Comparison of two dose-response relationship of noise exposure evaluation results with high frequency hearing loss / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Complex noise and its relation to hearing loss are difficult to measure and evaluate. In complex noise measurement, individual exposure results may not accurately represent lifetime noise exposure. Thus, the mean L Aeq,8 h values of individuals in the same workgroup were also used to represent L Aeq,8 h in our study. Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did.</p><p><b>METHODS</b>A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China. We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times, respectively. A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance.</p><p><b>RESULTS</b>We observed that 88.3% of workers were exposed to more than 85 dB(A) of occupational noise (mean: 89.3 ± 4.2 dB(A)). The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A), respectively. In the binary logistic regression analysis, we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable. The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable. Furthermore, we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was. The CNEg model was better than the CNEp model. In this circumstance, we can measure some subjects instead of the whole workgroup and save manpower.</p><p><b>CONCLUSIONS</b>In a complex noise environment, the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.</p>

Noise exposure assessment with task-based measurement in complex noise environment / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Task-based measurement (TBM) is a method to assess the eight-hour A-weighted equivalent noise exposure level (L(Aeq.8h)) besides dosimeter. TBM can be better used in factories by non-professional workers and staffs. However, it is still not clear if TBM is equal or similar with dosimeter for L(Aeq.8h) measurement in general. This study considered the measurement with dosimeter as real personal noise exposure level (PNEL) and assessed the accuracy of TBM by comparing the consistencies of TBM and dosimeter in L(Aeq.8h) measurement.</p><p><b>METHODS</b>The study was conducted in one automobile firm among 387 workers who are exposed to unstable noise. Dosimeters and TBM were used to compare the two strategies and assess the degree of agreement and causes of disagreement. Worker's PNEL was measured via TBM for noise; the real PNEL was also recorded. The TBM for noise was computed with task/position noise levels measured via sound level meter and workers' exposure information collected via working diary forms (WDF) filled by participants themselves. Full-shift noise exposure measurement via personal noise dosimeters were taken as the real PNEL. General linear model (GLM) was built to analyze the accuracy of TBM for noise and the source of difference between TBM for noise and real PNEL.</p><p><b>RESULTS</b>The L(Aeq.8h) with TBM were slightly higher than the real PNELs, except the electricians. Differences of the two values had statistical significance in stamping workers (P < 0.001), assembly workers (P = 0.015) and welding workers (P = 0.001). The correlation coefficient of L(Aeq.8h) with TBM and real PNELs was 0.841. Differences of the two results were mainly affected by real PNEL (F = 11.27, P = 0.001); and work groups (F = 3.11, P < 0.001) divided by jobs and workshops were also independent factors. PNEL of workers with fixed task/position ((86.53 ± 8.82) dB(A)) was higher than those without ((75.76 ± 9.92) dB(A)) (t = 8.84, P < 0.01). Whether workers had fixed task/position was another factor on the accuracy of TBM for noise (F = 4.36, P = 0.038).</p><p><b>CONCLUSION</b>TBM for noise has acceptable accuracy on workers' PNEL measurement. The accuracy is affected by job categories, workshops and variability of task/position. TBM for noise can yield a relatively conservative result of worker's PNEL in most cases, so it can be used to measure and assess workers' real PNEL.</p>

Risk factors analysis of low back pain among workers in a foundry factory of the automobile company / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the main risk factors of low back pain of workers ina foundry factory of the automobile company using cross sectional epidemiological investigation, and to provide scientific base for preventing the disorder.</p><p><b>METHODS</b>The low back pain and work loads of 1340 workers in a foundry factory of the automobile company were investigated using questionnaire, and logistic regression analysis was used to analyze the risk factors.</p><p><b>RESULTS</b>The one-year morbidity of low back pain in workers was 58.9% the morbidities of low back pain in workers engaged in foundry, transportation and modeling were 64.6%, 64.6% and 62.5%, respectively. The lifting with squat postures, bending trunk heavily, bending trunk with twisting and moving the heavy objects were found to be the most dominant risk factors for low-back pain, the OR values were 2.085, 1.961, 1.967 and 1.956, respectively. The distributions of risk factors were different among the different jobs. The logistic regression analysis showed that moving the heavy objects, lifting with squat postures, bending trunk heavily, bending trunk with twisting existed simultaneously, also the work years and gender were the risk factors.</p><p><b>CONCLUSION</b>The manual moving heavy objects, awkward working posture or both were the most important risk factors for low-back pain. The intervene ergonomic study should be performed in future to reduce the morbidity of low-back pain.</p>

Cohort mortality study of workers in an automobile foundry factory / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To understand the major causes of death in automobile foundry workers and investigate casting manipulations hazards to health.</p><p><b>METHODS</b>A cohort study of 3529 foundry workers registered in one big automobile factory in Shiyan city of China was performed. Standardized mortality ratios (SMRs) were calculated for the main causes of death by using Chinese national mortality rates as reference.</p><p><b>RESULTS</b>The cohort mortality was traced from 1980 to the end of 2005 with an accumulation of 84 999 person-years, revealed 265 deaths. The results of this study showed that the standardized mortality ratio for all subjects was 0.96 (95% CI: 0.85 approximately 1.08), which was very close to that expected on the basis of the China national mortality rates. The SMR increased with age, the SMR became greater than 1 in all groups of age 50 and higher. The results showed that malignant neoplasm (3.43%), accidents (1.16%), cerebro-vascular diseases (1.08%), cardio-vascular diseases (0.79%) were the first four illnesses that threatened workers' life span. Statistically significant mortality of malignant neoplasm (SMR = 7.87), accidents (SMR = 2.70), cardio-vascular diseases (SMR = 2.68) and digestive diseases (SMR = 2.79) were found in the foundry workers. The relative risk of malignant neoplasm for first line workers to assistant workers was 1.99 (P < 0.05).</p><p><b>CONCLUSION</b>The occupational hazards in foundry factory have harmful impact on the workers' health and life span.</p>