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 Laura.Solem@pca.state.mn.us