Hi,
Assuming that you use CL_GUI_ALV_TREE .
Is 'SAFETY' is a quantity field and it can be in different unit of measures ?
Are you using by chance LVC_S_FCAT-CFIELDNAME ?
If possible I recommend that you also use LVC_S_FCAT-REF_TABLE and LVC_S_FCAT-REF_FIELD.
Regards.