Health-Based Values and Risk Assessment Advice for Water

On this page:
Health-Based Values (HBV)
Risk Assessment Advice (RAA)

For a complete list of MDH water guidance values, see the Human Health-Based Water Guidance Table.

Health-Based Values

A Health Based Value (HBV) is the concentration of a chemical (or a mixture of chemicals) that is likely to pose little or no risk to human health. HBVs are calculated using the methodology adopted in the Health Risk Limits (HRLs) Rules. HBVs meet the same data requirements as HRLs.

HBVs have not been promulgated using the public process described by the Administrative Procedures Act (Minnesota Statutes Chapter 14). Instead, an HBV is technical guidance made available by MDH. These values may be used by the public, state and local risk managers, and other stakeholders to assist in evaluating potential health risks to humans from exposures to a chemical. If a chemical has been detected in water, MDH anticipates that HBVs for Minnesota's groundwater will become HRLs (i.e., be promulgated) at the time that MDH next amends the Health Risk Limits for Groundwater rule.

For additional information see: Health-Based Guidance Development Process.

Risk Assessment Advice

Risk Assessment Advice (RAA) for water is technical guidance concerning exposures and risks to human health. RAA may be quantitative (e.g., a concentration of a chemical that is likely to pose little or no health risk to humans) or qualitative (e.g., a written description of how toxic a chemical is in comparison to a similar chemical). Generally, RAA contains greater uncertainty than HRLs and HBVs because the available information is more limited. Sometimes MDH derives guidance as RAA because new risk assessment methodology was applied to develop the value.

RAA guidance is not likely to be promulgated, either because of a high level of uncertainty about the numeric guidance; because the methods used to develop the guidance are different than the methods in rule; or because the resulting guidance is qualitative rather than a water value. RAA water values can be applied at the discretion of risk assessors and risk managers in the same way that HBVs and HRLs are applied.

MDH also develops RAA on a case-by-case basis for specific conditions or specific sites. It is not appropriate to apply this site-specific RAA to other sites without consulting with MDH.

For additional information see: Health-Based Guidance Development Process.

For a complete list of MDH water guidance values, see the Human Health-Based Water Guidance Table. Note: MDH does not post site-specific RAA in the air or groundwater values tables.