The Santa Susana Field Laboratory SSFL : Exposure Pathways and Community Exposures

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The Santa Susana Field Laboratory (SSFL)
Exposure Pathways and Community Exposures

• Public Health Support Services for
  ATSDRSubcontract CDC-0901/7-1
• Prime contract number CDC 205-95-0901
• UCLA

Team Members Yoram Cohen Tom Harmon Adrienne
Katner Gregory Lewis Lyle Chinkin Neil J. M.
Wheeler Patrick A. Ryan
Independent Critical Peer Review Analysis
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Areas of Concern
Bell Canyon Brandeis-Bardin Institute Santa
Monica Mountains Conservancy Sage Ranch Simi
Valley Santa Susana Knolls Chatsworth Ahmanson
Ranch West Hills Canoga Park Woodland Hills
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Our Approach
Establish Scope of Critical Assessment and
Analysis Methods
Data/Information Compilation Review
Identify and Rank Chemicals of Concern
Identify and Evaluate Chemical Transport Pathways
Air 1. Identify quantify emission sources 2.
Dispersion modeling
Groundwater/ subsurface contamination (on-site
off-site)
Surface water (contamination migration pathway)
Integrated multimedia analysis
Exposure/dose analysis
What are the questions to be answered?
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• Monitoring versus Modeling
• Monitoring data chemical analysis (in the
  field/laboratory) of contaminants in and around
  SSFL
• Modeling use analytical and computer-based
  models to simulate the migration and distribution
  of contaminants
• Multimedia (air, water, soil, groundwater,
  vegetation, livestock, etc.)

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What are the key questions to be answered?

• Is there evidence of significant community
  exposures to toxic chemicals and radionuclides
  from SSFL?
• Has the site been adequately evaluated with
  respect to its potential impact on the
  surrounding community?

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Sources of Information
ICF Kaiser IT Corporation Lafflam, S.R. Lawrence
Livermore National Lab. McLaren/Hart Montgomery
Watson Morgenstern, H. Oak Ridge Associated
Universities Oldenkamp, R.D. and Mills,
J.C. Ogden Inc. Precise Environmental
Consultants RWQCB Reynolds et al. Rocketdyne
Propulsion and Power, Boeing Inc. Rockwell
International. Rutherford P.D. Science
Applications International Corporation Techlaw,
Inc. Tuttle, R.J. U.S. EPA U.S.G.S. V.C.A.P.D. Upp
er LA River Area Watermaster WHO US. Census
Tracts
ABB Environmental Services, Inc. Atomics
International Agency for Toxic Substances and
Disease Registry California Department of Health
Services CH2M Hill Cohen, Y., Winer, A., Suffet,
M. Colburn, I., L.R. Saul and A.A.
Almgren Committee to Bridge the Gap Dempsey,
G DHS EGG DOE Ecology and Environment
Inc. EMCON Environmental Restoration
Division Resolution Resources EPA Finlayson-Pitts,
B., and Pitts, J. Froines, J. Groundwater
Resource Consultants Haley-Aldrich Hargis, and
Associates Hughes Missile Systems Group IARC,
(International Agency for Research on Cancer)
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Transport pathways and Exposure

• Identify and rank SSFL contaminants of potential
  concern (COPCs).
• Identify contaminants associated with the site
  and emissions.
• Assess transport and fate of COPCs.
• Compare and rank COPCs based on potential impact.
• Determine potential dispersion and exposure
  pathways of COPCs.
• Identify exposures receptor sites from air
  dispersion and subsurface transport, monitoring
  data, well use surveys and land permits.
• Estimate likely range of multimedia contaminant
  concentrations at receptor sites using monitoring
  data and multimedia distribution models.
• Estimate potential cumulative dose

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EXPOSURE CRITICAL ISSUES

• Contaminant detection in environmental media is
  an insufficient indicator of exposure!
• Exposure may be inferred from monitoring of
  various media for chemicals of concern, from
  knowledge of emissions and model simulations.

• Exposure/dose can be affected by various
  factors including

• Uncertainties in quantitative exposure
  assessment can be large.

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Limitations Uncertainties

• Insufficient monitoring data for accurate
  quantitative exposure assessment
• Concerns regarding the reliability and accuracy
  of monitoring data
• e.g. Radiation Monitoring Problems
• RD heats soils (8 hours at 500C)- sufficient to
  volatilize radionuclides(e.g., Cs-137, Sr-90).
• Vegetation washed and ashed- contamination washed
  off before counting.
• Spikes not always run to verify accuracy and
  precision of methods.
• Unfiltered samples had higher activity than
  filtered samples from same area (alpha/beta).
• Inconsistent inventories, treatment logs and
  waste emission reports
• Permit violations
• Private well and historical well use information
  is lacking

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Phases of Our Study

• Phase I
• Compile review available SSFL related studies
  and other pertinent site information
• Attend public and technical meetings with various
  parties
• Site visits
• Establish scope of work and methods
• Phase II (in progress)
• Exposure pathways
• Groundwater contamination
• Emission sources
• Air dispersion modeling

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Progress (Contd)

• Phase III (in progress)
• Intermedia contaminant transport analysis
  (e.g., volatilization from soil subsurface, wet
  deposition)
• Multimedia exposure analysis
• Phase IV (in progress)
• Final draft report (December 2003)
• Review period (1 month)
• Public release of final report March 2004

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Outline

• The study area
• Our approach
• Study phases
• Information sources
• Critical issues in exposure analysis