Baseline survey of psychosocial factors levels and their health effects in a cohort study of natural gas field workers / 中华劳动卫生职业病杂志

Objective: To investigate the level of psychosocial factors in workplace and their health effects among workers in a natural gas field. Methods: A prospective and open cohort of natural gas field workers was established to study the level of workplace psychosocial factors and their health effects, with a follow-up every 5 years. In October 2018, a cluster sampling method was used to conduct a baseline survey of 1737 workers in a natural gas field, including a questionnaire survey on demographic characteristics, workplace psychosocial factors and mental health outcomes, physiological indicators such as height and weight, and biochemical indicators such as blood routine, urine routine, liver function and kidney function. The baseline data of the workers were statistically described and analyzed. The psychosocial factors and mental health outcomes were divided into high and low groups according to the mean score, and the physiological and biochemical indicators were divided into normal and abnormal groups according to the reference range of normal values. Results: The age of 1737 natural gas field workers was (41.8±8.0) years old, and the length of service was (21.0±9.7) years. There were 1470 male workers (84.6%). There were 773 (44.5%) high school (technical secondary school) and 827 (47.6%) college (junior college) graduates, 1490 (85.8%) married (including remarriage after divorce), 641 (36.9%) smokers and 835 (48.1%) drinkers. Among the psychosocial factors, the detection rates of high levels of resilience, self-efficacy, colleague support and positive emotion were all higher than 50%. Among the mental health outcomes evaluation indexes, the detection rates of high levels of sleep disorder, job satisfaction and daily stress were 41.82% (716/1712), 57.25% (960/1677) and 45.87% (794/1731), respectively. The detection rate of depressive symptoms was 22.77% (383/1682). The abnormal rates of body mass index (BMI), triglyceride and low density lipoprotein were 46.74% (810/1733), 36.50% (634/1737) and 27.98% (486/1737), respectively. The abnormal rates of systolic blood pressure, diastolic blood pressure, uric acid, total cholesterol and blood glucose were 21.64% (375/1733), 21.41% (371/1733), 20.67% (359/1737), 20.55% (357/1737) and 19.17% (333/1737), respectively. The prevalence rates of hypertension and diabetes were 11.23% (195/1737) and 3.45% (60/1737), respectively. Conclusion: The detection rates of high level psychosocial factors in natural gas field workers are high, and their effects on physical and mental health remain to be verified. The establishment of a cohort study of the levels and health effects of psychosocial factors provides an important resource for confirming the causal relationship between workplace psychosocial factors and health.

Occurrence pattern of musculoskeletal disorders and its influencing factors among manufacturing workers / 北京大学学报(医学版)

OBJECTIVE@#To explore the occurrence pattern and its influencing factors of multi-site work-related musculoskeletal disorders (WMSDs) of the main affected body sites among manufacturing workers.@*METHODS@#Musculoskeletal disorders questionnaire was adopted to investigate the prevalence of WMSDs and the influencing factors among workers from four manufacturing factories in China. The case of WMSDs was defined as the one who had symptoms such as pain, numbness, discomfort, or limitation of activities in one or more of the nine body sites, including neck, shoulder, elbow, wrist/hand, upper back, lower back, hip/thigh, knee and ankle/foot during the last year, which lasted for more than 24 hours and did not completely relieve after rest. Besides, trauma, disability, other acute injuries or sequelae were excluded. The correlation of WMSDs between different body sites was estimated by the prevalence ratio (PR) calculated by log-binominal model. The influencing factors of multi-site WMSDs of the main affected body sites were analyzed by multinomial logistic regression model.@*RESULTS@#The overall prevalence rate of WMSDs was 79.7% among the manufacturing workers. The main affected body sites were lower back, neck, shoulder and upper back, of which the prevalence rates were 62.3%, 55.7%, 45.6%, and 38.7%, respectively. The PR values of WMSDs among these sites were relatively high. The prevalence of multi-site WMSDs involving these four sites at the same time was 25.2%, and that of three to four sites was 41.4%. Multinomial Logistic regression analysis suggested that influencing factors of multi-site WMSDs in 3-4 sites of neck, shoulder, upper back and lower back involved several aspects. Among these factors, females (OR=2.86, 95%CI 2.38-3.33) and individuals with job tenure of 15-19 years (OR=1.87, 95%CI 1.49-2.34) might have higher risk of disease. Biomechanical factors, such as often bending neck forward or holding neck in a forward position for long periods (OR=2.15, 95%CI 1.86-2.48), often twisting neck or holding neck in a twisted position for long periods (OR=1.64, 95%CI 1.40-1.92) and often twisting trunk heavily (OR=1.40, 95%CI 1.20-1.64) might be risk factors. In the aspect of work organization, doing the same work every day (OR=1.73, 95%CI 1.44-2.08), shortage of workers (OR=1.50, 95%CI 1.31-1.71) and often working overtime (OR=1.38, 95%CI 1.20-1.60) might increase the risk of disease. Factors, such as often standing for long periods at work (OR=0.77, 95%CI 0.65-0.91) and feeling breaks sufficient (OR=0.51, 95%CI 0.44-0.59) were suggested to be protective factors with OR<1.@*CONCLUSION@#The pre-valence rates of WMSDs in neck, shoulder, upper back, and lower back were high among manufacturing workers in this study. The correlation of WMSDs of these four sites was close in this study, and the comorbidity rate of 3-4 sites of these sites was relatively high, suggesting that there might be a multi-site occurrence pattern of WMSDs in "neck-shoulder-upper back-lower back" among manufacturing workers. The main influencing factors of this pattern included individual factors, biomechanical factors and work organization factors.

The Effect of PCDH15 Gene Variations on the Risk of Noise-induced Hearing Loss in a Chinese Population / 生物医学与环境科学（英文）

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.

Clinicopathological analysis on mercury poisoning-associated nephritic syndrome / 中国职业医学

OBJECTIVE: To explore the clinicopathological characteristics and therapeutic approach for mercury poisoningassociated nephritic syndrome. METHODS: Clinical and pathological data of 9 patients diagnosed with mercury poisoningassociated nephritic syndrome were analyzed. RESULTS: Among the 9 cases,2 cases were mercury smelters,1 case was instrument production worker,1 case was traditional Chinese medicine preparation worker,4 cases were psoriasis treated by folk prescription of traditional Chinese medicine,and 1 case used cosmetics for whitening and freckle removal. All cases showed clinical manifestation of nephritic syndrome that included large amount of proteinuria,hypoalbuminemia,edema and hyperlipidemia. The concentrations of urine mercury in the patients were from 0. 09 to 0. 75 mg / L before treatment.Pathology examination on renal biopsy showed that there were 4 cases of minimal change nephropathy and 5 cases of membranous nephropathy at stage Ⅰ. The patients with nephritic syndrome were cured after mercury driving and treatment with corticosteroid. CONCLUSION: The kidney histopathology changes in patients with mercury poisoning-associated nephritic syndrome are primarily characterized by minimal change and membranous nephropathy. The mercury driving combined treatment with corticosteroid can completely relieve the clinical symptoms of the patients with mercury poisoningassociated nephritic syndrome.

Development of Job Burden-capital Model of Occupational Stress: An Exploratory Study / 生物医学与环境科学（英文）

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.

How Work Organization Affects the Prevalence of WMSDs: A Case-control Study / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>In this study, we aimed at exploring the association between work-related musculoskeletal disorders (WMSDs) and work organization based on a case-control study.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Evidence-based study of chromate exposed workers' health surveillance indexes / 中华预防医学杂志

<p><b>OBJECTIVE</b>The health surveillance proposal for chromate exposed workers was provided and analyzed on the evidence-based study and then to be improved.</p><p><b>METHOD</b>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.</p><p><b>RESULT</b>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) .</p><p><b>CONCLUSION</b>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.</p>

Co-effect of Demand-control-support model and effort-reward imbalance model on depression risk estimation in humans: findings from Henan Province of China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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).</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

The epidemiological characteristics and correlated factors of daily hassles for thermal power plant workers / 中华预防医学杂志

<p><b>OBJECTIVE</b>This study aimed to investigate the epidemiological characteristics and correlated factors of daily hassles among thermal power plant workers.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Distribution of chromium in whole blood and urine among general population in China between year 2009 and 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

The assessment of reliability and validity of musculoskeletal questionnaire / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To evaluate the reliability and validity of musculoskeletal questionnaire.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>The modified Musculoskeletal Questionnaire is a valid and reliable tool for measuring musculoskeletal workload.</p>

Effects of carbon disulfide on cardiovascular system of workers occupationally exposed to carbon disulfide / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of long-term exposure to carbon disulfide (SC(2)) on cardiovascular system of workers.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>There were no significant effects of CS(2) exposure on the indexes of cardiovascular system of workers.</p>

Carbon disulfide exposure level of workers in a chemical fiber industry / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the exposure levels of carbon disulfide (CS(2)) for a chemical fiber industry.</p><p><b>METHODS</b>The concentration of CS(2) was monitored in representative workshops and types of work, and the datas of that over the years were collected.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

The improvement of determination method of carbon disulfide in workplace air with gas chromatography / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>Establishment of determination method of carbon disulfide in charcoal tube with low toxicity solvents desorption-gas chromatography.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>With the use of chloroform, the health hazard to laboratory personnel and environment pollution as well as the costs of experiments are reduced.</p>

The optimization of 2-thiothiazolidine-4-carboxylic acid back extraction in urine and determination by HPLC / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>Establishment of determination method of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine with HPLC.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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%.</p><p><b>CONCLUSION</b>The method was accurate and sensitive to detect TTCA in urine.</p>

The rervising of biological exposure index for carbon disulfide exposuring / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the biological exposure index of carbon disulfide in China.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The biological exposure index of CS(2) in China might be revised for 1.2 mg/g Cr.</p>

Effect of occupational combined exposure of chromium and iron on erythrocyte metabolism / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of combined occupational exposure of chromium and iron on erythrocyte metabolism, and the possible mechanism.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>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.</p>

Risk factors of low back pain among the Chinese occupational population: a case-control study / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To explore the risk factors of low back pain among the Chinese occupational population in several major industries.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

A study of the impact of occupational stress on sleep disorders among male freight train dispatchers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore tentatively the impact of occupational stress on sleep disorders.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The sleep disorders are associated with some aspects of occupational stress among male freight train dispatchers.</p>

Association between occupational stress and musculoskeletal disorders in lower extremity / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the relationship between occupational stress and musculoskeletal disorders in lower extremity.</p><p><b>METHODS</b>The cross-sectional study was used to investigate 5338 workers in 13 factories and companies for prevalence of musculoskeletal disorders in lower extremity, working postures and occupational stress were investigated with questionnaires for past year. Perceived occupational stress was evaluated by the Chinese version of the Job Content Questionnaire (JCQ) and Effort-Reward Imbalance (ERI) Model Questionnaire. Logistic regression analyses were conducted to estimate the associations between occupational stress and prevalence of musculoskeletal disorders in lower extremity.</p><p><b>RESULTS</b>In the main dimensions of job strain and ERI model, physical demands and effort were risk factors of hip disorders, but job control was a protective factor of hip disorders. When job strain and ERI model scales were analyzed simultaneously, only physical demands were risk factor of hip disorders. When job strain and the effort-reward imbalance were computed by creating four independent categories, job strain was a risk factor of hip disorders, ERI was a risk factor of hip and knee disorders. The risk of imbalance between job strain and effort-reward the protective effect of job control increased with the disorder regions. According to continuous variable analysis, job strain by calculated with physical demands was risk factor of hip disorders, continuous ERI variable was risk factor of hip and knee disorders.</p><p><b>CONCLUSION</b>Occupational stress is associated significantly with musculoskeletal disorders in lower extremity. The control of occupational stress and increase of job control should be considered for preventing the musculoskeletal disorders in lower extremity.</p>