1. Department of Environmental Epidemiology, University of Occupational and Environmental Health, Kitakyushu, Japan;
2. Finnish Institute for Occupational Health, Helsinki, Finland;
3. Japan Occupational Safety and Health Center, Tokyo, Japan;
4. Department of Work, Systems and Health, University of Occupational and Environmental Health, Kitakyushu, Japan;
5. Liaoning Provincial Centre for Disease Prevention and Control, Shenyang, People’s Republic of China;
6. National Institute for Occupational Safety and Health, Washington, DC, USA