Sodium Nitrite - Toxicity

Toxicity

While this chemical will prevent the growth of bacteria, it can be toxic in high amounts for animals, including humans. Sodium nitrite's LD₅₀ in rats is 180 mg/kg and its human LD_Lo is 71 mg/kg, meaning a 65 kg person would likely have to consume at least 4.615 g to result in death. To prevent toxicity, sodium nitrite (blended with salt) sold as a food additive is dyed bright pink to avoid mistaking it for plain salt or sugar. Nitrites are a normal part of human diet, found in most vegetables. Spinach and lettuce can have as high as 2500 mg/kg, curly kale (302.0 mg/kg) and green cauliflower (61.0 mg/kg), to a low of 13 mg/kg for asparagus. Nitrite levels in 34 vegetable samples, including different varieties of cabbage, lettuce, spinach, parsley and turnips ranged between 1.1 and 57 mg/kg, e.g. white cauliflower (3.49 mg/kg) and green cauliflower (1.47 mg/kg). Boiling vegetables lowers nitrate but not nitrite. Fresh meat contains 0.4-0.5 mg/kg nitrite and 4–7 mg/kg of nitrate (10–30 mg/kg nitrate in cured meats). The presence of nitrite in animal tissue is a consequence of metabolism of nitric oxide, an important neurotransmitter. Nitric oxide can be created de novo from nitric oxide synthase utilizing arginine or from ingested nitrate or nitrite. Most research on the negative effects of nitrites on humans predates the discovery of nitric oxide's importance to human metabolism and human endogenous metabolism of nitrite.