4-(Methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanol

4-(Methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanol (abbreviated as NNK) is a carcinogenic compound found in tobacco smoke and is a known potent lung carcinogen. It is formed during the curing and processing of tobacco leaves and can also be formed during the combustion of tobacco in cigarettes. NNK is a member of the nitrosamine family of chemicals, which are known for their cancer-causing properties. NNK is a highly reactive molecule that can bind to DNA and cause mutations in cells. This can lead to the development of cancerous tumors in the lungs and other organs. NNK is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), which means that it is a known human carcinogen. In addition to its role in cancer development, NNK can also cause other health problems. It has been shown to cause respiratory problems, cardiovascular disease, and other negative health effects. NNK has also been linked to decreased fertility in both men and women. Due to its harmful properties, efforts have been made to reduce the levels of NNK in tobacco products. Some countries have implemented regulations requiring lower levels of NNK in tobacco products, and some tobacco companies have developed products with reduced levels of NNK. However, NNK is still a major health concern and efforts to reduce its exposure to humans should continue.