Ole Olsen1
, Karen Albertsen1
, Martin Lindhardt Nielsen1,2
, Kjeld Børge Poulsen1,3
, Sisse Malene Frydendal Gron1,4
and Hans Lennart Brunnberg5,6 
1National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark
2Clinic of Occupational Medicine, Hillerød Hospital, Helsevej 2, DK-3400 Hillerød, Denmark
3Child Health Promotion, Odsherred Municipality, Vesterlyngvej 8, DK-4500 Nykøbing Sjælland, Denmark
4Center of Maritime Health and Safety, University of Southern Denmark, Niels Bohrs Vej 9, DK-6700 Esbjerg, Denmark
5Stockholm Center for Public Health, Stockholm County Council, PO box 17533, SE-118 91 Stockholm, Sweden
6Department of Public Health Sciences, Karolinska Institute, SE-171 76 Stockholm, Sweden