 The addition of ascorbate to cured meat reduces formation of nitrosamines (see below), but increases the nitrosylation of iron.The use of nitrite and nitrate salts for meat in the US has been formally used since 1925.Because of the relatively high toxicity of nitrite (the lethal dose in humans is about 22 mg/kg of body weight), the maximum allowed nitrite concentration in meat products is 200 ppm.