 In the "1951 Recommendations" the commission recommended a maximum permissible dose of 0.5 roentgen (0.0044 grays) in any 1 week in the case of whole-body exposure to X and gamma radiation at the surface, and 1.5 roentgen (0.013 grays) in any 1 week in the case of exposure of hands and forearms.Maximum permissible body burdens were given for 11 nuclides.At this time it was first stated that the purpose of radiological protection was that of avoiding deterministic effects from occupational exposures, and the principle of radiological protection was to keep individuals below the relevant thresholds.