The Effect of PCDH15 Gene Variations on the Risk of Noise-induced Hearing Loss in a Chinese Population.

Noise-induced hearing loss (NIHL) is a complex disease caused by interactions between environmental and genetic factors. This study investigated whether genetic variability in protocadherin related 15 (PCDH15) underlies an increased susceptibility to the development of NIHL in a Chinese population. The results showed that compared with the TT genotype of rs11004085, CT/CC genotypes were associated with an increased risk of NIHL [adjusted odds ratio (OR) = 2.64; 95% confidence interval (CI): 1.14-6.11, P = 0.024]. Additionally, significant interactions between the rs11004085 and rs978842 genetic variations and noise exposure were observed in the high-level exposure groups (P < 0.05). Furthermore, the risk haplotype TAGCC was observed when combined with higher levels of noise exposure (P < 0.05). Thus, our study confirms that genetic variations in PCDH15 modify the susceptibility to NIHL development in humans.

Development of Job Burden-capital Model of Occupational Stress: An Exploratory Study.

This study proposes a new framework as job burden-capital model for comprehensive assessment on occupational stress. 1618 valid samples were recruited from electronic manufacturing service industry in Hunan province by self-rated questionnaires after written consent. Structural equation model analysis was employed to verify the model by the data collected. The final fitting model has satisfactory fitting goodness (CMIN/DF=5.78, AGFI=0.937, NNFI=0.960, IFI=0.968, RMSEA=0.054). Both of the measurement model and structural model have acceptable path loadings. Job burden and capital could either directly affect occupational outcomes or indirectly influence them through personality. Multi-group structural equation model analyses indicate general applicability of the model to the basic features of such population. The job burden-capital model opens up new horizons for more in-depth study on occupational stress.

Establishment of a reference value for chromium in the blood for biological monitoring among occupational chromium workers.

The concentration of chromium in the blood (CrB) has been confirmed as a biomarker for occupational chromium exposure, but its biological exposure indices (BEIs) are still unclear, so we collected data from the years 2006 and 2008 (Shandong Province, China) to analyze the relationship between the concentration of chromium in the air (CrA) of the workplaces and CrB to establish a reference value of CrB for biological monitoring of occupational workers. The levels of the indicators for nasal injury, kidney (ß2 microglobulin (ß2-MG)), and genetic damages (8-hydroxy-deoxyguanosine (8-OHdG) and micronucleus (MN)) were measured in all subjects of the year 2011 (Henan Province, China) to verify the protective effect in this reference value of CrB. Compared with the control groups, the concentrations of CrA and CrB in chromium exposed groups were significantly higher (P < 0.05). Positive correlations were found between CrA and CrB in chromium exposed groups (r 2006 = 0.60, r 2008 = 0.35) in the years 2006 and 2008. According to the occupational exposure limitation of CrA (50 µg/m(3), China), the reference value of CrB was recommended to 20 µg/L. The levels of nasal injury, ß2-MG, 8-OhdG, and MN were not significantly different between the low chromium exposed group (CrB ≤ 20 µg/L) and the control group, while the levels of ß2-MG, 8-OHdG, and MN were statistically different in the high chromium exposed group than that in the control group. This research proved that only in occupational workers, CrB could be used as a biomarker to show chromium exposure in the environment. The recommended reference value of CrB was 20 µg/L.

How Work Organization Affects the Prevalence of WMSDs: A Case-control Study.

OBJECTIVE: In this study, we aimed at exploring the association between work-related musculoskeletal disorders (WMSDs) and work organization based on a case-control study. METHODS: A total of 1938 workers who claimed to suffer from WMSDs were selected from Beijing, Henan, Hubei, and the Guangdong province. The control group consisted of 2009 workers employed in similar industries without severe disease or musculoskeletal discomforts. We used a modified version of the questionnaire developed by the NMQ and the DMQ to investigate individual and work-related factors. RESULTS: A total of 13 variables (P<0.1) were selected by the chi-square test and finally, 7 variables entered into the equation, with 6 variables reaching statistical significance (P<0.05). The odds ratios (OR) of 'work changing with season' and 'sufficient rest time' did not reach 1 (0.749 and 0.441, respectively). In addition, 'sufficient rest time' seemed to be the stronger protective factor according to its higher standardized coefficient. And 'repetitive work every minute', 'constantly repetitive work' (every day), 'shortage of site personnel', and 'often switching shifts with others' seemed to be the risk factors. CONCLUSION: Work organization may have comprehensive effects on the occurrence of WMSDs. This pattern of associations suggests that further investigation into the mechanism of how work organization affects the prevalence of WMSDs is required.

Co-effect of Demand-control-support model and effort-reward imbalance model on depression risk estimation in humans: findings from Henan Province of China.

OBJECTIVE: To investigate the co-effect of Demand-control-support (DCS) model and Effort-reward Imbalance (ERI) model on the risk estimation of depression in humans in comparison with the effects when they are used respectively. METHODS: A total of 3 632 males and 1 706 females from 13 factories and companies in Henan province were recruited in this cross-sectional study. Perceived job stress was evaluated with the Job Content Questionnaire and Effort-Reward Imbalance Questionnaire (Chinese version). Depressive symptoms were assessed by using the Center for Epidemiological Studies Depression Scale (CES-D). RESULTS: DC (demands/job control ratio) and ERI were shown to be independently associated with depressive symptoms. The outcome of low social support and overcommitment were similar. High DC and low social support (SS), high ERI and high overcommitment, and high DC and high ERI posed greater risks of depressive symptoms than each of them did alone. ERI model and SS model seem to be effective in estimating the risk of depressive symptoms if they are used respectively. CONCLUSION: The DC had better performance when it was used in combination with low SS. The effect on physical demands was better than on psychological demands. The combination of DCS and ERI models could improve the risk estimate of depressive symptoms in humans.

[Evidence-based study of chromate exposed workers' health surveillance indexes].

OBJECTIVE: The health surveillance proposal for chromate exposed workers was provided and analyzed on the evidence-based study and then to be improved. METHOD: Firstly, the related literatures were searched about liver damage, micronuclei, urinary chromium and hexavalent chromium exposure in Evidence Based Medicine Reviews such as Cochran library, OVID Medline, Web of knowledge in December 2011; and then, these literatures were reviewed in according to inclusion and exclusion criteria; 22 articles totally were retrieved, evaluated and classified in according to the grading standard by Oxford Centre for Evidence-based Medicine.Finally, field epidemiological investigation was further adopted to confirm the efficiency and feasibility of this proposal, combined with cost-effectiveness analysis:the ratio of total cost divided survival years was used to express the cost-effectiveness. RESULT: Only the glutamic pyruvic transaminase test could not reflect liver damage caused by chromate exposure well; Urinary chromium correlated well with the index reflecting body damage caused by chromate exposure; Binucleated cells micronucleus index in peripheral blood lymphocyte could reflect the genetic damage caused by chromate exposure. As for health economic evaluation of chromate lung cancer, the value of cost/effectiveness was ¥42 321.61 per year that was far below the value of common people (¥252 868.97 per year) . CONCLUSION: It was suggested that serum glutamic pyruvic transaminase test should be replaced by liver function test, urinary chromium should be classified as a compulsory index and binucleated cells micronucleus index in peripheral blood lymphocyte should be supplied as a recommended index.

Risk factors of low back pain among the Chinese occupational population: a case-control study.

OBJECTIVE: To explore the risk factors of low back pain among the Chinese occupational population in several major industries. METHODS: A total of 7200 subjects (3600 cases and 3600 controls) were randomly sampled from a cross-sectional study, and they were investigated for individual and occupational factors of low back pain. The potential risk factors were first selected by using chi-square tests. Secondly, collinearity diagnosis proceeded by using the Kendall's rank correlation. Finally, binary logistic regression model was used for multi-factor analysis. RESULTS: Collinearity diagnosis showed that there was a severe collinearity problem among the potential risk factors of low back pain. Logistic regression model included 20 variables with statistical significance. Bending neck forward or holding neck in a forward posture for long periods (OR=1.408) was the most important risk factor inducing low back pain in this study, followed by bending heavily with the trunk (OR=1.402), carrying out identical work almost for the whole day (OR=1.340). Additionally, sufficient normal break was a protective factor of low back pain. CONCLUSION: Low back pain among the Chinese occupational population was associated with body height, occupation, work organization, physical work, working posture, and others. All these risk factors could be regarded as the indicators of low back pain, and some relevant preventive measures should be taken to reduce low back pain risk.

[Dynamic observation of pulmonary ventilation function in workers contacting chromate].

OBJECTIVE: To explore changes of pulmonary ventilation function of chromate exposed workers. METHODS: Ninety-five chromate exposed workers were used as exposure group, and forty-two workers without chromate exposure as control group. Pulmonary ventilation function was performed two times in the winter of 2010 and 2011 respectively in one chromate manufactured factory in Henan Province. RESULTS: In 2010, pulmonary ventilation function of chromate exposed group compared with the control group, forced vital capacity [FVC, (75.38±15.23) L vs. (83.99±26.52)L], forced expiratory volume in one second [FEV1,(82.13±16.51)L vs.(91.24±30.03)L], FEV1/FVC(112.10±13.23 vs. 116.18±11.32), peak expiratory flow [PEF,(74.31±28.09) L/s vs.(78.13±28.34)L/s], maximal expiratory flow [MEF,(101.23±46.37) L/s vs. (110.02±41.40)L/s], maximum ventilation volume [MVV,(90.82± 16.89)L/min vs. (99.95±22.61)L/min]were significantly decreased(P<0.05). In 2011, pulmonary ventilation function of chromate exposed group compared with the control group, FVC[(72.34±14.18)L vs.(81.01±20.79)L], FEV1[(76.04±16.20)L vs.(86.71±24.53)L], FEV1/FVC(109.10±16.18 vs.114.08±10.79), PEF[(71.35±24.87 )L/s vs.(75.36±20.67)L/s], MEF[(96.51±30.17)L/s vs.(107.11±34.81)L/s], MVV[(84.85±21.22)L/min vs. (96.77±22.63)L/min] were also significantly decreased(P<0.05). 2011 compared with 2010, pulmonary ventilation function of chromate exposed group FEV1[(76.04±16.20)L vs.( 82.13±16.51)L], MEF[(96.51±30.17)L/s vs. (101.23±46.37)L/s], MVV[(84.85±21.22)L/min vs. (90.82±16.89)L/min] were significantly decreased(P<0.05). Comparing the classification and category of pulmonary dysfunction based on FVC, FEV1, FVC/ FEV1, no difference was found for classification between the two groups and the category of pulmonary dysfunction almost belongs to limit type, which did not change with exposed time. CONCLUSION: Chronic chromate exposure can cause significant effects on pulmonary function of the workers, and the types of work in production can affect the results.

[The epidemiological characteristics and correlated factors of daily hassles for thermal power plant workers].

OBJECTIVE: This study aimed to investigate the epidemiological characteristics and correlated factors of daily hassles among thermal power plant workers. METHODS: A mass screening of daily hassles and correlated factors was conducted on 498 workers from a thermal power plant in Zhengzhou in July, 2008. The questionnaires included Daily Hassles Questionnaires, Work Roles Questionnaires, Job Content Questionnaires (Chinese version), Effort-Reward Imbalance (Chinese version), Work Locus of Control Scale and Type A Behavior Scale, with content covering demographic characters and occupational stress correlated factors among subjects. The daily hassles was divided into lower level and higher level according to scores, and the epidemiological characteristics and correlated factors of daily hassles were analyzed. RESULTS: A total of 446 qualified questionnaires were obtained, effective response rate was 89.6% (446/498). For respondents, the age was (36.96 ± 6.49) years old, working length of the current job was (12.05 ± 7.54) years, the daily hassles scores was (9.01 ± 2.50), and the prevalence rate of the higher level of daily hassles was 34.1% (152/446). The multiple non-conditional logistic regression analysis showed 5-14 years' working length of current job (OR = 0.451, 95%CI: 0.225 - 0.904), average income > 3000 yuan(OR = 0.372, 95%CI: 0.202 - 0.684), reward (OR = 0.557, 95%CI: 0.325 - 0.954) and coping strategy (OR = 0.552, 95%CI: 0.330 - 0.925) were negatively correlated with daily hassles, and shift-work (OR = 1.887, 95%CI: 1.108 - 3.215), effort (OR = 2.053, 95%CI: 1.198 - 3.519), psychological demand (OR = 1.797, 95%CI: 1.049 - 3.078), negative affectivity (OR = 3.421, 95%CI: 2.065 - 5.668) were positively correlated with daily hassles. CONCLUSION: The prevalence rate of the higher level of daily hassles was considerable high for thermal power plant workers. Its negative correlated factors included 5 - 14 years' working length of the current job, average income > 3000 yuan, reward and coping strategy and its positive corelated factors included shift-work, effort, psychological demand and negative affectivity.

[Effect of occupational combined exposure of chromium and iron on erythrocyte metabolism].

OBJECTIVE: To investigate the effect of combined occupational exposure of chromium and iron on erythrocyte metabolism, and the possible mechanism. METHODS: A total of 115 chromate production workers were selected in a chemical factory of Jinan as exposure group, Dec, 2008, and 60 healthy residents from a community which was far away from the factory were enrolled as control group. Environmental concentrations of chromium and iron were collected by filter membrane sampling and determined. The peripheral blood of subjects were collected for determination of chromium, iron, copper in whole blood and folate, vitamin B12 in serum, mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) and correlation analysis was conducted. RESULTS: The median (quartile interval) concentration of air-chromium and air-iron in workplace were 9.0 (10.5) and 11.2 (10.1) µg/m³, respectively, which were significantly higher than that of the control (0.1 (0.1) and 7.2 (2.5) µg/m³) (all P values < 0.01). Blood-chromium and blood-iron of the exposed group were 15.5 (14.1) µg/L and (895.1 ± 90.2) mg/L, which were significantly higher than the counterpart of the control (3.6(2.0) µg/L, (563.7 ± 49.3) mg/L) (all P values < 0.01). Serum folate ((6.9 ± 2.5) µg/L), serum vitamin B12 ((396.4 ± 177.0) µg/L) and blood copper ((777.6 ± 103.5) µg/L) of the exposed group were all significantly lower comparing to the control group ((558.0 ± 330.8), (8.1 ± 3.8), (812.1 ± 94.6) µg/L) (all P values < 0.05). The relationships between blood chromium and serum folate, serum vitamin B12 were statistical significant (r = -0.319 and -0.293, P < 0.01). Both serum vitamin B12 and blood copper correlated with mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) (r = -0.223, -0.242, -0.261, -0.292, all P values < 0.01). CONCLUSION: Combined chromium and iron exposure existed in the workplace. Adverse effect of Chromium on human erythrocyte may via folate and vitamin B12 metabolism, while iron may via copper metabolism.

[Distribution of chromium in whole blood and urine among general population in China between year 2009 and 2010].

OBJECTIVE: To evaluate the chromium (Cr) levels in blood and urine among general population in China between 2009 and 2010, and thereby to analyze its prevalent features. METHODS: From year 2009 to 2010, a total of 11 983 subjects of general population aged between 6 and 60 year-old were recruited from 24 districts in 8 provinces in eastern, central and western China mainland, by cluster random sampling method. The information about their living environment and health status were collected by questionnaire, and 11 983 blood samples and 11 853 urine samples were also collected. Inductively coupled plasma mass spectrometry (ICP-MS) was applied to test the Cr level both in blood and urine; and the Cr distribution in blood and urine among groups of population in different ages, genders and districts, were then analyzed. RESULTS: Among general population in China, the geometric mean (GM) of Cr concentration in blood was 1.19 µg/L, with median at 1.74 µg /L and 95% percentile at 5.59 µg/L. The Cr concentration in blood among males and females were separately 1.18 µg/L and 1.20 µg/L(P > 0.05); while its GM in the groups of population aged 6 - 12, 12 - 16, 16 - 20, 20 - 30, 30 - 45 and 45 - 60 years old were 1.00, 1.22, 1.01, 1.40, 1.27 and 1.30 µg/L (P < 0.01), respectively; and the figures in populations from eastern, central and western China were 1.00, 1.70 and 1.98 µg/L (P < 0.01), respectively. Among general population, the GM of Cr concentration in urine was 0.53 µg/L, with median was lower than 0.42 µg/L and 95% percentile at 3.53 µg/L. The Cr concentration in urine among males and females were separately 0.52 µg/L and 0.53 µg/L (P > 0.05);while its GM in the groups of population aged 6 - 12, 12 - 16, 16 - 20, 20 - 30, 30 - 45 and 45 - 60 years old were 0.56, 0.60, 0.52, 0.50, 0.52 and 0.46 µg/L (P < 0.01), respectively;and the figures in populations from eastern, central and western China were 0.58, < 0.42 and 0.60 µg/L (P < 0.01), respectively. CONCLUSION: The study reported the Cr levels in blood and urine among general population in China, and thereby provided basic data evidence for the following Cr biological monitoring studies in near future.

[The improvement of determination method of carbon disulfide in workplace air with gas chromatography].

OBJECTIVE: Establishment of determination method of carbon disulfide in charcoal tube with low toxicity solvents desorption-gas chromatography. METHODS: Four types of solvent with low toxicity are applied respectively as substitution of benzene to desorb the carbon disulfide in samples of charcoal tube. The signal strength and desorption efficiency of the detector are compared by using different solvents. RESULTS: Chloroform has been considered as the best alternative solvent of benzene. Carbon disulfide has a good linearity (R = 0.9997) over the concentration of 0 ∼ 54.7 µg/ml, detection limit can reach 0.2 µg/ml. When the sampling volume is 3.0 L, the minimum detectable concentration is 0.07 mg/m(3). CONCLUSION: With the use of chloroform, the health hazard to laboratory personnel and environment pollution as well as the costs of experiments are reduced.

[The optimization of 2-thiothiazolidine-4-carboxylic acid back extraction in urine and determination by HPLC].

OBJECTIVE: Establishment of determination method of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine with HPLC. METHODS: A volume of 0.5 ml hydrochloric acid (2 mol/L) and 0.5 ml pure water was added into 1 ml urine, and then extracted by 4 ml of diethyl ether by shaking for 2 min. Remove the water phase in a tube with plug and extract again, mix the two extraction diethyl ether together, take 4 ml by adding 2 ml borax-monopotassium phosphate buffer and shaking for 2 min to extract, then take the water phase to detect. A C(18) column and UV detector were used for separating and detecting. The wavelength was 273 nm, the flow rate was 1.0 ml/min, and the injection volume was 20 µl. RESULTS: TTCA has a good linearity (r = 0.9995) over the concentration of1 1 ∼ 10 µg and the minimum detectable concentration of TTCA in urine was 0.1 µg/ml. The within-day precision (RSD) were 8.4%, 3.0% and 1.7%, the between-day precision (RSD) were 11%, 3.8%, 1.9%, respectively. The extraction recovery were between 80% ∼ 102%. CONCLUSION: The method was accurate and sensitive to detect TTCA in urine.

[Effects of carbon disulfide on cardiovascular system of workers occupationally exposed to carbon disulfide].

OBJECTIVE: To study the effects of long-term exposure to carbon disulfide (SC(2)) on cardiovascular system of workers. METHODS: The concentrations of CS(2) were detected in the representative workshops with different exposure levels. The indicators related to cardiovascular system were tested in 633 workers occupationally exposed to CS(2), which included blood pressure, electrocardiogram, blood routine (blood RT), cholesterol (TCHO), triglyceride (TG) and so on. The data were analyzed by chi-square test and multiple logistic regression analysis. RESULTS: The exposure concentration of CS(2) for 389 workers was less than or equal to 5 mg/m(3), which for other 244 workers was higher than 5 mg/m(3). The maximum exposure concentration of CS(2) was 15.73 mg/m(3). There were no significant effects of CS(2) on the electrocardiogram, red blood cells, white blood cells, blood platelet, TCHO and TG of workers. However, the positive effects of CS(2) on blood pressure and negative effects of CS(2) on hemoglobin were found. The rates of high TCHO, TG and hypertension in male workers were significantly higher than those in female workers (P < 0.05). The rates of high TCHO, hypertension and sinus arrhythmia in older workers (≤ 30 years old) were significantly higher than those in young workers (> 30 years old) (P < 0.05). The rate of sinus arrhythmia in workers with 1 - 10 working years was significantly higher than that in workers with more than 10 working years (P < 0.05). The rate of hypertension in workers with 1 - 10 working years was significantly lower than that in workers with more than 10 working years (P < 0.05). CONCLUSION: There were no significant effects of CS(2) exposure on the indexes of cardiovascular system of workers.

[Carbon disulfide exposure level of workers in a chemical fiber industry].

OBJECTIVE: To investigate the exposure levels of carbon disulfide (CS(2)) for a chemical fiber industry. METHODS: The concentration of CS(2) was monitored in representative workshops and types of work, and the datas of that over the years were collected. RESULTS: The short-term exposure concentration of CS(2) about 80% of the type of work was less than or equal to 10 mg/m(3), which of more than 90% was less than or equal to 20 mg/m(3). The time weighted average concentration of CS(2) about 70% of the type of work was less than or equal to 5 mg/m(3), which of more than 90% was less than or equal to 10 mg/m(3). The short-term exposure concentration of CS(2) which was more than 15 mg/m(3) or the time weighted average concentration of CS(2) which was more than 30 mg/m(3) was only for little type of work. CONCLUSION: The concentration of CS(2) for the most type of work was lower, but there were still a number of types of work exposuring the higher concentration, which exceed the national occupational exposure limits.

[The rervising of biological exposure index for carbon disulfide exposuring].

OBJECTIVE: To study the biological exposure index of carbon disulfide in China. METHODS: High-performance liquid chromatography (HPLC) was used to detect the levels of 2-thiothiazolidine-4-carboxylic acid (TTCA) in the urine of the workers after working shift end, Gas chromatography was used to detect the concentrations of the carbon disulfide in the workplace air. The relationship between the urine TTCA levels and the concentrations of the carbon disulfide was analyzed, the biological exposure index and judgement result from PC-TWA were compared. RESULTS: The levels of TTCA in urine of workers occupationally exposed to carbon disulfide were closely and positively related with the concentrations of the carbon disulfide in the workplace air. The regression equation was Y = 0.265X - 0.165, The biological exposure index of carbon disulfide were calculated by regression equation according to occupational exposure limits of carbon disulfide in China. CONCLUSION: The biological exposure index of CS(2) in China might be revised for 1.2 mg/g Cr.

[The assessment of reliability and validity of musculoskeletal questionnaire].

OBJECTIVE: To evaluate the reliability and validity of musculoskeletal questionnaire. METHODS: A self-administered modified musculoskeletal questionnaire was used to investigate 12 098 workers from eight occupations, i.e. coal mining, petroleum, metallurgical, mechanical manufacturing, chemical, garment and railroad transportation industries and education. The Cronbach's α coefficient, analysis of covariance and multiple logistic regression were used to assess the reliability and validity of musculoskeletal questionnaire. RESULTS: The consistent test between total items of Musculoskeletal Questionnaire and each factor showed that the range of Cronbach's α was 0.52 ∼ 0.92, except from vibration factor, other Cronbach's α was more than 0.7. All 55 items of Musculoskeletal Questionnaire were subjected to factor analysis, and ten latent factors were identified, which explained 55.17% of the total variance. The potentially hazardous working conditions could be categorized into seven dimensions (force, dynamic load, static load, repetitive load, climate factors, vibration exposure and environmental ergonomic factor), which consisted with the theory model. The results of covariance analysis indicated that there were significant difference among 7 dimension indices in different jobs (P < 0.01). CONCLUSION: The modified Musculoskeletal Questionnaire is a valid and reliable tool for measuring musculoskeletal workload.

[The relationship between occupational stress and serum glycosylated hemoglobin A1c level].

OBJECTIVE: To explore the relationship between occupational stress and serum glycosylated hemoglobin A1c (HbA1c) level. METHODS: A cross-sectional epidemiological study was conducted in 115 dispatchers. The occupational stressors, personality, occupational strain and coping with stress were measured using Occupational Stress Instrument. Serum HbA1c levels were measured by stratigraphic analysis of cation exchange resin. RESULTS: Serum HbA1c level (6.63% ± 1.93%) in the shiftwork group was significantly higher than that (5.73% ± 1.57%) in the daily relay work group (P < 0.05). Spearman correlation analyses showed the positive correlation between type A behavior and serum HbA1c level (r = 0.221), the negative correlation between organizational commitment and serum HbA1c level (r = -0.218). Variance analyses revealed that serum HbA1c levels among high, middle and low job requirement groups and job control groups were significantly different (P < 0.05). There were significant differences of serum HbA1c levels among different type A behavior, internal control, susceptibility of stress and organizational commitment groups (P < 0.05). Stepwise regression analyses indicated that shiftwork affects obviously serum HbAlc level, internal control and job future were the predictors of serum HbA1c level (R2 = 0.082). CONCLUSION: Serum HbA1c may be a potential biomarker in field investigation of the effects of occupational stress.

[A study of the impact of occupational stress on sleep disorders among male freight train dispatchers].

OBJECTIVE: To explore tentatively the impact of occupational stress on sleep disorders. METHODS: ninety three male freight train dispatchers participated in this study (response rate 80.87%). Sleep disorders, occupational stressors, personalities, and occupational strain response were measured with questionnaires. RESULTS: Workers with high psychological demands, job stressors,depressive symptoms,physical symptoms, daily life stress, work locus of control had higher sleep disorders scores than their counterparts (P < 0.01 or P < 0.05), workers with high job control had lower sleep disorders scores than their counterparts (P < 0.05). Sleep disorders were positively related to psychological demands, job stressors, depressive symptoms, physical symptoms, daily life stress, state-anxiety, strait-anxiety, and susceptibility to stress (P < 0.01 or P < 0.05), but negatively to job control and mental health (P < 0.05). Low job control, depressive symptoms, daily life stress and meaningless job were risk factors of sleep disorders. CONCLUSION: The sleep disorders are associated with some aspects of occupational stress among male freight train dispatchers.

[Relationship between job satisfaction and occupational stress in the workers of a thermal power plant].

OBJECTIVE: To explore the relationship between job satisfaction and occupational stress in the workers of a thermal power plant. METHODS: The cluster sampling method was used to investigate 875 workers in a thermal power plant. The job satisfaction, occupational stressors, strains, personalities, meeting strategy and social support were measured using occupational stress instruments, job content questionnaire and effort-reward imbalance questionnaire. RESULTS: There were no significant differences of job satisfaction scores between different groups according to sex, educational level, marriage status, smoking and drinking (P > 0.05). But there were significant differences of job satisfaction scores between different age groups or between different service length groups (P < 0.01). The correlation analysis revealed that job satisfaction scores were related positively to responsibility for persons and things, promotion opportunity, job control, job stabilization, rewards, mental health, positive affectivity, self-esteem, superior support and coworker support scores (P < 0.05 or P < 0.01), negatively to role ambiguity and conflict, job future ambiguity, job demands, negative affectivity, depressive symptoms, patience, and mental locus of work control(P < 0.05 or P < 0.01). The results of variance analysis indicated that the job relationship, responsibility for persons and things, promotion opportunity, job control, job stabilization, reward, mental health, positive affectivity, self-esteem and buffer scores of the workers with high job satisfaction scores were significantly higher than those of workers with moderate and lower job satisfaction scores (P < 0.01), but the role ambiguity and conflict, job future ambiguity, job demands, and depressive symptoms scores and mental locus of work control of the workers with high job satisfaction scores were significantly lower than those of workers with moderate and lower job satisfaction scores (P < 0.05 or P < 0.01). The results of multivariate logistic regression analysis showed that the risk of job dissatisfaction for workers with low reward was about four times as high as that for workers with high reward (OR = 3.773), the risks of job dissatisfaction for workers with low social support and mental locus of external work control were about two times as high as that for workers with high social support or mental locus of internal work control (OR = 2.419 and 2.219, respectively). The daily life stress, low control strategy, low support strategy, low job control and negative affectivity were risk factors of job dissatisfaction (OR = 1.125 approximately 1.790), but the self-esteem and positive affectivity could reduce the risk of job dissatisfaction. CONCLUSION: Increasing the decision level, social support, meeting strategy and reward or decreasing the role conflict and ambiguity, demands and negative affectivity could improve worker's job satisfaction level.