Indirect human exposure to pharmaceuticals via drinking water.

There are numerous observations of pharmaceuticals (or their metabolites) as contaminants in wastewater, surface water and groundwater. This implies a potential for indirect human exposure to pharmaceuticals via drinking water supplies. Various effect benchmarks may be employed in an evaluation of the significance of such indirect exposure. In this study a comparison was made between reported concentrations of pharmaceuticals in German drinking water and therapeutic dose. The margin between potential indirect daily exposure via drinking water and daily therapeutic dose was at least three orders of magnitude and typically much more. For certain compounds it was also possible to benchmark exposure against ADIs derived within the context of meat and food stuff residues following veterinary use. In all cases potential exposure was less than the ADIs, similarly suggesting that for these compounds there are no substantial concerns with regards to indirect exposure via drinking water.