Environmental Risk Assessment and Risk Management Kevin L. Long ENVIRON International Corporation Academy Park High School May 12, 2010

2 Environmental Risk Assessment and Risk Management  About your guest lecturer –Manager at ENVIRON International Corporation –Risk Assessment, Remedial Engineering, Site Investigation, Litigation –B.S.E. and M. Eng. Civil and Environmental Engineering, Princeton University –Strath Haven High School  Outline of lecture –Basic approaches to environmental regulation –Risk management framework –Risk assessment methods and issues –Project overview and first assignment

3 Basic Approaches to Environmental Regulation  Early environmental regulations relied on technology-based approaches to control pollution: –Clean Air Act –Clean Water Act  Technology-based standards require the use of “best available technology” (also BACT, maximum achievable control technology)  Later regulations incorporated “risk-based” standards for hazardous waste management and cleanup of contamination: –Resource Conservation and Recovery Act –Comprehensive Environmental Response, Compensation, and Liability Act (Superfund)  Risk-based standards require protection of human health and the environment (“safe” does not mean “zero risk”)

4 Reference: Risk Commission 1997  Risk management is the process of identifying, evaluating, selecting, and implementing actions to reduce risks to human health and to ecosystems. The goal of risk management is scientifically sound, cost-effective, integrated actions that reduce or prevent risks while taking into account social, cultural, ethical, political, and legal considerations.  Risk assessment is the systematic, scientific characterization of potential adverse effects of human or ecological exposures to hazardous agents or activities. Risk assessment is performed by considering: –the types of hazards –the extent of exposure to the hazards –the relationship between exposures and responses Risk Management and Risk Assessment

5 Risk Management Framework 1.Define the problem and put it in context 2.Analyze the risks associated with the problem 3.Examine options for addressing the risks 4.Make decisions about which options to implement 5.Take actions to implement the decisions 6.Conduct an evaluation of the results of the action Reference: Risk Commission 1997

6 Risk Assessment Components Risk  Exposure  Hazard  Exposure scenarios  Dose estimates  Health effects  Dose- response

7 Exposure Assessment Exposure Scenarios  An exposure scenario is the set of facts, data, assumptions, and professional judgment about how an exposure occurs or doesn’t occur.  An exposure scenario addresses the following: –Contaminants and their sources –Exposed populations (or receptors) –Contaminant migration from sources to receptors –Routes of exposure ingestion dermal contact inhalation

8 Exposure Assessment Example Exposure Scenarios Reference: USEPA 1989

9 Dose= mg chemical per kg body weight per day C= contaminant concentration (mg/L or mg/kg) IR= intake rate (L/day or kg/day) FC= fraction contaminated (unitless) AF= absorbed fraction (unitless) EF= exposure frequency (days/year) ED= exposure duration (years) BW= body weight (kg) AT= averaging time (days) Exposure Assessment Ingestion & Dermal Dose Reference: USEPA 1989

10 EC= time-weighted average concentration (mg/m 3 ) C= contaminant concentration (mg/m 3 ) ET= exposure time (hours/day) EF= exposure frequency (days/year) ED= exposure duration (years) AT= averaging time (hours) Exposure Assessment Inhalation Exposure Concentration Reference: USEPA 2009

11 Modeling Variability in Exposures Example: Residential Inhalation 90th 95th50th 99th 99.9th98th

12 Key Issue in Exposure Assessment What exposure should we protect?  The EPA typically aims to manage environmental risks based on the “reasonable maximum exposure” or RME, which EPA defines as “conservative but within a realistic range of exposure.”  The RME should represent a reasonable worst-case, which is an exposure in the 90 th to approximately 98 th percentile range.

13  Hazard identification is the process of determining what adverse health effects may occur from exposure to a substance. Available Information on Health Effects of Benzene (ATSDR 2007)ATSDR 2007 Hazard Identification

14 Inhalation Exposure to Benzene (ATSDR 2007)ATSDR 2007 Dose-Response Evaluation LOAEL for BMD modeling MRL = ppm {

15 Dose-Response Evaluation Benchmark Dose (BMD) Modeling  Noncancer effects: the dose-response relationship is expressed as a reference dose (RfD) or reference concentration (RfC): where UFs of 10 (typically) account for: extrapolating animal data to humans; human variability; extrapolating subchronic to chronic; and extrapolating LOAEL to NOAEL  Cancer risk: the dose-response relationship is expressed as a cancer slope factor (SF) or inhalation unit risk (IUR):

16 Hypothetical study conducted with 50 animals per dose. Dose-Response Evaluation BMD Modeling to Derive RfD or RfC NOAEL BMR

17 Dose-Response Evaluation BMD Modeling to Derive SF or IUR Hypothetical study conducted with 50 animals per dose. NOAEL BMR

18  Cancer risk equation:  Noncancer hazard quotient (HQ) equation: HQs are calculated separately for acute, subchronic, and chronic exposures. Risk Characterization Ingestion & Dermal Risks

19 Risk Characterization Inhalation Risks  Cancer risk equation:  Noncancer hazard quotient (HQ) equation: HQs are calculated separately for acute, subchronic, and chronic exposures.

20 Risk Characterization Cumulative Cancer and Noncancer Risks  Cumulative cancer risk equation:  Cumulative noncancer hazard index (HI) equation: HQs are grouped by chemicals that have the same mode of action or target organ.

21 Risk Management Acceptable Risk Levels  In determining whether contamination poses an unacceptable risk, EPA generally considers RME risks to be acceptable when they do not exceed an excess lifetime cumulative cancer risk of or an HI of 1.  Some state agencies regulate contamination to an excess lifetime cancer risk of  For perspective, men in the United States have slightly less than a 1 in 2 risk of developing cancer over a lifetime, and women have a slightly more than 1 in 3 risk. (ACS 2009)ACS 2009

22 Key Points  Risk assessment involves the use of science, assumptions, and judgment. For example: –Exposure assessment: assumptions about the exposure scenario; estimate of the population’s dose distribution, and choice of percentiles to protect –Toxicity assessment: selection of test data; estimate of dose-response from test data, and extrapolation to lower doses and greater susceptibility  Risk estimates should be considered in light of the judgment and assumptions regarding exposure and toxicity.  Environmental risks should be considered in light of other risks we face, in deciding how much they should be reduced.

23 Vapor Intrusion - Overview Source: Taken from J&E 1991

24 Vapor Intrusion - Overview  Vapor intrusion pathway can be evaluated using the model developed by Johnson & Ettinger (J&E, 1991) – Heuristic Model for Predicting the Intrusion Rate of Contaminant Vapors into Buildings –J&E 1991 – presents the formal development of the model which describes the transport and fate of contaminant vapors through soil into a building  J&E model widely used by regulatory agencies for assessing potential vapor intrusion issues  Derived from fundamental principles for: –Contaminant partitioning from soil or groundwater –Transport through soil column via diffusion –Transport through building foundation via diffusion and advection –Enclosed-space mixing  Key model element: Algorithm for estimating attenuation factor ( α ) –Relates soil or groundwater concentration to modeled indoor air concentration –Semi-analytic solution for steady-state, 1-D case –Assumes infinite contaminant mass –Has numerous inputs

25 Vapor Intrusion - Overview The indoor air concentrations are estimated using the following relationships described by Johnson and Ettinger (1991): where C building is the indoor air concentration, C source is the source vapor concentration, given by the following equations:

26 Vapor Intrusion - Overview α is the attenuation coefficient, calculated as follows:

27 Vapor Intrusion - Overview Key Site Specific Parameters Model InputSymbol Distance between foundation to vapor “source”LTLT Area of foundation cracks through which vapors enter building A crack Area of enclosed spaceABAB Fraction of surface area open for vapor intrusion η Thickness of foundation for enclosed spaceL crack Building ventilation flow rateQ building Soil gas flow rate into building to its ventilation rateQ soil Effective diffusivity through cracksD eff crack Effective diffusivity through vadose zoneD T eff

28 Vapor Intrusion - Guidance  United States Department of Environmental Protection (USEPA) –OSWER (2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance)OSWER (2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance) –Johnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings – User’s GuideJohnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings – User’s Guide  New Jersey Department of Environmental Protection (NJDEP) –NJDEP Vapor Intrusion Guidance (2005)NJDEP Vapor Intrusion Guidance (2005) –New Jersey Johnson & Ettinger SpreadsheetsNew Jersey Johnson & Ettinger Spreadsheets

29 Vapor Intrusion - Guidance  United States Department of Environmental Protection (USEPA) –OSWER (2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance)OSWER (2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance) –Johnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings – User’s GuideJohnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings – User’s Guide  New Jersey Department of Environmental Protection (NJDEP) –NJDEP Vapor Intrusion Guidance (2005)NJDEP Vapor Intrusion Guidance (2005) –New Jersey Johnson & Ettinger SpreadsheetsNew Jersey Johnson & Ettinger Spreadsheets

30 Current Project Details

31 Current Project Details  Contaminated Site in New Brunswick, New Jersey –As a result of documented vandalism, a release of transformer oil occurred at the site in June –Approximately 1,100 gallons of polychlorinated biphenyls (PCB) oil and 1,200 gallons of non-PCB oil –Released oil flowed overland from the transformer area into a catch basin(s) connected to the facility storm water drain line which conveyed the oil to an on-site drainage swale –The oil then flowed via this swale to a storm water culvert pipe which conveyed the oil approximately 800 feet to a creek  Currently groundwater concentrations for a few constituents at levels above New Jersey’s Groundwater Quality Standards  Is groundwater vapor intrusion a concern for this site?

32 Current Project Details

33 Current Project Details

34 Kevin L. Long | Manager ENVIRON | Carnegie Center, Suite 200 | Princeton, NJ V: | F: | Contact Information