1. Department of Occupational and Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda 278-8510, Japan
2. Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
3. Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510300, China
4. Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108
5. Department of Diagnostic Pathology, Asahi University Murakami Memorial Hospital, Gifu 500-8523, Japan
6. Department of Environmental and Preventive Medicine, Jichi Medical University School of Medicine, Shimotsuke 329-0498, Japan
7. Department of Occupational and Environmental Management, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan