Human Health Risk AssessmentLibby, MT Superfund Site

Texas A&M University

CVEN610/PHEO650

April 29, 2004Presented 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.WellesRegional EPA AdministratorSeptember 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 American 1.22% Hispanic 0.61% Asian 0.15% African 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 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.

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

Cristina . . .

Chemicals Found at the Site

Compound

Contaminant Group

Media

Geometric

Mean (µg/L)

EPA Drinking Water & Soil Standards

1,1,1-TRICHLOROETHANE VOC Groundwater 6.92 0.2 ppm

1,2-BENZANTHRACENE PAH Groundwater .30 4 ppm1 ACENAPHTHYLENE PAH Groundwater 13.95 10 ppm2

ANTHRACENE PAH Groundwater 1.07 2,100 ppm2

ARSENIC Metals Groundwater --2 0.01 ppm BENZENE VOC Groundwater 5.98 CHROMIUM Metals Groundwater 7.33 100 ppm CHRYSENE PAH Groundwater .47 0.2 ppm3 COPPER Metals Groundwater 52.58 1.3 mg/L DIBENZOFURAN PAH Soil N/A N/A ETHYLBENZENE VOC Groundwater 5.62 0.7 mg/L FLUORANTHENE PAH Groundwater .55 280 ppm2

FLUORENE PAH Groundwater 8.89 280 ppm2

LEAD Metals Groundwater --3 15 ppm NAPHTHALENE PAH Groundwater 33.23 1 ppm NICKEL Metals Groundwater 14.25 0.7 mg/L PAH (BENZO(A)PYRENE) PAH Groundwater, Soil .52 24 ppb4 PENTACHLOROPHENOL (PCP) Base Neutral Acids Groundwater, Soil 89.49 1 ppm PHENANTHRENE PAH Groundwater, Soil 8.63 10 ppm2

PYRENE PAH Groundwater, Soil .62 210 ppm2

TOLUENE VOC Groundwater 5.12 1 mg/L XYLENE VOC Groundwater 17.55 10 ppm ZINC Metals Groundwater 555.78 5 mg/L

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 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 Wisconsin’s drinking water standard. 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

Compound

Carcinogenicity

Oral Slope Factor1

EPA/ATSDR Priority Level2

BENZENE A (yes) 1.5 E-2 to 5.5 E-2 per

(mg/kg)/day High/ 6

BENZO(a)PYRENE A (yes) 7.3E+0 per (mg/kg)/day High/ 8

CHRYSENE B (probable) N/A Mid/ 117

FLUORANTHENE D (no) ---- Mid/ 106

NAPHTHALENE C (possible) N/A Mid/ 77

PENTACHLOROPHENOL B (probable) 1.2E-1 per (mg/kg)/day High/ 43

PYRENE D(no) ---- Low/ 259

1 Values taken from individual profiles listed in the Integrated Risk Information (IRIS) website, http://www.toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?IRIS. 2 Numerical standing taken from the 2003 CERCLA Priority List of Hazardous Substances as listed on the Agency for Toxic Substances and Disease Registry, http://www.atsdr.cdc.gov/clist.html

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: PathwaysScenario Comments

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

PWI86

SDI 86

HVI 86 ShB86

Tot

Adult RiskAdult Hazard

Children RiskChildren Hazard

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

Pathway Dependent Risk/Hazard for Children & Adults in 1986

Adult Risk

Adult Hazard

Children Risk

Children Hazard

Dhananjay . . .

Risk Characterization Ingestion of potable water

Hazard index for non-carcinogens

Adult Child RfD HQA HQC Fluoranthene 3.76E-04 3.76E-04 4.00E-02 9.40E-03 9.40E-03 Naphthalene 4.55E-02 1.06E-01 2.00E-02 2.28E+00 5.30E+00 Pyrene 5.66E-04 1.32E-03 3.00E-02 1.89E-02 4.40E-02 Total HI 2.30E+00 5.35E+00

Risk Characterization

Libby 1986 Potable Water Non-Cancer Risks for Adults

Risk CharacterizationLibby 1986 Potable Water Non-Cancer Risks for Children

Risk CharacterizationTable 5.1.1A-Ingestion of Potable Water Exposure (1986)

Adults Children

Cancer risk

Non-cancer risk cancer risk Non cancer

Chemicals risk % Total risk

Hazard % Total Hzard

Risk % Total risk

Hazard

%

Total Hazard

Benzene 2.03E-7

0.14 4.09E-2 23.96 9.05E-8

0.14 9.55E-2 23.96

Benzo(a)-pyrene

2.38E-5

15.79 1.18E-6 0 1.11E-5

15.79 2.77E-6 0

Chrysene 6.62E-7

0.44 1.76E-3 1.03 3.09 0.44 4.11E-3 1.03

Fluoranthene 0 0 3.76E-4 0.22 0 0 8.78E-4 0.22

Naphthalene 0 0 4.55E-2 26.63 0 0 1.06E-1 26.63

PCP 1.26E-4

83.63 8.17 47.82 5.88E-5

83.63 1.90E-1 47.82

Pyrene 0 0

1.50E-4

5.66E-4 0.33

1.70E-1

0 0

7.03E-5

1.32E-3 0.33

3.98E-1

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

PWI86

SDI 86

HVI86

ShB86

Tot

Adult Risk

Children Risk0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

Pathway Dependent Risk/Hazard for Children & Adults in 1986

Adult Risk

Adult Hazard

Children Risk

Children Hazard

PWI03

SDI 03

HVI 03

Tot

Adult Risk

Children Risk0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

Pathway Dependent Risk/Hazard for Children & Adults in 2003

Adult Risk

Adult Hazard

Children Risk

Children Hazard

Cristina . . .

Libby, MT Groundwater & Asbestos

http://www.highplainsfilms.org/mov/libby_t1.mov

Q&A