R4 AM Occurrence and Fate of Pharmaceutical and Other Emerging Wastewater Contaminants in Aquatic Systems
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in Ballroom 4

(ARM-1117-817021) Environmental occurrence and fate of selective serotonin reuptake inhibitors in aquatic environments.

Armbrust, Kevin¹, Kwon, Jeong-Wook¹, ¹ Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS, USA

ABSTRACT- Pharmaceuticals can enter aquatic environments after their prescribed use and lead to negative effects on aquatic organisms. Of particular concern are drugs that are hormonally active because disruption of physiological processes in aquatic organisms can occur at low environmental concentrations. Selective serotonin reuptake inhibitors (SSRIs) are among the most heavily prescribed drugs, they are hormonally active, low concentrations have been shown to affect aquatic organisms, and evidence indicates that they can be present in effluents from wastewater treatment plants. The present research includes the environmental fate of five SSRIs (citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline) and the their occurrence in surface waters. Analyses of SSRIs showed high water solubilities and relatively low octanol-water partition coefficients. Sediments and soils were used to measure adsorption coefficients. Values of K_f, K_d, and K_oc ranged from 39 to 18342, from 60 to 42579, and from 2256 to 1053380, respectively. In general, pH is the main factor influencing soil sorption. Paroxetine and fluvoxamine rapidly photodegraded and fluoxetine and citalopram are stable to photolysis at all pH ranges. Several degradation products for each SSRI were detected and identified. All SSRIs treated to irradiated water/sediment systems dissipated rapidly, in part due to photolysis but mostly due to adsorption to sediment. Nearly constant SSRI residues over time indicated that SSRIs resist microbial metabolism in sediments. Methods that employ solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the determination of five SSRIs and their metabolites in surface water samples have been developed. Fluoxetine and sertraline were detected in all samples, ranging in concentration from 0.006-0.076 ug/L and 0.007-0.061 ug/L, respectively. Citalopram was also detected in selected samples. Laboratory data indicates that the SSRIs as a general class are resistant to most forms of degradation in environmental systems and would partition to sediment where residues of these compounds would persist.

Key words: selective serotonin reuptake inhibitor, adsorption, photolysis, water/sediment systems