Effect of eight common Brazilian drugs on Lemna minor and Salvinia auriculata growth

The growth of two species of macrophytes (Lemna minor and Salvinia auriculata) under the effect of a mixture of amoxicillin, caffeine, carbamazepine, dipyrone, ibuprofen, losartan, omeprazole, and tenivastatin was investigated by bioassay. Three concentration levels were utilized in this study (10, 200, and 500 μg L−1) using a growth inhibition test based on the OECD 221/2006 guidelines. The frond number, total area, and chlorophyll a level were selected as suitable end points. For L. minor, at all concentrations, a significant difference in the total frond number was observed and the growth inhibition varied from 30 to 70% at the low and high concentrations, respectively. No significant growth change was observed to S. auriculata exposed to the mixture of drugs. Thus, individual drug tests were performed for L. minor which demonstrated stimulation in growth, when exposed to most drugs individually, except tenivastatin which was identified as the drug responsible for the significant growth inhibition seen in the mixture. The L. minor enhanced growth was probably caused by N molecule transformation to ammonium and nitrate, essential nutrients for plants.