In accordance with our results, markers of both oxidant and antioxidant activities increased after intranasal silica exposure in rats [53]; however, in other rat models of intranasally-provoked silicosis, a significant rise in malonyldialdehyde and nitrite/nitrate content in the lung was associated with a decline in lung glutathione content and SOD activity [22]. Here, SOD1 is linked to silicosis.