Depressing news about antidepressants

Posted on July 1, 2013

It’s known that human pharmaceuticals can pass through wastewater treatment plants and enter aquatic ecosystems.  Some of these chemicals, such as antidepressants, have negative effects on freshwater organisms.  For example, antidepressant SSRIs (selective serotonin reuptake inhibitors) depress spawning in bivalves, penile erection in snails, fecundity in water fleas, prey capture ability in striped bass, and anti-predator escape efficiency in minnow larvae.  In recent tests with two species of freshwater snail (the pleurocerid Leptoxis carinata and the lymnaeid Stagnicola elodes), both species lost their ability to attach to the substrate when they were exposed to venlafaxine and citalopram, two of the most prevalent antidepressants in wastewater streams.   The lowest test concentrations at which snail dislodgement occurred were well below the highest concentrations found in wastewater-impacted streams: 4000 times lower for venlafaxine and over five times lower for citalopram.  Because dislodgement can prevent feeding and lead to predation, drying out and current-borne transport to unfavourable habitats, and because pleurocerid and lymnaeid snails have wide distributions and occur at high densities, anti-depressant contamination may have significant effects on invertebrate community structure and nutrient cycling. 

Reference:  Fong, P.P. & Hoy, C.M.  2012.  Antidepressants (venlafaxine and citalopram) cause foot detachment from the substrate in freshwater snails at environmentally relevant concentrations.  Marine and Freshwater Behaviour and Physiology 45 (2), 145–153.