EPA Risk Characterization: Level of Concern Threshold risk:values less than the MOE or greater than the RfD are of concern. Cancer(non-threshold) expressed as a probability ->10-6 increased chance of developing cancer 08 (nim) OSU 0regomstate EPA Risk Characterization: Level of Concern • Threshold risk: values less than the MOE or greater than the RfD are of concern. • Cancer (non-threshold) – expressed as a probability – >10-6 increased chance of developing cancer