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Health Risk Limit Rule Revision Minnesota Department of Health
Environmental Health Division
Health Risk Limit
Rule Revision
Chemical Review Process Minnesota Department of Health
Environmental Health Division
Levels of Review
Primary
Identify existing toxicity and regulatory values
Evaluate studies and state of knowledge
Develop value
Secondary
Re-evaluate studies and thought process
Final
Review for thoroughness and consistency Minnesota Department of Health
Environmental Health Division
Review Process -- Overview
Regulation in Minnesota and
elsewhere
Current toxicity controversy
Toxicity evaluation
Risk evaluation
Endpoints
Cumulative risk issues Minnesota Department of Health
Environmental Health Division
Regulation in Minnesota
Regulatory status
Health Risk Limit (HRL)
Health Based Value (HBV)
New request
Existing groundwater value
Health endpoint
Source of value Minnesota Department of Health
Environmental Health Division
Sources of Water Values
US E.P.A. Office of Drinking Water (ODW)
Maximum Contaminant Level (MCL)
Maximum Contaminant Level Goal (MCLG)
Health Advisories: childs one-day; childs ten-day
California Office of Environmental Health
Hazard (OEHHA)
Public Health Goal (PHG)
Maximum Contaminant Level (MCL) Minnesota Department of Health
Environmental Health Division
Current Toxicity Controversies
Examples
Two slope factors or a range of slope factors
Vinyl chloride
TCE
Margin of exposure approach
Alachlor
Awaiting a cumulative risk assessment
Phorate
Complex treatment of uncertainty factors
Boron
TCE Minnesota Department of Health
Environmental Health Division
Toxicity Evaluation
Cancer versus noncancer
Distinguish carcinogens from noncarcinogens
Different assumptions about how they cause
toxicity
Different statutory requirements
Values will be developed for both cancer and
noncancer endpoints, if data allow
Potential impacts on multiple systems Minnesota Department of Health
Environmental Health Division
Toxicity Evaluation
Toxicity Values
US E.P.A.
Pesticide Reregistration Eligibility Decisions
(REDs)
Integrated Risk Information System (IRIS)
Health Effects Assessment Table (HEAST)
California Office of Environmental
Health Hazard (OEHHA)
Agency for Toxic Substances and
Disease Registry (ATSDR)
Peer reviewed scientific journals
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Can Non

cer can
cer Minnesota Department of Health
Environmental Health Division
Toxicity Evaluation
Critical and supporting studies
Species
Dosing
Duration of exposure
Time during subjects life
Route of exposure
Method of dosing
Effects
Thoroughness of examination
No effect level
Lowest level effect
Dose-response relationship
Severity of effect Minnesota Department of Health
Environmental Health Division
Toxicity Evaluation
Quality of data
Quality issues relating to individual studies
Size of study
Number of doses
Dose range
Consistency with other studies
Quality issues relating to entire database
Number of studies
Types of studies
Multiple species represented
Consistency of results
Plausibility of effect in humans Minnesota Department of Health
Environmental Health Division
Toxicity Evaluation
Dose-response relationship
Severity of effect
Rapid change of effect
Lowest effect level
Cause and effect relationship
Adversity or biological significance
No effect level
Benchmark dose
ED
01
, ED
10 Minnesota Department of Health
Environmental Health Division
Risk Evaluation
Noncarcinogen uncertainty analysis
Five possible areas of uncertainty, a modifying
factor, and the FQPA factor
Value
May be 1 (no uf), 3, 5, or 10 (default)
Maximum value recommended by EPA is 3000
Application
Factors applied are multiplied
Used to divide (reduce) the dose identified as the
no effect level, e.g., no effect level
uf * uf Minnesota Department of Health
Environmental Health Division
Risk Evaluation
Noncarcinogen uncertainty analysis
Uncertainty factors
Variation in sensitivity within a species
Due to genetic variation, age, health status
Extrapolation between species
Lack of an identified no effect level
Duration of the study
How complete the database is
Food Quality Protection Act Factor
Modifying factor Minnesota Department of Health
Environmental Health Division
Risk Evaluation
Carcinogens
Standard risk assessment practice
Default assumption: any amount of a
carcinogen, no matter how small, is associated
with some risk of cancer
Derive a concentration associated with a lifetime
risk of 1 cancer per 100,000 population
Will deviate from standard practice if
justified by data Minnesota Department of Health
Environmental Health Division
Risk Evaluation
Carcinogens
Test doses higher than anticipated
exposures
Start with lowest effective level
Take upper 95% confidence limit on
this estimate
Draw a straight line down to zero Minnesota Department of Health
Environmental Health Division
Risk Evaluation
Carcinogens
Dose Minnesota Department of Health
Environmental Health Division
Endpoints
Cancer vs. noncancer
Critical, co-critical, and secondary
Characterized for purpose of additivity
Specific endpoints of concern
Neurological
Developmental
Reproductive
Endocrine
Immunological Minnesota Department of Health
Environmental Health Division
Endpoints
Development as a stage, not an endpoint
E.g., cardiac effects occurring during fetal
development
Significant for purposes of additivity
Distinction between developmental and
reproductive effects
Viability and health of a fetus versus ability of an
organism to successfully reproduce
Developmental and reproductive effects Minnesota Department of Health
Environmental Health Division
Endpoints
Developmental and reproductive effects
Testing for developmental or reproductive
effects
No developmental or reproductive effects
Effects only at high doses
Effects at lowest doses; basis for regulatory value
Inadequate testing: add database uncertainty
factor or FQPA factor
No testing for developmental or reproductive
effects
Add database uncertainty factor or FQPA factor
Further analysis Minnesota Department of Health
Environmental Health Division
Other Issues
Volatility
Are there likely to be inhalation exposures?
Is there a toxicity value for inhalation?
Relative Source Contribution (RSC)
Is there a data supporting an RSC other
than the default? Minnesota Department of Health
Environmental Health Division
To regulate
or not to regulate?
Health Risk Limits
+
Minnesota rules: have regulatory authority
+
Suggests a level for cleanup
-
Inflexible: set until next revision
Health Based Values
+
Flexible: can respond to new research
+
Suggests a level for cleanup
-
Not rules: less regulatory authority
No value
-
May be misconstrued to mean chemical is safe
+
Doesnt imply certainty we dont have