Potential impact of pharmaceuticals on environmental health. (2003)

For much of the last thirty years, research on the effects of chemical pollution of the environment has focused almost exclusively on conventional priority pollutants. These pollutants are chemicals that have specific effects on organisms, such as the impacts that organotin compounds (used in antifouling paints on ships) are known to have on marine life. There is, however, another highly variable group of chemical compounds that have the potential to cause harm but which receive relatively little attention as possible environmental pollutants. These are pharmaceuticals, including both human and veterinary drugs, and even illicit (recreational) drugs. Presence of pharmaceuticals in aquatic systems Around the world, thousands of tons of pharmacologically active substances are used annually but surprisingly little is known about the ultimate fate of most drugs after their intended use. A large proportion of an administered dose (up to 90%) may be excreted, unchanged, while metabolites can be converted back to the active compound via bacterial action (Jones OAH, Voulvoulis N, Lester JN. Human pharmaceuticals in the aquatic environment: a review. Environmental Technology 2001;22:1383-94). In addition, the general public often disposes of unused medicines through the sewage system. From published occurrence data it seems likely that a large proportion of urban sewage is contaminated with drug compounds, differing only in the type and abundance of the substances present. Recent studies have demonstrated that many pharmaceuticals are incompletely eliminated at sewage treatment plants. The existence of drugs in surface waters, groundwater and even marine systems has been confirmed at concentrations of high ng/litre to low [mu]g/litre, rivalling the levels of some pesticides (Daughton CG, Ternes TA. Pharmaceuticals and personal care products in the environment: agents of subtle change? Environmental Health Perspectives 1999;107:907-42). Drug compounds disposed of in domestic refuse can end up in landfills, where they also pose a threat to surface and underlying groundwater. Furthermore, by contrast with more regulated pollutants-which often have longer environmental half lives--the continual introduction of drugs by sewage effluent may make them pseudopersistent, with unknown consequences for aquatic organisms that may be subjected to continuous exposure. The possible effects of the presence of drugs in aquatic systems are unknown and, consequently, in recent years they have been attracting increasing attention as potential pollutants. The fact that any commercially produced chemical may find its way into the environment is not surprising in itself; the interesting point about pharmaceutical pollution is that it does not result primarily from manufacturing but rather from widespread and continual use, excretion, and improper disposal of both human and veterinary medicines. Pharmaceuticals are potentially ubiquitous pollutants because they could be found in any environment inhabited by man. As yet, there is little evidence that pharmaceuticals are present in the environment in sufficient quantity to cause significant harm, though their use is expected to grow with the completion of the human genome project and the rising age of the population. Pharmaceuticals and their metabolites are more and more likely to be found in the receiving waters of areas adjacent to human activity and therefore further research in this area is warranted. Determining the extent of the problem With recent advances in analytical techniques (such as gas and liquid chromatography and mass spectrometry) detailed investigation has become possible (Ternes TA. Analytical methods for the determination of pharmaceuticals in aqueous environmental samples. Trends in Analytical Chemistry 2001;20:419-34). The data collected in studies to date, however, rarely provide information on the various processes that determine the fate of these compounds in the system under investigation; although drug substances receive considerable pharmacological and clinical testing during development, there is a severe paucity of data on the ecotoxicity of the majority of them. …