Article pubs.acs.org/est
Aqueous Phototransformation of Diazepam and Related Human Metabolites under Simulated Sunlight Charles E. West and Steven J. Rowland* Petroleum & Environmental Geochemistry Group, Biogeochemistry Research Centre, Plymouth University, Drake Circus, Plymouth, Devon, PL4 8AA, U.K. S Supporting Information *
ABSTRACT: Phototransformation of the widely used benzodiazepine pharmaceuticals diazepam and human metabolites nordiazepam, temazepam and oxazepam under simulated sunlight in water was investigated. Photolysis experiments were conducted in the presence and absence of humic acids. Halflives for each of the benzodiazepine pharmaceuticals were 2 pg g−1 to >24 ng g−1 with concentrations in water of 0.25 to ca. 4 μg L−1.13 A comprehensive deterministic and probabilistic risk assessment for diazepam was published recently.11 It was noted that little sorption of diazepam to sludge occurs during sewage treatment and that most diazepam enters receiving waters with the sewage effluents, where it is then diluted and advected. Measured environmental concentrations of diazepam in surface waters were in the range
