Proposals for Quality Criteria for Surface Waters

Chemical risk assessments are carried out by comparing environmental concentrations with the associated quality standards. If the environmental concentration exceeds the quality standard, a risk for aquatic organisms can be assumed. A comparison of the environmental concentration and the acute quality standard may be helpful for assessing the likelihood of possible damage to the organisms within the next 24 to 96 hours. Chronic quality standards are recommended for water quality monitoring. They can be used for assessing pollution over an extended time period. For the continuous input of micropollutants from treated effluents, the chronic quality standard is particularly relevant and helps to protect the organisms against the consequences of long-term pollution. The Ecotox Centre has derived quality criteria for numerous substances.

Furthermore, the Ecotox Centre provides quality criteria for additional substances that have either been determined by other organisations or for which no complete data research has been carried out. These values should primarily be used to verify the environmental relevance of substances measured in surface water monitoring campaigns. Some of the values are environmental quality standards for priority substances under the EU Water Framework Directive, national environmental quality standards or national quality criteria proposals. The environmental quality criteria of the EU and its member states were determined using the same method as the quality criteria proposals of the Ecotox Centre and are therefore just as reliable. The other part are ad hoc quality criteria. These values are based exclusively on the registration data and not on a complete data research. The complete list of all current quality criteria can be downloaded as an Excel file with additional information.

In April 2020, the quality criteria proposals of the Ecotox Centre for 19 pesticides and 3 pharmaceuticals were included in the Water Protection Ordinance as numerical requirements (these substances are marked in the table with an *). The complete list of the current values can also be downloaded as Excel file including additional information on the assessment of mixture toxicity. The derivation of the values can be followed using the data sheets linked in the table. Data sheets that are not linked can be obtained from the Ecotox Centre on request.

If you would like to be informed about changes or new values, please register for regular info mails at anke.schaefer@oekotoxzentrum.ch.

¹I: industrial chemical, P: pesticide, P (T): transformation product of pesticide, Ph: pharmaceutical or steroid hormone, Ph (T): transformation product of pharmaceutical 

^*The values for this substance have been included in the Water Protection Ordinance as numerical requirements 

^**In surface waters that are used for the production of drinking water, a limit value of 0.1 μg/L is set to protect the drinking water quality.

^aSubstances for which there may be a secondary intoxication risk that has not been numerically considered to date.

^bFor some substances, the chronical (CQC) and the acute quality criteria (AQC) are identical. This may happen if the acute and the chronic toxicity are very similar. Then, if a larger assessment factor is used for the calculation of the CQC than for the calculation of the AQC (100 instead of 10), the AQC would be lower than the CQC. In this case, the technical guidance document for deriving EQS specifies to raise the AQC to the CQC.

^cThis value is not based on direct (chronic) toxicity, but is intended to protect organisms of higher trophic levels against secondary poisoning. The chronic quality standard refers to the concentration in the water phase, while the biota EQS refers to the concentration in the whole fish.