Cognitive performance and subjective experience during combined exposures to whole-body vibration and noise

Objective The goal of this study was to examine the effects of noise and whole-body vibration, individually and combined, and at various stimulus intensity levels, on cognitive performance and subjective experience.Method Fifty-four participants (27 men and 27 women) with a mean age of 25 years, ranging from 19 to 30, were exposed for 20 min each to a 16-Hz sinusoidal whole-body vibration, a helicopter sound at 21 Hz, both stimuli combined, and a control condition. Participants were randomly assigned to one of three groups: low intensity [77 dB(A) noise and 1.0 m/s² vibration], medium intensity [81 dB(A)/1.6 m/s²] or high intensity [86 dB(A)/2.5 m/s². During each environmental exposure, short-term memory performance was tested with a visual Sternberg paradigm. Reaction time was measured as a dependent variable. Directly following each environmental exposure, participants rated the difficulty of the task and the annoyance level of the exposure stimulus.Results Results revealed no significant changes in reaction times due to environmental exposure or intensity level. However, participants significantly rated the combined exposure as both more annoying and more difficult than the other conditions. Further, the high-intensity group rated subjective annoyance significantly higher than the other groups for all conditions.Conclusions The results from this study indicate that performance alone is not a sufficient measure for the study of the effects of combined stimuli on a human operator.     

Sensory-neural hearing loss during combined noise and vibration exposure

Summary A detailed analysis of risk factors for the development of sensory-neural hearing loss (SNHL) was carried out on 122 forest workers. These forest workers were selected from a larger group (n = 217) by restricting the age range to 30–55 years. The hearing threshold of the left ear at 4000 Hz was measured and the effect of age, exposure, systolic and diastolic blood pressure (DBP), presence of vibration-induced white finger (VWF), tobacco smoking and use of earmuffs were evaluated in multiple linear regression analysis. Robinson's nonlinear model was used to evaluate the rate of hearing loss. Aging was the major risk factor and it explained 15.4% of the variance of the SNHL. The presence of VWF was the second most important single risk factor and explained a further 5.2% of the SNHL. Elevation of DBP correlated significantly with SNHL and explained an additional 4.1% of the SNHL. These main factors were able to explain about 26% of the spread of SNHL. Additional factors in the analysis, e.g. smoking, systolic blood pressure, did not significantly contribute to the genesis of SNHL. When Robinson's model was applied to the SNHL data, on a group basis, we did not observe any exaggerated risk of hearing loss due to combination of noise and vibration. In combined exposure subjects with VWF as well as subjects with enhanced DBP will run a higher risk for SNHL.     

Psychophysical assessment of sinusoidal whole-body vibration in z-axis between 0.6 and 5 Hz combined with different noise levels

Summary Nine healthy sitting males evaluated the intensity of vertical whole-body vibration (WBV) in z-axis at four frequencies (F1 = 0.63 Hz, F2 = 1.25 Hz, F3 = 2.5 Hz, F4 = 5 Hz) and two intensities (11 = 1 ms^–2 rms, 12 = 2 ms^–2 rms) by cross-modality matching (CMM). The subjects were simultaneously exposed to low-frequency noise at two levels (L1 = 65 dBA, L2 = 86 dBA). L1 and L2 were context conditions which did not have to be evaluated by CMM. The results indicate a flat response between F2 and F3; the sensitivity increases towards F1. Different exponents of Stevens' power law for the frequencies of WBV contradict the frequency range tested to be a sensory continuum. L2 caused practically significantly stronger sensations of the WBV-intensity from F1 to F3 (I1) and at F2 (I2). No synergistic effect of noise and WBV was shown at F3I2. Weighting factors were calculated for all exposure conditions using Stevens' power law. The weighting of F2 and F3 contradicts that of the International Standard ISO 2631-1985 (E). The results enable recommendations for the frequency weighting of WBV between 0.63 and 1 Hz, as well as for the equivalence of noise and WBV with combined exposure.This work was done in the Temporary International Research Team on combined Effects of Noise and Vibration of the Council of Mutual Economic Assistance of the Socialist Countries     

Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship

Summary The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I₁ = 1.5 ms^–2 rms; I₂ = 3.0 ms^–2 rms). The compressive forces acting on the disc L3-4 during the extreme values of acceleration were predicted on the basis of anthropometric data, EMG of back muscles and the acceleration of the upper trunk, using a simple biomechanical model. The estimated mechanical activity of back muscles was not able to protect the spine under many exposure conditions. The highest compressive forces were predicted for WBV with 7.5, 8 and 4.5 Hz. The results suggest the possibility of fatigue failures at the endplates of lumbar vertebrae after intense long-term exposure to WBV.The authors gratefully acknowledge the help and assistance of G. Menzel, R. Vizcaino, and A. Weissmüller     

噪声作业工人听力影响因素的因子logistic回归分析

[目的]用因子logistic回归分析的方法探讨噪声作业工人听力的影响因素。[方法]调查某钢铁企业的2 491名噪声作业工人,对可能影响听力结果的13项指标进行研究,找出其公因子再与电测听结果作逐步logistic回归分析。[结果]血压、烟酒嗜好、日均接触时间、噪声接触、心脏功能、症状等6个回归因子对作业工人听力有一定的影响。[结论]噪声作业工人应减少不良嗜好,加强个体防护。     

饮酒与职业噪声暴露对听力损失的联合作用

目的 探讨饮酒与听力损失的关系以及饮酒和职业性噪声对听力损失的联合作用.方法 利用回顾性队列研究,选择广州市某大型空调生产企业连续性噪声作业人员2.44名男性饮酒者为饮酒组,在相同的噪声暴露环境中选择140名男性不饮酒者为对照组,两组间除饮酒外,其他均均衡可比.按照<作业场所噪声测量规范>(WS/T 69-1996)要求对噪声暴露作业场所进行测点选择和噪声强度测量[dB(A)],并计算累积噪声暴露量(CNE).按GB7583-87要求,对工人进行左、右耳500～6000Hz内6个频率的纯音气导听阈测试,并问卷调查其一般情况、个人生活史、职业史、噪声暴露史、家族性耳聋史以及耳毒性药物使用史等.利用t检验、有序多分类logistic回归分析、卡方检验分析噪声和饮酒对听力的影响以及两者的联合作用.结果 同一噪声暴露环境下,在4 000 Hz频段,饮酒组左、右耳听阈位移分别为(29.9±12.9)dB和(30.0±13.5)dB;6000Hz听闻位移为(26.9±11.8)dB和(27.3±15.3)dB,均高于对照组(P<0.05).饮酒组听力损失的发生率为21.7%,对照组为10.7%,两组比较差异有统计学意义(P<0.01),年饮酒量达32L及以上听力损失发生的相对危险度是不饮酒的2.632倍(P<0.05).累积噪声量达80 dB(A)及以上时,饮酒和职业噪声听力损失的RR值分别为3.353和4.643,饮酒与职业噪声联合作用的RR值(9.662)大于两个变量独立作用之和.结论 大量饮酒可导致听力损失发生率增高,在高强度噪声暴露情况下,饮酒和职业噪声暴露对听力损失存在协同作用.     

高温与噪声的联合作用对玻璃制瓶工听力的影响

选择4组组间基本均衡的现场进行噪声和高温测试,分析4组研究对象听力水平的差异。对68名不同高温噪声暴露时间的玻璃制瓶工进行听力水平比较。结果发现,对语频听阈和高频听阈,单纯高温组与对照组相比差异无显著性(P>0.05),噪声组、高温噪声组与对照组相比差异有显著性(P<0.01),高温噪声组明显高于噪声组(P<0.01)。语频听阈和高频听阈随高温噪声暴露时间的延长而增高(P<0.01)。提示高温本身对语频听阈和高频听阈没有影响,但高温与噪声的联合作用可加重噪声对听力的损害,且可能具有时间依赖性。     

Long-term effects of whole-body vibration: a critical survey of the literature

Summary The relevant literature on the long-term effects of whole-body vibration (wbv) was analyzed in order to obtain condensed information concerning a possibly higher health risk due to long-term exposure, the relationships between the quality of exposure (intensity, duration, frequency) and pathological effects, the significance of individual factors, conclusions for standard setting, and medical health care of workers exposed to wbv. Vibration exposure was characterized by measured values in one third of papers, whereas more than 30% of the publications selected did not contain any exposure data. Health data of about 43 000 workers exposed to wbv and 24 000 persons in control groups were reported.The results indicate an increased health risk of the spine and of the peripheral nervous system after intense long-term wbv. With a lower probability, the digestive system, the peripheral veins, the female reproductive organs, and the vestibular system were also affected. Long-term effects on other organs cannot be precluded. Wbv can worsen certain endogenous conditions. Specific diagnostic features of pathological changes induced by wbv with frequencies below 20 Hz do not exist. On average, the health risk increases with higher intensity or duration of exposure, however, quantitative exposure-effect relationships cannot be derived at present. Since wbv near the Exposure Limit of the International Standard IS 2631 is not completely safe, this survey provides arguments in favour of a lower limit. Contra-indications for professional exposure to wbv and further research needs are discussed.The authors gratefully acknowledge the help and assistance of Mrs. R. Vizcaino     

Self-reported back pain in tractor drivers exposed to whole-body vibration

Summary A postal questionnaire on symptoms of ill health and exposure to whole-body vibration was completed by 577 workers (response rate 79%) who were employed in certain functions by two companies 11 years before. The relation between the occupational history of driving vibrating vehicles (mainly agricultural tractors) and back pain has been analyzed. The prevalence of reported back pain is approximately 10% higher in the tractor drivers than in workers not exposed to vibration. The increase is mainly due to more pain in the lower back and more pain lasting at least several days. A vibration dose was calculated by assigning each vehicle driven a vibration magnitude, estimated on the base of vibration measurements. The prevalence of back pain increases with the vibration dose. The highest prevalence odds ratios are found for the more severe types of back pain. These prevalence odds ratios do not increase with the vibration dose. This might be due to health-related selection which is more pronounced for severe back pain than for back pain in general. The two components of the vibration dose, duration of exposure and estimated mean vibration magnitude, have also been considered separately. Back pain increases with duration of exposure but it does not increase with the estimated mean magnitude of vibration. This is probably due to the inaccuracy of this estimate. The higher prevalence of back pain in tractor drivers might be (partly) caused by whole-body vibration, but prolonged sitting and posture might also be of influence.     

冲床噪声与稳态噪声致工人高频听力损害的对比研究

目的 了解冲床噪声对工人高频率段听力的影响,并与稳态噪声进行对比.方法 接触冲床噪声的38名锻压车间工人为冲床噪声接触组,62名接触稳态噪声的拉丝、磨粉等工人为稳态噪声组.用个人声暴露计采集工作期间噪声暴露数据,计算40h等效声级(LEX,W)和累积噪声暴露量(CNE).按GBZ 49-2007《职业性噪声聋诊断标准》对工人测试听力并计算和判定结果.结果 冲床噪声接触组CNE[(97.0±6.4) dB (A)·年]与稳态噪声接触组CNE [(97.6±5.7)dB(A)·年]比较,差异无统计学意义(P＞0.05).冲床噪声接触组高频听力损失率(55.3％)明显高于稳态噪声(32.3％),差异有统计学意义(CMHX2=6.928,P=0.0085);冲床噪声接触组于CNE 95～104 dB(A)·年内损失率(13/19,68.4％)明显高于稳态噪声组( 13/37,35.1％),差异有统计学意义(P=0.018).logistic回归模型显示,冲床噪声组、稳态噪声组CNE与高频听力损失率均呈剂量-反应关系(P＜0.01).结论 应用个体噪声暴露数据计算时,在能量相同的情况下,冲床噪声所致高频听力损失的危害大于稳态噪声.     

Back disorders in crane operators exposed to whole-body vibration

Summary In The Netherlands so far little research has been carried out to investigate the health effects of exposure to whole-body vibration at work. In a retrospective (10-year) follow-up study, the incidence of permanent work disabilities in crane operators exposed to vibration was compared to that of a control group. The emphasis in this presentation is on disablement because of back disorders. Among the crane operators with more than 5 years of exposure to vibration, more disability due to back trouble occurred than in the control group. The incidence density ratio (IDR) exceeded 2 for disability because of degeneration of the intervertebral disc, after adjustment for age, nationality, shift work and calendar year. With increasing years of exposure, the risk ratio for disability because of intervertebral disc disorders also increased. The risk ratio for a disability pension due to disease of the intervertebral disc for crane operators with more than 5 years of exposure was almost 3 compared to the control group. A combination of exposure to whole-body vibration, an unfavorable posture, and climatic conditions is responsible for the development of these health effects.Supported by a grant from the Ministry of Social Affairs and Employment     

长期接触中低强度噪声对作业人员心电图及听力的影响

目的探讨中低强度高频噪声对作业人员心电图及听力的影响。方法对某石油化工公司炼油车间作业环境进行卫生学调查及对249名接触噪声人员的心电图及听力进行分析,并与92名对照组进行比较。结果作业现场共测95个噪声点,噪声强度为53.6～98.0(81.7±5.8)dB(A),其中有15个点超过国家卫生标准,超标率为15.8%;作业组人员心电图总异常率为28.1%,明显高于对照组的16.3%(P<0.05),尤其是窦性心律不齐较明显(11.6%);作业人员的听力损失为18.9%,明显高于对照组的7.6%(P<0.01);其损害程度随着工龄的增加而增加,特别是工龄在15年以上的更明显。结论作业人员长期在平均噪声强度低于卫生标准下工作,仍可有一定程度的心电图改变和听力损失。     

Suppressive mechanism of gastric motility by whole-body vibration

Objective: To investigate the mechanism of gastric motility suppression by exposure to whole-body vibration (WBV). Methods: The gastric motility was evaluated by electrogastrography (EGG) under food intake and autonomic nerve blocking agents in ten healthy volunteers. Sinusoidal vertical vibration with a frequency of 4 Hz (1.0 ms⁻² rms) was given to the subject for 10 min. Results: The amplitude of EGG wave and the power spectrum corresponding to the slow wave component was remarkably decreased by vibration exposure. Food intake enhanced the gastric motility about 2.5-fold in the power spectral density. During and after vibration exposure, the response mode was similar to those at fasting states. Under the influence of anticholinergic (scopolamine) and alpha-adrenergic blocking agents (prazosin), the power spectra were decreased. A further decrease was observed during vibration exposure. A beta-adrenergic blocking agent (propranolol) led to a marked increase in the amplitude of EGG and its power spectrum. With pretreatment by a beta-adrenergic blocking agent, however, vibration exposure reduced both of them. Conclusions: These results suggest that short-term exposure to WBV can suppress the gastric myoelectric activity, the responses on which may be mediating by neurohumoral effects as well as the mechanical effect of WBV. Received: 7 September 1998 / Accepted: 9 May 1999     

铁路发电车噪声作业环境对乘务员的听力和心血管系统的影响

目的了解噪声对发电车乘务员的听力损害程度及对心血管系统的影响。方法对272名发电车乘务员进行血压、心电图、纯音气导听阈检查。结果血压正常、正常高值、高血压检出率分别为21．7％、55．9％、22．4％,心电图异常主要表现为心律的改变、左室高电压及电轴左偏、ST段和T波异常。纯音气导听阈检查结果显示,接触噪声工龄10～19a年双耳高频平均听阈≥40dB的检出率（12．6％）明显高于接噪工龄〈10a的检出率（3．4％）,差异有统计学意义（X2=5．71,P〈0．05）。双耳高频平均听阈在26～39dB的检出率为18．3％,并且接噪工龄10～19a、≥20a双耳高频平均听阈在26～39dB的检出率（分别为22．5％、29．4％）明显高于〈10a的检出率（9．0％）,差异有统计学意义（X2分别为7．13、5．53,P〈0．01和〈0．05）。结论噪声对发电车乘务员听力的损害随接噪工龄增加而加重,应重视该岗位作业人员血压在正常高值及纯音听阈在26—39dB范围检出率较高这一情况。应在隔音降噪、合理安排作息时间等防护方面做积极努力。     

噪声和手传振动协同作用对工人听力的影响

目的 分析噪声、手传振动对听力功能的影响,评估手传振动和噪声对作业人员听力的协同作用,为职业健康监护提出建议。
方法 2018年5月选取某金属加工企业473名操作工,以同时接触噪声、手传振动的操作工为观察组,单纯接触噪声的操作工为对照组。通过纯音听阈测试检测工人高频和语频听力损失情况,并进行统计学分析。
结果 观察组的高频听力损失检出率（40.8%）和语频听力损失检出率（4.3%）均高于对照组（26.3%和1.8%）,观察组和对照组的高频听力损失检出率均高于语频听力损失检出率,以上差异均有统计学意义（P < 0.05）。观察组3~6年工龄段的语频听力损失检出率（10.2%）高于0~3年工龄段（2.3%）。
结论 噪声与手传振动相结合,可导致语频和高频的听力损失率增加。随着工作时间的增长,语频听力损失的概率进一步提升。噪声作业人员的职业体检中,需要考虑振动的影响,对于既受到振动又受到噪声影响的工人,应缩短体检间隔时间,提高体检频率,及时发现损害。
     

广州市部分企业噪声作业工人听力损失现况分析

目的对广州市部分企业噪声作业工人听力损失现况进行分析,以达到保护工人听力的目的。方法以部分企业长期接触噪声的440名工人为研究对象,测量等效A声级(LAeq)。按等能量原则将LAeq和噪声作业工龄合并计算累积噪声暴露量(CNE);用logistic回归模型分析听力损失的相关因素。结果作业环境噪声强度超标率为41.20%,噪声强度均值为(89.30±4.57)dB(A)。440例噪声作业工人听力损失检出率为23.86%,听力损失与耳塞防护、工龄、年龄和CNE存在正相关关系(P0.05)。非条件logistic回归分析结果显示,年龄、工龄可能是听力损失的危险因素(偏回归系数为正值,OR值1)。结论在有佩戴耳塞防护的情况下,CNE作为听力损失的评价指标不敏感,佩戴耳塞仍是目前最好的防护措施。     

Combined effects of noise,vibration and visual field stimulation on electrical brain activity and optomotor responses

Summary Eye movements and electroencephalographs (EEG) were recorded in intact rabbits during an optokinetic test. The animals were exposed to pure tone noise (85 dB at 4000 Hz), impulse noise (159 dB), and vibration directed at the abdomen (amplitude 0.9 mm at frequencies of 40, 80, and 120 Hz). The velocity of optokinetic nystagmus (OKN) significantly increased with these stimuli. The increase seen with vibration was greater than the noise-induced increase. The response was strongest when noise and vibration were combined. The increase in OKN induced by vibration was successive and dependent on frequency. The increase was weakest during exposure to vibration at 40 Hz and strongest at 120 Hz. EEGs of the dorsal hippocampus, amygdaloid complex, midbrain reticular formation, and frontal motor cortex were all activated during noise and vibration exposure, but activation of the hippocampal EEG was the most closely related to the increase in OKN. Combination of the different stimuli indicated that their interaction could not be predicted on the basis of responses to single stimuli, and, in most cases, the result was indifference due to the high alerting effect of vibration alone. The findings can be related to the non-specific dizziness found in aerospace workers exposed to excessive noise and vibration.This paper was presented at The 1st International Conference on the Combined Effects of Environmental Factors     

Long-term sick leave and disability pensioning due to back disorders of tractor drivers exposed to whole-body vibration

Summary In a historical 11-year follow-up study, disability pensioning and the incidence of the first sick leave of 4 weeks or longer due to back disorders has been investigated in a group of drivers exposed to whole-body vibration (WBV), mainly of agricultural tractors. The reference group comprised workers not or only slightly exposed to WBV from the same and another company. The vibration exposure of the tractor drivers was roughly around the ISO-2631 fatigue-decreased proficiency limit. The incidence of a first long-term sick leave due to back disorders was 3 per 100 person-years in tractor drivers and 2 per 100 person-years in the entire reference group. However, the incidence was not substantially increased in tractor drivers when the referents comprised only those working at the same company, suggesting selection bias. The highest relative risk (ca. 3) was found for long-term sick leave due to intervertebral disc disorders and this risk seemed to increase with the received WBV dose. That especially the incidence of intervertebral disc disorders increased, agrees well with findings in other studies. Data on disability pensioning due to back disorders are too scarce to be conclusive, but a trend towards younger disablement in tractor drivers is evident. Exposure to WBV, together with twisted posture and prolonged sitting, are considered to be responsible for the increased incidences observed in tractor drivers.     

听力损伤的累积噪声暴露阈值研究

目的根据不同累积噪声暴露量与工人语频听力损伤发生率间的关系,探讨和评价引起职业性听力损失的临界累积噪声暴露阈值.方法应用Logistic回归模型分析1 435名不同累积噪声暴露强度的听阈数据.结果语频损伤和高频损失发生率随暴露水平而增高;累积噪声暴露量与语频损伤发生率的Logistic回归分析显示,听阈水平随累积噪声暴露量增高而上升并有明显相关性;预测模型显示语频损伤的临界累积噪声暴露阈值为100dB(A).结论听力损伤的临界累积噪声暴露阈值100dB(A)与我国现执行的噪声卫生标准具有一致性,可探讨作为对个体职业噪声暴露危害程度警告的阈值指标.     

某市2家机械制造企业噪声接触人员听力防护调查

目的通过了解噪声作业人员个体防护设备的使用及认知情况,找出问题,为今后制定防护对策提供可靠的依据。方法以宜兴市2家噪声危害比较严重的机械制造企业作为调查对象,2011年9月通过问卷和现场调查获得个人防护用品使用情况及噪声防护的认知情况;用国产HS6288B噪声频谱分析仪检测车间噪声;噪声性耳聋由具有诊断资质机构的医师集体依据GBZ 49-2007《职业性噪声聋诊断标准》进行诊断。结果 9个车间中4个车间的噪声超过85 dB(A),最高达92.1 dB(A);听力检查发现有高频听力损失者34人,检出率为14.8%,发现噪声聋患者7人,检出率为3.0%;2个企业的噪声接触人员耳塞佩戴培训率为66.1%,参加噪声危害教育率比较低,为42.2%;全程佩戴耳塞的人员为67.8%,能够完全正确佩戴耳塞的人员仅占18.7%,不戴耳塞的主要原因是与人交流不方便,占48.9%;噪声危害的知晓率为71.7%;正确使用防护用品的知晓率为63.0%。结论企业需要采取综合性的措施提高噪声作业人员耳塞的正确佩戴率,才能达到保护作业人员健康的目的。