Occupational exposure to unburnt bidi tobacco elevates mutagenic burden among tobacco processors

The nature of mutagenic burden due to occupational exposure to tobacco flakes and dust was determined among 20 female tobacco processors (TP) and 20 matched controls (C) by testing urinary mutagenicity in the Ames assay. In addition, urinary cotinine mutagenicity in the Ames assay. In addition, urinary continine was estimated as a marker of tobacco absorption. Workers and controls were sub-divided into those with no tobacco habit (NH) and those habituated to use of masheri (a pyrolysed form of tobacco) as a dentifrice (MH). Cotinine was not detected in samples from C-NH while the mean urinary cotinine levels in TP-NH and TP-MH were significantly higer than that in C-MH (3.46 ± 0.95 and 3.57 ± 0.46 versus 1.80 ± 0.58 mM/M creatinine; P < 0.02). The majority of the urine samples from C-NH were non-mutagenic in the presence or absence of rat liver S9 while those from C-MH were mutagenic to TA98,TA100 and TA102 strains upon metabolic activation. On the other hand, direct mutagenicity to TA98, TA100 and TA102 strains respectively was noted in 6/10, 5/10 and 8/10 samples from TP-NH and 7/10, 4/10, and 3/10 samples from TP-MH. Generally, ß-glucuronidase treatment reduced or abolished the mutagenic potential of workers' urine samples indicating that glucuronide conjugates may have partially contributed to direct mutagenicity. Experiments using scavengers of reactive oxygen species revealed mainly via hydroxyl radicals. The results clearly demonstrate that tobacco processors are exposed to a wide spectrum of mutagens that cause frame-shift, base pair substitution and oxidative damage

Mutagenic potential of Indian tobacco products

The mutagenic potential of aqueous extracts of masheri (ME), chewing tobacco alone (CTE) and a mixture of chewing tobacco plus lime (CTLE) was tested using the Ames assay. ME exhibited mutagenicity in Salmonella typhimurium TA98 upon metabolic activation with aroclor-1254-induced rat liver S9, while nitrosation rendered it mutagenic in TA100 and TA102. CTE exhibited borderline mutagenicity in the absence or presence of S9 in TA98 and TA100 and after nitrosation in TA102, while nitrosation led to doubling of TA98 and TA100 revertants. In contrast, CTLE exhibited direct mutagenicity in TA98, TA100 and TA102, was mutagenic to TA98 upon S9 addition and induced mutagenic responses in all three tester strains after nitrosation. Experiments using scavengers of reactive oxygen species (ROS) suggested that CTLE-induced oxidat-ive damage in TA102 was mediated by a variety of ROS. The high mutagenic potency of CTLE vis a vis that of CTE may be attributed to changes in the pH leading to differences in the amount and nature of compounds extracted from tobacco. Thus, exposure to a wide spectrum of tobacco-derived mutagcns and promutagens may play a critical role in the development of oral cancer among users of tobacco plus lime

Long-term carcinogenicity of pan masala in Swiss mice

Carcinogenicity of pan masala, a dry powdered chewing mixture of areca nut, catechu, lime, spices and flavoring agents was evaluated by means of the long-term animal bio-assay 6- to 7-week old male and female S/RVCri mice were divided randomly into intermediate and lifetime exposure groups and fed normal diet without pan masala - (zero dose) or diet containing 2.5% and 5% pan masala. Animals in the intermediate-exposure group (n = 10/gender/dose group) were killed after 6, 12 or 18 months of treatment, while those in the lifetime-exposure group (n = 54/gender/dose group) were killed when moribund or at the termination of the experiment at 24 months. Several tissues were processed for histopathological examination. The body weight and survival rate of mice fed pan masala were lower than that of the controls. Histopathological observations of tissues from control animals did not reveal any neoplastic alterations. However, lifetime feeding of pan masala induced adenoma of the liver, stomach, prostate and sebaceous glands, also forestomach papilloma, liver hamartoma, hepatoma and hemangioma, carcinoma of the forestomach, adenocarcinoma of the lung and liver, and testicular lymphoma. Neoplastic lesions appeared mainly in the liver (n = 13), stomach (n = 3) and lung (n = 8). Lung adenocarcinoma, the most frequent malignant tumor type, was observed in 2/120 mice in the intermediate-exposure group and in 8/216 animals in the lifetime-exposure group. Statistical analysis of tumor-induction data revealed a significant dose-related increase in lung adenocarcinomas but not in liver and stomach neoplasms indicating that lung is the major target tissue for the carcinogenic action of pan masala

Mutagenicity of processed bidi tobacco: possible relevance to bidi industry workers

The genotoxic potential of bidi tobacco was evaluated by mutagenicity testing of aqueous, aqueous: ethanolic, ethanolic and chloroform extracts of processed tobacco used in the manufacture of 'bidis', indigenous forms of cigarettes smoked in India. The Salmonella/mammalian microsome test (Ames assay) was used to detect mutagenicity in tester strains TA98, TA100 and TA102. The extracts were tested in the absence and presence of metabolic activation using liver S9 from rat and hamster, and following in vitro nitrosation with sodium nitrite at acidic pH. All the extracts were non-mutagenic in the absence of nitrosation. The nitrosated aqueous extract was mutagenic in strains TA98 and TA100. While weak mutagenicity was elicited by the nitrosated aqueous: ethanolic extract in TA100, the nitrosated ethanolic extract induced a 3-fold increase in the number of revertants in the same strain. Moreover both these extracts elicited a strong mutagenic response in TA102, while the chloroform extract was non-mutagenic even after nitrite treatment. The present study indicates that workers employed in the bidi industry are exposed to potentially mutagenic and genotoxic chemicals in the course of their occupation

Occupational exposure to tobacco and resultant genotoxicity in bidi industry workers

In India, over 3 million workers employed in the bidi industry receive massive, chronic exposure to unburnt tobacco, mainly by the cutaneous and nasopharyngeal routes. While the hazards of habitual tobacco usage are well established, very little information is available about the effects of occupational tobacco exposure. In the present study, tobacco processing plant workers (TPPW) and bidi rollers (BR) with or without tobacco habits were monitored for occupation-related exposure to tobacco and resultant genotoxicity. Salivary cotinine levels were determined as an index of tobacco exposure and micronucleated buccal epithelial cell (MNC) frequency was recorded as a genotoxic endpoint. Occupational tobacco exposure led to the detection of cotinine in the saliva of 19% of BR and 100% of TPPW with no tobacco habit (NH). The greater degree of exposure in TPPW was evident from the significantly higher mean salivary cotinine level in TPPW-NH as compared to BR-NH (2.86 ± 0.48 vs. 0.84 ± 0.26 μg/ml; p < 0.01). The effect of occupational exposure was also evident in TPPW and BR with the masheri habit. A moderate but statistically significant increase in MNC frequency was observed in habit-free as well as masheri-habituated TPPW and BR as compared with the respective controls. The findings provide preliminary evidence for the clastogenic effects of occupational tobacco exposure

Impaired cell motility in chronic myeloid leukemic granulocytes related to altered cytoskeletal pattern

193-202The bactericidal activity of polymorphonuclear leucocyte (PMNL) against infection stimulates cytoskeletal changes accompanied with alteration in adhesion and locomotion. Microfilaments, the motile apparatus is known to regulate these changes by polymerization of monomeric G-actin to fibrous F-actin. PMNL from chronic myeloid leukemia (CML) patients have been reported to be defective in locomotion in response to synthetic peptide, n-formyl-methionyl-leucyl-phenylalanine (fMLP) but the mechanism leading to defective locomotion and their spatial reorganization remains unclear. Therefore, in order to study the cause of defective motility of PMNL from CML patients the spatial distribution and reorganization of microfilaments and microtubules in response to fMLP have been examined by transmission electron (TEM) and scanning electron microscopy (SEM). Under SEM, the PMNL-CML surface appeared smoother with reduced ruffling resulting in rounding off cells with lesser polarized morphology. Unstimulated PMNL from normal as well as CML subjects showed shorter and fewer microtubules and evenly distributed microfilaments as compared to fMLP stimulated PMNL. It is proposed that the cause of defective locomotion was due to reduced surface activity as a consequence of altered cytoskeletal configuration. This phenomenon seems to be related to impaired functional appendages and as a whole led to the defective cell motility and hence reduced chemotaxis in PMNL from CML patients

Polymorphism at GSTM1, GSTM3 and GSTT1 gene loci and susceptibility to oral cancer in an Indian population

This study evaluates the influence of genetic polymorphism at GSTM1, GSTM3 and GSTT1 gene loci on oral cancer risk among Indians habituated to the use of, smokeless tobacco, bidi or cigarette. DNA extracted from white blood cells of 297 cancer patients and 450 healthy controls by the proteinase K phenol-chloroform extraction procedure were analyzed by the polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) analyses. Lifetime tobacco exposure was evaluated as a risk factor in relation to the polymorphism at the GST gene loci using logistic regression analysis. There was no significant difference in the distribution of the GSTM3 and GSTT1 genotypes between oral cancer patients and controls. In contrast, a significant 3-fold increase in risk was seen for patients with the GSTM1 null genotype (age adjusted OR = 3.2, 95% CI 2.4-4.3). The impact of the GSTM1 null genotype on oral cancer risk was also analyzed in separate groups of individuals with different tobacco habits. The odds ratio associated with the GSTM1 null genotype was 3.7 (95% CI 2.0-7.1) in tobacco chewers, 3.7 (5% CI 1.3-7.9) in bidi smokers and 5.7 (95% CI 2.0-16.3) in cigarette smokers. Furthermore, increased lifetime exposure to chewing tobacco appeared to be associated with a 2-fold increase in oral cancer risk in GSTM1 null individuals. The results suggest that the GSTM1 null genotype is a risk factor for development of oral cancer among Indian tobacco habitues

Effects of an aqueous extract of processed bidi tobacco on the growth of hamster tracheal epithelial cells

Inhalation of tobacco dust is responsible for elevated genotoxicity and pulmonary ailments in workers engaged in processing tobacco for the manufacture of bidis, the Indian version of cigarettes. Tracheal tissue being the major site of interaction with tobacco dust, the effects of different concentrations of an aqueous extract of bidi tobacco (ATE) on the growth of a hamster tracheal epithelial cell line (HTE) were investigated. Colony forming efficiency assay revealed that ATE was cytotoxic only at the highest concentration of 5.0 mg/ml. In cultures treated with 1.25 mg/ml ATE, the cell doubling time and growth rate were similar to that of the controls, while a significant increase in cell doubling time (29.4±0.3 h vs 14.0±3.75 h, P<0.001) was observed at 2.5 mg/ml ATE concentration. Exposure of HTE cells to the non-toxic ATE concentration of 2.5 mg/ml was found to stimulate ornithine decarboxylase (ODC) activity, incorporation of [3H] methyl thymidine into DNA and increase in the S phase fraction was seen by flow cytometry. However, a 56% reduction in the growth rate of cultures treated with 2.5 mg/ml ATE was related to the prolongation of the traverse of cells through S phase. ATE-induced growth suppression was reversed when cultures were grown in ATE-free medium or upon repeated exposure to ATE. The findings suggest that increased tracheal cell proliferation induced by chronic inhalation of tobacco dust may contribute to the development of pulmonary disorders and possibly neoplasia in exposed individuals