Where It Comes From
Forms when the tobacco alkaloid nornicotine reacts with nitrite during curing/processing or in saliva; present in tobacco products and in mainstream and secondhand smoke [1].
How You Are Exposed
Using smokeless tobacco; smoking; breathing secondhand smoke; working where tobacco is made or processed [1][3].
Why It Matters
IARC classifies NNN as carcinogenic to humans (Group 1); it is linked to cancers of the mouth and esophagus and causes DNA damage [2][1].
Who Is at Risk
People who smoke or use smokeless tobacco; those regularly around secondhand smoke; workers with occupational tobacco exposure [1][4].
How to Lower Your Exposure
Don’t use tobacco; keep homes and cars smoke‑free; if you use nicotine, switch to FDA‑approved cessation aids (patch, gum, lozenge) that don’t contain NNN; follow workplace protections [4][5].
References
- [1]IARC Monographs, Vol. 89: Smokeless Tobacco and Some Tobacco-specific N-Nitrosamines. 2007. https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Smokeless-Tobacco-And-Some-Tobacco-specific-N-nitrosamines-2007
- [2]IARC Monographs, Vol. 100E: A Review of Human Carcinogens: Personal Habits and Indoor Combustions. 2012. https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Personal-Habits-And-Indoor-Combustions-2012
- [3]CDC: Smokeless Tobacco—Health Effects. https://www.cdc.gov/tobacco/basic_information/smokeless/health-effects.html
- [4]CDC: Health Effects of Secondhand Smoke. https://www.cdc.gov/tobacco/data_statistics/fact_sheets/secondhand_smoke/health_effects/index.htm
- [5]CDC: Quit-Smoking Medicines. https://www.cdc.gov/tobacco/campaign/tips/quit-smoking/quit-smoking-medications/index.html