicals on 365 consecutive days, and the 95 percentile of the results per site have been mapped.

European data


Additional information

The method to simulate chemicals concentrations is discussed by van Gils et al., 2020 ( The method to calculate the msPAF is discussed by Posthuma et al., 2019 (


Geographic coverage

Temporal coverage


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Filed under: chemicals, freshwater
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