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Monitoring of medical residues in aquatic environments and evaluation of the risks for the environment and human health were the topics of the seminar organised by Onema on 25 and 26 May in Paris.Some 80 health and environmental experts shared their knowledge.The goal was to launch a coordinated action programme to improve our knowledge and contribute to preparing the future national plan for medical residues in water.

Over two days, researchers, water policy-makers, experts from the health and environmental agencies and from the medical and water-treatment industries met in Paris to draw up a status report and determine needs in terms of monitoring and evaluation of the risks linked to the presence of medical residues in aquatic environments.

Analysis of some 30 studies carried out in France over the past 10 years in the framework of the national health and environment plan has confirmed the presence of traces (nanogrammes per litre) of medical residues, e.g. hormones, antibiotics, anti-inflammatory and anti-cancer drugs, etc., in most natural aquatic compartments, primarily in surface waters, but also in groundwater.

The origin of the contamination is mainly domestic wastewater, unfortunately wastewater-treatment plants rarely represent an effective barrier, capable of eliminating the residues. Small hydrosystems are potentially vulnerable due to the weak dilution of the pollution and the less advanced wastewater-treatment systems used.

It is however difficult to provide a firm diagnosis because the data is limited and cannot always be extrapolated, e.g. 25% of the studies concern only 10 molecules and there is little data on the presence of degraded pharmaceutical compounds or veterinary products. Are these products, present at low concentration levels, toxic for aquatic ecosystems? The experts are unsure. Certain effects have been proven in the lab, but the results must be validated in the field. Unfortunately, the methods and tools to evaluate the toxicity in situ do not exist. The experts would particularly like to have tests on the chronic effects of low concentrations of mixes of substances.

Over the two days, Onema collected the proposals made on how to improve our knowledge. Recommendations were drafted at the end of the seminar and presented to the National scientific council for water and aquatic environments. With its partners, Onema will soon present a key document intended to contribute to the preparation of the Knowledge section in the future national plan for medical residues in water. It will promote a multi-disciplinary programme to monitor residues in aquatic environments, including both short-term operational goals and R&D efforts required to improve risk evaluation.

Contact: pierre-franç

For more information, see (in french)

Recommendations made during the seminar
  • Improve knowledge on substances in water
    - Define and upgrade criteria on determining priority substances for monitoring
    - Select a representative sample of study sites
    - Optimise and intercalibrate analysis techniques
    - Launch targeted analysis campaigns to enhance existing knowledge
    - Study and control contamination of water resources used for drinking water
    - Examine transfer of innovative techniques for substance monitoring and analysis
  • Needed research
    - Enhance simulation tools for the transfer of medical residues
    - Develop suitable tests on chronic effects (low concentrations of substance mixes, bioaccumulation, potentialisation of effects)
    - Develop biological indicators to diagnose residue presence in the environment and assess effects
    - Set toxicological thresholds
    - Develop bioanalytical tools
    - Study the possible relation between antibiotic residues and emergence of antibiotic resistance