Description
Serious questions have been raised about the environmental and health impacts of pharmaceuticals in our nations water resources. As the use of illicit drugs continues to grow, it is important to understand their source, levels, and fate in our urban waters. In this study, amphetamine, methamphetamine, cocaine and benzoylecgonine (BE), the metabolite of cocaine, were detected and quantitated in raw composite wastewater influent samples from the Ray Stoyer Water Recycling Facility and Forester Creek in Santee, California. Solid phase extraction and analysis by LC-MS/MS were used to detect and quantitate the illicit drug residues in wastewater with 100% frequency. Mean concentrations were 1.03 ± 0.27, 9.02 ± 3.32, 1.70 ± 0.80, and 0.36 ± 0.09 μg/L for amphetamine, methamphetamine, BE, and cocaine respectively. Back-calculations of per-capita community drug consumption rates were then estimated and yielded values for amphetamine, methamphetamine and cocaine at 590.99, 5396.57, and 750.62 mg/d/1,000 people, respectively. Notably, methamphetamine per-capita consumption rates determined in the present study were the highest rates ever reported by this “sewage epidemiology” method for the U.S. and Europe. Nonparametric testing by Spearman Rank Correlation showed significant (p<0.05) positive correlations (.0480-.0783) between the illicit drugs and traditional chemical markers (caffeine and sucralose) of sewage, with the exception of cocaine and sucralose. The results of the study suggest that illicit drugs, particularly BE, a metabolite unique to human excretion, should be considered an excellent chemical indicator of human sewage contamination of surface waters.
