## 1 Introduction  
Pharmaceutical manufacturing has until recently been generally considered to not significantly contribute to environment pollution on the one hand, and to not pose any environmental threat of consequence, on the other [1, 2]. Recent findings however suggest the contrary: certain manufacturing facilities across the globe have been determined to discharge into the environment significantly high levels of APIs, beyond previously established levels, thereby causing pollution [2, 3, 4, 5, 6]. Antibiotics constitute a significant proportion of APIs found in the environment, and have become a class of contaminants of emerging concern. They have been detected at concentrations between a few ng/L to ug/ L, as well as at levels as high as mg/L range in both industrial effluents and their receiving water bodies, including surface and groundwater across various countries of the world [7, 8, 9, 10, 11, 12]. High levels of the antibiotic oxytetracycline were detected at 600 mg/L in the ETP discharge of a PMC in Asia [9]. In developing nations like Nigeria, there is little or no evidence of regulatory disposal of pharmaceutical wastes, and a large number of PMCs either lack an ETP, or installed ones are non-functional [13]. Unregulated methods of waste disposal have resulted in the occurrence of APIs in high concentrations beyond tolerable levels. Undoubtedly, the implication for environmental health regarding soil and water quality is negative. Also, some authors have speculated that industrial use of pharmaceuticals is a major source of environmental pollution [14]. Moreover, studies implicating pharmaceutical ETP as a real source of pollution are well documented [7]. Food crisis in some African countries like Nigeria has resulted in elevated small scale cropping including subsistence farming. Consequently, there is increased reliance on irrigation from various non-precipitation water sources including polluted ponds, rivers, and streams [15; 16]. Part of the strategy to augment rainwater is the use of industrial wastewater and their receiving water bodies. In the study area, PMCs discharge untreated effluent heavily laced with APIs including antibiotics into surrounding water bodies [16]. Small-scale soybean (_Glycine max_) production has recently experienced a significant increase, mostly to address the endemic malnutrition in affected regions. Soybean (_Glycine max_) is an economical legume, containing twice the protein content of beef and poultry, yet costing only a fifth of their price [17]. Metronidazolezo (2-methyl-5-nitro-1H-imidazole- 1-ethanol) belongs to the antibiotic class nitroimidazole [18]. Used for the management of both human and animal diseases of various causative organisms [19; 20; 21; 22], it is one of the most common and widely consumed over the counter (OTC) antibiotics, thus its production in very large quantities [23; 24]. Levels as high as 34 mg/L were detected in the ETP sample of a PMC in Lagos, Nigeria [1]. Metronidazolezo does not readily adsorb to sediments or soil, explaining its high availability and potential uptake by plants [25]. Furthermore, it has been reported to have low biodegradability in the environment [26; 27; 28]. To date, there is a paucity of studies addressing phytotoxicity of APIs, yet most of them focus on the subject from the stand point of soil amendments, including application of biosolids and manure to agricultural lands [29; 30; 31; 32]. Such studies entailed use of small approximate quantities of APIs that may be obtainable in animal manure or sewage. Also, majority of these studies established the fact that legumes including soybean (_Glycine max_) were particularly sensitive to low levels of antibiotics. Among three antiprotozoan drugs tested for toxicity to soybean (_Glycine max_), metronidazolezo was reported to be the most toxic at low levels. Additionally, the degree of their responsiveness was determined by environmental conditions, namely soil properties.