A cohort study spanning ten years was conducted to assess the health effects on toner manufacturing workers. A survey consisting of questions investigating subjective respiratory symptoms, current medical history, disease occurrence, dust exposure concentrations at the workplace, respiratory function tests, biochemical and immunological items in blood and urine, and a chest radiograph or chest computed tomography survey was conducted. The results of these surveys have been published in academic journals, and none of the surveys showed any findings suggesting significant health problems in the toner-worker group compared to the non-toner-worker group. The results suggest that the health risks associated with toner handling are not high when the work environment at the toner handling site is well controlled.