Objective To analyze the effect of hand transmitted vibration on fingertip thermotactile perception threshold (TPT) among grinding workers in a sports equipment manufacturing enterprise. Methods A total of 151 male grinding workers from a sports equipment manufacturing enterprise in Guangdong Province were enrolled in the vibration exposure group, and 51 male workers without hand-transmitted vibration exposure were enrolled in the control group, using the judgment sampling method. Basic health conditions of the workers were surveyed in both groups. The TPTs of the distal phalanges of the index and little fingers on both hands were tested using an HVLab thermal perception tester. Results The detection rates of finger numbness and tingling among workers in the vibration exposure group were higher than those in the control group (92.1% vs 7.8% and 59.6% vs 0.0%, respectively, both P<0.01). The detection rates of numbness or tingling of different fingers in the vibration exposure group descended in the following order: index finger, middle finger, ring finger, thumb and little finger. The hot threshold of the index finger and little finger increased (all P<0.01), while the cold threshold decreased (all P<0.01) in the vibration exposure group, compared with the control group. The results of generalized linear regression analysis showed that with the increase of the duration of hand-transmitted vibration, the hot threshold of the index finger and the little finger of both hands increased (all P<0.01), and the cold threshold decreased (all P<0.01). The hot thresholds of workers with numbness of both the index fingers and left little finger were higher than those of workers without numbness of the same finger (all P<0.05). The hot threshold of workers with tingling of the left index finger was higher than those without tingling (P<0.05). The cold thresholds of workers with tingling of the both index fingers and left little finger were lower than those without tingling of the same finger (all P<0.05). The hot threshold of the right little finger increased with age (P<0.01), while the cold thresholds of both little fingers decreased with age (all P<0.01). Conclusion Hand-transmitted vibration exposure increases fingertip hot threshold and decreases fingertip cold threshold of workers exposed to hand-transmitted vibration. Years of service in hand-transmitted vibration work, finger numbness or tingling, and age were influencing factors of TPT. Fingertip TPT examination can be used to assist in the early detection of vibration-induced nerve injury in workers exposed to hand-transmitted vibration.

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.

Objective: To analyze the current status of work-related musculoskeletal disorders (WMSDs), work fatigue and musculoskeletal pain in Chinese occupational population, and to study the relationship between work fatigue and musculoskeletal pain and WMSDs. Methods: A total of 66 961 employees from 323 enterprises in 15 key industries in China were selected as the study subjects using stratified cluster sampling method. The incidence of WMSDs in the past year was investigated using the Chinese version of the Musculoskeletal Disorders Questionnaire, and the work fatigue and musculoskeletal pain were investigated using Borg 6-20 Rating of Perceived Exertion Scale and visual analogue scale. The data were standardized using the age composition data of 18 to 60 years from the seventh national population census. Results: The standardized annual incidence of WMSDs was higher in the front-line workers than that in the administrative and other supportive staff (38.82% vs 36.30%). The detection rates of work fatigue and musculoskeletal pain in the study subjects were 44.54% and 63.08%, respectively. The result of S-curve fitting showed that the risk of WMSDs increased with the level of work fatigue (P<0.01). Among the front-line workers, the average of monthly fatigue frequency in the neck, shoulder, lower back, upper back, wrist/hand, foot and ankle, knee, leg, and elbow were higher in the group with WMSDs compared to those without WMSDs (all P<0.01). The pain degree of musculoskeletal pain was higher in all nine sites in the fatigued group than in the no-fatigue group (all P<0.01). The standardized detection rate of musculoskeletal pain was higher in the fatigued group than in the non-fatigued group (80.38% vs 25.71%). The work fatigue was moderate and positively correlated with musculoskeletal pain in all seven sites except the lower back and elbow, with Kendall Tau-b correlation coefficients ranging from 0.423 to 0.546 (all P<0.01). Conclusion: There is a good correlation between work fatigue and local musculoskeletal pain, work fatigue and WMSDs in Chinese occupational population. Implementing ergonomic interventions to control the development of work fatigue can be an effective measure for preventing WMSDs.

Objective: To analyze the status of noise hazard in workplace of key industries in Guangdong Province. Methods: A total of 1 061 enterprises from 14 key industries in 21 prefecture-level cities in Guangdong Province were selected as the research subjects using stratified sampling method. The occupational health survey was carried out, and the noise intensity in the workplace was detected. Results: There were 12 606 workplaces and 5 570 work sites involved among 1 061 enterprises. The median and the 0-100th percentile value ［M (P₀-P₁₀₀)］ of noise intensity in workplace were 82.6 (46.5-112.6) dB(A), and 35.03% of the workplace exceeded the national noise intensity standard. The regions and industry with the highest rate of noise exceeded the national noise intensity standard in workplace were in the northern part of Guangdong and the stone processing industry respectively. The M (P₀-P₁₀₀) of noise intensity in the work sites was 83.7 (47.5-106.2) dB(A), and 36.00% of the work sites exceeded the national noise intensity standard. The regions and industry with the highest rate of noise exceeded the national noise intensity standard in work sites were in the Pearl River Delta region and the ferrous metal mining and dressing industry respectively. The rate of noise protection facilities setting was 66.45%, and the validity of personal protection was 61.73%. The occupational medical examination was performed in 73.24% of the research subjects, and 3.25% of the result was abnormal. The industry with the highest occupational medical examination rate was nonferrous metal smelting and rolling processing, and the industry with the highest abnormal rate of occupational medical examination was stone processing industry. Conclusion: Noise hazards in workplaces of key industries in Guangdong Province are relatively severe, necessitating strengthened supervision and management, noise control measures, and efforts to reduce noise exposure levels in workplaces and work sites.

OBJECTIVE: To determine the prevalence and influencing factors of work-related musculoskeletal disorders(WMSDs) among workers in a shipyard. METHODS: A total of 496 workers in a large shipyard in Guangdong Province were selected as research subjects using the convenient sampling method. The Questionnaire of Musculoskeletal Disorders was used to investigate the prevalence of WMSDs in various regions of the body in the past year.Multivariate logistic regression was used to analyze the potential influencing factors of WMSDs in the frequently affected body parts. RESULTS: The prevalence of WMSDs was 70.2%(348/496). The prevalence rates of WMSDs in different body regions were: lower back/waist(43.1%), neck(29.4%), shoulder(29.0%), hand/wrist(25.4%), knee(22.4%), hip/leg(14.3%), ankle/foot(12.1%), upper back(11.3%) and elbow(9.3%). Multivariate logistic regression analysis results showed that increased risk of lower back/waist WMSDs occurred in workers who carry heavy objects>5.0 kg, who work in uncomfortable positions, who repeatedly perform the same work every day, and who repeatedly perform the same action using the lower limbs and ankles(P<0.05). Employees working ≤8 hours or more than 8 hours per day had higher risk of developing lower back/waist WMSDs compared with workers working 8-10 hours per day(P<0.05). CONCLUSION: The prevalence of WMSDs among workers in the shipyard is high.The lower back/waist WMSD is the most common one. The influencing factors include work organization and adverse ergonomic factors.

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.

OBJECTIVE: To analyze the characteristics of noise hazard in a nuclear power station. METHODS: The workplaces and working posts which exposed to occupational noise from two 1 000 MW power units in one nuclear power station in Guangdong Province was selected as study subjects using the convenience sampling method. Occupational health survey, noise measurement in the workplace and personal noise dosage measurement were used to monitor noise exposure, and to analyze the characteristics of occupational noise in the nuclear power station. RESULTS: The noise sources of the nuclear power plant were mainly distributed in the nuclear island, conventional island, and peripheral workshops. A total of 237 points of noise intensity were measured in the workplace. The intensity of noise ranged from 66.0 to 99.6 dB(A). The noise intensity in 62.4%(148/237) of points was equal or greater than 80.0 dB(A) and 34.2%(81/237) equal or greater than 85.0 dB(A). The percentage of detection points with noise intensity was equal or greater than 85.0 dB(A) from low to high were nuclear island, conventional island, and peripheral workshops with 22.0%, 37.5% and 53.8% respectively(P<0.01). The personal noise intensity of three positions including inspectors of operation department, preparation and main engine positions of mechanical department exceeded the occupational exposure limit(OEL), and the percentage of positions whose noise intensity exceeded the OEL was 9.7%(3/31). CONCLUSION: High-intensity noise sources of the nuclear power plant are widely distributed in the workshop areas of nuclear island, conventional island, and peripheral workshops. The noise level of some positions exceeded the standards of noise intensity. The prevention and control measures of noise hazards in posts with excessive noise should be strengthened.

OBJECTIVE: To analyze the effects of hand-transmitted vibration operation on nailfold capillaroscopy( NFC) in fine sanding workers. METHODS: A total of 57 fine sanding workers of one golf ball production enterprise in Guangdong Province were selected as vibration exposure group and 30 workers without exposure to hand-transmitted vibration as control group by a judgement sampling method. NFC examination was carried out in workers of these two groups. RESULTS: The capillary haemorrhage detection rates,percentage of abnormal capillary loops and total capillary width in the vibration exposure group were higher than that in the control group [43. 9% vs 13. 3%,( 56. 6 ± 20. 9) % vs( 41. 2 ± 14. 5) %,( 44. 7 ± 4. 9) vs( 42. 4 ± 4. 9) μm,P < 0. 05]. The capillary density,capillary length and branch diameter in the vibration exposure group were lower than that in the control group [( 7. 7 ± 1. 0) vs( 8. 8 ± 1. 0) per mm,( 185. 1 ± 33. 9) vs( 205. 6 ± 23. 2) μm,( 18. 3 ± 1. 9) vs( 19. 6 ± 2. 6) μm,P < 0. 05]. No significant difference was found in the diameter of apical part and branch of capillaries between the two groups( P > 0. 05). In the vibration exposure group,the percentage of abnormal capillary loops in the left hand was lower than that in the right hand [( 53. 1 ± 20. 6) % vs( 61. 5 ±24. 2) %,P < 0. 01],the capillary length in the left hand of vibration exposure group was longer than that in the right hand [( 187. 2 ± 33. 5) vs( 179. 4 ± 35. 4) μm,P < 0. 05]. No significant difference was found in the capillary density,total capillary width,apical part diameter,output branch diameter and input branch diameter between two hands in the vibration exposure group( P > 0. 05). CONCLUSION: The hand-transmitted vibration can lower the nailfold capillary density,shorten and widen capillary loops, increase percentage of abnormal capillary loops and induce capillary haemorrhage. NFC could be used to assist early detection of microvascular damage induced by hand-transmitted vibration.

OBJECTIVE: To evaluate the exposure status of hand-transmitted vibration(HTV)in golf ball head grinding workers.METHODS: The golf ball head grinding positions in a sports equipment factory were selected as the research subjects by the judgement sampling method.The HTV exposure level of the workers in 66 grinding positions was measured,the key control points for HTV hazards were identified,and the damage of HTV was classified.RESULTS: The median(M)of 4 hours energy equivalent frequency-weighted acceleration to vibration[a_(hw(4))]of grinding positions in this sports equipment factory was 4.21 m/s~2,and the a_(hw(4)) over standard rate was 50.0%(33/66).The a_(hw(4)) of rough grinding positions was higher than that of fine grinding positions(M:5.50 v.s 3.94 m/s~2,P<0.05).In both rough grinding positions and fine grinding positions,the a_(hw(4)) of different ball head grinding types from high to low were hollow titanium alloy ball heads, hollow stainless steel ball heads,and solid stainless steel ball heads(rough grinding positions M:7.41 vs4.43 vs 3.11 m/s~2,P<0.01; fine grinding p ositions M:5.24 vs 4.21 vs 2.93 m/s~2,P<0.01).For the hollow titanium alloy ball head grinding positions,the a_(hw(4)) of rough grinding was higher than that of fine grinding(M:7.47 vs 5.24 m/s~2,P<0.01).Rough grinding positions,especially hollow stainless steel ball heads and hollow titanium alloy ball head grinding positions were key control points for HTV hazards.In the 66 grinding positions,the HTV hazards were classified as grade 0,Ⅰ,Ⅱ,and Ⅲ in the grinding positions accounted for 3.0%,47.0%,40.9%,and 9.1%,respectively,and those with grade Ⅱ and above were 50.0%(33/66). CONCLUSION: The exposure level of HTV in golf ball head grinding workers is high,with a trend of exceeding the standard.The golf ball head grinding workers have a high occupational health risk.

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.