Volatile nitrosamines and tobacco-specific nitrosamines in the smoke of Thai cigarettes: a risk factor for lung cancer and a suspected risk factor for liver cancer in Thailand

In Thailand, smoking of commercial cigarettes and of handmadecigarettes has drastically increased in recent decades. Cancerof the lung and of the upper aerodigestive tract have also increasedin Thailand as they have in many other countries. It is ourworking hypothesis that the increase of primary cancer of theliver, especially of cholangiocarcinoma in the north-easternprovinces of Thailand is associated with the use of tobaccoin men infested with the liver fluke Opisthorchis viverrini(OV). Bioassays have shown that volatile nitrosamines and tobacco-specificnitrosamines induce cholangiocarcinoma in laboratory animalsand that the hepatocarcinogenic action of nitrosodimethylaminein hamsters is significantly increased by infestation with theliver fluke OV. The endogenous formation of nitrosamines issignificantly increased by OV infestation. This report presentsanalytical data on the concentration of volatile nitrosaminesand tobacco-specific nitrosamines in mainstream smoke of nineleading brands of commercially produced Thai cigarettes whichrepresent ~85% of the market share in Thailand. Observed ranges(ng/cigarette) were 8.5–31.9 for nitrosodimethylamine,8.8–49.6 for nitrosopyrrolidine and 4.2–18.9 fornitrosodi-n-butylamine. These values are exceptionally highcompared with the smoke of light and blended cigarettes fromNorth America and Western Europe. Among the tobacco-specificnitrosamines, the range was 28–730 for nitrosonornicotineand 16–370 for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.There was a correla-tion between volatile and tobacco-specificnitrosamines, and tar and nicotine deliveries in the mainstreamsmoke. The analytical data are in line with the rate for lungcancer and support our working hypothesis that nitrosamines,and especially the tobacco-specific nitrosamines, are associatedwith the increased risk for primary liver cancer among thoseThai people who smoke cigarettes and also carry OV infestation.