The comparative study of the effects of Fe2 O3 and TiO2 micro- and nanoparticles on oxidative states of lung and bone marrow tissues and colony stimulating factor secretion. 
Nowadays, increased use of nanomaterials in industry and biomedicine poses potential risks to human health and the environment.  Studying their possible toxicological effects is therefore of great significance.  The present investigation was designed to examine the status of oxidative stress induced by nanoparticles (NPs) of ferric oxide (Fe2 O 3 ) and titanium oxide (TiO 2 ) with their micro-sized counterpart on mouse lung and bone marrow-derived normal tissue cells.  We assessed the induction of oxidative stress by measuring its indicators such as antioxidant scavenging activity of superoxide dismutase and catalase as well as malondialdehyde concentration.  Moreover, colony formation of bone marrow cells was assayed following induction with colony stimulating factor (CSF) from lung cells.  NPs had a more potent stimulatory effect on the oxidative stress status than their micron-sized counterparts.  In addition, the highest level of oxidative stress derived from TiO 2 NPs was observed in both tissue types.  Cotreatment with NPs and the antioxidant α-tocopherol reduced antioxidant activities and membrane lipid peroxidation (LPO) in the lung cells, but increased CSF-induced colony formation activity of bone marrow cells, suggesting that oxidative stress may be the cause of the cytotoxic effects of NPs.  It is concluded that free radicals generated following exposure to NPs resulted in signiﬁcant oxidative stress in mouse cells, indicated by increased LPO and antioxidant enzyme activity and decreased colony formation.