About the Authors
- Sven Drefahl
- Demography Unit, Department of Sociology, Stockholm University, Stockholm, Sweden
- Sven Drefahl, Anders Ahlbom, Karin Modig
- Institute of Environmental Medicine, Division of Epidemiology, Karolinska Institutet, Stockholm, Sweden
The authors have declared that no competing interests exist.
Conceived and designed the experiments: SD AA KM. Analyzed the data: SD. Wrote the paper: SD AA KM.