Asbestos ; toxicity ; Humans ; Occupational Exposure ; adverse effects ; Pulmonary Alveolar Proteinosis

Asbestos ; adverse effects ; chemistry ; classification ; Carcinogens ; Fibrosis ; Humans ; Occupational Exposure

OBJECTIVETo determine if there are excessive risks of malignant tumors or not among workers exposed to asbestos by applying a meta-analysis technique.

METHODSAll data meeting the criteria of cohort studies on cancer mortality of digestive system among workers exposed to asbestos would be incorporated into the meta-analysis. The pooled standardized mortality ratios (SMR) and their corresponding 95% confidence intervals (CIs) for main cancer sites of digestive system were calculated by using two approaches of un-weighted ratio and random effects model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test.

RESULTS69 asbestos-exposed cohorts were summarized. The significantly elevated meta-SMR for all deaths (1.16), all cancers (1.42), cancer of digestive system (1.15) and cancer of stomach (1.20) among workers exposed to chrysotile alone or mixed asbestos were observed (P < 0.01). The stomach cancer SMR was significantly increased in the asbestos cement workers, the screening mine workers and the insulators, (1.27, 1.21 and 2.13 respectively) (P < 0.05). meta-SMR for cancers at other sites of digestive system including esophagus, colon, rectum and liver were not significant.

CONCLUSIONThere are likely excessive risks of cancer of stomach among workers exposed to asbestos. However, there is likely no convincing indication of an etiological association between asbestos exposure and cancers at other sites of digestive system.

Asbestos ; adverse effects ; Carcinogens, Environmental ; adverse effects ; Cohort Studies ; Digestive System Neoplasms ; chemically induced ; mortality ; Humans ; Occupational Exposure ; adverse effects

Asbestos, Crocidolite ; adverse effects ; Female ; Humans ; Mesothelioma ; etiology ; Middle Aged ; Pleural Neoplasms ; etiology

OBJECTIVETo study the relationship between glutathione S-transferase M1 (GSTM1) genotypes and lipid peroxidation of asbestos workers.

METHODS94 asbestos workers and 51 controls were selected as subjects. The general information, occupational history and individual habits were collected by questionnaires in all participants. The venous blood was sampled and the plasma was separated for the detection of malondialdehyde (MDA) level and lymphocytes for DNA isolation and GSTM1 genotyping.

RESULTSMDA level was significantly higher in asbestos workers [(0.283 +/- 0.054) nmol/L] than that in controls [(0.163 +/- 0.053) nmol/L, P < 0.01], however, neither duration of exposure nor accumulated asbestos exposure dose was related to MDA levels; MDA levels in control workers with GSTM1 +/- genotype [(0.190 +/- 0.034) nmol/L] were significantly higher than that in control workers with GSTM1 +/+ genotype [(0.138 +/- 0.055) nmol/L, P < 0.01]. Among asbestos workers, the same trend could be found, but the differences was not significant(P > 0.05). When the workers were stratified by duration of exposure or accumulated asbestos exposure dose, MDA levels in individuals with GSTM1 -/- genotype were also higher than those with GSTM1 +/+ genotype, but the differences were also not significant(P > 0.05).

CONCLUSIONBoth exposure to asbestos and deficiency of GSTM1 genotype were related to lipid peroxidation in workers, but the role of the former may be more important than that of the latter.

Asbestos ; adverse effects ; Genotype ; Glutathione Transferase ; genetics ; Humans ; Lipid Peroxidation ; Malondialdehyde ; analysis ; Occupational Exposure

Asbestos ; adverse effects ; Humans ; Mesothelioma ; chemically induced ; diagnosis ; Peritoneal Neoplasms ; chemically induced ; diagnosis

Asbestos ; adverse effects ; Humans ; Lung Neoplasms ; chemically induced ; Mesothelioma ; chemically induced ; Peritoneal Neoplasms ; chemically induced

Asbestos ; adverse effects ; Environmental Exposure ; GPI-Linked Proteins ; metabolism ; Humans ; Population Surveillance

OBJECTIVETo determine there was excessive risk of malignant tumors or not among workers exposure to chrysotile fiber alone by applying a meta-analysis technique.

METHODSAll data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile would incorporate into the meta-analysis. The pooled standardized mortality ratios (SMR) and their corresponding 95% confidence intervals (95% CI) for main cancer sites were calculated using two approaches of unweighted ratio and random effects model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test.

RESULTS26 chrysotile-exposed alone cohorts were summarized. The significantly elevated meta-SMRs for all deaths (1.28), all cancers (1.26), cancers of respiratory organs (2.24), cancer of lung (2.29) and cancer of stomach (1.27) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.64), asbestos products manufacturers (3.07), miners and millers (2.24), cement products workers (1.22), and for stomach cancer among asbestos products manufacturers (1.48). Meta-SMRs for cancers at other sites were not significant.

CONCLUSIONThere were excessive risks of lung cancer and mesothelioma among workers exposure to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.

Asbestos ; poisoning ; Asbestos, Serpentine ; poisoning ; Cohort Studies ; Humans ; Neoplasms ; etiology ; mortality ; Occupational Exposure ; adverse effects ; Respiratory Tract Neoplasms ; etiology ; Survival Rate

OBJECTIVETo understand the effects of exposure to asbestos and GSTM1 genotypes on plasma activity of glutathione S-transferases (GSTs).

METHODSNinety-four workers exposed to asbestos and 51 controls were selected, and their general information, occupational history and personal behavior were collected by questionnaire. Venous blood specimen was collected from each of them and plasma was separated for detection of GSTs activity and lymphocytes for DNA extraction and GSTM1 genotyping.

RESULTSPlasma activity of GSTs in the asbestos-exposed workers (23.0 +/- 6.9) U/L was significantly lower than that in the controls (32.6 +/- 11.8) U/L, which declined with the length of employment in asbestos industry and the increase of cumulated dose of asbestos. Stratification of workers by GSTM1 genotypes showed that plasma activity of GSTs in asbestos-exposed workers with GSTM1+/+ or GSTM1-/- were (24.0 +/- 6.1) and (22.5 +/- 7.3) U/L, respectively, lower than those in the controls with the same genotypes (38.1 +/- 13.2) and (26.8 +/- 6.6) U/L. Plasma activity of GSTs in the control workers with GSTM-/- was significantly lower than in those with GSTM+/+, and, so did in asbestos-exposed workers, but without statistically significant difference.

CONCLUSIONExposure to asbestos could significantly decrease plasma activity of GSTs, and GSTM1 genotypes could affect on the activity of GSTs in the control workers, which was not so obvious in asbestos-exposed workers.

Adult ; Asbestos ; adverse effects ; Gene Frequency ; Genotype ; Glutathione Transferase ; blood ; drug effects ; genetics ; Humans ; Middle Aged ; Occupational Exposure ; adverse effects ; Time Factors