[Impact of work-related musculoskeletal disorders on work ability among workers].

OBJECTIVE: To assess the impact of work-related musculoskeletal disorders (WRMDs) on work ability among workers. METHODS: A total of 1686 workers in various occupations, such as administration and education, were enrolled as subjects using the random cluster sampling method. The WRMDs and work ability of all subjects were evaluated using standardized Nordic questionnaires for the analysis of musculoskeletal symptoms and the Work Ability Index (WAI) scale, respectively. Comparison of work ability and its classification between the disease group and the non-disease group was performed by paired t test, RxC table χ2 test, and the Wilcoxon rank-sum test. The relationship between work duration and work ability was analyzed by the Spearman correlation test and a multi-level model. RESULTS: (1). The work ability of workers in the disease group was significantly lower than that in the non-disease group (P<0.0 1). (2) There were significant differences in work ability between workers with different work durations (<10 years, 10-20 years, and ≥20 years) (F=22.124, P< 0.01). With the increase in work duration, the work ability of workers declined in both groups, and the work ability of workers in the disease group (Spearman coefficient rs=-0. 172, P<0.01) had a more significant decline than that in the non-disease group (Spearman coefficient rs=-0.104, P<0.01). WRMDs were important risk factors for the decrease in work ability among workers. (3) There were significant differences in constituent ratios and levels of work ability classification between the disease group and the non-disease group (χ2=121.097, P<0.01; Z=-10.699, P<0.01). The proportions of workers with poor and medium work ability in the disease group were significantly higher than those in the non-disease group, while the proportion of works with excellent work ability in the disease group was significantly lower than that in the non-disease group. The similar characteristics in constituent ratios and levels of work ability classification could be found between the disease group and the non- disease group in various occupations (P<0.01). CONCLUSION: WRMDs have a harmful effect on the work ability of workers, and the work ability of workers substantially declines with the increase in exposure time (work duration).

[Distribution and main influential factors of mental workload of middle school teachers in Nanchang City].

OBJECTIVE: To investigate the distribution and main influential factors of mental workload of middle school teachers in Nanchang City. METHODS: A total of 504 middle school teachers were sampled by random cluster sampling from middle schools in Nanchang City, and the mental workload level was assessed with National Aeronautics and Space Administration-Task Load Index (NASA-TLX) which was verified in reliability and validity. RESULTS: The mental workload scores of middle school teachers in Nanchang was approximately normal distribution. The mental workload level of middle school teachers aged 31 -35 years old was the highest. For those no more than 35 years old, there was positive correlation between mental workload and age (r = 0.146, P < 0.05). For those more than 35 years old, the levels of their mental workload had no statistically significant difference. There was a negative correlation between mental workload and educational level(r = -0.172, P < 0.05). The middle school teachers with lower educational level seemed to have a higher mental workload (P < 0.01). The longer a middle school teacher worked per day, the higher the mental workload was. Working hours per day was the most influential factor on mental workload in all influential factors (P < 0.001). CONCLUSION: Mental workload of middle school teachers was closely related to age, educational level and work hours per day. Working hours per day was the important risk factor of mental workload. Reducing working hours per day, especially reducing it to be no more than 8 hours per day, may be a significant and useful approach alleviating mental workload of middle school teachers in Nanchang City.

[Effects of mental workload on work ability in primary and secondary school teachers].

OBJECTIVE: To investigate the change pattern of primary and secondary school teachers' work ability with the changes in their mental workload. METHODS: A total of 901 primary and secondary school teachers were selected by random cluster sampling, and then their mental workload and work ability were assessed by National Aeronautics and Space Administration-Task Load Index (NASA-TLX) and Work Ability Index (WAI) questionnaires, whose reliability and validity had been tested. The effects of their mental workload on the work ability were analyzed. RESULTS: Primary and secondary school teachers' work ability reached the highest level at a certain level of mental workload (55.73< mental workload ≤ 64.10). When their mental workload was lower than the level, their work ability had a positive correlation with the mental workload. Their work ability increased or maintained stable with the increasing mental workload. Moreover, the percentage of teachers with good work ability increased, while that of teachers with moderate work ability decreased. But when their mental workload was higher than the level, their work ability had a negative correlation with the mental workload. Their work ability significantly decreased with the increasing mental workload (P < 0.01). Furthermore, the percentage of teachers with good work ability decreased, while that of teachers with moderate work ability increased (P < 0.001). CONCLUSION: Too high or low mental workload will result in the decline of primary and secondary school teachers' work ability. Moderate mental workload (55.73∼64.10) will benefit the maintaining and stabilization of their work ability.

[A multilevel model analysis of correlation between population characteristics and work ability of employees].

OBJECTIVE: To analyze the correlation between population characteristics and work ability of employees with a multilevel model, to investigate the important influencing factors for work ability, and to provide a basis for improvement in work ability. METHODS: Work ability index (WAI)was applied to measure the work ability of 1686 subjects from different companies (n=6). MLwi N2.0 software was applied for two-level variance component model fitting. RESULTS: The WAI of employees showed differences between various companies (χ2=3.378 6, P=0.0660); working years was negatively correlated with WAI (χ2=38.229 2, P=0.0001), and the WAI of the employees with 20 or more working years was 1.63 lower than that of the employees with less than 20 working years; the work ability of manual workers was lower than that of mental-manual workers (χ2=8.2726, P=0.0040), and the work ability showed no significant difference between mental workers and mental-manual workers (χ2=2.086 0, P=0.148 7). CONCLUSION: From the perspective of probability, the multilevel model analysis reveals the differences in work ability of employees between different companies, and suggests that company, work type, and working years are the important influencing factors for work ability of employees. These factors should be improved and adjusted to protect or enhance the work ability of employees.

[Study on current status of work-related musculoskeletal disorders evaluation].

OBJECTIVE: To characterize the distribution of work-related musculoskeletal disorders (WRMD) among the occupational population. METHODS: A total of 1686 people of various occupations were recruited with random cluster sampling. Standardized Nordic questionnaires for the analysis of musculoskeletal systems were used to evaluate WRMD at the neck, shoulder, or lower back in the past one year. The annual prevalence of WRMD was determined. Difference analysis was performed with t-test, ANOVA, or chi-square test. The relationship between personal characteristics and WRMD was analyzed by unconditional logistic regression. RESULTS: (1) WRMD were most frequently observed at the neck, followed by the lower back, and was least observed at the shoulder (P < 0.05). The prevalence of WRMD among mental workers was significantly higher than those among physical workers and mental-physical workers (P < 0.01). The prevalence of WRMD among female workers was significantly higher than that among male workers (P < 0.05). (2) In general, the prevalence of WRMD significantly rose with the increases in age (<30, 30∼, 40∼, and ≥ 50 years) or working years (<10, 10∼, and ≥ 20 years) (P < 0.05). (3) In the face of sickness or injury, physical workers and mental workers showed a relatively high absence rate but a relatively low medical visiting rate (13.05%). (4) Unconditional logistic regression analysis showed that mental work, gender, and working year were the main influential factors for WRMD among workers. CONCLUSION: Workers of different types of occupation, genders, ages, and working years have different risks of WRMD at the neck, shoulder, and lower back.

[The dose-response relationship of chrysotile asbestos exposure and lung cancer in cohort study].

OBJECTIVE: To clarify the dose-response relationship between asbestos dust exposure and lung cancer incidence in chrysotile asbestos miners by fixed cohort study and to investigate the incidence rates of lung cancer in exposure to different concentrations of asbestos dust. METHODS: A retrospective cohort study was conducted in 1932 asbestos miners who registered from January 1, 1981 to December 31, 1988, had worked for at least 1 year, and had no obvious cardiopulmonary diseases; the cohort study began in July 2009 and covered a time span of 29 years (1981 - 2009). The personal information, occupational history, disease history, and health data of these miners were recorded, and the monitoring data on dust concentrations in the mine over the years were collected. The dose-response relationship between asbestos dust concentration and lung cancer incidence was established by the method of life table; a regression equation was fitted to predict the excess incidence rates of lung cancer under the conditions of different working years and dust concentrations. RESULTS: A significant dose-response relationship was observed between cumulative exposure (Ce) and cumulative probability (Px) of lung cancer incidence, and the smokers hada higher Px than nonsmokers. When Ce was less than 2000 mg/m(3)·each year, Px reached 6.58/10000; when Ce was not less than 2000 mg/m(3)·and less than 3000 mg/m(3)·each year, Px reached 91.72/10000; when Ce was more than 5000 mg/m(3)·each year, Px was as high as 141.02/10000. The three models were fitted to obtain the optimal regression equation: Px = -0.0004Ce(2) + 0.0052Ce - 0.0011 (r(2) = 0.9387). In the workshop of asbestos mine in this study, the average dust concentration was 85 times higher than the limit in 2009, so the excess incidence rate of lung cancer was 112.598/10000 if the miners worked under this condition for 40 years, according to the equation. CONCLUSION: There is a significant dose-response relationship between cumulative asbestos exposure and lung cancer incidence in chrysotile asbestos miners. The risk for lung cancer rises as asbestos exposure increases.

Cause-specific mortality in relation to chrysotile-asbestos exposure in a Chinese cohort.

INTRODUCTION: The carcinogenic potency of chrysotile asbestos remains a contentious topic, and more data are needed to address this issue. We examine cause-specific mortality, especially lung cancer, and its association with chrysotile-asbestos exposure in a Chinese cohort. METHODS: A cohort of 577 workers from a chrysotile-textile plant was followed prospectively from 1972 to 2008. Occupational history, exposure information, and smoking data were obtained from company records and personal interviews; vital status and causes of death were ascertained from death registries and hospitals. Workers were classified into three exposure levels on the basis of exposure assessments of different workshops. Standardized Mortality Ratios (SMRs) were calculated in terms of exposure levels and other indices. RESULTS: Among 259 identified deaths, 53 died from lung cancer, with an SMR of 4.08 (95% confidence interval 3.12, 5.33), and 96 from all cancers with an SMR of 2.09 (1.71, 2.55). In addition, two deaths from mesothelioma were observed. Increased mortality from respiratory diseases was also observed (SMR 3.38, 95% confidence interval 2.72, 4.21). Asbestos-exposure levels, exposure years, and birth cohorts showed a clear trend of risk for lung cancer and respiratory diseases. CONCLUSION: The current analysis indicated that exposure to chrysotile asbestos was closely associated with excess mortality from lung cancer and respiratory diseases.

Analysis of mortality in chrysotile asbestos miners in China.

In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile, a fixed cohort of 1932 workers in chrysotile asbestos mine was established in 1981 and followed till June 1, 2010. Information on vital status, cause of death and smoking habits was collected. The workers were divided into two groups according to their exposure status. The exposed group was composed of frontline workers who worked directly on mining or processing asbestos products. The control group consisted of those who were not directly exposed to asbestos in their work. Standardized mortality ratio (SMR) was calculated according to Chinese national death rates. Cox proportional hazards model was applied to estimate the adjusted relative risks of deaths from major causes in exposed and control groups. The results of this study showed that main causes of mortality were malignant neoplasm, cardiovascular disease, cerebrovascular disease and respiratory disease for chrysotile miners. The mortality rate was 939.20 per 100 000 person-years for workers. The SMR for all causes of death was 1.46 in the cohort. Statistically significant mortality excesses were found for lung cancer (SMR=1.51), pulmonary heart disease (SMR=2.70), respiratory disease (SMR=1.93), asbestosis (SMR=9.62), and accident (SMR=1.59). The mortalities from malignant neoplasm, lung cancer, cerebrovascular disease and digestive disease in the exposed group were significantly higher than those in the control group. The findings indicate that chrysotile exposure is a risk factor for lung cancer, respiratory disease, cerebrovascular disease and digestive disease.

Mortality in a Chinese chrysotile miner cohort.

BACKGROUND: Few data were available to address cause-specific mortality in asbestos miners in China. This study observed a cohort of workers from the largest chrysotile asbestos mine to evaluate the association between asbestos exposure and cause-specific mortality. METHODS: The cohort consisting of 1,539 male workers was observed from 1981 to 2006. Information on occupational and smoking history and vital status was obtained through personnel records and individual contact. Causes and dates of deaths were verified from hospitals. Workers were divided into two groups: miners and millers (miner group) and control group (not direct exposed). Recent asbestos dust measurements in the workplaces showed that the concentrations ranged from 12 to 197 mg/m(3). Amphibole contamination was very low. Cox proportional hazard models with competing risks were fit to estimate hazard ratios for cause-specific mortality associated with asbestos exposure (miners vs. controls). In addition, standardized mortality ratios (SMRs) were calculated based on national mortality rates. RESULTS: All mortality rates of selected causes, particularly lung cancer, were substantially higher in the miner group than in the controls. SMRs of lung cancer and nonmalignant respiratory diseases in the miners were 4.71 (95% CI, 3.57, 6.21) and 3.53 (2.78, 4.48), respectively. The controls had similar mortality rates of all causes, lung cancer, all cancers as national rates, but a higher mortality from respiratory diseases. Asbestos exposure was related to a 4.6-fold mortality risk for lung cancer and over threefold risk for all cancers and respiratory diseases, while smoking and age were adjusted. The highest SMR of lung cancer was observed in miners who smoked. CONCLUSION: The results suggested excessive cause-specific mortality, in particular from lung cancer and respiratory diseases, in the cohort, which was associated with exposure to chrysotile asbestos.

A 37-year observation of mortality in Chinese chrysotile asbestos workers.

OBJECTIVES: This 37-year prospective cohort study was undertaken to provide additional evidence for mortality risks associated with exposure to chrysotile asbestos. METHODS: 577 asbestos workers and 435 control workers in original cohorts were followed from 1972 to 2008, achieving a follow-up rate of 99% and 73%, respectively. Morality rates were determined based on person-years of observation. Cox proportional hazard models were constructed to estimate HRs of cause-specific mortality, while taking into account age, smoking and asbestos exposure level. RESULTS: There were 259 (45%) deaths identified in the asbestos cohort, and 96 died of all cancers. Lung cancer (n=53) and non-malignant respiratory diseases (n=81) were major cause-specific deaths, in contrast to nine lung cancers and 11 respiratory diseases in the controls. Age and smoking-adjusted HRs for mortality by all causes and all cancers in asbestos workers were 2.05 (95% CI 1.56 to 2.68) and 1.89 (1.25 to 2.87), respectively. The risks for lung cancer and respiratory disease deaths in asbestos workers were over threefold that in the controls (HR 3.31(95% CI 1.60 to 6.87); HR 3.23 (95% CI 1.68 to 6.22), respectively). There was a clear exposure-response trend with asbestos exposure level and lung cancer mortality in both smokers and non-smokers. CONCLUSION: Data from this prospective cohort provide strong evidence for increased mortality risks, particularly from lung cancer and non-malignant respiratory diseases, associated with exposure to chrysotile asbestos, while taking into account of the smoking effect.

[Study on mental workload of teachers in primary schools].

OBJECTIVE: To investigate the distribution characteristics and influencing factors of mental workload of teachers in primary schools. METHODS: National Aeronautics and Space Administration-Task Load Index (NASA-TLX) was used to assess the mental workload levels for 397 teachers of primary schools in a city. RESULTS: The mental workload (64.34+10.56) of female teachers was significantly higher than that (61.73+ 9.77) of male teachers (P<0.05). The mental workload (65.66+10.42) of "-35" years old group was the highest. When age of teachers was younger than 35 years old, there was a positive correlation between the mental workload and age (r=0.146, P<0.05). When age of teachers was older than 35 years old, there was a negative correlation between the mental workload and age (r=-0.190, P<0.05). The teachers with higher education level felt higher mental workload (unstandardized coefficients B=1.524, standardized coefficients /=0.111, P<0.05). There was a positive correlation between the mental workload and working hours per day (unstandardized coefficients B =4.659, standardized coefficients/3 =0.223, P<0.001). CONCLUSION: Mental workload of the teachers in primary schools is closely related to age, educational level and work hours per day. Work hours per day is an important risk factor for mental workload. Reducing work hours per day (8 hours) is an effective measure of alleviating the mental workload of teachers in primary schools.

Lung cancer mortality from exposure to chrysotile asbestos and smoking: a case-control study within a cohort in China.

OBJECTIVE: To confirm the association between exposure to chrysotile asbestos and lung cancer risk and to demonstrate the combined effect of smoking and asbestos exposure. METHODS: A case-control study of 1139 asbestos workers identified 41 male lung cancer cases in 2001; each case was matched by age (±5 years) with five controls. Workers in seven workshops were categorised into high-, medium- and low-exposure subgroups, and conditional logistic regression was applied to estimate the odds ratios for lung cancer risk associated with the different exposure levels. Smoking, age at first exposure, and exposure duration were considered as covariates/confounding factors. A joint effect of asbestos exposure and smoking on lung cancer risk was analysed using a conditional logistical model. RESULTS: 54% of cases had high exposure and 24% low exposure, while 24% of controls had high exposure and 44% low exposure. Smoking was more common in cases (90%) than in controls (73%). The adjusted OR for lung cancer was 3.66 (95% CI 1.61 to 8.29) for high exposure and was elevated slightly for medium exposure (1.25; 95% CI 0.47 to 3.31). Smoking was related to lung cancer risk (OR 3.33; 95% CI 1.10 to 10.08). In comparison with the low-exposure non-smoking group, the OR for the high-exposure smoking group was 10.39 (1.34 to 82.45), in contrast to 5.23 (0.50 to 54.58) for high-exposure non-smoking workers. CONCLUSIONS: These results confirm the strong association between exposure to chrysotile asbestos and lung cancer risk, and support an interactive effect of asbestos exposure and smoking which is more than additive.

Longitudinal changes in pulmonary function of asbestos workers.

OBJECTIVE: To observe the longitudinal changes in pulmonary function associated with exposure to asbestos in a group of highly exposed workers. METHODS: Pulmonary diffusing capacity (DLco) and spirometry of 243 Chinese asbestos workers were measured and remeasured after 5 and 10 yr. Their annual changes in relation to cumulative asbestos exposure and asbestosis were determined using multivariate analysis. RESULTS: The greatest annual decline was observed in DLco, particularly in workers with asbestosis, followed by FVC and FEV(1). A greater decline in DLco accorded with a higher level of cumulative asbestos exposure. A similar trend was also seen in FVC, in which the highest exposure level was associated with 223 ml loss over each 5 yr period or 45 ml/yr. CONCLUSIONS: There were substantial declines in DLco and FVC over time in the asbestos workers, and a dose-response trend between asbestos exposure and accelerating functional loss.

[Effect of occupational stressors on coping resources of nurses in Nanchang].

OBJECTIVE: To study the effects of occupational stressors on coping resources of nurses. METHODS: Coping resources (recreation, self-care, social support, rational coping) and occupational stressors (role overload, role insufficiency, role ambiguity, role boundary, responsibility, physical environment) were measured on 387 nurses by personal resources questionnaire (PRQ) and Occupational Role Questionnaire (ORQ) respectively. RESULTS: The higher the level of occupational stressors was, the lower the coping resources of nurses were (P < 0.01). The level of occupational stressors was in a negative correlation with the coping resources of nurses, and the correlation with social support was the closest (P < 0.01). Except responsibility, all items in occupational stressors were correlated negatively with coping resources. The role insufficiency and role ambiguity in occupational stressors were in a closer correlation with coping resources (P < 0.01). CONCLUSION: Decresing the levels of occupational stressors for nurses in Nanchang, especially decreasing the levels of role insufficiency and role ambiguity, would enhance the coping resources of nurses, so as to enhance their capability to relieve strain.

[A survey report on dermatitis patients in hospital in Baoan district of shenzhen city from 1992 to 2006].

OBJECTIVE: To analyse the epidemiological distribution of dermatitis patients in hospital and provide basis for studying the basic conditions and the prevention of dermatitis especially TCE-induced dermatitis in Baoan District of Shenzhen City. METHODS: All dermatitis patients in hospital in Baoan District from 1992 to 2006 were descriptively analysed. RESULTS: There were 645 dermatitis patients in hospital in Baoan District. The total number of patients is tended to rise in recent years. The main age group of 16 approximately years old, followed by 26 approximately years old, the majority are workers. The clinical diagnosis are allergic dermatitis, drug-induced dermatitis, TCE-induced dermatitis. Compared with other dermatitis, women are more than men in TCE-induced dermatitis (P < 0.05). The risk of hepatic dysfunction in TCE-induced dermatitis was significantly greater than other dermatitis (P < 0.05). It is mainly distributed in electronic, metal, electroplating industry. CONCLUSION: The TCE-induced dermatitis was one of the main occupational hazards in Baoan district. To strengthen self-protection awareness of workers, pay more attention to early work observed and occupational screening in key industries and trades workers, reduce opportunities for occupational exposure, all above can effectively reduce the occurrence of TCE-induced dermatitis.

[Development and evaluation of Comprehensive Work Ability Index scales].

OBJECTIVE: To compile the instrument of comprehensive work ability evaluation-Comprehensive Work Ability Index (CWAI) scales. METHODS: One hundred and ninety-eight employees were selected with the random cluster sampling method from a factory. On the basis of the work ability theory, CWAI scales, a self-rating scales on work ability, was developed according to the standardized processes of scales compilation. Item differentiation analysis, principal component analysis and factor analysis as well as intra-item reliability were used for selecting the item of CWAI scales. RESULTS: Work ability was assessed with a comprehensive work ability index, which was a comprehensive indicator constructed on the basis of the responses to the scales. It was derived as the sum of the five items including self-rating work ability domain, physiological domain (disease, sick leave etc.), psychological domain (work satisfaction, mental state etc.), social functions dominant (social support, social flexibility etc.) and work ability prediction domain. CONCLUSION: CWAI scales correspond with the theoretical structure. However, the reliability and validity of CWAI scales must be assessed before the formal application.

[Reliability and validity of Comprehensive Work Ability Index scales].

OBJECTIVE: To test the reliability and the validity of Comprehensive Work Ability Index (CWAI) scales. METHODS: For evaluating the reliability and validity of CWAI scales, 1959 subjects employed in various kinds of occupations were selected with the random cluster sampling method. 245 subjects of them were retested at intervals of 2 to 4 weeks in order to assess the test-retest reliability. The sample for criterion validity consisted of 86 subjects. The inter-item consistency (Cronbach's alpha coefficient, Spearman-Brown coefficient, theta coefficient and Omega coefficient), test-retest reliability (intra-class correlation coefficient) and Pearson correlation were calculated to assess the reliability of CWAI scales. Pearson correlation analysis, and factor analysis were used to assess the validity of CWAI scales. RESULTS: The reliability analysis showed that CWAI was significantly correlated with the item scores (P < 0.01), and most of the correlation coefficients were higher than 0.30. Generally speaking, Cronbach's alpha coefficients (ranging from 0.701 to 0.808), theta coefficient (ranging from 0.703 to 0.845) and Omega coefficient (ranging from 0.802 to 0.942) and Spearman-Brown coefficient (0.860) conformed to the requirements of psychometric study. The intra-class correlation coefficient (ranging from 0.597 to 0.897) suggested that the test-retest consistency was good at intervals of 2 to 4 weeks. In point of the theoretic concept and development method, the content validity of CWAI scales was satisfactory. The intra-class correlation coefficient for the concurrent validity was 0.650 (P < 0.01) when WAI scales were taken as the criterion. Factor analysis revealed that when eight common factors were drawn from the 17 items of CWAI scales, the cumulative variance of eigenvalues amounted to 71.894%. Each item had communality over 0.60 and its factor loading (0.538 approximately 0.948) attached to the relevant common factor was over 0.40. The common factors with higher factor loading were basically consistent with the theoretic concept of CWAI scales. CONCLUSION: CWAI scales are reliable and valid.

Cancer mortality and asbestosis among workers in an asbestos plant in Chongqing, China.

OBJECTIVE: To investigate whether asbestosis is a risk factor for mortality of lung cancer. METHODS: A fixed cohort study was established in an asbestos plant in Chongqing, China, and followed up for 30 years from the beginning of 1972. Basic personal information on life state, cause of death, and diagnosis of asbestosis was collected. Multiple logistic regressions were applied to analyze risk factors. RESULTS: During the 30-year follow-up, 584 male workers constituting a total of 14,664 person-years were monitored and data were analyzed. Among them, 203 (34.8%) died and the mortality rate was 13.8 per 1000 person-years, cancer accounting for 37.4%. Excess risks were observed for lung cancer (OR = 3.72) and nonmalignant respiratory diseases (OR = 2.73) among workers with asbestosis. High-exposure level was another risk factor for lung cancer (OR = 3.20). Workers with category II of asbestosis demonstrated a higher OR of both lung cancer and nonmalignant respiratory diseases than those with category I of asbestosis. CONCLUSION: High asbestos exposure level and asbestosis were the risk factors for death of lung cancer and nonmalignant respiratory diseases. Asbestosis is an independent risk factor for lung cancer among Chinese workers exposed to chrysotile, the risk increases with the increasing profusion of opacities of lung.

[Sub-health condition of teachers of the middle school evaluated by two means in Nanchong City].

OBJECTIVE: To evaluate the sub-health condition of teachers of the middle schools. METHODS: The method of cluster random sampling trial was adopted. The sub-health condition was interviewed by the questionnaire made by ourselves, and was detected by multifunctional microscopy diagnostic instrument for 693 teachers in study group and 970 persons in control group. RESULTS: The results showed that the questionnaire could get a good reliability and validity. The results of questionnaire inspection were accordant with the multifunctional microscopy diagnostic instrument in evaluating sub-health condition. The incidences of sub-health condition in study group were more higher (58.8%) than those in the control group (50.0%) (P < 0.05), and the incidences of sub-health condition in female teachers (60.9%) were more hither than those in male teachers(55.9%) (P < 0.05), and the incidences of sub-health condition at the age of 30-45 years (73.0%) were more higher than those in any other ages (P < 0.05). CONCLUSION: The results indicated that teachers of the middle schools could easily suffer from sub-health condition.