National, European and international organisations and bodies need scientific facts and concepts to set limit values for hazardous chemicals like carcinogenic substances  at the workplace or in consumer products. Two toxicologists of the project group  (Hermann M. Bolt, Gisela H. Degen) work with different regulatory bodies (AGS/UA III, MAK, SCOEL, SCCP/SCCS) in order to propose limit values and to ensure a safe handling of hazardous materials.