Distributing cumulative spinal loads among a diverse workforce – using math modelling to explore workload equality vs MSD risk equity in workload assignment policies

Workers' risks to develop musculoskeletal disorders (MSD) are influenced by work-related and individual risk factors (RF). If workers have different levels of vulnerability (individual RF), managers face the decision whether to foster equality (an equal distribution of work-related RF levels) or equity (an equal distribution of net resulting MSD risk) when designing work plans. We use a mathematical model to assess the consequences of equality and equity policies for workers' MSD risks. We also aim at raising researchers' and practitioners' awareness for these kinds of questions. The model builds upon the assessment of workers' MSD risks using logistic regression. Applying the model to epidemiological data suggests that neither administrative risk control strategy provides a net benefit at the group level as risks can only be shifted between workers but not be reduced. These results suggest that real workforce level risk reductions may require engineering controls to reduce MSD risks.<b>Practitioner summary:</b> Existing epidemiological MSD risk evidence is used to analyse the impacts of policies of workload equality and injury risk equity. The policies have little impact on overall workforce MSD rates. This illustrates how administrative control policies may be ineffective at managing workforce injury risks. Engineering controls to reduce workload levels are recommended instead.