Affiliation: | (1) Laboratory for Radiation Research, R.I.V.M., A. Van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands;(2) Present address: Institute for Soil Fertility, P.O. Box 48, 6700 AA Wageningen, The Netherlands;(3) Commission of the European Communities, DG XII/F/1, Wetstraat 200, B-1049 Brussels, Belgium |