1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
2. Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York City, New York, USA
3. The Norwegian Cancer Registry, Oslo, Norway
4. National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA