Occupational stress and its influencing factors of primary health care workers during COVID-19 / 环境与职业医学

Background Since the outbreak of COVID-19, primary health care workers have been facing unprecedented work pressure, and their occupational stress should be taken seriously. Objective To analyze the occupational stress situation and its influencing factors of primary health care workers in Guangdong Province, and to propose targeted interventions. Methods Using a multi-stage stratified random sampling method, each prefecture-level city in Guangdong Province was classified into "good", "medium", or "poor" category based on its gross domestic product (GDP) in 2019 released by the Guangdong Provincial Bureau of Statistics. In September 2021, four primary health care institutions were randomly selected from each stratum, and a total of 1327 staff members were selected for the study. The Core Occupational Stress Scale (COSS) and a basic information questionnaire designed by the authors were used. Mann-Whitney U test was used to compare the means between two groups, and Kruskal-Walis H test was used to compare the means among multiple groups. The comparison of categorical data was performed by trend χ2 test or Pearson χ2 test; the analysis of factors influencing occupational stress was performed by dichotomous multiple logistic regression analysis. Results There were 365 health care workers reporting occupational stress in this survey, and the positive rate of occupational stress was 27.5%. The total occupational stress score in M (P25, P75) and the scores of social support, organization and reward, demand and effort, and control were 45.0 (40.0, 50.0), 20.0 (17.0, 21.0), 14.0 (12.0, 17.0), 12.0 (10.0, 15.0), and 5.0 (4.0, 6.0), respectively. The results of dichotomous multiple logistic regression analysis showed that high education, low income, doctor positions, long working hours in a day, and shift work were associated with the occurrence of reporting occupational stress (P<0.05). Conclusion Education, average monthly income, job category, daily working hours, and shifts are factors influencing the occurrence of reporting occupational stress in primary health care workers; targeted interventions should be implemented to reduce their occupational stress levels.

Local muscle load and fatigue of simulated high-voltage cable climbing task of operation inspection personnel by surface electromyography / 环境与职业医学

Background Climbing pylons during high-voltage cable maintenance is not only a labor-intensive task, but also a challenge bringing about heat stress and mental pressure from working at height, which may lead to accumulation of muscle fatigue and work-related musculoskeletal disorders. Objective To record the local muscle fatigue during a simulated climbing task by high-voltage cable electricians based on surface electromyography (sEMG) signals, explore the characteristic changes in sEMG signals and their relationship with subjective fatigue evaluation of the task, and provide data support for developing task specific objective assessment tools for local muscle fatigue and prevention of work-related musculoskeletal disorders. Methods Ten male college students were recruited to conduct a test of a simulated pylon climbing task. The climbing distance was 60 m, and a task segment was set for every 20 m (about 100 s), recorded as T1, T2, and T3, respectively. After completing each task segment, the subjects were required to rate their subjective fatigue using the Borg's RPE Scale. Fatigue was defined by rating of perceived exertion (RPE) score ≥ 14 in this study. The sEMG signals of trapezius, erector spinae, rectus femoris, and gastrocnemius muscles were recorded wirelessly. The standardized maximal voluntary electrical activation (MVE) obtained by standardizing the root mean square (RMS) of the time domain index and the median frequency (MF) of the frequency domain index were estimated for the recorded sEMG signals, and joint amplitude and spectrum analysis (JASA) was used to evaluate local muscle fatigue of target muscles involving in the climbing task. Results The RPE scores of T1, T2, and T3 were 11.9, 15.3, and 17.4, respectively. Subjective fatigue was found in T2 and T3 but not in T1. With the extension of climbing time, the MVE values of left and right erector spinae muscles, left and right rectus femoris, and right gastrocnemius muscle increased gradually, while the MVE values of left and right trapezius muscles and left gastrocnemius muscle increased first and then decreased. The MF values of left and right rectus femoris increased at first, then remained unchanged, while the MF values of the other muscles remained basically unchanged. In T1, three muscles, including left trapezius muscle and both side of erector spinae muscles, showed fatigue; in T2, five muscles, including both sides of erector spina muscles, right trapezius muscle, and both sides of gastrocnemius muscle appeared fatigue; in T3 , except for left rectus femoris, the other seven muscles were fatigue. Conclusion The characteristic changes of electromyography signals in the simulated climbing task are not completely consistent with the typical amplitude increase and left shift of the frequency spectrum of sEMG signals in static tasks, indicating that the application of time-domain and frequency-domain analysis methods in the evaluation of muscle fatigue in climbing tasks needs further discussion. Trapezius muscles and erector spinae muscles are the first to show fatigue in the simulation, and may be the sensitive muscle groups of muscle fatigue associated with climbing movement. Compared with subjective evaluation, surface electromyography is more sensitive in the assessment of body fatigue. Fatigue is reported about 100 s of climbing (the climbing length is about 20 m).

Effect of long working hours on work-related musculoskeletal disorders among operation and maintenance workers of power supply enterprises / 环境与职业医学

Background Long working hours is harmful to the physical and mental health of occupational groups, and should receive active attention. Objective To evaluate the current status of long working hours among operation and maintenance workers of power supply enterprises, and explore its effects on work-related musculoskeletal disorders (WMSDs) of the population. Methods From March to June 2021, a cross-sectional survey was conducted among 1433 operation and maintenance workers from 10 power supply enterprises in Jilin Province, Shandong Province, and Tianjin Municipality using cluster sampling. A total of 1433 copies of revised Mus-culoskeletal Disorders Questionnaire were distributed, 1343 questionnaires were recovered, and the recovery rate was 93.72%. The questionnaire included general information, personal health behaviors, weekly working hours, work-related factors, and musculoskeletal pain or discomfort in nine body parts in the past 12 months. χ2 test and multiple logistic regression models were used to investigate the relationships between long working hours (>40 h per week) and WMSDs. Results The average age of the workers was (39.42±9.89) years, and the average work experience was 11.00 (5.00, 21.00) years. There were 1158 males (86.22%) and 185 females (13.78%). The average weekly working hours of the workers were (47.98±11.35) h, and the proportion of long working hours (>40 h per week) was 61.06% (820/1343). The proportions of long working hours were higher among the workers with characteristics of male, power distribution, shift work, often/very often long-time standing, often/very often holding awkward postures, often handling heavy objects, limited space to operate, long-time neck tilting backward, keeping arms above shoulders, frequent elbow bending, repeating knee movement every minute, and repeating lower limb or foot movement every minute (all P<0.05). The prevalence rate of WMSDs was 81.53% (1095/1343) among the workers. The results of multiple logistic regression showed that after adjusting education, smoking, exercise, awkward postures, often handling heavy objects, limited space to operate, long-time heavy trunk bending, long-time neck tilting backward, and keeping arms above shoulders, compared with working ≤40 h per week, the risk of WMSDs among workers working >49 h per week was higher (OR=1.406, 95%CI: 1.011-1.955). Conclusion Long working hours is prominent among operation and maintenance workers of power supply enterprises, and increases the risk of reporting WMSDs.

Association between wrist pain and awkward postures among workers in 10 key industries / 环境与职业医学

Background Prolonged awkward postures during occupational activities can lead to excessive musculoskeletal load on the wrist of workers and symptoms such as wrist pain or discomfort. Objective To survey the prevalence of wrist pain among workers in 10 key industries and analyze its correlation with wrist working postures. Methods By using stratified cluster sampling method, workers from 10 key industries, such as footwear manufacturing industry, shipbuilding manufacturing industry, and automobile manufacturing industry, were selected from seven regions in North China, East China, Central China, South China, Southwest China, Northwest China, and Northeast China. The demographic information, wrist working postures, pain in wrist of the workers were collected through a cross-sectional survey. Pearson χ2 test was used to compare prevalence by selected factors, trend χ2 test for between group comparison, and unconditional logistic regression models for the association of wrist working postures with wrist pain. Results There were 64052 workers enrolled in this survey, and 56286 provided valid questionnaires (the effective rate was 87.8%). According to the survey, the prevalence of wrist pain was 23.3% (13112/56286), and the industries with higher prevalences were footwear manufacturing (27.1%, 1927/7106), automobile manufacturing (24.9%, 5378/21560), and shipbuilding and related equipment manufacturing (24.4%, 850/3488) industries. Finger pinching (OR=2.09, 95%CI: 1.95-2.24), frequent wrist bending (OR=2.03, 95%CI: 1.92-2.15), fixed wrist bending (OR=1.77, 95%CI: 1.69-1.85), wrist on hard edge (OR=1.34, 95%CI: 1.28-1.40), and arms over shoulders (OR=1.11, 95%CI: 1.05-1.17) increased the risk of reporting wrist pain. Conclusion Awkward postures are related to wrist pain among workers in selected 10 key industries. The related factors are wrist on hard edge, frequent wrist bending, finger pinching, fixed wrist bending, and arms over shoulders.

Neck and shoulder pain among operation and maintenance workers of selected power supply enterprises / 环境与职业医学

Background Power grid is a basic industry of national economy. The occupational health problems among operation and maintenance workers in this industry have become increasingly prominent in recent years, and they should receive enough attention. Objective To estimate the prevalence of work-related musculoskeletal disorders (WMSDs) of neck and shoulder among operation and maintenance workers of power supply enterprises, and analyze related influencing factors. Methods From March to June 2021, a total of 1433 operation and maintenance worker from 10 power supply enterprises in three provinces of North China were selected as research subjects using cluster sampling method. A revised Musculoskeletal Disorders Questionnaire was used to investigate the prevalence and ergonomic factors of neck and shoulder pain in the past year. χ2 test and logistic regression model were used to explore influencing factors of neck and shoulder pain among operation and maintenance workers. Results A total of 1343 valid questionnaires were recovered and the effective recovery rate was 93.72%. The neck pain prevalence was 66.0% (886 cases) and the shoulder pain prevalence was 54.1% (727 cases). The multiple logistic regression analysis results showed that often/very often long-time sitting (OR=1.864, 95%CI: 1.236-2.811; OR=1.659, 95%CI: 1.091-2.524), sometimes holding awkward postures (OR=1.695, 95%CI: 1.294-2.219; OR=1.596, 95%CI: 1.218-2.092), often/very often holding awkward postures (OR=2.416, 95%CI: 1.618-3.607; OR=2.058, 95%CI: 1.405-3.015), long-time slight neck tilting forward (OR=1.327, 95%CI: 1.023-1.722; OR=1.571, 95%CI: 1.221-2.022), long-time elbows bending (OR=1.327, 95%CI: 1.023-1.722; OR=1.506, 95%CI: 1.112-2.040) and department or team staff shortages (OR=1.578, 95%CI: 1.153-2.161; OR=1.831, 95%CI: 1.320-2.539) were associated with higher neck and shoulder pain prevalence rates. While exercise (OR=0.630, 95%CI: 0.492-0.809; OR=0.707, 95%CI: 0.557-0.899) was associated with lower neck and shoulder pain prevalence rates. Doing same work every day (OR=1.704, 95%CI: 1.305-2.225) was associated with a higher neck pain prevalence rate. Awkward postures with ineffectual force (OR=1.808, 95%CI: 1.226-2.665) and often keeping arms above shoulders (OR=1.424, 95%CI: 1.017-1.992) were associated with a higher shoulder pain prevalence rate. Conclusion The prevalence rates of neck and shoulder pian are high among operation and maintenance workers of power supply enterprises in selected three provinces of North China, and the main associated factors include individual factors, awkward work postures, and labor organization.

Prevalence of work-related musculoskeletal disorders and its influencing factors among workers involving climbing task in power supply enterprises / 环境与职业医学

Background Operation and maintenance work in the power grid industry often involving climbing, manual handling, and poor postures causing serious problems like work-related musculoskeletal disorders (WMSDs). The influencing factors of WMSDs are not very clear, but the problem has been widely concerned in this industry. Objective To understand the prevalence and influencing factors of WMSDs among climbing task-involved workers in power supply enterprises. Methods Using a cross-sectional design, a total of 702 workers involving climbing task from 10 power supply enterprises in Jilin Province, Tianjin Municipality, and Shandong province were selected as study subjects using cluster sampling. The Musculoskeletal Disorders Questionnaire which was revised by Lei Yang was used to estimate the prevalence and identify related factors of WMSDs. \begin{document}$ {\chi

Work-related musculoskeletal disorders and their prevention and control / 环境与职业医学

Work-related musculoskeletal disorders (WMSDs) are chronic and cumulative disorders that are affected by multiple ergonomic factors. They are widespread in occupational populations and have a high prevalence. They have caused a substantial economic and social burden, which has become a major occupational health problem worldwide. The mechanism of WMSDs needs to be clarified. More authoritative and unified diagnostic criteria and specific therapeutic drugs are required. Therefore, an in-depth epidemiological investigation on WMSDs involving occupational ergonomics is of great scientific value and practical significance, which aims to improve hazard identification and ergonomic load risk assessment and to facilitate the prevention, control, and intervention of WMSDs. This article introduced the concept, status report, risk factors, ergonomic assessment methods, and preventive measures of WMSDs. This special column on "occupational ergonomics and work-related musculoskeletal disorders" presented the prevalence and related risk factors of WMSDs in different industries, as well as working condition simulation studies for specific tasks, aiming to provide objective and detailed scientific data for the prevention and control of WMSDs.

Metabolomics study of rat tail vibration model / 环境与职业医学

Background The metabolites and metabolic pathways of hand-arm vibration syndrome have not yet been elucidated. Objective To investigate the effect of local vibration on endogenous metabolites in rat serum by metabolomic analysis, to preliminarily explore the potential metabolic pathway of endogenous metabolites, so as to provide evidence for further research on the mechanism of hand-arm vibration syndrome. Methods Thirty-two SPF male SD rats, (211.3±11.1) g, 7−8 weeks of age, were selected and randomly divided into three groups: control group (14 rats, without vibration), 7 d vibration group (9 rats, continuously vibration for 7 d), and 14 d vibration group (9 rats, continuous vibration for 14 d). The vibration rats were vibrated every day for 4 h, the frequency weighted acceleration was 4.9 m·s−2, the vibration frequency was 125 Hz, and the vibration direction was one-way vertical vibration. The control group had the same conditions except not contacting vibration. After the vibration exposure, the blood samples taken from the abnormal aorta of rats were collected, and the changes of rat serum metabolome were analyzed by ultra-performance liquid chromatography-tandem time-of-flight mass spectrometry. Principal components analysis (PCA) was used to explore changes in rat serum metabolic profile, and orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to screen out differential metabolites. Combined with online databases, a metabolic pathway enrichment analysis of differential metabolites was performed. Results The PCA analysis showed that compared with the control group, the rat serum metabolic profiles in the 7 d group and the 14 d group were clearly differentiated, and the rat serum metabolic profiles in the 7 d group and the 14 d group partially overlapped. The OPLS-DA analysis showed significant differences between groups. The main parameters were: model interpretation rate R2Y=0.914, model predictive ability Q2=0.58. The OPLS-DA analysis screened out 26 and 119 differential metabolites from the 7 d group and the 14 d group respectively, and there were 24 common differential metabolites between the 7 d group and the 14 d group. The metabolomic pathway analysis showed that local vibration-induced changes in rat serum metabolism were mainly related to arachidonic acid metabolism in the 14 d group, among which the metabolites with significant effects were arachidonic acid, prostaglandin E2, and prostaglandin D2. Conclusion Local vibration could affect the normal metabolism in rats, and the metabolic pathway with significant influence is arachidonic acid metabolism after a 14 d exposure and the involved metabolites are arachidonic acid, prostaglandin E2, and prostaglandin D2.

Expression changes of prostacyclin and thromboxane in blood of rats with tail vibration / 环境与职业医学

Background Long-term exposure to hand-transmitted vibration can lead to hand-arm vibration syndrome, one manifestation of which is impaired peripheral blood circulation in the arms. Altered expressions of prostacyclin I2 (PGI2) and thromboxane A2 (TXA2) in blood may be one of the important mechanisms of vibration-induced hand-arm vibration syndrome. Objective To reveal the effects of rat tail vibration on the expressions of PGI2 and TXA2 in plasma, and to establish the correlation between the change of rat plasma PGI2 to TXA2 ratio and rat tail vibration. Methods Fifty SPF-grade male SD rats were randomly divided into five groups: control group, 1 d exposure group, 3 d exposure group, 7 d exposure group, and 14 d exposure group, with 10 rats in each group. The rats were placed in rat immobilizes on a immobilization table, and the rats' tails were connected to a shaker and fixed with medical tape. There was no overlap between the immobilizes and between the rats' tails by no contact between the immobilization table and the shaker. The exposure dose was 125 Hz, 5.9 m·s−2, 4 h·d−1, and the vibration direction was linear vertical vibration. Abdominal aortic blood was taken at the end of vibration exposure, and the expressions of PGI2, TXA2, and their hydrolysates 6-keto-prostaglandin F1α (6-keto-PGF1α) and thromboxane B2 (TXB2) were measured by enzyme-linked immunosorbent assay, and the 6-keto-PGF1α/TXB2 values were calculated. Spearman rank correlation was used to analyze whether the expression of vascular factors correlated with the accumulated time of vibration. Results The expression levels of plasma 6-keto-PGF1α were (896.12±124.37), (1068.13±119.41), (1215.26±122.64), and (1317.94±106.54) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (830.60±109.47) ng·L−1 (P<0.001). The PGI2 expression levels were (86.49±2.40), (107.90±2.65), (114.02±2.16), and (126.95±1.94) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, all higher than (60.09±2.11) ng·L−1 in the control group (P＜0.001). The expression levels of TXB2 were (132.14±4.10), (145.52±4.09), (179.91±4.98), and (204.10±3.22) ng·L−1 in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (106.08±3.26) ng·L−1 (P<0.001). The expression levels of plasma TXA2 were (211.99±3.24), (236.33±3.88), and (245.45±4.23) ng·L−1 in rats in the 3 d, 7 d, and 14 d groups, respectively, which were all elevated compared with (174.79±4.19) ng·L−1 in the control group (P<0.001). Compared with the control group, the 6-keto-PGF1α/TXB2 values were decreased in the 7 d and 14 d groups (P<0.05). The 6-keto-PGF1α, PGI2, TXB2, and TXA2 expressions were positively correlated with vibration accumulation time (r=0.84, 0.84, 0.80, 0.84, P<0.001) and the 6-keto-PGF1α/TXB2 values were negatively correlated with vibration accumulation time (r=-0.24, P=0.003). Conclusion Local exposure of rat tail to vibration could increase the expressions of PGI2 and TXA2 in blood, and the elevated expressions show a dose-effect relationship with the duration of vibration exposure, but the PGI2/TXA2 tends to decrease with the accumulation of vibration exposure.

Effects of vibration on expressions of vascular endothelial inflammatory factors and IncRNA MEG3 in vitro / 环境与职业医学

Background Prolonged exposure to vibration can cause vascular endothelial injury, and inflammatory response plays an important role in vascular endothelial injury. Studies have shown that long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) is involved in regulating the expression of inflammatory injury of endothelial cells. Objective To investigate the effects of vibration on the secretion of inflammatory factors and the expression of IncRNA MEG3 by vascular endothelial cells in vitro. Methods Human umbilical vein endothelial cells (HUVEC) were divided into two categories: vibration and control. The vibration exposure included 63 Hz (6.76 m·s−2), 200 Hz (5.08 m·s−2), and 250 Hz (4.56 m·s−2) frequency bands, and 1 and 2 d exposure time with 1 to 4 h of daily vibration. The control treatment was the same as the vibration category except that they were not exposed to vibration. CCK-8 was used to detect the effects of different vibration frequencies and time on the viability of HUVEC. The expression levels of tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), interleukin-4 (IL-4), and interleukin-10 (IL-10) in the cells and supernatants were detected by enzyme-linked immunosorbent assay. The expression levels of IncRNA MEG3 were detected by real-time fluorescence quantitative PCR. Results Compared with the cells with the control treatment, the cell viability of the 1-day exposure group increased after 1.5 h and 3 h of vibration at 63 Hz, while decreased after 2 h and 2.5 h; the cell viability of the 2-day exposure group increased at the frequency of 63 Hz for 1.5 h, but decreased at 2 h and 2.5 h. At the frequency of 200 Hz, the cell viability of the 1-day exposure group increased at 2 h and 4 h, but decreased at 2.5 h and 3 h; the cell viability of the 2-day exposure group increased at 1.5 h and decreased at 2.5 h. For the vibration exposure at frequency of 250 Hz, the cell viability of the 1-day exposure group increased at 1.5 h and 2.5 h, but decreased at 3 h; of the 2-day exposure group, the cell viability increased at 1.5 h and decreased at 3 h. For the exposure settings of 63 and 200 Hz vibration for 2.5 h and 250 Hz vibration for 3 h, and with the control treatment as reference, the expression levels of TNF-α, IL-8, IL-4, and IL-10 in cells and supernatants were increased in the 1 d and 2 d exposures; the expression level of lncRNA MEG3 decreased in the 1 d exposure group; however, for the 2 d exposure, the expression level of lncRNA MEG3 decreased only in the 63 Hz vibration exposure. All of these results were statistically significant (P<0.05). Conclusion Vibration could induce an increase in the levels of inflammatory factors TNF-α, IL-8, IL-4, and IL-10 and a decrease in the expression level of lncRNA MEG3 in vascular endothelial cells in vitro.

Correlation between hand-arm vibration disease and vasoactive factors / 环境与职业医学

Background Hand-arm vibration disease (HAVD) is a chronic progressive disease caused by long-term exposure to hand-transmitted vibration, but the mechanism by which vibration affects peripheral vascular function of fingers is not completely clear. Objective To study the association between vasoactive factors and HAVD, and to screen specific indicators for its early diagnosis and prevention. Methods Judgmental sampling method was used to select workers with (HAVD group) and without HAVD (vibration contact group), and non-hand-transmitted vibration operation workers (control group), with 60 workers in each group. The levels of leukotriene B4 (LTB4), vascular endothelial growth factor (VEGF), 5-hydroxy tryptamine (5-HT), interleukin-1β (IL-1β), and calcitonin gene-related peptide (CGRP) in plasma of the three groups were measured by enzyme-linked immunosorbent assay. The association between vasoactive factors and HAVD was analyzed using logistic regression, and the diagnostic HAVD indicators were screened by receiver operator characteristic (ROC) curve of a multivariate model indicator \begin{document}$ \widehat{Y} $\end{document}. Results The hand symptom rates of the HAVD group, the vibration contact group, and the control group were 26.7%, 66.7%, and 96.7% respectively, with a significant difference (P<0.05). The levels of LTB4, 5-HT, IL-1β, and CGRP in the HAVD group were the highest followed by the vibration contact group, and lowest levels were in the control group (P<0.05). There was no significant difference in the VEGF level among the three groups (P>0.05). The logistic regression results showed that higher levels of LTB4 (OR=1.048, 95%CI: 1.022-1.076), 5-HT (OR=1.011, 95%CI: 1.004-1.018), IL-1β (OR=1.148, 95%CI: 1.071-1.230), and CGRP (OR=1.055, 95%CI: 1.008-1.104) were associated with a higher risk of HAVD (P<0.05). The order of the potential indicators' area under the ROC curve from high to low was:\begin{document}$ \widehat{Y} $\end{document} (0.969) > IL-1β (0.907) > LTB4 (0.876) > 5-HT (0.858) > CGRP (0.836). Conclusion The expression levels of LTB4, 5-HT, IL-1β, and CGRP are altered with occupational exposure in hand-transmitted vibration operations and may be associated with HAVD; VEGF is not found to be associated with HAVD. The accuracy of early screening for HAVD can be improved by combining the monitoring of various biochemical indicators.

Peripheral circulation and peripheral nerve injury in workers exposed to vibration at two different frequencies / 环境与职业医学

Background Hand-arm vibration disease is harmful to human body, but there are no effective diagnosis and treatment so far, and current occupational exposure limits underestimate the health damage caused by high-frequency vibration exposure. Objective To evaluate and compare the damage to workers' peripheral circulation and peripheral nerve caused by different frequencies of vibration operation. Methods Drilling workers (n=187) from a mining company in Shandong Province and golf club head grinding workers (n=228) from a sports equipment factory in Guangdong Province were selected as study subjects. Hand symptoms were investigated. SV106 vibration meter was used to measure the target operation-associated vibration frequency spectrum. The 8 h energy-equivalent frequency weighted acceleration, cumulative vibration exposure level (CVEL), and the working age related to causing white finger in 10% of an exposed group were calculated. Result The study subjects were all male. More grinding workers reported hand symptoms than the drilling workers, e.g. peripheral circulation injury (52.6% vs 19.3%), peripheral nerve injury (71.5% vs 23.0%), hand stiffness (64.0% vs 7.0%), and deformed fingers (69.7% vs 4.3%) (all P<0.001). The main vibration frequencies of grinding operation (500-800 Hz) were much higher than those of drilling operation (125~160 Hz). CVEL and working age of vibration exposure showed a linear rising relationship with the cumulative prevalence rate of peripheral circulation and peripheral never injury, the fitting lines all showed good fitting effects (R2=0.812-0.988), and the slope of the fitting line of the grinding workers was larger than that of the drilling workers. The working age of vibration exposure associated with 10% cumulative prevalence of white finger was shorter in the grinding workers than in the drilling workers (6.81 years vs 10.27 years). According to the ISO prediction formula, the working age of vibration exposure was associated with 10% white finger prevalence shorter in the drilling workers than in the grinding workers (3.12 years vs 8.23 years). Conclusion Both the vibration exposure level and the prevalence of hand symptoms are high in two groups of workers with different vibration frequencies, and vibration exposure at a higher frequency tends to have severer damage to workers' hands.

Epidemiological analysis of jellyfish stings in coastal bathing beaches in Qinhuangdao City from 2017 to 2019 / 中华危重病急救医学

Objective:To analyze the distribution and composition characteristics of jellyfish stings in various coastal baths in Qinhuangdao City from 2017 to 2019, and to provide scientific basis for the prevention, control and early warning of jellyfish stings.Methods:Statistics and analysis of the age, gender, time of stings, location of injury, first symptoms, and playing time in the sea at the time of the sting, etc. of people with jellyfish stings in various bathing beaches along the coast of Qinhuangdao from 2017 to 2019 (July to August) were conducted.Results:The number of jellyfish stings in the coastal bathing beaches of Qinhuangdao City in 2017, 2018, and 2019 was decreasing year by year, with 1 890, 492, and 171 cases respectively. Among them, Qianshuiwan Bathing Beach and Dongshan Bathing Beach had more stings (60.90% and 35.08% respectively in 2017, 24.39% and 64.23% respectively in 2018, 16.96% and 16.42% respectively in 2019). There was no significant change in the gender and age distribution of jellyfish stings each year [57.99% males in 2017, with a median age of 13 (8, 31) years old; 63.21% males in 2018, with a median age of 25 (8, 29) years old; and 59.65% males in 2019, with a median age of 12 (7, 31) years old]. Stings were mainly located at the lower limbs (the proportion of lower limb injuries: 46.54% in 2018, 45.61% in 2019), followed by upper limbs (upper arm, elbow, forearm), trunk, etc. The first symptom was mainly pain (89.43% in 2018, 38.29% in 2019), followed by rash (64.43% in 2018, 59.43% in 2019), numbness, blisters, etc. Sting incidents mainly occurred from 13:00 to 17:59 (the proportion of sting incidents in this time period in 2018 and 2019 were 68.09% and 52.63%, respectively).Conclusions:Jellyfish stings in coastal baths in Qinhuangdao City are mainly distributed in Qianshuiwan Baths and Dongshan Baths. The management of these sea areas should be strengthened, and scientific publicity and medical rescue should be strengthened to prevent jellyfish stings in peak hours and related baths.

Effects of laser radiation on the subjective symptoms of eyes / 中国职业医学

OBJECTIVE: To investigate the subjective symptoms of eyes induced by laser radiation in workers and its related influencing factors. METHODS: A total of 82 workers exposed to laser radiation were taken as exposure group, and 71 workers without laser radiation exposure as control group by judgment sampling method. The questionnaire survey and subjective symptoms of eyes were surveyed in these two groups. The work-site surveys of laser radiation job posts and laser irradiation testing were conducted to evaluate the exposure level of laser radiation on each post. The basic eye use and eye discomfort symptoms were investigated. RESULTS: The median of the laser radiation in 12 workplaces was 2.18×10~(-5) W/cm~2, and it was below occupational exposure limit(2.22×10~(-3) W/cm~2). The total detection rate of subjective discomfort of eyes in the exposed group was significantly higher than that in the control group(35.4% vs 15.5%, P<0.05). The results of multivariate logistic regression analysis indicated that laser exposure and smoking were the risk factors of subjective symptoms of eyes(P<0.05). CONCLUSION: Laser radiation operation has the risk of causing the subjective symptoms of eyes in exposed workers.

Inter-laboratory comparison result analysis of noise measurement in simulated workplace in three years / 中国职业医学

OBJECTIVE: To analyze the influence of noise measuring skills by continuous inter-laboratory comparison among occupational hygiene technical service organizations. METHODS: The results of 68, 55 and 50 occupational hygiene technical service organizations(reference organizations) participating in the inter-laboratory comparison of workplace noise measurement in 2014, 2017 and 2018 respectively were collected. The measurement operation and the calculation of equivalent sound level were evaluated according to the GBZ/T 189.8-2007 Measurement of Physical Agents in Workplace--Part 8: Noise.The measured results were analyzed by z score evaluation method. RESULTS: The results of noise measurement field operation of the reference organizations in the year 2014, 2017 and 2018 show that the accuracy rates of instrument setting was 89.7%, 98.2% and 100.0%, the accuracy rates of measuring position were 52.9%, 81.8% and 94.0%, the accuracy rates of sound level meter holding were 54.4%, 80.0% and 92.0%, the accuracy rates of microphone pointing were 98.5%, 98.2% and 94.0%, and the accuracy rates of noise type recognition were 83.8%, 92.7% and 84.0%, respectively. Among them, the accuracy of instrument setting, measurement position and sound level meter holding showed an increasing trend year by year(P<0.01). The pass rates of measurement results were 91.2%, 94.5% and 88.0% in 2014, 2017 and 2018 respectively. The pass rates of equivalent sound level calculation were 73.5%, 92.7% and 88.0%. The pass rates of comprehensive evaluation were 70.6%, 89.1% and 80.0% respectively. Among them, the pass rates of equivalent sound level calculation and comprehensive evaluation in 2017 were higher than that in 2014(P<0.017). There was no significant difference in the three-year comprehensive assessment total pass rate between private organizations and non-private organizations(84.0 % vs 75.5%, P>0.05). There was no significant difference in the total pass rate of three-year comprehensive evaluation between non-Pearl-River-Delta organizations and Pearl-River-Delta organizations(70.3% vs 81.6%, P>0.05). CONCLUSION: Continuous inter-laboratory comparison in occupational hygiene technical service organizations is beneficial to improve on-site noise measure capability.

Effects of hand-transmitted vibration on subjective symptoms in mine drilling workers / 中国职业医学

OBJECTIVE: To investigate the effect of hand-transmitted vibration on the subjective symptoms of mine drilling workers. METHODS: A total of 117 mine drilling workers exposed to hand-transmitted vibration were selected as the exposure group, and 46 workers without hand-transmitted vibration exposure were selected as control group by judgment sampling method. The Occupational Epidemiology Questionnaire of Mine Drilling Workers was used to investigate their subjective symptoms. RESULTS: The prevalence of tinnitus, hearing loss, cough and sputum in the exposure group was higher than that in the control group(P<0.05). The occurrence rate of numbness, tingling, self-reported white fingers and cold hands in the exposure group was higher than that in the control group(P<0.05). The total rate of symptoms of hand in the exposure group was higher than that in the control group(38.5% vs 21.7%, P<0.05). The multivariate logistic regression analysis results indicated that hand-transmitted vibration exposure and service length were risk factors of abnormal hand symptoms(P<0.05). CONCLUSION: Occupational hand-transmitted vibration exposure can affect the hand subjective symptoms of mine drilling workers, and the length of service is a synergistic influencing factor.

Establishment and evaluation of acute diquat poisoning model in Wistar rats / 中华劳动卫生职业病杂志

Objective@#To establish the Wistar rat model of acute diquat poisoning and observe the pathological damage of main target organs.@*Methods@#Thirty-six Wistar rats were randomly divided into six groups (n=6) , including one normal saline control group and five treatment groups which were separately given single-dose of intragastric administration at the doses of 46.2 mg/kg, 77.0 mg/kg, 115.5 mg/kg, 231.0 mg/kg and 346.5 mg/kg. The pathological changes of lung, liver and kidney were observed by hematoxylin and eosin (HE) and Masson staining. The optimal dose was determined according to the general situation and pathological changes. Thirty-six Wistar rats were randomly divided into five treatment groups and one normal saline control group. Treatment groups were given single-dose of intragastric administration according to the optimal dose. The rats were sacrificed at 1st, 3rd, 7th, 11th and 14th day after exposed, respectively. The activity of serum glutamic-pyruvic transaminase (ALT) and glutamic-oxalacetic transaminase (AST) were measured by chemical colorimetry. The pathological changes of lung, liver and kidney were observed by HE and Masson staining.@*Results@#According to 14 d survival rate, the toxic symptoms and pathological changes, 115.50 mg/kg was determined the best dose. Given single-dose of intragastric administration at the doses of 115.50 mg/kg, it was found that the serum AST and ALT activity of rats on the first and third day of exposure was significant higher than those in control group. The results of pathological examination exhibited that in 115.50 mg/kg group, the pathological changes of lung, liver and kidney began to appear on the first day of exposure, the pathological changes were the most serious on the third day, and then gradually alleviated. On the 14th day, the alveolar septum was slightly widened, with inflammatory cell infiltration, local alveolar cavity became narrow, atrophy, peripheral alveolar compensation, bronchi and alveolar septum collagen fiber proliferation; The local renal tubular epithelial cells were enlarged and necrotic; the central vein surrounding hepatic cells showed vacuolar degeneration with punctate necrosis.@*Conclusion@#The rat model of acute diquat poisoning can be successfully induced by single-dose of intragastric administration. The condition of wistar rats and the pathological damage of the main target organs could be observed during the whole course of 115.50 mg/kg administration.

Analysis of inter-laboratory comparison results of noise measuring instruments / 中国职业医学

OBJECTIVE: To evaluate the interlaboratory comparison results of noise measuring instruments in the occupational hygiene technical service institutions. METHODS: The basic performance data, multi-frequency acoustic calibration measurement results and simulated workplace noise at fixed points of 60 noise measuring instruments were collected. The instruments were from 60 occupational health technical service institutions who participate in the inter-laboratory comparison study in noise measuring instruments. The results of the measurements were analyzed using quartile robust statistical technology and z score evaluation method.RESULTS: All 60 participating comparison noise measuring instruments were examined or calibrated, and 58 instruments(96.7%) were used within the term of validity of examination or calibration. The 58 instruments were tested by multi-frequency noise calibration measurement. The comparative passing rate of the instrument accuracy was 94.8%(55/58); and the linearity test passing rate was 87.9%(51/58). There were 59 instruments participated in the simulated workplace noise at fixed points. The z-score pass rate of the two comparison measurement points was 89.8%(53/58). A total of 57 enterprises participated all the instrument performance comparison tests, with a pass rate of 94.7%(54/57). CONCLUSION: Performance of noise measuring instruments from the occupational hygiene technical service institutions is generally good. However, there are a small number of instruments have poor accuracy and linearity, and there are measurement bias that require improvement.

The change of psychomotor neurobehavioral function in workers exposed to ultra-high frequency radiation / 中国职业医学

OBJECTIVE: To explore the effect of ultra-high frequency radiation on psychomotor neurological behavior in workers with exposure. METHODS: A total of 85 workers who exposed to 40.68 MHz radiofrequency were recruited as the exposure group by judgment sampling method. A group of 121 workers without occupational EMR exposure were recruited as the control group. Workers in both groups were from the same shoe factory. The electric field intensity(EFI) of ultra-high frequency radiation of workplace in the exposure group was measured. The computerized neurobehavioral evaluation system in Chinese version 3 was used to evaluate the psychomotor neurobehavioral function which included the neurobehavioral ability index(NAI) of simple visual reaction time(SVRT), digital screening and fit curve and the general NAI(GNAI) of the above 3 indexes. RESULTS: The median of the workplace EFI of ultra-high frequency radiation in the exposure group was 119.0 V/m, and all of them exceeded the national occupational exposure limit. NAI of digital screening in exposure group was lower than that in the control group(P<0.05). There is no statistically significant difference in the NAI of SVRT, fit curve and GNAI(P>0.05). Meanwhile, there is no statistically significant difference in abnormal rate of NAI of SVRT, digital screening, fit curve and GNAI(P>0.05). The results of multiple linear regression analysis showed that the ultra-high frequency radiation EFI exposure was negatively correlated with NAI of digital screening(P<0.05) after eliminating the influence of confounding factors such as age, working age, gender, education level, smoking, drinking and staying up late. CONCLUSION: The digital screening of psychomotor neurobehavioral function in the exposure workers was adversely affected by the ultra-high frequency radiation. The neural behavioral ability of eye-hand coordination and precise movement may be the specific performance.

Investigation and analysis on fingertip vibrotactile perception threshold at two frequencies in mine drilling workers / 中国职业医学

OBJECTIVE: To analyze the characteristic change of fingertip vibrotactile perception threshold(VPT) at two different frequencies among mine drilling workers. METHODS: A total of 48 mine drilling workers exposed to hand-transmitted vibration for at least 1.0 year were selected from mines in Hubei Province as the vibration exposure group by using the random number table method, and workers without hand-transmitted vibration exposure were selected as the control group. An HVLab vibrotactile perception meter was used to measure the fingertip VPT at 31.5 and 125.0 Hz in workers of these two groups. RESULTS: None of the workers in these two groups showed any clinical symptoms associated with occupational hand-arm vibration diseases. At 31.5 and 125.0 Hz, the fingertip VPT in the vibration exposure group was higher than that in the control group(P<0.01), the fingertip VPT of the little fingers was higher than that of the index fingers(P<0.01). At 125.0 Hz, the fingertip VPT of the fingers in dominant hands was higher than that in non-dominant hands in workers of the vibration exposure group(P<0.01). CONCLUSION: The mine drilling workers with hand-transmitted vibration exposure had higher fingertip VPT. There were differences of VPT in fingers and dominant hands.