The following study presents typical results that are found when risk assessment methods are applied to pharmaceutical compounds in surface waters as sources of drinking water. The study authors state:
“This evaluation indicates that predicted levels of atomoxetine, duloxetine, and olanzapine that might be found in surface waters are significantly below PNECs. We acknowledge that uncertainties exist when estimating exposure and calculating PNECs, but the methods used in this analysis were designed to identify any significant likelihood of risk to human health based on currently available information. Even using an approach designed to maximize estimated exposure, there is a large margin of safety for each API when comparing the PNEC to the possible residue levels in the surface water. This is consistent with risk assessments for other pharmaceutical compounds (Schwab et al., 2005; Webb et al., 2003; Schulman et al., 2002; Christensen, 1998).”
Keep in mind that a fish is usually much less mass than a human, so that for any given water concentration the exposure on a mg/kg/day basis will be greater for a fish (or fresh water fish at least) than for a human…..so such trace pharmaceutical residues in a surface water have greater potential for ecologocial effects than for human effects….
Bercu, J.P., N.J. Parke, J.M. Fiori, and R.D. Meyerhoff 2008. Human health risk assessments for three neuropharmaceutical compounds in surface waters, Regulatory Toxicology and Pharmacology 50, 420–427.
Click here for the abstract (also below) and to obtain the paper (fee).
Abstract: Enhanced sensitivity of analytical chemistry methods has enabled the detection of low-levels of pharmaceuticals in the environment, resulting in questions about the safety of surface waters used for drinking supplies. Human health risk assessments were performed to evaluate the risks from residues of atomoxetine, duloxetine, and olanzapine, which might be found in surface waters. Preclinical safety studies and human clinical data were used to determine an acceptable daily intake (ADI) for each compound: atomoxetine, 1.4 ug/kg/day; duloxetine, 1.8 ug/kg/day; and olanzapine, 1.4 ug/kg/day. The calculated predicted no-effect concentrations (PNECs) for children were 25.7, 19.1, and 35.9 ug/L for atomoxetine, duloxetine, and olanzapine, respectively. Estimated exposure concentration determined using United States Food and Drug Administration guidelines and predicted exposure concentrations from the PhATE model were compared with each PNEC to determine margins of safety, which ranged from 147 to 642. Based on currently available data used in this assessment, no appreciable human health risks exist from exposure to the highest 99th percentile of predicted residue levels of atomoxetine, duloxetine or olanzapine in surface waters under low-flow conditions.