O. A. H. Jones

Aquatic environmental assessment of the top 25 English prescription pharmaceuticals

An environmental assessment is presented for the 25 most used pharmaceuticals in the National Health Service (NHS) in England in 2000. Predicted environmental concentrations (PECs) for the aquatic environment were calculated using conservative assumptions and all PECs exceeded 1 ng 1 (-1). The calculation of predicted no-effect concentration (PNEC) based on aquatic toxicity data from the literature was possible for eleven of the pharmaceuticals. PNECs were predicted with ECOSAR for 12 of the remaining 14 but no data was available for two of the compounds. The PEC/ PNEC ratio exceeded one for Paracetamol, Amoxycillin, Oxytetracycline and Mefenamic acid. Comparisons of the predicted concentrations of the compounds in sewage sludge based on either calculated sludge-water coefficients (Kd), octanol water coefficients (K(ow)), acid base constants (pKa) or environmental modelling revealed large variations. No toxicity data was available for the terrestrial environment and no assessment was made.

Human Pharmaceuticals in the Aquatic Environment a Review

There has been increasing concern in recent years about the occurrence, fate and toxicity of pharmaceutical products in the aquatic environment. Many of the more commonly used drug groups (for example antibiotics) are used in quantities similar to those of pesticides and other organic micropollutants, but they are not required to undergo the same level of testing for possible environmental effects. The full extent and consequences of the presence of these compounds in the environment are therefore largely unknown and the issue as a whole is ill-defined. Although these compounds have been detected in a wide variety of environmental samples including sewage effluent, surface waters, groundwater and drinking water, their concentrations generally range from the low ppt to ppb levels. It is therefore often thought to be unlikely that pharmaceuticals will have a detrimental effect on the environment. However, the lack of validated analytical methods, limited monitoring data and the lack of information about the fate and toxicity of these compounds and/or their metabolites in the aquatic environment makes accurate risk assessments difficult.

Human Pharmaceuticals in Wastewater Treatment Processes

The presence of human pharmaceutical compounds in surface waters is an emerging issue in environmental science. In this study the occurrence and behavior of human pharmaceuticals in a variety of wastewater treatment processes is reviewed. Although some groups are not affected by sewage treatment processes others are amenable to degradation, albeit incomplete. While water purification techniques such as granular activated carbon could potentially remove these pollutants from wastewater streams, the high cost involved suggests that more attention should be given to the potential for the optimization of current treatment processes, and reduction at source in order to reduce environmental contamination.

Potential Ecological and Human Health Risks Associated With the Presence of Pharmaceutically Active Compounds in the Aquatic Environment

ABSTRACT Recently, considerable interest has developed regarding the presence of pharmaceuticals in the environment, but as yet the potential ecological effects associated with the presence of these compounds have been largely ignored. In this review, laboratory-based acute and chronic toxicity data, as well as studies concerned with the effects of pharmaceuticals on a variety of different organisms, are examined, along with the reported environmental concentrations of pharmaceuticals in aquatic systems. The possible sources and pathways of these compounds to the environment and the effects of a variety of medicines on a range of organisms are also highlighted, and recommendations are made for further research.

Potential impact of pharmaceuticals on environmental health

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. …

Chapter 3.3 Ecotoxicity of pharmaceuticals

Publisher Summary The contamination of surface waters by pharmaceutical chemicals raised concern among environmental scientists in recent years because of their potential to induce adverse biological effects, especially in aquatic environments. This chapter presents some of the suggestions that are relevant to the undertaking of ecological risk assessments for the pharmaceuticals. The effects induced by pharmaceutical compounds depend on the dose, exposure route and timing, pharmacokinetic mechanisms, and the physiological status of the target organism. Life cycle studies linking different habitats and exposure routes of organisms at various life stages to a mixture of substances help to assess the effects of drugs on individual species. Sewage treatment works are the most significant source of human medicinal compounds to surface waters while the application of contaminated livestock manure may also contribute veterinary drugs to the aqueous phase after run-off events. To facilitate accurate exposure assessments, speciation, bioaccumulation, and bioavailability of pharmaceuticals in the environment should be examined. Pollution from pharmaceuticals poses challenges to policymakers, because the potential risks are poorly defined and interventions are costly and only marginally effective.