[Evaluation of workload in middle-aged steel workers by measuring urinary excretion of catecholamines and cortisol]

To evaluate physical and mental workload in middle-aged workers, urinary excretion of catecholamines and cortisol and self-reported scores of fatigue, stress and arousal in middle-aged steel workers were compared with those in young steel workers. Noradrenaline excretion in daytime of the day-off was higher in middle-aged workers than that in young workers. In the work days, noradrenaline excretion during working hours increased in both age groups when compared with that in the day-off. The work-related increase in noradrenaline excretion was more evident in the middle-aged group than in the young group. Adrenaline excretion during working hours was greater in the middle-aged group than that in the young group, whereas the adrenaline value in the day-off was almost the same in the two age-groups. Age-difference was hardly observed in dopamine and cortisol excretion. These findings suggest that the workload in middle-aged workers was greater than that in young workers. However, self-reported scores of fatigue and stress in middle-aged workers were less than those in young workers, suggesting inconsistency between subjective score of workload and urinary levels of catecholamines. These age-related differences in urinary levels of noradrenaline and adrenaline were not so obvious in workers engaged in automated and mechanized work (vigilance task) when compared to workers engaged in less automated and less mechanized work. It is considered that factory automation might reduce the workload in middle-aged workers.