An exposure model that linked exposure, back pain and back disability, and identified core elements in exposure assessment for epidemiological research on back disorders was discussed. This dynamic model utilized three principal health grades: no back problem; back problem with no disability; and disability due to back problem. Older traditional models were based on unidirectional exposure/response relationships that defined risk factors and back disorders as static entities. The dynamic model defined occupational exposure within the dynamic relations between a work environment that offers physical and psychological challenges to workers who experience various degrees of pain. The model acknowledged that within a workforce, several subcohorts exist with different risks for back disorders. The model used four general classes of risk factors: physical workload, psychological factors, individual traits, and organizational factors. Strategies for quantitative assessment of physical and psychological risk factors were designed relative to the risk factors of interest, the measurement devices, and the range in exposure/dose experienced. The authors conclude that the main challenge in designing epidemiological studies of back disorders is addressing all of the main risk factors that contribute to the occurrence of such disorders.

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