Nanoparticles, chemical structures between 1-100 nm in size, are one of the most promising elements of a new era in technology and science. NPs-based products are growing rapidly in a variety of fields such as health and fitness, electronics and computers, cosmetics, home and garden, food and beverage as well as biomedical applications (Mnyusiwalla et al. 2003; EPA, 2007). The Nanotechnology Consumer Products Inventory report, released in October 2013, listed 1814 nano-containing consumer products, in which the largest group of these products (37%) contains metals and metal oxides NPs (Vance et al. 2015). NPs potentially cause harm to both humans and the environment due to their unique physicochemical properties, size, shape and solubility (Maynard et al. 2006). NPs can easily penetrate the cell membrane due to their very small size and alter the crucial functions of cells. Growing evidence shows that various molecular mechanisms such as DNA damage, oxidative stress, mitochondrial disruption, apoptosis resulting in morphological changes and eventually cell death are responsible for the toxic effects of NPs (Ray et al. 2009; Dhawan and Sharma, 2010; Iavicoli et al. 2013).Bi 2 O 3 is one of the significant metal oxides which has rapidly attracted attention, perhaps because of its use in technology, industry and biomedical sciences (Hyodo et al. 2000; Rabin et al. 2006; Taufik et al. 2011). Despite Bi 2 O 3 -NPs widespread usages and the increasing intentional or unintentional exposure, there is limited knowledge about their toxicity (Thomas et al. 2012; Hernandez-Delgadillo et