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WATER CONTAMINATION BY MEDICINAL RESIDUES

Antibiotics, antidepressants, beta blockers and oral contraceptives are all medicines that are subsequently found in natural surface and groundwater, as well as in treated water intended for human consumption.Their presence has been proven, however little is known about the effects and risks.

In the framework of the National health and environment plan 2004-2008, exploratory efforts were made to measure the contamination of surface and groundwater by 76 pharmaceutical compounds, including 23 veterinary products, 42 for humans and 11 metabolites. Water samples were drawn from 141 sites in three pilot river basins, Seine-Normandie, Rhône-Alpes and Adour-Garonne, and analysed.

The results showed that at least one compound was present in surface water on all sites. Almost 40% of all groundwater, however, was completely devoid of the substances. Two of the most commonly detected products were Carbamazepine and Iopromide. The first is an anticonvulsant and the second is a radiopaque contrast enhancer.

Substance concentrations in surface and groundwater are generally about 10 nanogrammes per litre (ng/l). Some sites, e.g. the effluents of water-treatment plants, showed higher levels of contamination. Certain products, such as Diclofenac, an anti-inflammatory, and Pronanolol, a beta blocker, reached concentrations of approximately one microgramme per litre (μg/l), i.e. 100 to 1 000 times higher. One microgramme per litre is a threshold above which chronic ecotoxicological effects (disturbances to reproduction, growth, etc.) are observed.

In terms of environmental-risk management, highly contaminated sites reveal that hospital waste is the main culprit because it has the highest levels of active medicinal residues. Experiments have revealed that these effluents are genotoxic, i.e. they can cause modifications in genomes by altering DNA molecules. They are thus likely to provoke genetic mutations. This characteristic is due to their composition, notably in anti-cancer products.

Groups of medicines requiring priority monitoring

Certain groups of pharmaceutical compounds, e.g. anticonvulsants and anti-inflammatories, are regularly present in water samples and even in water treated for human consumption. It is these compounds that most interest researchers.

In addition, hormonal compounds, which are among the medicinal residues detected systematically in surface water, were subjected to specific studies concerning the Seine, Marne and Oise rivers. At the observed concentrations, these compounds can cause endocrine disruptions resulting in alterations to growth, organ development or reproduction. Fortunately, the hormonal compounds are rarely detected in ground water or treated water, which should limit any direct effects on human health.

Antibiotics are also a group presenting risks. They are present in all aquatic compartments (surface and groundwater) and have accumulated in sediment. Researchers suspect that continuous environmental exposure to these residues has facilitated the development of antibiotic-resistant bacterial strains that may infect animals, including humans, thus constituting a theoretical risk for health. Though a direct link between the emergence of antibiotic resistance and the presence of antibiotic residues in aquatic environments has not yet been established, the precautionary principle is already applied. For example, preventive use of these medicines in aquaculture has been halted and certain types, e.g. quinolones, that are used therapeutically for human health, are no longer employed for livestock.

Necessary research and action programmes

The effects of water contamination due to medicinal residues are not well known. The interactions between medicinal products and other pollutants have not been fully studied. Similarly, very little data is available on their impregnation in aquatic organisms or on their nocivity over the long term and at low concentrations.

In 2008, efforts were launched by Ineris and Cemagref to provide information on emerging contaminants in European waters (Norman network) and in treated and wastewater in France. An inventory of labs specialised in detecting and analysing such substances is also underway. The medicinal substances requiring priority monitoring will be identified in 2009. In addition, innovative in vitro biological techniques must be developed to monitor emerging contaminants in rivers.

In 2009, Cemagref drew up an inventory of wastewater-treatment processes designed to eliminate medicinal residues. The inventory was carried out in conjunction with the AMPERES programme (Analysis of priority and emerging micropollutants in raw and treated water output by wastewater-treatment plants).

A working seminar on "Medicinal residues in aquatic environments - Needs and tools for monitoring and risk evaluation" was organised by Onema on 25 and 26 May 2009, after which recommendations for the national plan for medical residues in water were issued.

For more information, contact:
pierre-francois.staub@onema.fr