A roadmap for assessing the diagnostic usefulness of neurosensory testing and an updated method for exposure assessment among vibration-exposed workers in northern Sweden.

Workers who use handheld vibrating machines such as grinders, hammers and chainsaws expose themselves to hand-arm vibration (HAV). Exposure to HAV may cause injuries to both the neurological and the vascular system. The occupational health services (OHS) in Sweden use a formal guideline for secondary prevention focusing on early detection of vibration-related injuries. The guide includes several screening tools, such as a screening questionnaire, clinical examinations, and laboratory tests. There are no studies, to our knowledge, on the diagnostic value of the separate items on symptoms in the screening questionnaire in relation to the laboratory tests or the clinical examinations performed during a medical examination among patients exposed to HAV. Furthermore, the recently presented ISO standard for HAV measurements (ISO/TR 18,750) has only been tested for vascular injuries and not neurological injuries. This research roadmap aims to evaluate separate items in a screening questionnaire on neurological symptoms in relation to laboratory and clinical tests among HAV exposed workers in the Arctic region of Northern Sweden. It also covers a comparison of the dose-response of the current ISO 5349-1 measurement standard and the new suggested standard ISO/TR 18,750 with the neurosensory outcomes. This manuscript describes the study rationale, design, methods, and significance.

Serum levels of biomarkers related to severity staging of Raynaud's phenomenon, neurosensory manifestations, and vibration exposure in patients with hand-arm vibration injury.

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud's phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere's trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

Carpal tunnel syndrome and occupational hand exposures: a Danish nationwide cohort study.

OBJECTIVES: The aim was to examine exposure-response relations between occupational hand exposures and carpal tunnel syndrome (CTS) and to compare the relation between surgery-treated and non-surgery-treated CTS. The secondary aim was to study sex-specific differences in exposure-response relations. METHODS: We conducted a nationwide register-based cohort study of all persons born in Denmark (1945-1994). During follow-up (2010-2013), we identified first-time events of CTS. Occupational hand exposure estimates the year before each follow-up year were obtained by linking individual occupational codes with a job exposure matrix. We used multivariable logistic regression equivalent to discrete survival analysis based on sex and surgery. The excess fraction of cases was calculated. RESULTS: For both sexes, exposure-response relations were found for all occupational hand exposures. Among men, we found ORadj of 3.6 (95% CI 3.2 to 3.8) for hand-related force, 2.9 (95% CI 2.5 to 3.2) for repetitive hand movements, 3.8 (95% CI 2.7 to 5.2) for non-neutral hand posture and 2.5 (95% CI 2.2 to 2.7) for hand-arm vibration in the highest exposure groups. For combined exposure (hand load), ORadj was 3.5 (95% CI 3.1 to 4.0). Slightly higher ORsadj were generally found for surgery-treated CTS compared with non-surgery-treated CTS for both sexes. When comparing sex, somewhat higher ORsadj were found among men. The excess fraction was 42%. CONCLUSIONS: Occupational hand exposures carried a 3-5-fold increased risk of CTS with slightly higher risks for surgery-treated compared with non-surgery-treated CTS. Even though CTS occurs more frequently among women, somewhat higher exposure-response relations were found for men compared with women. In the general working population, a substantial fraction of first-time CTS could be related to occupational hand exposures.

Effects of whole-body vibration on bone mineral density in postmenopausal women: an overview of systematic reviews.

OBJECTIVE: The aim of this study is to evaluate the findings of existing systematic reviews (SRs) and provide scientific evidence on the efficacy and safety of whole-body vibration (WBV) in improving bone mineral density (BMD) in postmenopausal women, to provide recommendations and guidance for future high-quality clinical research and SRs. METHODS: We conducted searches in six databases (SinoMed, CNKI, Cochrane Library, Embase, PubMed, Web of Science) from the inception of the databases until July 31, 2023. The language was limited to Chinese or English. The methodological quality, risk of bias, and evidence grade of outcomes were evaluated using AMSTAR-2, ROBIS, and GRADE, respectively. Additionally, the degree of overlap in randomized controlled trials (RCTs) among the SRs was calculated using corrected covered area (CCA). Furthermore, we performed quantitative synthesis or descriptive analysis of the relevant data. All relevant operations were independently conducted by two individuals. RESULTS: A total of 15 SRs were included in the analysis, out of which three were qualitative descriptions and 12 were meta-analyses. According to AMSTAR-2, only two SRs were rated as low or moderate, while the remaining 13 SRs were rated as critically low quality. The ROBIS assessment indicated that seven SRs had a low risk of bias, while 8 SRs had a high risk of bias. The overall findings suggest that WBV does not have a significant advantage in improving BMD in postmenopausal women. Furthermore, the CCA results revealed a high overlap in RCTs across five outcomes among the 15 SRs. Only five SRs reported specific adverse reactions/events experienced by participants after WBV interventions, and none of the SRs reported any severe adverse events. CONCLUSION: The existing evidence cannot establish definitive advantages of WBV in improving BMD in postmenopausal women. Therefore, we do not recommend the use of WBV for improving BMD in postmenopausal women. However, WBV may have potential value in maintaining BMD in postmenopausal women, further research is needed to confirm these findings.

Investigation of structural parameters influencing vibration characteristics of heavy-duty truck diesel tanks.

The working conditions of heavy-duty trucks are very complicated as the diesel shaking and resonance problems, which causes weld tears, separators to fall off, and other failures occur. Through experiments and finite element simulation, the natural frequency and vibration mode of a given 400 L diesel tank were calculated to study the influences of structural parameters such as the fill ratio (0.1-0.9), the number of baffle plates (0, 1, 2), the spacing of the plates (240 mm, 400 mm, 560 mm) and the aperture (38 mm, 78 mm, 118 mm) on the modal parameters with the wet mode method. The results of the hammering mode test and the simulation modal analysis agree well with the maximum error is 4.8%; the natural frequency of the diesel tank will increase with fill ratio decrease; the increase of the baffle plate number (0, 1, 2) can effectively increase the first-order natural frequency of the diesel tank, but the change of the natural frequency is not obvious on the higher order; the higher plates spacing has a smaller natural frequency; increasing the aperture will highly increase the natural frequency, 188 mm has better vibration safety.

Risk of hand and forearm conditions due to vibrating hand-held tools exposure: a retrospective cohort study from Sweden.

OBJECTIVES: The occurrence of hand and forearm disorders related to vibration exposure, adjusted for relevant background factors, is scarcely reported. We analysed the prevalence of such conditions in a large population cohort, stratified by sex, and associations with exposure to vibrating hand-held tools. DESIGN: This is a retrospective cohort study. SETTING: Individuals in the Malmö Diet and Cancer Study cohort (MDCS; inclusion 1991-1996; followed until 2018) were asked, 'does your work involve working with vibrating hand-held tools?' (response: 'not at all', 'some' and 'much'). Data were cross-linked with national registers to identify treatment for carpal tunnel syndrome (CTS), ulnar nerve entrapment (UNE), Dupuytren's disease, trigger finger or first carpometacarpal joint (CMC-1) osteoarthritis (OA). Cox regression models, unadjusted and adjusted (age, sex, prevalent diabetes, smoking, hypertension and alcohol consumption), were performed to analyse the effects of reported vibration exposure. PARTICIPANTS: Individuals in the MDCS who had answered the questionnaire on vibration exposure (14 342 out of the originally 30 446 individuals in MDCS) were included in the study. RESULTS: In total, 12 220/14 342 individuals (76%) reported 'no' exposure, 1392/14 342 (9%) 'some' and 730/14 342 (5%) 'much' exposure to vibrating hand-held tools. In men, 'much' exposure was independently associated with CTS (HR 1.71 (95% CI 1.11 to 2.62)) and UNE (HR 2.42 (95% CI 1.15 to 5.07)). 'Some' exposure was independently associated with UNE in men (HR 2.10 (95% CI 1.12 to 3.95)). 'Much' exposure was independently associated with trigger finger in women (HR 2.73 (95% CI 1.49 to 4.99)). We found no effect of vibration exposure on Dupuytren's disease or CMC-1 OA. 'Much' vibration exposure predicted any hand and forearm diagnosis in men (HR 1.44 (95% CI 1.08 to 1.80)), but not in women. CONCLUSIONS: Vibration exposure by hand-held tools increases the risk of developing CTS and UNE and any common hand and forearm conditions in men, whereas women only risk trigger finger and CMC-1 OA. Adjustment for relevant confounders in vibration exposure is crucial.

Investigating visual preferences of clinical mechanical anesthetic vibration: a cross-sectional image survey.

While mechanical vibration lessens discomfort associated with injection site pain (ISP), many local anesthetic injectors (LAIs) do not use vibratory anesthetic devices (VADs). Injector preference of vibration device is influenced by functional concerns, but qualitatively there is an element of adoption that is driven by visual feedback. We sought to capture operator preferences of vibration device design elements to further understand why injectors do not use these devices. We conducted a survey of image preferences among nurses and medical assistants employed at 8 dermatological clinics to investigate barriers to VAD use. Images were electronically modified with features distinct from the original device (a VAD commonly used in clinical practice). Participants rated their likelihood and comfort of use of each VAD represented in the images. Two-sample t-tests were used to compare the rating of the unmodified VAD to each modified VAD within participants. A response rate of 100% was achieved with 35 participants (average age, 38.5 years; 6 (17.1%) male, 29 (82.9%) female). Despite 28 (80%) participants knowing that mechanical vibration reduces ISP, only 16 (45.7%) endorsed ever using mechanical vibration as topical anesthetic. Images modified by pattern, color, and sterility covering were rated significantly lower than the original, unmodified VAD image (plain white VAD), confirming that visual feedback does impact adoption. Through independent comment categorization, aesthetics were found to be important to LAIs. Aesthetic preferences opposing functional concerns may factor into the lack of VAD use. Defining these visual preference barriers to adoption may help promote VAD use during dermatologic procedures.

Exploring the link between occupationally relevant whole body vibration and headache and neck pain: is elevated muscle tension an intermediary factor?

Whole body vibration (WBV) is linked to short- and longer-term adverse health outcomes, including cognitive impairment, stress and memory loss, loss of balance, reduced proprioception, visual and vestibular disturbances, gastrointestinal problems, and musculoskeletal disorders. Epidemiological evidence supports the link between WBV and headache and head discomfort, but few experimental studies have examined this relationship, particularly with increased muscle tension, as an intermediary. This study aimed to investigate the relationship between muscle tension and vibration intensity, between perceived neck pain and headache/head discomfort and vibration intensity, and between muscle tension and reported neck pain and headache symptoms from simulated WBV based on field measurements of all-terrain vehicle operation on farm terrain. We observed significantly higher electromyography amplitude in the High condition (equivalent to EU Directive's Exposure Limit Value) compared to both Low (equivalent to EU Directive's Exposure Action Value) and Control (quiet sitting) conditions at the left upper trapezius muscle but there were no significant time effects. Neck pain and headache/head discomfort significantly increased after both Low (91% increase from baseline) and High (154% increase from baseline) vibration conditions but there were no significant differences between conditions. Based on simple regression modeling, the relationship between muscle activity and neck pain or headache was very weak (R2 = 0-0.093). Given the possibility of multiple factors contributing to headache symptoms, future research should not only consider the role of muscle tension but also sensory conflict, excessive noise, biodynamic responses, and a combination of these factors.

Manikin study showed that neonates are exposed to high sound and vibration levels during helicopter incubator transports.

AIM: This initial Norwegian study aimed to quantify the vibrations and sounds experienced by neonates when they were transported by helicopter in an incubator. METHODS: Two neonatal manikins weighing 500 and 2000 g were placed in a transport incubator and transported in an Airbus H145 D3 helicopter during standard flight profiles. The vibrations were measured on the mattress inside the incubator and the sound levels were measured inside and outside the incubator. RESULTS: The highest vibration levels were recorded during standard flight profiles when the lighter manikin was used. These ranged 0.27-0.94 m/s2, compared to 0.27-0.76 m/s2 for the heavier manikin. The measurements exceeded the action levels set by the European Union Vibration Directive for adult work environments. The sound levels inside the incubator ranged 84.6-86.3 A-weighted decibels, with a C-weighted peak level of 122 decibels. The sound levels inside the incubator were approximately 10 decibels lower than outside, but amplification was observed in the incubator at frequencies below 160 Hz. CONCLUSION: Vibrations were highest for the lighter manikin. The sound levels during helicopter transport were higher than recommended for neonatal environments and sounds were amplified within the incubator at lower frequencies.

Blood biomarkers for occupational hand-arm vibration exposure.

Hand-arm vibration is a common occupational exposure that causes neurological impairment, myalgia, and vibration-induced Raynaud's phenomena or vibration white fingers (VWF). The pathological mechanism is largely unknown, though several mechanisms have been proposed, involving both immunological vascular damage and defective neural responses. The aim of this study was to test whether the substances interleukin-33 (IL-33), macrophage-derived chemokine (MDC), interleukin-10 (IL-10), endothelin-1 (ET-1), C-C motif chemokine ligand 20 (CCL20), calcitonin, and thromboxane (TXA2) changed before and after occupational hand-arm vibration exposure. 38 full-time shift workers exposed to hand-arm vibration were recruited. All the participants underwent medical examinations regarding symptoms of Raynaud's phenomena. In 29 of the participants, the concentration of IL-33, MDC, IL-10, ET-1, CCL20, calcitonin, and TXA2 was measured before and after a workday. There was a significant increase in ET-1 and calcitonin concentration and a decrease in the CCL20 concentration after the work shift in all participants. In the group suffering from VWF, but not in the non-VWF group, MDC was statistically significantly lower before the work shift (p = .023). The VWF group also showed a significant increase in MDC after the work shift. Exposure to occupational hand-arm vibration is associated with changes in ET-1, calcitonin, and MDC concentration in subjects suffering from vibration white fingers, suggesting a role of these biomarkers in the pathophysiology of this condition.

What characteristics are most important in stratifying patients into groups with different risk of diabetic foot ulceration?

AIMS/INTRODUCTION: This study aimed to assess if patients can be divided into different strata, and to explore if these correspond to the risk of diabetic foot complications. MATERIALS AND METHODS: A set of 28 demographic, vascular, neurological and biomechanical measures from 2,284 (1,310 men, 974 women) patients were included in this study. A two-step cluster analysis technique  was utilised to divide the patients into groups, each with similar characteristics. RESULTS: Only two distinct groups: group 1 (n = 1,199; 669 men, 530 women) and group 2 (n = 1,072; 636 men, 436 women) were identified. From continuous variables, the most important predictors of grouping were: ankle vibration perception threshold (16.9 ± 4.1 V vs 31.9 ± 7.4 V); hallux vibration perception threshold (16.1 ± 4.7 V vs 33.1 ± 7.9 V); knee vibration perception threshold (18.2 ± 5.1 V vs 30.1 ± 6.5 V); average temperature sensation threshold to cold (29.2 ± 1.1°C vs 26.7 ± 0.7°C) and hot (35.4 ± 1.8°C vs 39.5 ± 1.0°C) stimuli, and average temperature tolerance threshold to hot stimuli at the foot (43.4 ± 0.9°C vs 46.6 ± 1.3°C). From categorical variables, only impaired sensation to touch was found to have importance at the highest levels: 87.4% of those with normal sensation were in group 1; whereas group 2 comprised 95.1%, 99.3% and 90.5% of those with decreased, highly-decreased and absent sensation to touch, respectively. In addition, neuropathy (monofilament) was a moderately important predictor (importance level 0.52) of grouping with 26.2% of participants with neuropathy in group 1 versus 73.5% of participants with neuropathy in group 2. Ulceration during follow up was almost fivefold higher in group 2 versus group 1. CONCLUSIONS: Impaired sensations to temperature, vibration and touch were shown to be the strongest factors in stratifying patients into two groups with one group having almost 5-fold risk of future foot ulceration compared to the other.

The effects of standing foot-transmitted vibration on self-reported discomfort ratings.

BACKGROUND: Occupational foot-transmitted vibration (FTV) exposure is common in industries like mining, construction, and agriculture, often leading to acute and chronic injuries. Vibration assessments require technical expertise and equipment which can be costly for employers to perform. Alternatively, researchers have observed that self-reported discomfort can be used as an effective indicator of injury risk. OBJECTIVE: This study aimed to investigate the effect of standing FTV exposure on self-reported ratings of discomfort, and whether these subjective ratings differed by body area and exposure frequency. METHODS: Participants (n = 30) were randomly exposed to standing FTV at six frequencies (25, 30, 35, 40, 45, and 50 Hz) for 20-45 seconds. Following each exposure, participants rated discomfort on a scale of 0-9 in four body areas: head and neck (HN), upper body (UB), lower body (LB), and total body. RESULTS: Results indicated that participants experienced the most discomfort in the LB at higher frequencies (p < 0.001), consistent with the resonance of foot structures. The HN discomfort tended to decrease as the exposure frequency increased, although not statistically significant (p > 0.0167). The UB discomfort remained relatively low across all frequencies. CONCLUSIONS: The study suggests a potential connection between resonant frequencies and discomfort, potentially indicating injury risk. Although self-reported discomfort is insufficient for directly assessing injury risk from FTV, it provides a simple method for monitoring potential musculoskeletal risks related to vibration exposure at resonant frequencies. While professional vibration assessment remains necessary, self-reported discomfort may act as an early indicated of vibration-induced injuries, aiding in implementing mitigation strategies.

Determinants of discomfort from combined exposure to noise and vibration in dumper operators of mining industry in India.

In the mining industry, dumper operators are exposed to combined noise and vibration, leading to discomfort. Dumpers are heavy earth-moving machines that are used for carrying bulky material in mining industries. Dumper operators are exposed to physical hazards such as vibration, noise, heat, and humidity, throughout their lifetime of work. Fifty-four dumper operators working in mines were selected for this study. Noise was measured as per the guidelines of the Directorate General Mining Safety, India, and whole-body vibration was measured as per the guidelines of ISO 2631-1::1997. Noise Pro DLX, Type 2 noise dosimeters were used for the measurement of personal noise exposure while SV-106 six channels vibration meters were used for whole body vibration (WBV) exposure measurement. Discomfort was calculated using the regression equation developed by Huang and Griffin (2014). The total discomfort level of mine operators was about 192. A predictive equation was derived by using a regression model to determine the contribution of individual variables causing discomfort. It was observed that for every unit increase in noise (LAeq), discomfort increased by 10.20 units, a one-unit increase in vibration (A (8)) led to a 51.7-unit increase in discomfort, while an increase of one unit of exposure time increased the discomfort level by 5.24 units.

The after-effects of occupational whole-body vibration on human cognitive, visual, and motor function: A systematic review.

Whole-body vibration (WBV) is prevalent in labour-related activities and can have adverse effects on the health and performance of the individuals exposed. However, evidence regarding the extent to which human functionality is affected following occupational WBV exposure has not been collated. The current systematic review sought to synthesize existing literature and assess the strength and direction of evidence regarding the acute after-effects of occupational WBV exposure on cognition, visual function, postural stability, and motor control. We conducted a comprehensive search of AMED, CINAHL, MEDLINE, PubMED, Psychology and Behavioural Sciences Collection, SPORTDiscus, APA PsychInfo, Cochrane Library, EMBASE, HMIC, Global Health, ProQuest Central, Scopus, Web of Science, and the US National Technical Information Service on April 26, 2023. Studies that quantified vibration exposure and measured acute changes in cognition, visual function, postural stability, and motor control from baseline to post-vibration were considered without date restriction. Out of the 2663 studies identified, 32 were eligible for inclusion. Based on the Risk of Bias in Non-Randomized Studies of Exposure (ROBINS-E) tool, the studies demonstrated low (66%), moderate (25%) and high risk of bias (9%). The findings indicate that after exposure to WBV, postural stability either deteriorates or remains unchanged. Inconsistent effects of WBV on cognition were reported, while visual function and motor control showed no pronounced changes following WBV. This might be attributed to assessment limitations such as learning effects in neuropsychological and motor tasks, and non-functional measures of vision employed. There was a lack of consistency in the characterization of vibration exposure and the assessment of associated effects on functional performance. Current evidence is therefore insufficient to provide definitive guidance for updating occupational health and safety regulations regarding WBV. However, this review highlights the potential for WBV to jeopardize post-exposure human performance and, consequently, safety. The completion of the review was supported by a UKRI EPSRC training grant. The review has been registered on PROSPERO (ref CRD42023391075).

Physical and psychosocial work-related exposures and the occurrence of disorders of the shoulder: A systematic review update.

This review is an update of a previous systematic review and assesses the evidence for the association of work-related physical and psychosocial risk factors and specific disorders of the shoulders. Medline, Embase, Web of Science Core Collection, Cochrane Central and PsycINFO were searched and study eligibility and risk of bias assessment was performed by two independent reviewers. A total of 14 new articles were added with the majority focusing on rotator cuff syndrome (RCS) with seven studies. Nine articles reported psychosocial exposures in addition to physical exposures. The strongest evidence was found for the association between elevation, repetition, force and vibration and the occurrence of SIS and tendinosis/tendonitis. Evidence also suggests that psychosocial exposures are associated with the occurrence of RCS and tendinosis/tendonitis. Other findings were inconsistent which prevents drawing strong conclusions.

Evaluation of Hand-Arm Vibration Syndrome Owing to Nerve Conduction Study and Cumulative Exposure Index-A 2.5-Year Cohort Study.

OBJECTIVE: This study aims to clarify the relationship between peripheral neuropathy in hand-arm vibration syndrome and cumulative exposure index. METHODS: 68 participants without symptoms were surveyed. The participants were divided into three groups based on past and current vibration exposure (VE). RESULTS: Comparison among groups according to past VE showed that the median and ulnar sensory nerve conduction velocities and median sensory nerve action potential (SNAP) amplitude were significantly lower in past high and low exposure groups than in the past nonexposure group. Comparison among groups according to current VE showed that the median and ulnar SNAP amplitudes were significantly lower in the current high exposure group than in the current low or nonexposure group. CONCLUSIONS: Vibration tool handlers have potential peripheral nerve lesions at a certain stage without subjective symptoms of the finger.

Effect of concurrent exposure to noise and hand-transmitted vibration on auditory and cognitive attention under simulated work with construction tools.

Objectives. This study aimed to investigate the effects of separate and concurrent exposure to occupational noise and hand-transmitted vibration (HTV) on auditory and cognitive attention. Methods. The experimental study was conducted with 40 construction workers who were exposed to noise (A-weighted equivalent sound pressure level of 90 dB) and to HTV (10 m/s2 at 31.5 Hz), and concurrent exposure to both for 30 min under simulated work with vibrating equipment used in construction. Cognitive performance aspects were then evaluated from each individual in two pre-exposure and post-exposure settings for each session. Results. The effect sizes of concurrent exposure (HTV + noise) and separate exposure to noise on auditory attention were very close (effect size = 0.648 and 0.626). The largest changes in the difference of response time in both types of attention (selective and divided attention) were related to the concurrent exposure scenario and then exposure to HTV, respectively. The highest effects for the correct response of selective and divided attention are related to concurrent exposure (HTV + noise) and then noise exposure, respectively. Conclusion. The HTV effect during concurrent exposure is hidden in auditory attention, and noise has the main effects. The divided attention was more affected than the selective attention in the different scenarios.

Noise and Vibration Generation and Response of Mice (Mus musculus) to Routine Intrafacility Transportation Methods.

Intrafacility transport of mice is an essential function for both laboratory and husbandry personnel. However, transport may induce a stress response that can alter research findings and negatively impact animal welfare. To determine minimally adverse intrafacility transport methods, in-cage noise and vibration exposure during transport on a variety of transport vehicles (hand carrying, stainless steel rack, flatbed cart, metal teacart, plastic teacart, and a cart with pneumatic wheels) were measured. Under-cage and in-cage padding was tested for its ability to decrease noise and vibration on each vehicle. Behavioral (open field test and elevated plus maze) and corticosterone responses of mice were then measured following transport on the most adverse (metal teacart) and least adverse (pneumatic cart) methods of multicage transport. Behavioral measures showed no difference between transported mice and untransported mice in both single- and group-housed settings. Plasma corticosterone was significantly elevated in mice transported on the metal teacart immediately following transport and continued to have elevated trends in circadian peaks during the 48h of sampling. The cart with pneumatic wheels was most effective at reducing noise and vibration, reflected in posttransport corticosterone readings that remained equivalent to those in untransported mice. This study demonstrates that mitigation of noise and vibration during cart transport may decrease the impact of transport on certain stress parameters in mice.

Investigating the effect of hot and cold polyurethane foam on reducing whole body vibration of forklift operators.

BACKGROUND: Vibration is one of the harmful factors for forklift drivers. The use of non- standard seats and not paying attention to how the seats are maintained can be affected by the amount of vibration transmitted to the person. OBJECTIVE: This study investigates the amount of vibration transmitted from the forklift and the effect of different types of polyurethane foam in reducing the vibration transmitted from the forklift seat. METHODS: This descriptive-analytical study was performed on 38 forklifts in 4 diesel models with the same weight class. The amount of vibration transmitted from forklift seats according to ISO2631 standard, taking into account the effect of various factors such as foam type (hot and cold), thickness (6-12 cm), load and year Function was measured. The amount of vibration caused by the forklift on the seat and under the seat was evaluated using ISO7096 standard. RESULTS: The average total vibration of the whole body in all foams in no-load mode is more than with load. The transmission vibration of cold polyurethane foam is less than that of hot polyurethane foam. With increasing thickness, the efficiency of cold polyurethane foam increases by 12 cm and in the loaded state 40.63% and in the unloaded state 49.58% in reducing the vibration transmitted to drivers. CONCLUSION: The results of this study show that cold foam has better effectiveness and efficiency than hot polyurethane foam. Also, the thicker the foam, the less vibration is transmitted to the driver.