A description of the risk characterization may be expressed qualitatively or quantitatively. Qualitative terms such as ‘high’, ‘medium’, ‘low’, ‘negligible’ or ‘indeterminate’ (e.g., due to uncertainty or lack of knowledge) have been used to characterize the overall risk of an LMO.

In rare instances, the risk characterization results in a quantitative value (e.g. 6% of a population will be exposed to a stressor, and of that percentage half will experience mortality). More frequently, the risk characterization for an LMO will be qualitative. In such cases, description of the risk characterization may be expressed as, for instance, ‘high’, ‘medium’, ‘low’, ‘negligible’ or ‘indeterminate due to uncertainty or lack of knowledge’.