| Pharmaceuticals occur in surface but their effects on the environment are not well understood. To test this hypothesis, a total of 17 common pharmaceuticals were screened in the laboratory and in three separate semi-field studies. Field experiments assessed a mixture of three pharmaceuticals, eight-pharmaceuticals, and four tetracycline drugs. Oxygen concentration was consistently reduced relative to control in each study. Direct toxicity in the microcosms was attributed to selective serotonin reuptake inhibitors (SSRI) and antibiotic algal toxicity and zooplankton effects of SSRIs. Indirect treatment effects were noted in each experiment including effects on oxygen via algal toxicity and changes in zooplankton community structure. Recovery and resilience were noted in a number of parameters in each study, with the exception of oxygen concentration. In the tetracycline experiment, it was possible to attribute the lack of recovery to impacted function. Overall there was a low environmental hazard associated with these compounds. Uncertainty factors of less than 1000 applied to acute laboratory and literature data encompassed the observed microcosm effects. |
