Medical and veterinary drugs

Quite recently, attention has been drawn to the environmental contamination caused by pharmaceutical products and drugs. These groups constitute an enormous number of different substances, selected and/or manufactured for the purpose of biochemical and physiological activity and interference. By definition, such substances can act as toxicants in elevated concentrations and especially in the wrong situations or places. Furthermore, modem dmg design in many cases is directed towards the development of products with high bioavailability and 

Drugs or medicines are composed of pharmaceutically active substances together with other constituents such as colors, preservatives, fillers, etc. Of these, it is the active substance and on some occasions the preservatives, e.g. mercury, that might be of environmental concern. 

Environmental monitoring of dmgs has revealed the occurrence of many substances in terrestrial as well as aquatic environments. Thus, antibiotics (e.g. oxytetracycline in the order of mg/kg dry weight) have been detected in sediments and in wild fish in the surroundings of fish farms (Jacobsen and Berglind, 1988 Bjorklund et al., 1990), river sediments have been shown to contain human as well as veterinary dmgs (Zuccato et al., 2000) and so has municipal wastewater (Temes, 1998). Of special concern in this context are the endocrine-disrupting substances (Tyler et al., 1998). 

Urine and faeces (Unchanged drugs, mefabolifes and conjugates) 

For most of the drug substances the environmental impact is unknown, but for different types of antibiotics or antimicrobials a lot of concern is raised because of the development of bacterial resistance towards the drugs through different molecular mechanisms (Kruse and Sorum, 1994). This poses a threat to animals as well as humans, with the development of multiresistant, sometimes pathogenic, microbial strains (Midtvedt, 1998) 

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