Do pharmaceuticals affect freshwater invertebrates? A study with the cnidarian Hydra vulgaris

Pharmaceuticals enter natural waters through sewage effluent and landfill leachates and present an unknown risk to aquatic species including freshwater invertebrates. In this study the acute and chronic toxicity of 10 drugs, commonly prescribed in the UK i.e. ibuprofen, paracetamol, acetylsalicylic acid, amoxicillin, bendroflumethiazide, furosemide, atenolol, diazepam, digoxin, amlodipine were assessed using the cnidarian Hydra vulgaris. In a 7 day exposure period there were no effects on survival at concentrations up to 1.0 mg l(-1) and after 17 days neither feeding nor bud formation were adversely affected. However the ability of dissected polyps to regenerate a hypostome, tentacles and foot was inhibited by diazepam, digoxin and amlodipine at 10 microg l(-1). It is suggested that other drugs targeted at mammalian receptor systems may also affect aquatic invertebrates although it is unlikely, at their low environmental concentrations, that those examined in this study actually present a risk.