mpca and the risk assessment processpschoff/documents/solem.pdf · • 1938 federal food, drug, and...
TRANSCRIPT
MPCA and the Risk Assessment Process
Laura Solem, Ph.D. December 10, 2004
Topics
• MPCA • Overview of Risk Assessment Process • Application of Risk Assessment Process
MPCA The Minnesota Pollution Control Agency (MPCA) was established in 1967 and charged with protecting human health and the environment in Minnesota.
• Its purpose is to protect Minnesota's environment through monitoring environmental quality and enforcing environmental regulations.
• http://www.pca.state.mn.us/
MPCA Mission
To help Minnesotans protect their environment
• Issue permits to control potential sources of pollution • Ensure compliance with environmental laws • Set standards • Assist in the development of new laws • Monitor the environment • Restore contaminated land to productive use
• 1938 Federal Food, Drug, and Cosmetic Act (FFDCA) • 1947 Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) • 1948 Federal Water Pollution Control Act (1977 Clean Water Act) • 1958 Delaney Clause • 1969 National Environmental Policy Act (NEPA) • 1970 Clean Air Act • 1971 LeadBased Paint Poisoning Prevention Act • 1974 Safe Drinking Water Act • 1976 Resource Conservation and Recovery Act (RCRA) • 1976 Toxic Substances Control Act (TSCA) • 1980 Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA or Superfund) • 1986 Superfund Amendments and Reauthorization Act (SARA) • 1996 Food Quality Protection Act (FQPA)
Major Milestones in Risk Assessment Guidance Major Milestones in Risk Assessment Guidance Microbial Risk Assessment Guidelines
2007
2004 EPA’s Risk Assessment Staff Paper
Final Revised Cancer Guidelines
2004
Topics
• MPCA • Overview of Risk Assessment Process • Application of Risk Assessment Process
Risk Assessment
The systematic sciencebased process used to characterize potential adverse health effects to humans or ecosystems resulting from exposure to hazardous agents.
Risk
“The likelihood or probability of an adverse outcome”
Basic Concept: Risk = (Toxicity) x (Exposure)
Risk Assessment Steps
• Hazard Identification • Toxicity (DoseResponse) Assessment • Exposure Assessment • Risk Characterization
Hazard Identification
• Type of contaminant • Extent and magnitude of contamination
Toxicity Assessment
What are the health effects associate with different exposure levels??
Toxicity Assessment (doseresponse)
%
R e s p o n s e
Theory
Exposure (dose)
Toxicity Values
Noncancer Values: Reference Dose (mg/kgday) Reference Concentration (mg/m 3 )
Cancer Values: Slope Factor lifetime risk per (mg/kgday) Unit Risk lifetime risk per (µg/m 3 ) or (µg/L)
Exposure Assessment
• WHAT? • WHO? • HOW?
• WHERE? • WHEN?
Risk Characterization
1) Concise and accurate summary of information used (e.g., toxicity, exposure)
2) Risk estimates for each receptor and exposure period
3) Evaluate uncertainty
Risk Characterization
Noncancer Risk Individual Chemical: Hazard Quotient = Expo/RfD
or Air Conc/RfC
Multiple Chemicals: Hazard Index = HQ1 + HQ2 . . + HQn For each target endpoint
Risk Characterization
Cancer
Excess Lifetime Cancer Risk (ELCR) Individual Contaminant:
ELCR = Lifetime Exposure x Slope Factor
Multiple Contaminants: ELCR = ELCR1 + ELCR2 + . . . .
Risk Management
“ A process by which policy or regulatory decisions are made”
[Considers: risk assessment information as well as statutory, technology, economic, social and political factors]
Risk Assessment Process
Problem Formulation
Toxicity
Assessment
Exposure
Assessment
Data A
cquisition
Risk Characterization
Risk Assessment/Risk Management Interaction
Risk Management Decision
Statutory Requirements Technical Feasibility Economics Social Factors Political Factors
Uses of the Risk Assessment Process
• Estimation of potential risk resulting from a current situation or a proposed project
• Development of “riskbased” criteria or standards
Topics
• MPCA • Overview of Risk Assessment Process • Application of Risk Assessment Process
Development of RiskBased Criteria
• Determine media concentrations that would not pose unacceptable risks to human health or ecological receptors
• CERCLA (Comprehensive Environmental Response, Comprehensive Liability Act 1980) – RAGS (Risk Assessment Guidelines for Superfund 1989)
• MERLA (Minnesota Environmental Response and Liability Act 1983) – RBSE (RiskBased Site Evaluation – 1996) – SRVs (Soil Reference Values)
Development of RiskBased Criteria
Risk Concept: Risk = (Toxicity) (Exposure)
= (Toxicity) (Media Concentration) (Intake)
Rearranged: Media Concentration = Risk
(Toxicity) (Intake)
What are Soil Reference Values?
Soil concentrations which correspond to a specified target risk level based on a specific exposure scenario.
Used as a decision criteria in assessing potential human health concern at contaminated sites.
Development of SRVs Exposure Scenarios
Use and Receptor Basis
• Residential/Unrestricted Commercial – Young child and older child/adult
• Recreational – Young child and older child/adult
• Industrial/Restricted Commercial – Adult worker
Development of SRVs Exposure Scenarios
Exposure Pathways
• Incidental ingestion of soil
• Dermal contact with soil
• Inhalation of outdoor vapor/particulate
Development of SRVs Toxicity Values
• Minnesota Department of Health • USEPA (IRIS, HEAST, STSCNCEA) • California EPA • ATSDR • Literature
Estimation of Incidental Soil Ingestion Exposure
C soil x IR s x CF x EF s x ED BW x AT
Where: C soil = Soil concentration (mg/kg) IR s = Soil Ingestion Rate (mg/day) (100 (child); 80 (worker)) CF = Conversion Factor (1E6 kg/mg) EF s = Exposure Frequency (days/yr) (350 (child); 250 (worker)) ED = Exposure Duration (yrs) (6 (child); 25 (worker)) BW = Body weight (kg) (15 (child); 70 (worker)) AT = Averaging Time (days) (2190 (child); 9125 (worker))
Estimation of Dermal Exposure
C soil x SA x AF x ABS x CF x EF d x ED BW x AT
Where: C soil = Soil concentration (mg/kg) SA = Skin surface area (cm 2 ) (2000 (child); 3400 (worker)) AF = Adherence factor (mg/cm 2 ) (0.2 (child); 0.13 (worker)) ABS = Absorption factor (default for organics – 10%) CF = Conversion Factor (1E6 kg/mg) EF s = Exposure Frequency (days/yr) (150 (child and worker)) ED = Exposure Duration (yrs) (6 (child); 25 (worker)) BW = Body weight (kg) (15 (child); 70 (worker)) AT = Averaging Time (days) (2190 (child); 9125 (worker))
Estimation of Inhalation Exposure
C air x EF a x ED x CF AT
Where: C air = Air concentration (mg/m 3 )
= Csoil x (1/Particulate Emission Factor) (1/PEF: residential 1E9 kg/m 3 ; industrial 3E9 kg/m 3 )
EF s = Exposure Frequency (days/yr) (350 (child); 250 (worker)) ED = Exposure Duration (yrs) (6 (child); 25 (worker)) AT = Averaging Time (days) (2190 (child); 9125 (worker)) CF = Conversion Factor (1E+3 ug/mg)
Calculation of Residential SRV
. HQ x AT . ED X IR x CF x EF + SA x AF x ABS x CF x EF + EF x CF
BW x RfD BW x RfD PEF x RfC
Media Concentration = Risk (Toxicity) (Intake)
Risk Assessment Process
Problem Formulation
Toxicity
Assessment
Exposure
Assessment
Data A
cquisition
Risk Characterization
Risk Assessment/Risk Management Interaction
Risk Management Decision
Statutory Requirements Technical Feasibility Economics Social Factors Political Factors
SRV Webpage
• http://www.pca.state.mn.us/cleanup/riskbasedoc.html #pathway
Laura E. Solem, Ph.D. Minnesota Pollution Control Agency [email protected]