title: Localized formation of micronuclei in the oral mucosa and tobacco-specific nitrosamines in the saliva of "reverse" smokers, Khaini-tobacco chewers and gudakhu users.
abstract: "Reverse"-cigar smokers (who hold the burning end of cigars within the mouth), dippers (who place a mixture of Khaini-tobacco and slaked lime into the lower gingival groove) and users of tobacco-containing toothpaste (gudakhu) in Orissa, India, were examined for precancerous oral lesions, the frequency of micronucleated cells at 3 different intra-oral sites, and levels of tobacco-specific nitrosamines (TSNA) in the saliva. Among reverse-cigar smokers, a high incidence of leukokeratosis nicotina palati, an elevated frequency of micronucleated cells in the palate (2.5% as compared to 0.6% in non-smokers and non-chewers of tobacco) and tongue (2.1%) from which carcinomas preferentially develop, and up to 5890 ppb nitrosonornicotine and up to 1880 ppb N-nitrosoanatabine in the saliva were found. Among Khaini-tobacco chewers, the frequency of micronucleated cells was elevated to 2.1% in the gingival groove, and up to 1580 ng N-nitrosonornicotine, 690 ng N-nitrosoanatabine, 90 ng N-nitrosoanabasine, and 180 ng 4-(methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone) per ml of saliva were observed. The localized elevation of the frequency of micronuclei and cancer development is probably due to a synergistic effect of hyperthermia and tobacco-related carcinogens among reverse-cigar smokers, and to the close, prolonged contact between the mucosa and tobacco among Khaini-tobacco/slaked lime dippers. Neither pre-cancerous lesions nor an elevated frequency of micronuclei were seen in the oral mucosa of users of gudakhu, a tobacco-containing toothpaste, which may be due to the low amount of TSNA released from the gudakhu and the short exposure time, which is restricted to the period of tooth brushing.
authors.affiliation: Cancer Imaging, British Columbia Cancer Research Centre, Vancouver, Canada.
authors.forename: H F
authors.initials: HF
authors.lastname: Stich
authors.forename: B B
authors.initials: BB
authors.lastname: Parida
authors.forename: K D
authors.initials: KD
authors.lastname: Brunnemann
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007972:Leukoplakia, Oral / Q000209:etiology; D008297:Male; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects*; D008875:Middle Aged; D009061:Mouth Mucosa / Q000187:drug effects / Q000648:ultrastructure*; D009062:Mouth Neoplasms / Q000175:diagnosis / Q000209:etiology; D009602:Nitrosamines / Q000009:adverse effects* / Q000378:metabolism; D010947:Plants, Toxic; D011230:Precancerous Conditions / Q000175:diagnosis / Q000209:etiology; D012307:Risk Factors; D012463:Saliva / Q000378:metabolism*; D012907:Smoking / Q000009:adverse effects* / Q000378:metabolism; D014030:Tobacco, Smokeless / Q000009:adverse effects*; D014100:Toothpastes
chemical_list: D009602:Nitrosamines; D014100:Toothpastes