Human Health Risk Assessment Libby, MT Superfund Site Texas A&M University CVEN610/PHEO650 April 29, 2004 Presented by: Cristina Baker, Fuman Zhao, Dhananjay Kulkarni & Robert Wilcox

“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 September 26, 1986

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 AmericanNative American 1.22% HispanicHispanic 0.61% AsianAsian 0.15% African AmericanAfrican American 0.53% from other races

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

Site History Source of Contamination arises from the abandoned wood treating operations of the the Stimson Lumber Company’s 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

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.

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)

Site History--Timeline : J. Neils Lumber Co : 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 : Champion International Corp.

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

Cristina...

Chemicals Found at the Site [1][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 Florida’s drinking water standard. [2][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][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 Wisconsin’s drinking water standard. [4][4] An upper limit estimate of the national background exposure (ATSDR, Public Health Statement, August 1995)

Principle Contaminant Groups Creosote: A complex mixture of > 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.

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

Chemicals of Concern

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.

PCP Target Organs: Hepatocellular Degeneration Reproductive Neurological (Indirectly) Immune System

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)

Benzene Target Organs: Hematopoetic Tissues Central Nervous System Immune System

Fuman...

Exposure Assessment: Pathways ScenarioComments 1. Potable Water (PWI)Ingestion of contaminated groundwater from wells 2. Home Grown Vegetables (HGV)Ingestion of contaminated vegetables irrigated from contaminated groundwater 3. Soil and Dust (ISD)Ingestion of contaminated soil/dust that absorbed contaminated groundwater 4. Showering and Bathing (ShB)Inhalation of aromatic vapors from steam and by dermal exposure (Benzene only)

Exposure Assessment: Population Potentially exposed population All 2,622 residents of the City of Libby Sensitive receptors: Children Pregnant women

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

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

Exposure Assessment: Results

Dhananjay...

Risk Characterization Ingestion of potable water Hazard index for non-carcinogens

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

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

Risk Characterization

Libby 1986 Potable Water Cancer Risks for Adults

Risk Characterization Libby 1986 Potable Water Cancer Risks for Children

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

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 A&M 2000 data) Benzene test results for the ShB pathway were not available in the Texas A&M 2000 data

Cristina...

Libby, MT Groundwater & Asbestos

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