title: Photochemical fate of atorvastatin (lipitor) in simulated natural waters.
abstract: Cholesterol-lowering statin drugs are among the most frequently prescribed for reducing human blood cholesterol and they have been detected as contaminants in natural waters. In this study the photochemical behavior of atorvastatin (lipitor) was investigated at two different concentrations of 35.8 μM (20 mg L(-1)) and 35.8 nM (20 μg L(-1)) using a solar simulator and a UV reactor. Photochemical fate in natural waters can be described in most cases by the sum of the loss due to hydrolysis, direct photolysis, and, reaction with hydroxyl radical (•OH), singlet oxygen ((1)O(2)) (or O(2) ((1)D)), and excited state dissolved organic matter (DOM). The absolute bimolecular reaction rate constant with OH was measured, using pulsed radiolysis, (1.19 ± 0.04) × 10(10) M(-1) s(-1). The reaction rate constant of (1)O(2) was determined to be (3.1 ± 0.2) × 10(8) M(-1) s(-1). Under the experimental conditions used, at high atorvastatin concentration (35.8 μM) the contribution of singlet oxygen ((1)O(2)) to the photodegradation of atorvastatin in natural waters was higher than that of hydroxyl radical, and accounted for up to 23% of the loss in aqueous solutions. Whereas, at a concentration of 35.8 nM, (1)O(2) (and •OH) both played a minor role in the removal of this compound. Lastly, it also appears that atorvastatin reacts with (3)DOM* contributing to its loss in simulated natural waters.
authors.affiliation: Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA. brazavi@uci.edu
authors.forename: Behnaz
authors.initials: B
authors.lastname: Razavi
authors.forename: Sihem
authors.initials: S
authors.lastname: Ben Abdelmelek
authors.forename: Weihua
authors.initials: W
authors.lastname: Song
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
authors.forename: William J
authors.initials: WJ
authors.lastname: Cooper
mesh_terms: D000069059:Atorvastatin; D006538:Heptanoic Acids / Q000737:chemistry* / Q000528:radiation effects; D017665:Hydroxyl Radical / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D011758:Pyrroles / Q000737:chemistry* / Q000528:radiation effects; D026082:Singlet Oxygen / Q000737:chemistry; D013472:Sunlight; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D006538:Heptanoic Acids; D011758:Pyrroles; D014874:Water Pollutants, Chemical; D014867:Water; D026082:Singlet Oxygen; D017665:Hydroxyl Radical; D000069059:Atorvastatin