1. Department of Epidemiology, UNC Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
2. Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
3. Department of Child Development and Mental Health, and
4. Department of Genes and Environment, Norwegian Institute of Public Health, Oslo, Norway
5. Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
6. Department of Genetics, Environment and Mental Health, Norwegian Institute of Public Health, Oslo, Norway
7. Haukeland University Hospital, Department of Occupational Medicine, Bergen, Norway
8. Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, USA