Human Health Risk Assessment Libby, MT Superfund Site

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Human Health Risk AssessmentLibby, MT Superfund
Site

• Texas AM University
• CVEN610/PHEO650
• April 29, 2004
• Presented by Cristina Baker, Fuman Zhao,
• Dhananjay Kulkarni Robert Wilcox

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I have determined that, as a first plan of
action, the Buy Water plan with ordinance at
the Libby, Montana ground water contamination
site is a cost-effective remedy, is consistent
with a permanent remedy, and as a first plan of
action provides protection of public health,
welfare, and the environment. John
G.Welles Regional EPA Administrator Septembe
r 26, 1986
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City of Libby -- Demographics

• Population 2,626 people, 1,132 households, 669
  families
• EPA estimates a total surrounding population of
  11,000
• Ethnic Demographics
• 95.51 White
• 1.26 Native American
• 1.22 Hispanic
• 0.61 Asian
• 0.15 African American
• 0.53 from other races

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Site Location Description

• Libby, Montana Site Lincoln County
• Name Libby Groundwater Contamination
  (aka Champion Mill Site)
• Size 1,500 acres
• Site Champion Mill and the City of Libby
• Bordering Highways, Railways Waterways
• Highways 2 40
• Burlington Northern Railroad
• Rivers Creeks
• North Kootenai River
• East Libby Creek
• West Flower Creek

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Site History

• Source of Contamination arises from the abandoned
  wood treating operations of the the Stimson
  Lumber Companys Mill Site
• Wood treating operations began in 1946 and ended
  in 1969
• First reported complaint of creosote odors from
  private water well in April of 1979

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Site History

• On site Waste water was dumped/stored in
  on-site pits. Also, stored in the pits was the
  sludge that was periodically drudged up from the
  bottom of the treatment tanks.
• Over the next twenty-three years, 45,000 cubic
  yards of soil would become contaminated with PAH,
  PCP, Creosote, and heavy metals.

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Site History

• Site first became a concern in 1979 due to an
  increase use of well water and the installation
  of new private wells
• Field monitoring began in June 1981 (EPA, ROD
  1986)
• 32 of the private off-site ground water wells are
  known to be contaminated with PCP, VOCs, PAH
  (Creosote)

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Site History--Timeline

• 1946-1957 J. Neils Lumber Co.
• 1957-1985 St. Regis Paper Co.
• 1979 Public complains that well water smells
  like creosote
• 1981(June) EPA begins field monitoring
• 1982 (December) Proposed NPL site
• 1983 (Spring) Phase I confirmed groundwater
  contamination
• 1983 (September) Finalized NPL site
• 1985- 1993 Champion International Corp.

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Site History--Timeline

• 1985 (Summer) Champion International Corp.
  begins offering Buy Water plan to owners of
  identified and contaminated wells.
• 1986 (July) City of Libby enacts new groundwater
  ordinance (1344)
• 1986 (September) First ROD
• 1988 (December) Second ROD
• 1989 Champion signs Consent Decree
• 1993- Current Stimson Lumber Co.
• 1993 (September) EPA begins clean-up of lower
  aquifer

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Cristina . . .
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Chemicals Found at the Site

1 Attempts to set an EPA drinking water
standard have been hindered by the lack of data
and presence as a complex mixture of various
PAHs. Drinking standard listed reflects
Floridas drinking water standard.
2 No geometric mean concentration is estimated
since the compound was either detected in only
one well or only one time during the 1985
sampling program. (EPA, ROD 1986)
3 Attempts to set an EPA drinking water
standard have been hindered by the lack of data
and presence as a complex mixture of various
PAHs. Drinking standard listed reflects
Wisconsins drinking water standard.
4 An upper limit estimate of the national
background exposure (ATSDR, Public Health
Statement, August 1995)
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Principle Contaminant Groups

• Creosote A complex mixture of gt 200 organic
  compounds and contains 85 PAHs, 12 phenolic
  compounds, 3 heterocyclic nitrogen, oxygen, and
  sulfur compounds.
• PCP (Pentachlorophenol) Initial concentrations
  detected were about 3,200 µg/L. EPA standards
  for drinking water are .022or.1 mg/L.

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CoC Assumptions

• Arsenic and lead was isolated to only one well or
  was detected only once
• Benzo(a)pyrene will represent all known
  carcinogenic PAHs present in the soil
• Substantial contamination of ground water by PCP
  renders it a CoC
• It is assumed that contact with contaminated
  ground water would contaminate the irrigated soil

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Chemicals of Concern
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Principle Contaminant PCP

• Technical grade contains additional impurities
  including dibenzo-p-dioxins and dibenzofurans.
  May present actual cause for toxic effects.
• Mode of Operation Inhibits oxidative
  phosphorylation ? Increased body temperature,
  tachypnea, tachycardia.

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PCP

• Target Organs
• Hepatocellular Degeneration
• Reproductive
• Neurological (Indirectly)
• Immune System

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Secondary Contaminant Benzene

• Benzene is absorbed via inhalation, ingestions
  and skin applications. Humans can absorb up to
  80.
• Mode of Operation Targets hematopoetic organs ?
  Reduces red blood cell production ? Myeloblastic
  and erythroblastic leukemias (cancer)

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Benzene

• Target Organs
• Hematopoetic Tissues
• Central Nervous System
• Immune System

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Fuman . . .
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Exposure Assessment Pathways
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Exposure Assessment Population

• Potentially exposed population
• All 2,622 residents of the City of Libby
• Sensitive receptors
• Children
• Pregnant women

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Exposure Assessment Exclusions

• Pathways excluded
• Air contamination
• Injection
• Major Assumption
• All residents of Libby are exposed
• Residents used contaminated well water either for
  drinking or irrigation

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Exposure Assessment Conclusion

• The major pathway of exposure is
• Potable Water (PWI) Ingestion of contaminated
  groundwater from wells
• The secondary pathway of exposure is
• Showering and Bathing (ShB) -- Inhalation of
  aromatic vapors from steam and by dermal exposure
  (Benzene only)
• Children are at the greatest risk for both
  scenarios

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Exposure Assessment Results
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Dhananjay . . .
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Risk Characterization

• Ingestion of potable water
• Hazard index for non-carcinogens

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Risk Characterization
Libby 1986 Potable Water Non-Cancer Risks for
Adults
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Risk Characterization
Libby 1986 Potable Water Non-Cancer Risks for
Children
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Risk Characterization
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Risk Characterization
Libby 1986 Potable Water Cancer Risks for Adults
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Risk Characterization
Libby 1986 Potable Water Cancer Risks for
Children
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Risk Characterization Summary

• LCR adults 1.26E-4
• LCR children 5.88E-5
• The following pathways contribute less than 1/100
  of a percent of the total risk when compared to
  the Potable Water scenario
• Soil Dust Ingestion
• Homegrown Vegetable Exposure/Ingestion
• Showering and Bathing Inhalation/Dermal

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Conclusion Summary of Risks

• PCP poses the maximum carcinogenic risk
• Exposure to PCP through the Potable Water pathway
  is the primary contributor towards total
  carcinogenic risk
• Recent data shows a 53 decline in total
  carcinogenic risk after 15 years of groundwater
  remediation (Texas AM 2000 data)
• Benzene test results for the ShB pathway were not
  available in the Texas AM 2000 data

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Cristina . . .
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Libby, MT Groundwater Asbestos
http//www.highplainsfilms.org/mov/libby_t1.mov
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QA