1. Norwegian Institute for Agricultural and Environmental Research, Bioforsk, Fr. A. Dahls vei 20, NO-1432 Ås, Norway, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, NO-0403 Oslo, Norway, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SLU, SE-901 83 Umeå, Sweden, Department of Plant- and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway, and Department of Chemistry, University of Oslo, P.O. Box 1033, NO...