1. Colorado Injury Control Research Center, Department of Psychology, Colorado State University, Fort Collins, Colorado, USA
2. Epidemiology Department, College of Public Health
3. Department of Environmental, Agricultural and Occupational Health, University of Nebraska Medical Center, Omaha, Nebraska, USA
4. Epidemiology Branch, National Institutes of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
5. Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland, USA
6. Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA