Exposure-response relationship for vibration-induced white finger among forestry workers

Area of Science:

• Occupational Health
• Environmental Medicine
• Epidemiology

Background:

• Hand-transmitted vibration from tools like chain saws is a known occupational hazard.
• Vibration-induced white finger (VWF) is a recognized condition linked to prolonged vibration exposure.
• Understanding the dose-response relationship is crucial for setting effective workplace safety standards.

Purpose of the Study:

• To investigate the relationship between vibration exposure and the occurrence of VWF in forestry workers.
• To establish a dose-response curve for VWF based on measured vibration levels and exposure duration.
• To compare estimated VWF risk with existing international standards.

Main Methods:

• A cohort of 222 forestry workers and 195 controls were interviewed by occupational health physicians.
• VWF diagnosis was based on subjective symptoms and objective cold testing with plethysmography.
• Vibration exposure was quantified using 8-hour energy-equivalent frequency-weighted acceleration [A(8)] and lifetime dose estimation.

Main Results:

• The prevalence of VWF among forestry workers was 23.4%, compared to 2.6% in controls.
• A monotonic dose-response relationship was observed, with VWF risk increasing with vibration dose.
• Digital artery responsiveness to cold increased with higher vibration exposure levels.

Conclusions:

• The study confirms a significant association between vibration exposure from chain saws and VWF in forestry workers.
• The findings suggest an approximately linear relationship between VWF occurrence and vibration exposure parameters (A(8) or duration).
• Estimated VWF risk was lower than predicted by ISO 5349, supporting current EU vibration exposure level discussions.