Among the participants’ various occupations, those in which more than half of the workers were exposed to metal for longer
than 6 h per day were cloth-maker (71.4%), jeweler (67%), industrial worker (60%), constructor (50%) and hair dresser
(50%). Multivariate analysis showed that time of metal exposure of longer than 6 h/day increased the risk of NiCA by 3.1
times (P = 0.01).