Pharmaceutical Wastewater Effluent—Source of Contaminants of Emerging Concern: Phytotoxicity of Metronidazole to Soybean (Glycine max)

Industrial discharge of active pharmaceutical ingredients (APIs) into the environment in some middle- and low-income countries is not sufficiently regulated. The phytotoxicity of metronidazole (FLAGYL)—one of the most commonly used over the counter (OTC) antibiotics, to soybean (Glycine max) is investigated. Relative growth rate (RGR) expressed in gram per gram per day (gg(−1)d(−1)) was applied to plants destructively harvested at maturity (42 d), to determine the toxicological impact. Differences between mean RGR of the three groups were performed at 0.05 significance level. Multiple comparisons suggest that there was a statistical significant difference among mean RGR for all treatment groups. Metronidazole is toxic to soybean plants (Glycine max) based on dose-response criterion. There is a need to enforce treatment of pharmaceutical wastewater effluent by Pharmaceutical Manufacturing Companies (PMCs) before discharge into the environment.