Exposure-response relationship in the hand-arm vibration syndrome: an overview of current epidemiology research

The complex of vascular, neurologic, and osteoarticular disorders occurring in the upper limbs of vibration-exposed workers is called hand-arm vibration syndrome. There is epidemiologic evidence for an increased occurrence of peripheral sensorineural disorders in occupational groups working with vibrating tools. An excess risk for wrist osteoarthrosis and for elbow arthrosis and osteophytosis has been reported in workers exposed to shocks and low-frequency vibration of high magnitude from percussive tools. However, there are too few epidemiology data to enable reliable conclusions to be drawn about exposure-response relationships for both sensorineural disturbances and bone and joint disorders caused by hand-transmitted vibration. Cross-sectional and longitudinal epidemiology studies have shown that occupational exposure to hand-transmitted vibration from a great variety of hand-held tools is significantly associated with an increased occurrence of digital vasospastic disorders called vibration-induced white finger (VWF). The proposal of an exposure-response relationship for VWF has been included in an annex to the international standard ISO 5349. The findings of several epidemiology studies have shown a poor agreement between the risk for VWF observed in various occupational groups and that predicted by the ISO 5349 model. Both overestimation and underestimation of the occurrence of VWF have been reported by investigators. It has been argued that the current ISO frequency-weighting curve for hand-transmitted vibration may be inappropriate for the assessment of vibration-induced adverse vascular effects. Alternative exposure-response relationships for VWF have been suggested in recent epidemiology studies. The epidemiology data used to construct current exposure-response relationships for vibration-induced injuries are primarily derived from cross-sectional studies. Future epidemiology research should be based on prospective cohort studies because the design characteristics of such studies permit the study of cause-effect relationships and the formulation of etiologic hypotheses. Received: 16 March 1998 / Accepted: 6 July 1998     

Bone and joint pathology in workers using hand-held vibrating tools. An overview

A literature evaluation was made with regard to the radiological documentation of bone and joint pathology in the hands and arms of workers using vibrating tools. There is evidence that work with pneumatic percussive tools (such as chipping hammers and scalers) may cause premature elbow and wrist osteoarthrosis, although of very low prevalence. This work-related disorder is not specific to vibration exposure. Instead, it is likely to result from the strong dynamic and static joint loading (often in extreme positions of the joint) and the repetitive hand-arm movements (sometimes also repeated minor traumatization) typical for tool manipulation in any heavy labor. Exposure to low-frequency percussion may, however, play a particular etiologic role: damage to the joint cartilage by repeated shocks from the tool, additional articular load (and consequent strain) associated with a vibration-induced increase in the need for joint stabilization and higher gripping forces, the tonic vibration reflex (which increases muscle contraction), and a stronger grip induced when tactile sensibility is diminished by vibration. So far, no investigations have ventured into the great complexity of possible confounders and effect modifiers. -A constitutional susceptibility may be required to produce osteoarthrosis. -The allegation that hand-arm vibration exposure causes an excess prevalence of bone cysts, vacuoles, Kienb?ck's disease, or pseudarthrosis of the scaphoid has not been validly documented. -Exposure to vibration of higher frequencies (such as from rotating drills, grinders, and chain saws) does not seem to be associated with excess bone and joint pathology. -The observed large variation in the prevalence of skeletal disorders may be explained by biodynamic and ergonomic differences between various occupations.     

A study on the vibration-dose limit for Japanese workers exposed to hand-arm vibration.

To obtain a vibration-dose limit for Japanese workers exposed to hand-arm vibration, the prevalences of vibration-induced white finger (VWF) and numbness of the hand were studied in 5 different groups of workers exposed to segmental vibration. In addition, the prevalence of primary Raynaud's phenomenon (PRP) in the general population without occupational vibration exposure was computed. The vibration levels in the exposed groups (except chain saw operators) ranged from 124.1-129.2 dB (reference value, 10(-6) m/s2). The prevalence of VWF in these groups was 2.2-4.8%. This value was not statistically significant (p greater than 0.05) when compared to the prevalence of PRP in the general Japanese population (2.7-2.9% in our study and 0.5-4.6% in other surveys in Japan). Although the prevalence of numbness of the hands fluctuated among the groups, no significant differences could be demonstrated. Our results were then compared to those of previous reports by literature study [319 papers on hand-arm vibration syndrome (HAVS) and 25 reports on PRP]. At a glance the Japanese population showed a lower prevalence for PRP compared to other countries, which suggested that exposure to cold and biological abilities should also be considered to assess vibration syndrome. A comparison of the vibration characteristics of different tools and the occurrence of VWF in the hands of workers in the literature with those of our data suggested that a daily hand-arm vibration exposure at a level lower than 2.5 m/s2 (128 dB, reference value 10(-6) m/s2) could possibly decrease the risk of VWF among workers exposed to segmental vibration.     

Criteria for case definitions for upper limb and lower back disorders caused by mechanical vibration

BACKGROUND AND OBJECTIVES: This paper provides an overview on the evaluation and assessment of vibration exposure at the workplace, the long-term health effects caused by occupational exposure to hand-transmitted vibration and whole-body vibration, and the criteria for case definitions for vibration-induced upper limb and lower back disorders. Excessive exposure to hand-transmitted vibration from powered processes or tools is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and musculoskeletal systems of the upper limbs. The complex of these disorders is called hand-arm vibration syndrome. Long-term occupational exposure to intense whole-body vibration is associated with an increased risk for disorders of the lumbar spine and the connected nervous system. DISCUSSION AND CONCLUSIONS: The medical tools for the management of cases with suspected vibration-induced disorders include the case history, a complete physical examination, and special diagnostic investigations. The criteria for case definitions for upper limb disorders caused by hand-transmitted vibration (vascular, neurological, and musculoskeletal) and for lower back disorders caused by whole-body vibration are discussed on the basis of the guidelines suggested by the Italian Society of Occupational Medicine and Industrial Hygiene.     

Dose-response relation between exposure to two types of hand-arm vibration and sensorineural perception of vibration.

OBJECTIVES--31 railway workers and 32 lumberjacks were examined to compare the dose-response relation between the exposure to two types of hand-arm vibration and the sensory disturbances in peripheral nerves as evaluated by the vibration perception thresholds (VPTs). METHODS--Clinical examinations were carried out that included measurements of the VPTs, and electroneuromyography (ENMG), and an inquiry to confirm the use of vibrating tools. Diseases of the central nervous system and neuropathies were checked by inquiry and a clinical examination, diabetes was excluded by a blood sample analysis, and the subjects with carpal tunnel syndrome confirmed with ENMG were excluded from the study. RESULTS--Lifetime use of hand held tamping machines (railway workers) and chain saws (lumberjacks) had a significant correlation with the VPTs at frequencies from 32 to 500 Hz. The increase of the VPTs (250 Hz) in relation to use of vibrating tools was 1.8-fold higher on average in the whole group and 2.3-fold higher in the young (< 45) railway workers who had used hand held tamping machines, than in the corresponding groups of lumberjacks, who had used chain saws, whereas the frequency weighted acceleration of vibration in tamping machines was fourfold. CONCLUSION--There was a significant dose-response relation between the exposure to hand-arm vibration and the VPTs. The VPTs as a function of the frequency weighted acceleration of vibration and the exposure to vibration gave promising results for assessment of the risk of damage to sensory nerves induced by vibration.     

Hand-arm vibration syndrome in foundry workers

INTRODUCTION: The hand-arm vibration syndrome of the foundry workers using chipping hammers and grinders were analysed in Hungary last in 1950th-s years. Therefore it seemed necessary to consider the present situation of the disease. AIM: To study of the signs of the hand-arm vibration syndrome of the foundry workers using chipping hammers and grinders. METHOD: Retrospective analysis of the clinical findings of 154 foundry workers using chipping hammers and grinders. The examination included the vascular, neurological and musculoskeletal systems of the upper extremities in 95 patients. RESULTS: The first symptoms referring to hand-arm vibration syndrome appeared on the average after seven years exposure. The signs of the 95 patients were as follows: vascular disorders: 75 cases (78.9%), peripheral neurologic lesion: 62 cases (65.3%), osteoarticular damage: 35 patients (36.8%). The Raynaud's phenomenon developed more commonly on the left than the right hand. The rate of the improvement of the Raynaud's phenomenon on the average 6.5 years after the cessation of the exposure on the basis of the result of the cold provocation test was 32.8%. Lesion of the peripheral nerves of the upper limbs, mostly of distal type was experienced in 41, whereas tunnel syndromes of the upper extremities in 21 cases. The most common amongst the latter (18 cases) was the thoracic outlet syndrome. Osteoporosis of the carpal bones was detected in 36 patients (37.9%), but osteoarthrosis of the joints of the upper limbs in 12 cases (12.6%). There was no aseptic necrosis of the bones. Fatigue fracture of the spinous process of the cervical VII vertebra occurred in one single case. CONCLUSIONS: Using chipping hammers and grinders in foundry is one of the most dangerous hand-arm vibration exposure in Hungary. The most frequent signs are the vascular and neurological lesions. Due to relatively rare occurrence of osteoarticular damages X-ray examinations are not necessary during periodical medical follow up. The most effective possibility of the prevention is the diminishing of the daily exposure time.     

Neuropathies caused by vibrating instruments: clinico-diagnostic study of a group of symptomatic subjects

In order to evaluate the risk connected with hand-arm vibration exposure and associated disorders of the peripheral nervous system a study was made to assess the relationship between nervous symptoms and laboratory data to determine the kind of disorder. 40 male subjects with hand-arm vibration exposure for more than 5 years and nervous symptoms of the hands for more than 1 year and 2 control groups of non-symptomatic non-exposed subjects were considered. An electroneurophysiological study of the exposed subjects revealed 18 nerve conduction speed changes (12 median nerve, 4 ulnar nerve, 2 median and ulnar nerve), most of which were sensitivity-motor changes; only 9 Carpal Tunnel Syndromes were diagnosed. Some statistically significant differences between exposed subjects with negative results of the electroneurophysiological study and non-exposed subjects were observed. Prolonged vibration exposure seems to induce a hand-arm nerve suffering, initially with a progressive nerve conduction speed change and non-specific symptoms, but subsequently a peripheral nervous system disorder associated or not to a Carpal Tunnel Syndrome may occur.     

Quantitative exposure assessment for shipyard workers exposed to hand-transmitted vibration from a variety of vibration tools

The quantitative exposure to vibration for shipyard workers who have used several kinds of vibratory tools was studied. The dose-response relationship between lifetime exposure dose and hand-arm vibration syndrome also was studied. The study included 344 workers who were exposed to vibration in one shipyard and 53 unexposed workers in the same company. Vibration measurements were made on several vibratory tools according to the international standard, ISO 5349. The actual exposure times for the vibratory tools were measured. Questionnaires for demographics, exposure to vibration, and confounding factors were completed. A lifetime vibration dose was calculated for each worker using job categories, usage pattern of vibratory tools, and the measured vibration acceleration magnitude. Each worker was asked about vascular and neurological symptoms, and symptoms were classified according to the Stockholm workshop scale. The prevalence of vascular and sensorineural symptoms for workers exposed to vibration was 22.7 and 78.2%, which were significantly higher than 0 and 34.0% obtained in the nonexposed workers, respectively. The prevalence and severity of the hand-arm vibration syndrome was increased with an increased lifetime vibration dose. The lifetime vibration dose showed a significant association with both vascular and sensorineural symptoms. In conclusion, the lifetime vibration dose was a useful parameter for quantitative exposure assessment and showed a dose-response relationship between exposure and symptoms when adjusted for confounding factors.     

Nerve conduction in relation to vibration exposure - a non-positive cohort study

Background  

Peripheral neuropathy is one of the principal clinical disorders in workers with hand-arm vibration syndrome. Electrophysiological studies aimed at defining the nature of the injury have provided conflicting results. One reason for this lack of consistency might be the sparsity of published longitudinal etiological studies with both good assessment of exposure and a well-defined measure of disease. Against this background we measured conduction velocities in the hand after having assessed vibration exposure over 21 years in a cohort of manual workers.     

Health risks from occupational exposures to mechanical vibration

Health effects of occupational exposure to hand-transmitted vibration (HTV) and whole-body vibration (WBV) are reviewed. Excessive exposure to HTV from powered processes or tools is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and musculoskeletal systems of the upper limbs. This complex set of disorders is called hand-arm vibration syndrome. Long-term occupational exposure to intense WBV is associated with an increased risk for disorders of the lumbar spine and the connected nervous system. With a lower probability, the neck-shoulder, the gastrointestinal system, the female reproductive organs, the peripheral veins, and the cochleo-vestibular system are also assumed to be affected by WBV. However, there is weak epidemiological support for WBV-induced disorders of organ systems other than the lower back. In addition to the health effects of human vibration, this review provides information on methods for the protection and health surveillance of vibration-exposed workers according to the European Directive 2002/44/EC on mechanical vibration.     

Acute effects of vibration from a chipping hammer and a grinder on the hand-arm system.

OBJECTIVES--The purpose of this study was to compare various effects on the hand-arm system of vibration exposure from a chipping hammer and a grinder with the same frequency weighted acceleration. Grip and push forces were measured and monitored during the exposure. The various effects were: muscle activity (measured with surface electrodes), discomfort ratings for different parts of the hand-arm system (made during and after exposure), and vibration perception threshold (for 10 minutes before and 10 minutes after the exposure). RESULTS--No increase in muscle activity due to exposure to vibration was found in the hand muscle studied. In the forearm, conversely, there was an increase in both muscle studied. For the upper arm the muscle activity only increased when exposed to impact vibration. Subjective ratings in the hand and shift in vibration perception threshold were effected more by the grinder than the hammer exposure. CONCLUSION--These results show that the reaction of the hand-arm system to vibration varies with frequency quantitatively as well as qualitatively. They do not support the notion that one single frequency weighted curve would be valid for the different health effects of hand-arm vibration (vascular, musculoskeletal, neurological, and psychophysiological).     

Hand-arm vibration syndrome with concomitant arterial thrombosis in the hands

BACKGROUND: Hand-arm vibration syndrome (HAVS) refers to the vascular, neurological and musculoskeletal effects that may occur in workers with prolonged exposure to vibrating tools. Hypothenar hammer syndrome (HHS) is a lesion of the ulnar artery at the level of the hamate bone secondary to single or repeated episodes of trauma to the hypothenar eminence. The literature suggests that digital arterial thrombosis and HHS may be associated with the use of vibrating tools. AIM: This study will familiarize investigators with the range of vascular abnormalities seen in workers using vibrating tools, and highlight the importance of screening for arterial thrombosis in the hand when assessing hand-arm vibration-exposed patients. METHODS: In the patients referred to our clinic for HAVS assessment, three were identified during the period 2001 to 2004 who had vascular occlusions in the hands in addition to HAVS. In addition to standardized HAVS vascular investigations, all three patients had arteriograms based on a significantly positive Allen's test. RESULTS: All three cases had documented HAVS based on vascular testing. Arteriograms revealed a spectrum of severity of arterial thromboses from severe HHS, to occlusion limited to the digital arteries. CONCLUSION: Our study reports three cases of HAVS with concomitant HHS and/or digital artery thrombosis. These findings support previous reports of an association between HAVS and vascular thrombosis in the hands. Screening for arterial occlusive problems in the hands should be included in the HAVS work up.     

Hand-arm vibration syndrome with use of anti-vibration chain saws: 19-year follow-up study of forestry workers

Objectives: Hand-arm vibration syndrome (HAVS) consists of vascular and neurological component. Musculoskeletal component has not been delineated yet. In the present follow-up study, we evaluated the prevalence of HAVS and the cumulative exposure to vibration among a cohort of forestry workers. Special interest was given to numbness and musculoskeletal disorders of upper extremity and neck in forestry workers. Methods: A follow-up study starting from 1976 was conducted among forestry workers in Suomussalmi in Finland. Total exposure of hand-arm vibration was recorded during 11 cross-sectional surveys. The last study was carried out in 1995. The lifetime dose of vibration energy was calculated. A cohort of 52 forest workers participated to all 11 cross-sectional surveys 1976–1995. HAVS and musculoskeletal disorders were evaluated. Results: The prevalence of active vibration white finger (VWF) decreased from 13 to 4% in the cross-sectional study. In the cohort VWF decreased from 17 to 8% and numbness increased from 23 to 40%. Rotator cuff syndrome (P=0.034) and epicondylitis (P=0.004) associated with numbness. Regional neck pain was diagnosed in 38% of workers and associated with low back pain. In modeling VWF, the lifelong vibration energy (OR 1.03, CI 1.01–1.05), and smoking (OR 7.36, CI 1.07–50.76) were significant. Numbness was modeled by pain in upper extremities (OR 12.43, CI 2.42–63.80) and neck pain (5.97, CI 1.25–28.39), not by lifelong vibration energy. Right rotator cuff syndrome was modeled by age (OR 2.58, CI 1.04–6.41) and lifelong vibration energy (OR 1.04, CI 1.00–1.07). Conclusions: The prevalence of VWF constantly decreased. Numbness did not follow the vibration exposure profile. Numbness also associated with upper extremity musculoskeletal disorders. Hand-arm vibration associated with the right rotator cuff syndrome in forestry workers.     

煤矿掘进工手部循环功能与血管内皮活性物质的关系

[目的]探讨手臂振动对手部循环功能的影响及其与血管内皮活性物质之间的关系。[方法]以煤矿男性井下掘进工64名作为研究对象,按累积接振时间的长短分为高暴露组、中暴露组和低暴露组,并选22名非接振的健康人作为对照组,对每组进行血管内皮物质和冷水负荷试验测定,分析二者之间的相关关系。[结果]3个振动暴露组内皮素（ET）浓度、血栓素B2（TXB2）浓度均明显高于对照组（P〈0．01）;该3个暴露组的一氧化氮（NO）浓度、6．酮前列腺素Flu（6-keto-PGF1α）浓度均明显低于对照组（P〈0．01）0冷水试验前高暴露组皮肤温度明显低于对照组（P〈0．01）,冷水负荷试验后3个暴露组在5、10、30min的皮肤温度明显低于相同时间的对照组（P〈0．01）。10min复温异常率、30min复温异常率在对照组、低暴露组、中暴露组、高暴露组间差异有统计学意义（P〈0．01）;且呈明显的剂量．效应关系。将各组血管内皮物质与5min复温率、10min复温率进行相关分析,可见复温率与ET、TXB2呈明显的正相关关系（P〈0．01）,而与NO、6-keto-PGF1α呈明显的负相关关系（P〈0.01）。[结论]振动性血管内皮物质紊乱与手部复温情况具有一致性,提示振动性血管功能紊乱可以作为振动性血管损伤的评价参考指标。     

Human response to vibration stress in Japanese workers: lessons from our 35-year studies A narrative review

The occupational uses with vibratory tools or vehicles provoked health disorders of users. We reviewed narratively our articles of 35 yr studies and their related literatures, and considered the pathophysiology of the hand-arm vibration disorders. Concerning the risk factors of health impairments in workers with vibratory tools, there are two conflicting schools of the researchers: The peripheral school emphasizes that vibration only makes predominant impairments on hands and arms, showing typically Raynaud’s phenomenon in the fingers. In the systemic school, the health disorders are produced by combination with vibration, noise and working environment, namely vibratory work itself, leading to diversified symptoms and signs in relation to systemic impairments. Our 35 yr studies have evidently supported the systemic school, including disorders of the central and autonomic nervous systems. The genesis is vibratory work itself, including vibration, noise, cold working environment, ergonomic and biodynamic conditions, and emotional stress in work. Because the health disorders yield in the whole body, the following measures would contribute to the prevention of health impairments: the attenuation of vibration and noise generated form vibratory machines and the regulations on operating tool hours. In conclusion, this occupational disease results from systemic impairments due to long-term occupational work with vibratory tools.     

The hand-arm vibration syndrome: (II). The diagnostic aspects and fitness criteria

Part II of this paper reviews the clinical and laboratory methods to diagnose the neurological, vascular and osteoarticular components of the hand-arm vibration syndrome. The prognosis and reversibility of vibration-induced neurological and vascular disorders after cessation of vibration exposure or the introduction of powered tools equipped with vibration isolation systems are discussed on the basis of the results of follow-up clinical investigations and longitudinal epidemiologic studies. Finally, the review debates some of the methodological aspects connected with the health surveillance of vibration-exposed workers and considers the possible medical contra-indications for prolonged exposure to hand-transmitted vibration.     

Thermal perception thresholds among young adults exposed to hand-transmitted vibration

Introduction Quantitative sensory testing assesses non-invasively the function of the sensory pathways from receptors to cortex. Studies of workers exposed to vibration support evidence that neuro-sensory hand-arm vibration syndrome also encompasses neuropathy of the small-diameter nerve fibres. Objectives To assess the risk of disturbed thermal perception developing among young adults exposed to vibration and hand-intensive manual work. The aim also encompasses the study of alternative covariates in small-diameter nerve fibre neuropathy assessment. Methods This cross-sectional multi-centre study comprised 202 males and females from vocational school programs in auto mechanics, construction and catering. The testing included a baseline questionnaire, a clinical examination focusing on upper extremity disorders and quantitative somatosensory testing. Thermal perception thresholds were assessed, on both hands, second and fifth digits, using a modified Marstock method for warmth and cold. Results Reduced thermal perception sensitivity was found for digit II compared to digit V, for females compared to males, and between the two study centres. Subjects exposed to vibration at work showed reduced sensitivity to temperature compared to non-vibration exposed. In univariate analyses odds ratios of 1.06 (95% CI 1.006–1.118) and 1.02 (95% CI 0.971–1.078) for reduced perception to cold for the right and left hands, respectively, was found for vibration. This association was lost in multivariate analyses. The study centre was the strongest confounding influence. Conclusions Sensitivity to temperature appears to be reduced despite the subjects short exposure-time and low exposure to vibration. The effect is small in relation to other confounding factors. A low agreement between the modalities indicates the need for separate tests for cold and warmth. Hand-side, age, stature, and BMI were not important for thermal perception but study centre, gender and choice of digit were. Conventional electro-diagnostic investigations are inadequate for evaluating the status of the small-fibre afferent systems leaving QST of thermal perception as the preferred diagnostic tool.     

The SOBANE strategy for the management of risk, as applied to whole-body or hand-arm vibration

OBJECTIVE: The objective was to develop a coherent set of methods to be used effectively in industry to prevent and manage the risks associated with exposure to vibration, by coordinating the progressive intervention of the workers, their management, the occupational health and safety (OHS) professionals and the experts. The methods were developed separately for the exposure to whole-body and hand-arm vibration. RESULTS: The SOBANE strategy of risk prevention includes four levels of intervention: level 1, Screening; level 2, Observation; level 3, Analysis and; level 4, Expertise. The methods making it possible to apply this strategy were developed for 14 types of risk factors. The article presents the methods specific to the prevention of the risks associated with the exposure to vibration. CONCLUSIONS: The strategy is similar to those published for the risks associated with exposure to noise, heat and musculoskeletal disorders. It explicitly recognizes the qualifications of the workers and their management with regard to the work situation and shares the principle that measuring the exposure of the workers is not necessarily the first step in order to improve these situations. It attempts to optimize the recourse to the competences of the OHS professionals and the experts, in order to come more rapidly, effectively and economically to practical control measures.     

The European Directive 2002/44/CE on the protection of workers from risks resulting from mechanical vibration

This paper provides comments on the European Directive 2002/44/CE of 25 June 2002 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibration) (sixteenth individual Directive according to Article 16(1) of Directive 89/291/EEC). The European Directive on mechanical vibration was published in the Official Journal of the European Communities L 177/13 on 6 July 2002. The Directive includes the definitions of hand-arm vibration and whole-body vibration, establishes the daily exposure limit values and action values for mechanical vibration, and gives provisions related to (i) determination and assessment of risks, (ii) measures aimed at avoiding or reducing exposure, (iii) information, training, consultation and participation of workers, (iv) health surveillance of the exposed workers, and (v) derogations and transitional periods for the implementation of the obligations of employers when the daily exposure limit values are exceeded. The author discusses the strong link which exists between the assessment of risk due to vibration exposure at the workplace and the health surveillance of the exposed workers. The occupational health physician, as a specialist with expertise in human factors and in the early detection of vibration-related adverse health effects, will have an important role in the assessment of risks arising from mechanical vibration in order to implement an effective health surveillance of the exposed workers. The Member States must bring into force the requirements of the Directive no later than 6 July 2005.     

Understanding the ergonomic risk for musculoskeletal disorders in the United States agricultural sector

INTRODUCTION: Farming is a very large industry in the United States. Understanding the risks for injuries and more specifically musculoskeletal disorders in this industry poses a challenge for health officials. METHODS: A review was conducted of the existing peer-reviewed publications prior to December 2006 about injuries and musculoskeletal disorders for farmers and farm workers. The aim was to review existing knowledge concerning: (1) the prevalence, types, and causes of farm-related injuries, paying particular attention to musculoskeletal disorders and the special populations within the agricultural sector, and (2) interventions that have been developed to reduce risk factors associated with farm-related injuries. RESULTS: Farmers and farm workers experience high rates of low back, shoulder, and upper extremity disorders. Musculoskeletal disorders may disproportionately affect farm youth and migrant workers due to the types of farm tasks performed. There is an urgent need for improved and validated interventions to reduce exposures and to improve the health of farmers and farm workers. DISCUSSION: Future farm-related musculoskeletal disorder research should emphasize: (1) better identification of exposures for special populations, (2) development of interventions for diverse farm populations, and (3) identification of additional exposures for musculoskeletal disorders. Inadequate understanding of musculoskeletal disorders in farming impedes efforts to prevent this common and important type of occupational injuries on farms.