title: Predicting Whole-Body Vibration Exposure in Canadian Prairie Farmers.
abstract: Direct workplace whole-body vibration exposure assessment provides ecological validity for evaluating health risk in epidemiological studies, yet it is complex and expensive in practical applications. Exposure prediction modeling could be a cost-efficient alternative to directly assessing occupational vibration exposures. The objective of this study was to model directly measured whole-body vibration exposures with predictors from machinery, farm, and self-reported characteristics among Canadian prairies farmers. As per ISO 2631-1, whole-body vibration data were measured on the seat surface at three axes (x, y, z), then summarized into vector sums of the root-mean-squared (RMS) acceleration and the vibration dose value (VDV). All candidate predictors were obtained via questionnaires and onsite observations. A total of 87 whole-body vibration measurements were collected from 40 male farm workers located at 21 central Saskatchewan farms. Using log-transformed RMS and time-standardized VDV outcomes, modeling started from the bivariate analysis where predictors with P-values < 0.2 were considered eligible for multivariate analysis. With random effects of 'farm' and 'farmer', a series of mixed-effects models were constructed through the manual backward elimination method. Final models were internally validated by 1000 bootstrapped samples. The RMS model explained 47.7% of the variance in the directly measured RMS vector sum, with 42.7% obtained from five predictors of 'horsepower', 'transmission', 'vehicle year', 'jerk/jolt frequency', and 'seat bottom-out frequency', while the VDV model explained 19.5% of the variance in the directly measured VDV vector sum, with 11.6% described by the same five predictors as the RMS model. Predictive ability of the RMS model among 1000 bootstrapped samples can be anticipated to range from 14.3 to 69.1%, which may be considered adequate as exposure assessment tool for uses of epidemiological studies. The percentage of variance explained ranged from 0 to 40.5% for the VDV model, which is not robust and therefore likely not appropriate for use in survey-based exposure prediction. Whole-body vibration exposure modeling remains valuable, but is challenging in farming; the described model variance may increase with a more comprehensive list of candidate variables collected and quantified at machinery, farm, and farmer level. Predictors identified in the current and future models may provide a better understanding of how whole-body vibration exposure is modified, guide farmer's future decision on updating equipment, and allow for the development and initiation of interventions.
authors.affiliation: Department of Community Health and Epidemiology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan S7N 5E5, Canada.|Ergonomics Lab, Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z4, Canada.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Zeng
authors.affiliation: School of Physical and Health Education, Nipissing University, 100 College Drive, North Bay, Ontario P1B 8L7, Canada.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Kociolek
authors.affiliation: Department of Community Health and Epidemiology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan S7N 5E5, Canada.
authors.forename: Muhammad Idrees
authors.initials: MI
authors.lastname: Khan
authors.affiliation: School of Physical Therapy, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z4, Canada.
authors.forename: Stephan
authors.initials: S
authors.lastname: Milosavljevic
authors.affiliation: Ergonomics Lab, Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z4, Canada.|School of Physical Therapy, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z4, Canada.
authors.forename: Brenna
authors.initials: B
authors.lastname: Bath
authors.affiliation: Ergonomics Lab, Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, 104 Clinic Place, Saskatoon, Saskatchewan S7N 2Z4, Canada.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Trask
mesh_terms: D000382:Agricultural Workers' Diseases / Q000209:etiology*; D000383:Agriculture; D000067565:Farmers; D065948:Grassland; D006801:Humans; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000032:analysis*; D018570:Risk Assessment; D012525:Saskatchewan; D011795:Surveys and Questionnaires; D014732:Vibration / Q000009:adverse effects*; D017132:Workplace
keywords: ISO 2631-1; agriculture; exposure assessment; farm equipment; great plains; mechanical shock; prediction modeling