Health-Based Guidance Development Process
The Minnesota Department of Health (MDH) protects public health by adopting administrative rules that establish Health Risk Limits Rules (HRLs) for Groundwater.
MDH scientists develop other guidance for water to advise state agencies on the assessment of health risks from exposure to environmental contaminants. Our scientists develops these guidelines in two forms:
- Health Based Values (HBVs) are developed at the request of state agencies or through a public nomination process. For chemicals that have been detected in groundwater, HBVs are likely to be adopted as an HRL. HBVs calculated for a chemical not detected in groundwater will not be adopted as an HRL through rulemaking. In the event that MDH has an HRL and a more recent HBV listed for the same contaminant, we recommend using the most recently developed guidance.
- Risk Assessment Advice (RAA) is developed at the request of state agencies for chemicals that lack adequate data to develop an HBV. Because RAA is typically based on more limited data, it contains greater uncertainty.
An HRL is the concentration of a chemical (or mixture of chemicals) in groundwater that is likely to pose little or no risk to human health. These values are designed to protect populations who are most vulnerable to the potentially harmful effects of a contaminant, such as pregnant women, developing fetuses, and infants.
To support our mission to protect public health, MDH staff incorporate up-to-date information into its risk assessment methods. When new methods or toxicity information become available between formal rule adoptions, we may incorporate this information into guidance.
MDH scientists choose chemicals for review based on requests from other programs within MDH; from other state agencies, such as the Minnesota Pollution Control Agency (MPCA) and the Minnesota Department of Agriculture (MDA); and from the public through the Contaminants of Emerging Concern initiative.
MDH staff keep interested parties informed of the review process. We post a list of chemicals under review and invite interested parties to submit data that may be useful in the review. Our staff also communicate with interested parties via the GovDelivery email subscription service.
When developing guidance, MDH scientists use the methodology from the HRL Rules unless it finds that public health would be better protected by using different methods. If the available toxicity information is not sufficient, MDH may elect to develop qualitative RAA (e.g., narrative description of toxicity relative to a similar chemical). If there is insufficient scientific information, we may not issue guidance of any kind.
When we develop new guidance, such as HBV or RAA, based on the most recent methodology and scientific information, it is recommended that risk assessors and risk managers follow new guidance instead of a previously established HRL (this is referred to as dual guidance). Please refer to the MDH Dual Guidance for Drinking Water Methodology for more information about dual guidance.
Issuing and Using Guidance
MDH staff release an HBV or RAA to the public by posting the guidance and accompanying information on the Human Health Based Water Guidance Table. We notify subscribers via the GovDelivery email subscription service. While MDH always welcomes public comments, there is no formal public comment period for HBVs and RAA.
RAA intended for statewide use is included in our health-based guidelines table. MDH staff may develop RAA for specific conditions or specific sites when conditions unique to the location or exposure setting warrant such a site- or condition-specific response. RAA developed for specific conditions should not be applied to other sites without consulting someone at MDH. MDH does not post site-specific RAA in its health-based guidelines table.
In order to maintain accurate and current guidance values, all chemical guidance derived from 2008 to present using the methods described in the 2008 Statement of Need and Reasonableness (SONAR) (PDF) are re-evaluated on an approximately five year schedule. A chemical may be selected for re-evaluation based on, but not limited to, the following:
1) substantive new toxicological information;
2) programmatic need for an updated value, including selection of the chemical for rulemaking; and/or
3) change in MDH risk assessment methodology.
Guidance values that change as a result of re-evaluation will be updated on the Human Health-Based Water Guidance Table.