Toxicology and Risk Assessment of Pharmaceuticals

1 Introduction For many years, the main focus of environmental pollution has been on chemical and pharmaceutical manufacturers. Spectacular accidents, such as that at the BASF facility in amongst others, provided the impetus for improved safety and spillage regulations as well as driving the efforts for environmental modeling and improved analysis of environmental samples. More recently, attention has turned to the far less dramatic, but nonetheless important consideration of the potential effects of medication residues on the aquatic environment. As a complete analysis of national and international regulations governing all polar organic pollutants is beyond the scope of this chapter, only regulations and concerns with specific relevance for pharmaceuticals will be discussed here. Waste Water Treatment Plants (WWTPs) [1] have been identified as the major point source of pharmaceuticals in surface waters, but diffuse intake via runoff can also be an important route for veterinary pharmaceuticals [2]. The realization of the latter situation has led to a parallel increase in the number of surveys designed to investigate the levels of contamination of surface waters and attempts to characterize the potential risks posed by these substances to the aquatic environment [3-7]. These studies have led to the recognition that while the concentrations in the WWTPs are generally related to the population equivalents of the respective region and the highest concentrations of pharmaceuticals are measured at sites where WWTP effluent is introduced into the receiving water body, the concentration of the substances found downstream of the WWTPs is a function of the tributary rivers that can cause either an increase or a decrease in the concentration of a given substance in the main river, depending on their own pre-load [1]. While many pharmaceutically-active substances can indeed be broken down in modern sewage treatment plants, by their very nature and, perhaps more importantly, due to their continual infusion into the environment, several of them can be classified as persistent polar organic pollutants. The efficiency of the removal of pharmaceuticals from wastewater in WWTPs can vary based on a number of factors including the population served, precipitation volumes, ambient temperature and nutrient loads. The particular substance classes delivered in sewage to the WWTP can also First publ. in: Organic pullutants in the water cycle / Thorsten Reemtsma ...