A cohort study of respiratory effect on Japanese toner handling workers over the first 4 years: Biochemical indices and markers

Introduction
Since cases of siderosilicosis considered attributable to toner exposure were reported in The Lancet in 1994, cases of granulomatous pneumonitis have been reported sporadically. Little epidemiological research sufficiently examines the health effects of toner exposure. In order to clarify the relationship between toner exposure and health, we started a 10-year cohort study among employees in Japanese plants of a major office equipment manufacturer in 2006.

Methods
The subjects are male workers under 50 years, who work in the Japanese plants of a major office equipment manufacturer (2006, first investigation). They consist of a toner-handling (45 workers) and a non-handling (44 workers) group. The items investigated are 1) Questionnaire on subjective respiratory symptoms and allergic symptoms (after self-recording, the investigator confirms the content), 2) Respiratory function test, 3) Chest X-ray, 4) Chest CT and 5) Biochemical indices and inflammatory markers. This report presents the results of investigating biochemical indices and inflammatory markers (WBC, CRP, IgE, IL-4,-6 and -8, IFN-γ, urinary 8-OHdG/Cre(8-hydroxy 2’-deoxyguanosine/urinary creatinine), SP-D and KL-6) of a 5-year follow-up from the baseline in 2006 to 2010 (fourth investigation).

Results
Over 5 years, biochemical examination and various markers between the toner-handling and non-handling groups showed no consistent tendencies.

Discussion
This investigation shows no significant differences attributable to toner handling between the toner-handling and non-handling groups. Since this investigation was designed as a 10-year cohort study, data collection and analysis will continue.