Exposure-response relationships for the ACGIH threshold limit value for hand-activity level: results from a pooled data study of carpal tunnel syndrome.
Kapellusch-JM; Gerr-FE; Malloy-EJ; Garg-A; Harris-Adamson-C; Bao-SS; Burt-SE; Dale-AM; Eisen-EA; Evanoff-BA; Hegmann-KT; Silverstein-BA; Theise-MS; Rempel-DM
Scand J Work, Environ & Health 2014 Nov; 40(6):610-620
Objective: This paper aimed to quantify exposure response relationships between the American Conference of Governmental Industrial Hygienists' (ACGIH) threshold limit value (TLV) for hand-activity level (HAL) and incidence of carpal tunnel syndrome (CTS). Methods: Manufacturing and service workers previously studied by six research institutions had their data combined and re-analyzed. CTS cases were defined by symptoms and abnormal nerve conduction. Hazard ratios (HR) were calculated using proportional hazards regression after adjusting for age, gender, body mass index, and CTS predisposing conditions. Results: The longitudinal study comprised 2751 incident-eligible workers, followed prospectively for up to 6.4 years and contributing 6243 person-years of data. Associations were found between CTS and TLV for HAL both as a continuous variable [HR 1.32 per unit, 95% confidence interval (95% CI) 1.11-1.57] and when categorized using the ACGIH action limit (AL) and TLV. Those between the AL and TLV and above the TLV had HR of 1.7 (95% CI 1.2-2.5) and 1.5 (95% CI 1.0-2.1), respectively. As independent variables (in the same adjusted model) the HR for peak force (PF) and HAL were 1.14 per unit (95% CI 1.05-1.25), and 1.04 per unit (95% CI 0.93-1.15), respectively. Conclusion: Those with exposures above the AL were at increased risk of CTS, but there was no further increase in risk for workers above the TLV. This suggests that the current AL may not be sufficiently protective of workers. Combinations of PF and HAL are useful for predicting risk of CTS.
Exposure-assessment; Threshold-limit-values; Musculoskeletal-system-disorders; Carpal-tunnel-syndrome; Nerve-function; Long-term-study; Employee-exposure; Risk-analysis; Risk-factors; Statistical-analysis; Exposure-levels; Repetitive-work; Force; Hand-injuries; Overloading; Biomechanics; Epidemiology; Extremities;
Author Keywords: American Conference of Governmental Industrial Hygienists; biomechanical overload; CTS; epidemiology; HAL; hand force; MSD; musculoskeletal disorder; peak force; physical exposure; repetition; threshold limit value; upper extremity
Jay Kapellusch, Department of Occupational Science & Technology University of Wisconsin, Milwaukee, PO Box 413, Milwaukee, WI 53201, USA
Grant-Number-R01-OH-009712; M122014; Grant-Number-T42-OH-008429
Scandinavian Journal of Work, Environment and Health
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University of California, San Francisco