Mostafa Ghaffari - Department of Public Health Science, Karolinska Institutet
Akbar Alipour - Section for Personal Injury Prevention, Karolinska Institutet
Ali Asghar Farshad - Department of Occupational Health, Iran University of Medical Science
Irene Jensen - Dept of Medical Sciences, Occupational and Environmental Medicine, Uppsala Universitet

Low Back Pain (LBP) is one of the most common occupational health problems and accounts for a large number of compensation days and disability for workers in modern industrialized societies [1-5]. Extensive research into the role of occupational risk factors in the development of LBP has been carried out [2, 3, 6-12]. However, there are very few conclusive findings due to some common methodological flaws. It is believed that LBP is caused by multiple factors, generally categorized into physical, psychosocial and lifestyle factors. Various physical factors have been found to be associated with pain in different regions [13]. Heavy physical work, heavy or frequent manual operations, repeated rotation of the trunk, whole body vibration, and prolonged sitting were positively associated with LBP [14,15]. Psychosocial factors at work have also been shown to play important roles in the development of LBP. Factors such as work demands, decision latitude, symptoms of stress and social support have been reported as important psychosocial factors at work [2,16,17]. However, the causal and independent contribution of the work environment on the incidence of LBP is still debated, especially with regard to psychosocial factors [2, 18-20].