When sodium nitrite is added with the salt, the meat develops a red, then pink color, which is associated with cured meats such as ham, bacon, hot dogs, and bologna.In the early 1900s, irregular curing was commonplace. This led to further research surrounding the use of sodium nitrite as an additive in food, standardizing the amount present in foods to minimize the amount needed while maximizing its food additive role. Through this research, sodium nitrite has been found to give taste and color to the meat and inhibit lipid oxidation that leads to rancidity, with varying degrees of effectiveness for controlling growth of disease-causing microorganisms. The ability of sodium nitrite to address the above-mentioned issues has led to production of meat with extended storage life and has improved desirable color and taste. According to scientists working for the meat industry, nitrite has improved food safety. This view is disputed in the light of its ineffectiveness against botulism and the possible carcinogenic effects caused by adding nitrites to meat.Nitrite has the E number E250. Potassium nitrite (E249) is used in the same way. It is approved for usage in the EU, USA and Australia and New Zealand.In meat-processing, sodium nitrite is never used in a pure state but always mixed with common salt. This mixture is known as nitrited salt, curing salt or nitrited curing salt. In Europe, nitrited curing salt contains between 99.1% and 99.5% common
salt and between 0.5% and 0.9% nitrite.
Consequently, the addition of at least 550 ppm of ascorbic acid is required in meats manufactured in the United States. Manufacturers sometimes instead use erythorbic acid, a cheaper but equally effective isomer of ascorbic acid. Additionally, manufacturers may include α-tocopherol (vitamin E) to further inhibit nitrosamine production. α-Tocopherol, ascorbic acid, and erythorbic acid all inhibit nitrosamine production by their oxidation-reduction properties. Ascorbic acid, for example, forms dehydroascorbic acid when oxidized, which when in the presence of nitrosonium, a potent nitrosating agent formed from sodium nitrite, reduces the nitrosonium into nitric oxide. The nitrosonium ion formed in acidic nitrite solutions is commonly mislabeled nitrous anhydride, an unstable nitrogen oxide that cannot exist in vitro.Ingesting nitrite under conditions that result in endogenous nitrosation has been classified as "probably carcinogenic to humans" by International Agency for Research on Cancer (IARC).Sodium nitrite consumption has also been linked to the triggering of migraines in individuals who already experience them.One study has found a correlation between highly frequent ingestion of meats cured with pink salt and the COPD form of lung disease. The studys researchers suggest that the high amount of nitrites in the meats was responsible; however, the team did not prove the nitrite theory. Additionally, the study does not prove that nitrites or cured meat caused higher rates of COPD, merely a link. The researchers did adjust for many of COPDs risk factors, but they commented they cannot rule out all possible unmeasurable causes or risks for COPD.