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workers, building, architect

NORA Manufacturing Sector Strategic Goals

927002Q - Animal Models of Hand-Arm Vibration Syndrome

Start Date: 10/1/2004
End Date: 9/30/2009

Principal Investigator (PI)
Name: Kristine Krajnak
Phone: 304-285-5964
Organization: NIOSH
Sub-Unit: HELD
Funded By: NIOSH

Primary Goal Addressed

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

The goals of these studies are to use animal models to establish dose response relationships between vibration and soft tissue injuries, and understand the cellular mechanisms underlying the development of these injuries. Employees in the manufacturing, mining and construction sectors are often exposed to upper limb vibration through the use of powered hand tools. This type of vibration exposure can result in damage to soft tissues of the hands and arms. By understanding the cellular responses of soft tissues to vibration exposure, we can determine what types of vibration exposures are most damaging so that more effective prevention and treatment strategies can be developed. In addition, dose-response data can be used to improve existing guidelines limiting vibration exposure and guidelines describing methods for diagnosing vibration-induced injuries. These studies will contribute to the following sector and cross-sector strategic goals: Construction Sector Goal 7, Manufacturing Goal 3, and the musculoskeletal cross-sector goals 2 and 3. All these goals focus on reducing the number and severity of musculoskeletal disorders in the workplace.


It is hypothesized that prolonged exposure to vibration will cause peripheral and systemic changes in both vascular and nervous systems and that these changes are dependent in part on multiple exposure, environmental, and individual risk factors. Several different animal models will be developed to study the pathophysiological mechanisms associated with prolonged exposure to vibration. In some models, the tails, or paws of restrained rats are exposed to vibration under conditions in which the duration and magnitude of vibration are highly controlled. In another model, unrestrained rats are trained with operant conditioning techniques to voluntarily and repetitively pull on a vibrating bar to achieve prolonged vibration exposures. Each model has unique advantages that will allow for the study of different mechanisms associated with vibration-related occupational disorders. In all cases, the underlying cellular and molecular mechanisms of vibration-related disorders will be studied. Functional deficits concomitant with the prolonged vibration exposures also will be assessed with techniques commonly used with human subjects, such as temporary tactile and thermal perception shifts, peripheral blood flow, and neurometry, grip strength and manual dexterity. The principal investigators comprise a multidisciplinary team that is uniquely situated in a state-of-the-art research facility with access to advanced biological and engineering support. This project also will involve multiple internal and external collaborations with experts in the fields of hand-transmitted vibration, vascular biology, and neurophysiology.


• Characterize the cellular and molecular changes that occur in peripheral vasculature and nerves in response to prolonged vibration exposures.

• Characterize the functional changes and symptoms that occur in response to prolonged vibration exposures with assessment techniques commonly used with human subjects.

• Determine the exposure time course associated with the cellular, molecular, and functional changes.

• Determine how variations in the vibration parameters (i.e., frequency, amplitude, and force) and the ambient temperature either mitigate or exacerbate the pathophysiological response to vibration. Provide these data to the appropriate standards organizations so that current standard regarding vibration exposures can be improved.

• Explore how individual factors (i.e., diabetes, obesity, hypertension) affect the risk of developing HAVS.

• Develop biomarkers to improve diagnoses of HAVS

• Develop or identify objective, non-invasive tests that can be used to monitor workers and assess changes in sensory function that may proceed permanent nerve damage.

• Specific research goals will be set and progress assessed quarterly over the year. A mid-project review also will be performed in 2006 or 2007 to determine if the research path or hypotheses being pursued should be revised.

Mission Relevance

The Bureau of Labor Statistics (2004) reports that approximately 1.5 million workers use powered and pneumatic hand tools on the job. The majority of workers using these tools are employed in the manufacturing, mining and construction sectors. Workers using powered hand tools are exposed to high levels of upper limb vibration. Depending on occupation and other exposure factors, approximately 50% of these workers will develop Hand-Arm Vibration Syndrome (HAVS). HAVS is characterized by vasospasms in the fingers and hands, loss of tactile and thermal sensation in the digits, reductions in grip strength and reductions in manual dexterity. There is evidence that factors such as duration of exposure, acceleration rate of the vibration, and cold working environments serve as risk factors for developing HAVS. However, comprehensive surveillance and basic scientific studies in this area have been limited, precise exposure limits have not been determined, and the role that these factors play in the development of vascular, nervous system and muscle and joint damage has not been established. HAVS has significant long-term effects on vascular, sensory and motor function, and is a work-related musculoskeletal disorder and thus a NORA cross-sector-related research priority. The goal of these studies is to use animal models to determine the risk associated with factors linked to the development of HAVS (e.g., vibration frequency, amplitude, duration, and applied force) and to understand the underlying cellular mechanisms responsible for causing this disorder. These studies will provide data that can be used to improve exposure guidelines for the workplace and identify effective monitoring and prevention strategies, along with treatment interventions for HAVS.

Research results from the proposed studies will contribute to the following goals:

1) Strategic Goal 7 in the Construction Sector (25%): Reduce the incidence and severity of work-related musculoskeletal disorders among construction workers in the U.S.; Research Goal 7.3.3: Evaluate physical and psychosocial risk factors associated with work organization and project delivery and strategies to modify or replace these systems.

2) Strategic Goal 3 in the Manufacturing Sector (75%): Reduce the number of musculoskeletal disorders among manufacturing sector workers;

3) Strategic Goals 2, 3 in the Musculoskeletal Disorder Cross-Sector (100%), Strategic Goal 2: Definitive understanding of the multi-factorial relationships among exposures,risk factors, and MSDs; IG2.2 Understanding the continuum of biological mechanisms associated with the development of and recovery from MSDs; IG2.4 Understanding of host factors that influence the development of and recovery from MSDs. Strategic Goal 3: Definitive understanding of musculoskeletal disorders and their consequences; IG3.1 Robust, validated systems for measuring changes associated with development and occurrence of MSDs and the consequences; IG3.2 Valid measures for detection and classification, and grading of MSDs and associated processes; IG3.3 Understanding of functional, physiological and psychological outcomes by type, severity and chronicity of MSDs.