Risk assessment of selective serotonin reuptake inhibitors: comparing methods in tiered environmental risk assessment
Environmental detection of pharmaceuticals, including the selective serotonin reuptake inhibitor (SSRI) fluoxetine, has reinforced the need for environmental exposure, fate, effects, and hazard assessment of these chemicals. Environmental concentrations of SSRIs were predicted using current methodologies and compared to available measured environmental concentrations. The environmental fate of SSRIs fluoxetine, fluvoxamine, and sertraline was evaluated in microcosm model ecosystems; toxicity to algae and fish was evaluated at different tiers consisting of (quantitative) structure activity relationships, acute laboratory toxicity assays, and in microcosm model ecosystems. Hazard to fish and algae was evaluated using predicted environmental concentrations and toxicity values determined at each tier. The hazard at each tier was then compared to generate data-driven uncertainty factors (UFs) for extrapolation between tiers which were then used to extrapolate the additional hazard of the remaining SSRIs: citalopram and paroxetine. Furthermore, the utility of species sensitivity distributions (SSDs) and interspecies correlation estimation (ICE) was investigated as extrapolation methods and compared to pragmatic UFs. Overall, algae were found to be more sensitive than fish to SSRIs with sertraline being the most toxic of the SSRIs tested followed by fluoxetine and fluvoxamine. However, the hazard of SSRIs at current environmental concentrations is low. Moreover, SSDs and ICE show promise as extrapolation tools as they generated conservative hazard estimates that were more accurate than those derived using pragmatic UFs.