École pratique des hautes études,Institut national de la santé et de la recherche médicale (Inserm), ERI n°11, Vandœuvre-les-Nancy
Human and industrial activities lead to the release of numerous chemical compounds into aquatic ecosystems. Until recently, regulation and monitoring of water quality concerned mainly compounds used by industry or by agriculture. New issues are currently emerging, notably the ever increasing presence of drug residues in surface water likely to be used as human drinking water. The specific character of these compounds, which are approved for sale only after rigorous selection retaining those drugs with the most biological activity, makes them particularly worrisome, although they are found in aquatic environments in very low concentrations. Progress in analytic chemistry has demonstrated clearly that drug residues are present in some resources intended to furnish drinking water for household distribution. Despite the low concentrations currently detected, worry about their societal impact and possible health consequences is legitimate. Work is needed to improve the characterization of the hazards and exposures associated with these agents, by specifying in particular, their emission levels, their capacity for transformation during water treatment, and their environmental impact. Although the exposure margins seem adequate to protect consumers, health risk assessment for these residues is a difficult exercise that relies on indirect approaches involving specific limitations. We must improve our knowledge of the consequences of exposure to very low doses by redefining as necessary the target effect initially chosen for standard experiments; we must also learn more about other exposure routes to establish the relative roles of different sources. Finally we must extend our research of interactions with other compounds in aquatic environments. The multiplication of analytic measurements cannot alone resolve this problem, some aspects of which can be approached only via biological tools that are still too rarely used.