# Presentation: 415128

## A State’s Approach to Risk-Based Analysis:  Similarities to and Differences from EPA’s Principles and Practices

- Hillary M. Carpenter, Ph.D.
- Minnesota Department of Health

## Minnesota’s Groundwater and Air Rules

- The Minnesota Department of Health (MDH) is responsible for developing health-based values for chemicals that contaminate air and groundwater.
- The agency has promulgated two rules – one for groundwater and one for air – that provide guidelines that are used by MDH and other state agencies for protecting human health.

## Minnesota’s Groundwater and Air Rules

- When developing its groundwater and air rules, MDH relied heavily on the risk assessment techniques used by the U.S. EPA at the time of promulgation.
- In general, MDH concurred with the default assumptions and uncertainty factors applied by the U.S. EPA’s IRIS database.

## Health Risk Limits (HRLs)

- HRLs are health protective limits for concentrations of chemicals in groundwater.
- MDH develops and promulgates HRLs in accordance with the Minnesota’s *Groundwater Protection Act of 1989.*
- MDH first promulgated HRLs in 1993 and 1994.

## Health Risk Limits (HRLs)

- HRLs are expressed as μg of chemical per liter and considered to be the concentration of chemical in drinking water that is likely to pose little or no health risk to humans, including vulnerable subpopulations.

## Health Risk Limits (HRLs)

- HRLs were developed using EPA’s algorithm for RfDs.
- Estimations of exposure used the standard default of a daily intake of 2 liters of water per 70 kg of body weight (29 ml/kg-day).
- A relative source contribution was used in deriving noncancer HRLs

## Health Risk Values (HRVs)

- In August of 2002 MDH promulgated its Health Risk Value Rule.
- The rule sets values for concentrations of chemicals or defined mixtures of chemicals emitted to air that are unlikely to pose significant risk of harmful effects when humans are exposed to those chemicals over a specified time.

## Health Risk Values (HRVs)

- The authority for adoption of the HRV rule was set forth in *Minnesota Statutes*, section 144.12, subd. 1, item 14
- Subd. 1 of this statute provides the Commissioner of Health with the general authority to develop rules for the preservation of public health.
- Item 14 specifically deals with atmospheric pollution.

## Health Risk Values (HRVs)

- HRVs are health based values.  They serve as guidelines and are developed using the best peer-reviewed information available, but are not adjusted for for such technological considerations as limits of detection or ease and/or cost of removal.

## Health Risk Values (HRVs)

- Because HRVs are guidelines and their application will be a function of risk management, the rule does not specify applications.
- HRVs are not intended to address the risk management concerns of chemical impacts on quality of life issues such as odor.
- HRVs do not apply to the workplace.

## Health Risk Values (HRVs)

- As with the HRL rule, when MDH developed the HRVs it relied heavily on the risk assessment techniques used by the U.S. EPA.
- The IRIS database was the primary source of information that was used in the process.
- Also used the California RELs

## Health Risk Values (HRVs)

- One difference from the IRIS RfCs
- It was decided not to use an uncertainty factor for developing a chronic number from a subchronic dataset.
- Instead a separate group of subchronic HRVs was developed.
- Done to decrease the overall uncertainty of HRVs wherever possible.

## Health Risk Values (HRVs)

- MDH currently develops four types of HRVs:
**Acute **– which are compared to one hour averaged concentrations of chemicals or mixtures and expressed as μg of chemical per m3 of air.
**Subchronic **- which are compared to 13 week averaged concentrations or mixtures and expressed as μg of chemical per m3 of air

## Health Risk Values (HRVs)

**Chronic** – which are compared to an annual average concentration of chemicals or mixtures and expressed as μg of chemical per m3 of air.
**Multi-media** – for chemicals emitted to air but where non-inhalation routes of exposure are important for public health.  MHRVs are expressed as μg/kg/day of exposure.

## Minnesota’s Health Standards Statute

- In 2002 the Minnesota legislature passed the Minnesota Health Standards Statute.  This legislation called the question of whether or not current risk assessment practices are adequate for protecting the public’s health.

## Minnesota’s Health Standards Statute

- Requires that MDH, when developing or modifying air and water quality standards, “include a reasonable margin of safety to adequately protect the health of infants, children, and adults by taking into consideration risks to each of the following health outcomes: reproductive development and function, respiratory function, immunologic suppression or hypersensitization, development of brain and nervous system, endocrine (hormonal) function, cancer, general infant and child development, and other important health outcomes identified by the commissioner...”.

## Minnesota’s Health Standards Statute

- Minnesota’s legislature with this statute has issued a directive – if safety cannot be adequately demonstrated, the principles and practices currently in place in Minnesota must be changed so they are more protective.

## Proposed Changes in the Development of HRLs

- Intake rate adjustment for infants and children.
- For chemicals that exert developmental effects, the estimated adult intake rate of 29 ml/kg-day has been increased six times to approximate the intake rate of infants during the first six months of life.

## Proposed Changes in the Development of HRLs

- For other chronic effects, including cancer, the adult intake rate has been increased three-fold to approximate an intake rate appropriate for the minimum chronic exposure period with the highest intake rate – the first seven years of life.

## Proposed Changes in the Development of HRLs

- The standard 2 year cancer bioassay in rodents does not include early life exposures
- A limited amount of data suggests that there may be an increased sensitivity to carcinogens during early life stages
- To account for the potential extra risk that might result because of unexamined early life exposures, a two-fold factor has been applied to the cancer potency slope.

## Impact of Minnesota’s Health Standards Statute on HRVs

- MDH is in the early stages of a revision of the HRV rule.
- As previously stated the agency is required by statute to consider data deficiencies and apply additional safety factors where such deficiencies are noted.
- An adjustment factor based on differences in exposure - similar to the one proposed for the HRL revision - will be considered.

## Health Risk Values (HRVs)

**Acute HRVs for reproductive/ developmental toxicants are developed conservatively.**
- Experimental exposures to such toxicants are for 4-6 hours daily for several days during gestation.  When developing an acute HRV MDH assumes that a one hour exposure at any time during gestation is sufficient for toxicity.
- MDH also provides guidance to risk managers that these numbers be treated as ceiling values.

## Questions

- During Minnesota’s recent rule revision  a number of questions have arisen regarding the risk assessment tools and techniques currently used by the U.S. EPA.

## Questions

- EPA has clearly stated that data are examined before defaults are considered.  Often the reverse seems to be true.
- How much data are necessary before risk assessors are actually willing to consider departing from a default?

## Questions

- The NSC in its 1994 report suggesting that an important criterion in developing defaults was that their use should be seen as a tool for “maximizing incentives for research”.
- Has the apparent reluctance of risk assessors to discard defaults hampered research into the validity of defaults?

## Questions

- Has risk assessment done an adequate job of addressing the issues of early life exposures?
- Current toxicity regimes don’t include dosing that reflects exposure during early life stages.

## Questions

- Do the current research strategies and risk assessment practices really protect against less than lifetime exposures?
- When does damage actually occur?  Current testing is inadequate for determining the timing of actual toxic events.

## Questions

- Is there a consensus in the agency as to how the database deficiency uncertainty factor should be used?
- Examination of documents from various programs within the agency (and even different documents produced in the same program) indicate that this is not the case.

## Questions

- It was suggested by MDH staff that the use of defaults has stalled – they were a good idea to begin with, but the assumptions haven’t really been adequately modified to respond to advances in research.  This is thought to be particularly true with early life exposures.

## Summary

- Minnesota has relied on EPA’s principles and practices of risk assessment to develop air and water rules.
- MDH has been challenged by the Minnesota Legislature to prove the agency’s assertion that the numbers it develops are protective of sensitive portions of  the population.
- MDH has responded to this challenge by developing adjustment factors that attempt to compensate for the lack of information – particularly about early life exposures.

- e-mail:
- _[hillary.carpenter@health.state.mn.us](mailto:hillary.carpenter@health.state.mn.us)_
- MDH’s website:
- www.health.state.mn.us