Évaluation et gestion des risques en production d'eau potable. application au cas des médicaments et perturbateurs endocriniens
Risk assessment and risk management in driking water production. application to the case of pharmaceuticals and endocrine disrupters
SUEZ ENVIRONNEMENT, CIRSEE - 38 rue du Président Wilson, 78230 Le Pecq, France
Les médicaments et substances à effet perturbateur endocrinien ne font l'objet d'aucune réglementation spécifique dans l'eau potable, en Europe. La question de l'introduction dans la réglementation de valeurs paramétriques, pour les perturbateurs endocriniens, a été débattue à l'occasion du séminaire organisé par la Commission Européenne pour la révision de la directive 98/83/CE, en octobre 2003. A l'issue de ces débats, il a été considéré que l'introduction de valeurs paramétriques pour ces substances n'était pas recommandée, et qu'une approche par évaluation et gestion des risques, basée sur les principes HACCP (Hazard Analysis and Critical Control Points), telle que proposée par l'Organisation Mondiale de la Santé, était plus appropriée pour maîtriser les risques liés à ces composés. Les connaissances disponibles aujourd'hui sur les voies de diffusion de ces composés dans le cycle de l'eau, et sur les performances d'abattement des étapes de production d'eau potable, permettent en effet de mettre en oeuvre une telle approche.
Pharmaceuticals and endocrine disrupting chemicals (EDCs) are not specifically considered in the European drinking water regulations. The introduction of parametric values for EDCs was discussed at the seminar organized in October 2003 by the European Commission for the revision of the drinking water directive 98/83/EC. The conclusion of this discussion was that setting limit values for individual EDCs was not recommended, and that a risk assessment and risk management approach, based on the HACCP principles (Hazard Analysis and Critical Control Points), as proposed by the World Health Organization, was more appropriate to control the risk related to these compounds. The available knowledge on the diffusion pathways of these substances in the water cycle, and on the performance of the treatment steps applied for drinking water production, allow today to apply such an approach. One of the most important steps of a HACCP plan is hazard analysis, which includes hazard identification, hazard prioritisation, and identification of control measures. Prioritisation is a difficult, but necessary task in the case of pharmaceuticals and endocrine disrupters, because of the great number of compounds to consider (more than 550 potential or confirmed endocrine disrupting chemicals, more than 4000 pharmaceutical active substances). Criteria for prioritisation have been proposed. They consist of volumes commercialised and persistence in the environment, for pharmaceuticals, potential endocrine activity and occurrence already observed in the environment, for endocrine disrupters. Based on this prioritisation, lists of relevant compounds for the water cycle have been established. They include: - for pharmaceuticals, tranquillisers, analgesics and anti-inflammatory drugs, antibiotics, lipid regulators, anti-epileptics, iodised contrast
media. - for endocrine disrupters, natural (estradiol) and synthetic (ethinyl estradiol) hormones, pesticides, alkyl phenols, bisphenol A, phthalates, thbutyl tin. Knowing the use of these substances, their diffusion pathways in the water cycle can be established. Most of these pathways lead from waste waters to natural surface waters, and subsequently to ground waters. This is confirmed by the concentration gradient generally observed between these reservoirs. With the published data on generally observed concentrations in these media, and on the basis of descriptive information on the presence of potential pollution sources in the catchment area, it is possible to estimate the potential level of contamination of a raw water used for drinking water production. Data on the efficiency of the treatment steps applied for drinking water production have been published. Such information allows to estimate whether a treatment chain is appropriate in order to minimize the risk for the consumer. The most efficient treatment step for the removal of pharmaceuticals and endocrine disrupters is filtration on activated carbon. Such treatment is generally in place in production units using surface waters. Bank filtration, ozonation, disinfection with chlorine or chlorine dioxide are also efficient on antibiotics and estrogens. The studies conducted in Europe to detect pharmaceuticals and endocrine disrupters in distributed waters show that drinking water does not represent a significant way of exposure of the consumer to these compounds. However, the lack of information on the long term effects of multiexposure to low doses of contaminants should incite to take into account these pollutants in a HACCP plan. Solutions allowing to control pollution at the source should be favoured.
© ASEES 2005