Health Risk Limits

Background information

Under the Groundwater Protection Act of 1989, MDH protects public health by developing and establishing Health Risk Limits (HRLs) for contaminants in drinking water. The page How Health-Based Values and Health Risk Limits are Calculated provides information about the water guidance development process.

Health Risk Limits have been promulgated using the public process described in the Administrative Procedures Act (Minnesota Statutes Chapter 14). MDH will continue to conduct rulemaking in the future to promulgate additional HRLs.

Glossary

Terms used in the Health Risk Limits Rules are defined in this Health-Based Water Guidance Glossary (PDF)

Summary of Health Risk Limits (HRLs) Derived by MDH

• 2023 MDH-Derived HRLs (HRL₂₃)
• 2018 MDH-Derived HRLs (HRL₁₈)
• 2015 MDH-Derived HRLs (HRL₁₅)
• 2013 MDH-Derived HRLs (HRL₁₃)
• 2011 MDH-Derived HRLs (HRL₁₁)
• 2009 MDH-Derived HRLs (HRL₀₉)
• 2009 US EPA MCL-Based HRLs (HRL_MCL)
• 2007 MDH-Derived Temporary HRLs (now HRL₀₉)
• 1993/94 MDH-Derived HRLs (HRL₉₃ or HRL₉₄)

All current guidance can be found in the Human Health-Based Water Guidance Table.

2023 MDH-Derived HRLs:
In 2023, MDH added 17 new values to Minnesota Rules, part 4717.7860 and replaced 19 outdated values for a total of 36 new or updated values. Additionally, the value for n-hexane was repealed and replaced with Risk Assessment Advice rather than a new HRL.

2018 MDH-Derived HRLs:
In 2018, MDH added four new values to Minnesota Rules, part 4717.7860, and replaced 17 outdated values, for a total of 21 new or updated values.

2015 MDH-Derived HRLs:
In 2015, MDH promulgated eight new HRLs, and replaced six outdated HRLs, for a total of 14 (counting dimethenamid and dimethenamid-P as two chemicals). The 2015 HRLs were derived based on the methodology promulgated in the 2008/2009 rule.

2013 MDH-Derived HRLs:
In 2013, MDH promulgated six new HRLs, and replaced six outdated HRLs, for a total of 12. The 2013 HRLs were derived based on the methodology promulgated in the 2008/2009 rule.

2011 MDH-Derived HRLs:
In 2011, MDH promulgated 14 new HRLs, and replaced or repealed 26 outdated HRLs. The 2011 HRLs were derived based on the methodology promulgated in the 2008/2009 rule.

2009 MDH-Derived HRLs:
In 2008/2009 MDH revised the methods previously used for the 1993 and 1994 HRLs. The 2008/2009 methods are an improvement over the earlier method because they are designed to take sensitive or highly exposed populations (e.g., infants and children) into account and are specific for different durations of exposure. HRLs promulgated after 2008 are intended to protect human health for a specified length of exposure (e.g., one day, one month, a lifetime).

2009 US EPA-MCL-Based HRLs:
The US Environmental Protection Agency (US EPA) has established standards for public drinking water systems. The US EPA values are called Maximum Contaminant Levels (MCLs). In 2007, before MDH had finished developing the new methods referred to above, the Minnesota Legislature required MDH to set its HRL value at the MCL if the MCL was lower than the HRL value in effect at the time. These MCL-based HRL values initially went into effect in July 2007 and were included in the 2008 promulgation process. These values will remain in effect until replaced through new rulemaking. MCL-based HRLs are shown as HRL_MCL in the Human Health-Based Water Guidance Table.

2007 MDH-Derived Temporary HRLs:
In 2007, Minnesota Legislation (Minnesota Session Laws 2007, Chapter 37, Section 1) directed the Minnesota Department of Health to adopt HRL rules for the chemicals perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). The legislation authorized the commissioner to use the good cause exemption process for rule making. HRL values of 0.3 ug/L for PFOS and 0.5 ug/L for PFOS were added to the rules in 2007, as announced in "Adopted Exempt Temporary Rules Relating to Health Risk Limits for Perfluorochemicals" in the August 27, 2007 issue of the Minnesota State Register. Further rulemaking for these chemicals was completed in the 2009 rule amendments.

1993/1994 MDH-Derived HRLs:
HRLs were first promulgated in 1993 and 1994 using earlier US EPA methods based on protecting human health following a lifetime exposure to a groundwater contaminant.

For additional information about the MDH rulemaking process for HRLs, see Rulemaking Process.