1. Department of Occupational and Environmental Health, School of Public Health
2. Department of Respiratory and Critical Care Medicine, Qingdao Municipal Hospital, School of Medicine, Qingdao University, Qingdao 266021, China
3. Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131
4. State Key Laboratory of Organic Geochemistry, Guangdong Key Laboratory of Environment and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
5. Department of Toxicology, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
6. Henan Institute of Occupational Medicine, Zhengzhou, Henan 450052, China
7. Cancer Control and Population Sciences, University of New Mexico Comprehensive Cancer Center, Albuquerque, New Mexico 87131