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PRELIMINARY PUBLIC HEALTH ASSESSMENT

VANCOUVER WATER STATION NO. 1 CONTAMINATION AREA
VANCOUVER, CLARK COUNTY, WASHINGTON


SUMMARY

Vancouver Water Station No. 1 site (WS1) is a municipal well field located in Vancouver, Clark County, Washington. In March of 1988, the City of Vancouver, Public Works Department began monitoring the municipal water supply forvolatile organic compounds in response to the Federal Safe Drinking Water Act Amendments of 1986. Lowconcentrations of tetrachloroethylene were consistently found in water from WS1 production wells and reservoir. Laterin May of 1993, the City of Vancouver, Public Works Department placed five air stripping towers into operation treatinggroundwater contamination at WS1 to ensure concentrations of tetrachloroethylene in drinking water complied with theFederal Safe Drinking Water Standards.

The site poses no apparent health hazard to users of the WS1 municipal water supply (residents, workers, and students)as a result of past exposure to low concentrations of tetrachloroethylene in drinking water. Groundwater treatment haseliminated the possibility of current and future exposure to tetrachloroethylene by residents, workers, and students whouse water supplied from WS1. Past exposure to tetrachloroethylene may have occurred; however, because ofvolatilization, concentrations are anticipated to have been minimal and unlikely to cause adverse health effects.

It is uncertain whether exposure to tetrachloroethylene had occurred in the past, is presently occurring, or will occur inthe future to residents and workers who use water provided through private supply wells. Existing data is insufficient toadequately characterize groundwater contamination, and private supply well surveys are too limited to conclusivelyidentify all nearby private supply wells. To determine whether private supply wells are at risk to groundwatercontamination associated with WS1, it is necessary to further characterize groundwater contamination as well as to identifyall nearby private supply wells. Should private supply wells be identified at risk, periodic monitoring of these wells shouldbe conducted to be able to assess exposure to tetrachloroethylene and/or other hazardous substances and to predictassociated health risks.

After the public was notified of the discovery of volatile organic compounds in the municipal water supply, local citizensexpressed their health concerns to the City of Vancouver, Public Works Department. The citizens' primary concern wasabout the risk of developing cancer from exposure to tetrachloroethylene-contaminated drinking water. A discussion ofcommunity health concerns is included in the Public Health Implications section of this Preliminary Public HealthAssessment.

The Washington Department of Health and Agency for Toxic Substances and Disease Registry recommend to 1) furthercharacterize the extent and migration of groundwater contamination associated with WS1; 2) conduct a comprehensiveprivate supply well survey within the vicinity of WS1; 3) monitor water quality of private supply wells considered to beat risk from groundwater contamination; 4) notify owners of private supply wells within the vicinity of groundwatercontamination of the potential for exposure to contaminated groundwater; and 5) sample and analyze groundwater fromany private supply wells that may be installed in the future within the vicinity of groundwater contamination prior to use.

The data and information developed in the WS1 preliminary public health assessment have been evaluated by the ATSDRHealth Activities Recommendation Panel (HARP) for follow-up health actions. No actions are recommended at this time.


BACKGROUND

This Preliminary Public Health Assessment for the Vancouver Water Station No. 1 Superfund site (WS1) is prepared bythe Washington Department of Health (WDOH) under cooperative agreement with the Agency for Toxic Substances andDisease Registry (ATSDR) in accordance with the Comprehensive Environmental Response, Compensation, and LiabilityAct of 1980. In this document, available environmental and health data are evaluated to determine public healthimplications posed by the site.

A. Site Description and History

WS1 is located about one-half mile east of Interstate Highway 5 at the southeast corner of East Fourth Plain Boulevardand East Reserve Street (Figure 1 and 2). Consisting of ten production wells, WS1 generates an annual average of 6,000gallons per minute and has a peak production capacity of 18,000 gallons per minute. WS1 is one of several water stationsthat supply drinking water to about 108,000 people in the city of Vancouver and surrounding Clark County.

In March of 1988, the City of Vancouver, Public Works Department (Vancouver) began monitoring the municipal watersupply for volatile organic compounds (VOCs) in response to the Federal Safe Drinking Water Act Amendments of 1986. Results of the monitoring revealed VOCs in groundwater at Water Station No. 1, 3, and 4. VOCs detected at WS1, 1,1-dichloroethylene, 1,1,1-trichloroethane, tetrachloroethylene, and trichloroethylene, were at concentrations below theFederal Safe Drinking Water Standard Maximum Contaminant Levels (MCLs). Vancouver notified the public of thedetection of VOCs in the municipal water supply, focusing primarily on tetrachloroethylene discovered in groundwaterat Water Station No. 4 (WS4). As part of this notification effort, WDOH presented information on the health concernsof using tetrachloroethylene-contaminated drinking water (11).

Vancouver requested assistance from the Environmental Protection Agency (EPA) to investigate potential sources ofVOCs in the vicinity of WS1 and Water Station No. 3 (WS3). In 1989, Ecology and Environment, Inc. under contractwith EPA conducted a multi-phase study to identify potential sources of VOC contamination. Phase I of the studyinvolved the collection of 194 soil-gas samples and 12 groundwater samples to evaluate contaminant concentrationpatterns adjacent to WS1 and WS3. Because of limited groundwater sampling, definite conclusions regarding thedistribution of VOCs in groundwater could not drawn. However, sampling results suggested that tetrachloroethylene wasnot widely distributed in groundwater beneath the study area, while trichloroethane appeared to be more wide spread. Three VOCs tetrachloroethylene, trichloroethylene, and trichloroethane were consistently detected in soil-gas in thevicinity of WS1. The distribution patterns suggest that the source of trichloroethylene and trichloroethane may be differentthan the tetrachloroethylene source, and at least one additional potential source exists near WS1.

Phase II of the study focused on characterizing potential tetrachloroethylene sources which had been identified in previousinvestigations. This involved the collection of 130 soil-gas samples to determine the extent of tetrachloroethylenecontamination east of WS1 along Fourth Plain Boulevard and to identify additional potential sources in the area. Nogroundwater samples were collected as part of this study. Soil-gas results indicate two separate tetrachloroethylenesources east of WS1, and no potential sources were located to the west (9).

On July 24, 1992, EPA requested ATSDR to provide a health consultation evaluating health concerns associated with theuse of tetrachloroethylene-contaminated drinking water. Tetrachloroethylene contamination was detected at WS1 andWS4; combined these two water stations make up about 60 to 75 percent of the total municipal water supply. Water fromWS1 and WS4 production wells is pumped to a reservoir for storage before distribution to the public. Since June of 1991,increases in tetrachloroethylene concentrations had been observed at WS1. Results of sampling collected on April 13,1992 revealed concentrations at 15 microgram per liter (µg/L), 12 µg/L, and 18 µg/L in production wells 4, 5, and 6respectively. At the reservoir, water had concentrations ranging from 2 to 3 µg/L. The majority of the water stored at thereservoir was supplied from WS1.

Vancouver had scheduled to install five air stripping towers to treat contamination at WS1 by March 1993 and to beginoperation in June 1993. It was a concern that tetrachloroethylene concentrations at WS1 might exceed the MCL of 5 µg/Lbefore the installation of the treatment system. EPA action level for providing an alternative water supply was set at aconcentration of 69 µg/L for tetrachloroethylene. Based on this information, the ATSDR health consultation concludedthat increased risk of cancer to humans would be minimal should short-term exposure occur to tetrachloroethyleneconcentrations of 69 µg/L in drinking water.

WS1 was proposed for inclusion on the NPL to be investigated under Superfund, June 23, 1993, and later finalized as aNPL site, May 31, 1994. Vancouver completed the installation of the air stripping towers at WS1, bringing the towerson-line in May of 1993. Performance of the towers has been routinely monitored by Vancouver to ensuretetrachloroethylene concentrations in effluent drinking water meet the MCL of 5 µg/L.

B. Site Visit

On June 7, 1994, a site visit was conducted by Jack Morris and Trace Warner of WDOH under the guidance ofVancouver's Operations Superintendent and Assistant Operations Manager. A brief overview on the characteristics,activities, and monitoring program for WS1 was provided by the Operations Superintendent and Assistant OperationsManager.

Located at East Fourth Plain Boulevard and East Reserve Street, WS1 is situated among commercial and residentialdistricts. Immediately north along East Fourth Plain Boulevard are many small businesses, such as Burgerville U.S.A.,Tires Unlimited, and Royal Rest Mattress. Residential areas extend further north and west toward Interstate Highway 5,as well as directly east and south of the water station.

WS1 appears to be comprised of two distinct parts. The northern portion of the site is actually Waterworks Parksurrounding 9 of the 10 production wells, and is open to the public. The southern portion is completely secured by achain-linked fence. Inside this secured area are the five air stripping towers situated between a small covered reservoirand a water tower. Additionally, there is a larger covered reservoir with one production well located near the south endof the building. The nearest buildings off the site are an apartment complex and private residence about 50 feet south ofthe southern fenced boundary.

WDOH was informed during the site visit that Vancouver is presently conducting a wellhead protection study in the areato determine potential sources of contamination. This study may also determine the cone of depression influence on localgroundwater from production wells serving WS1.

C. Demographics, Land Use, and Natural Resource Use

Approximately 47,190 people live in Vancouver, Washington. The city of Vancouver is characterized by residentialneighborhoods, and is bisected by Interstate Highway 5, creating a corridor of light-industrial development. Land usesurrounding WS1 is similar to WS4, which is characterized by single and multi-family residences, as well as smallcommercial businesses. Schools located near WS1 include: Harney Elementary School, Fort Vancouver High School,Hudson's Bay High School, Clark College, State School for the Deaf, and the State School for the Blind.

The population uses groundwater from either public water systems or private supply wells. Production wells of WS1 access groundwater from the Upper Troutdale Formation aquifer at a depth approximately 200 to 250 feet below ground level. In general, the regional groundwater flows north to south/southwest towards the Columbia River. A supply well at the State School for the Blind also served as a small public water system supplying drinking water for approximately 150 school students and employees. In May of 1992, the State School for the Blind reconnected to the municipal water system for their water supply. The State School for the Blind no longer uses the supply well for drinking water or other purposes. The depth of this supply well is about 220 feet; however the aquifer it accesses is not defined in the available investigation reports.

Municipal water systems historically serviced the area minimizing the need for domestic supply wells. Phase I studyincluded an inventory survey to identify private supply wells in areas adjacent to potential sources and within a one-quartermile radius of WS1 and WS3 (Figure 3). This survey identified a limited number of functional drinking water wells. Fivedomestic supply wells were identified during the Phase I study. Two domestic supply wells, GW6 and GW11, wereconstructed at a depth of 200 feet. GW6 is located about one-half mile northwest of WS1 and GW11 about three-quartersof a mile north. Three of the domestic supply wells GW8, GW10, and GW12, ranged in depth from 30 to 65 feet and arelocated about one-half mile northwest of WS1. Three industrial supply wells GW5, GW7, and GW9 were also identified. These industrial wells ranged in depth from about 200 to 280 feet below ground surface. GW7 is located immediatelysouthwest of the site, and GW5 is about one-quarter of a mile southwest of WS1. Situated between WS1 and WS3, GW9is one-half mile northwest of WS1.

As part of WS4 remedial investigations, a survey was conducted identifying 28 existing private supply wells suitable formonitoring. Fourteen of these supply wells were used for domestic purposes. The wells ranged in depth from 11 to 396feet accessing either the Orchards or Upper Troutdale Formation aquifers. The survey area extended north/northeast ofWS4 which is about one-half mile south/southwest of WS1.

D. Health Outcome Data

Health outcome data are health data contained in databases such as cancer, birth defects, and vital statistic records. Usinghealth outcome databases, it may be possible to determine whether the occurrence of certain health outcomes are greaterthan expected in Clark County, Washington. Following are the health outcome databases available for the state ofWashington.

WDOH has a Vital Statistics Department and an Office of Registries. The Vital Statistics Department collects informationon the number of deaths, births, fetal deaths, marriages, and divorces for Washington State. Variables included in thisdatabase are geographic location (city, county, town), age, sex, race, cause of death, birth weight, gestational age, and birthdefects.

The Washington Birth Defects Registry is a registry of children with serious birth defects diagnosed before their firstbirthdays. The database contains information by major birth defect classification and by demographic factors: county ofresidence, sex, race, address, and mother's occupation, smoking history, and age. Information is available for the entirestate for the years 1986 through 1989.

The Cancer Surveillance System (CSS) for Washington State is kept by the Division of Public Health Sciences of the FredHutchinson Cancer Research Center in Seattle. The CSS works under contract to the Surveillance, Epidemiology, andEnd Results program of the National Cancer Institute. This database is the central repository for all newly diagnosedmalignancies (with the exception of nonmelanotic skin cancers) which occur in residents of 13 counties of northwestWashington State. The population covered is almost one million and includes five standard metropolitan statistical areas:the Seattle-Everett area (King and Snohomish counties), Tacoma (Pierce County), Kitsap, Thurston, and Whatcomcounties. The population-based cancer surveillance system monitors the incidence and mortality of specific cancers overtime. The variables collected in this database are designed to permit the detection of differential risks of cancer bygeographic region, age, race, sex, marital status, social security number, occupation, type of cancer, extent of disease,treatment, hospital identification, and other demographic data.

The health outcome data from relevant databases will be evaluated in the Health Outcome Data Evaluation section of thispublic health assessment.


COMMUNITY HEALTH CONCERNS

In February of 1989, Vancouver notified the public of the presence of VOCs in the municipal water supply, focusingessentially on tetrachloroethylene contamination discovered in production wells at WS4. In response to the announcementVancouver received 373 phone calls between February 7, 1989 and February 9, 1990. According to Vancouver andWDOH Drinking Water Program, the primary health concern of the community at that time was the risk of cancer fromdrinking tetrachloroethylene-contaminated water.

The public was officially invited to comment on the draft Preliminary Public Health Assessment for Vancouver WaterStation No. 1 Contamination, October 17, 1994 through November 18, 1994. The document was made available for publicreview at the Fort Vancouver Regional Library in Vancouver, Washington during this time. As of November 23, 1994, DOH had not received any public comments regarding this public health assessment.


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

Listed in the Table 1 is the contaminant of concern associated with WS1. The contaminants of concern are selected fromsampling data by comparing the maximum contaminant concentrations to comparison values, such as EnvironmentalMedia Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant health-based guidelines. The selected contaminants of concern are not necessarily contaminants that will cause adverse health effects fromexposure, but rather are contaminants to be evaluated further in the Public Health Implications section of this PreliminaryPublic Health Assessment.

EMEGs are estimated contaminant concentrations at which daily exposure would be unlikely to result in noncarcinogenichealth effects. Oral EMEGs for drinking water exposure are calculated from ATSDR Minimal Risk Levels (MRLs), basedon a child body weight of 10 kilograms (kg) and a child water consumption rate of 1 liter per day. ATSDR developedMRLs to evaluate health effects of contaminants commonly found at hazardous waste sites. MRLs are estimates of dailyexposure to contaminants below which noncarcinogenic adverse health effects are unlikely to occur. If a MRL does notexist for a specific contaminant, a comparison value is calculated from the EPA Reference Dose (RfD). RfDs are also anestimate of daily exposure to a contaminant that is unlikely to cause a noncarcinogenic adverse health effect.

CREGs are estimated contaminant concentrations at which exposure would not likely result in more than 1 excess cancerin 1 million persons exposed for a lifetime of 70 years. CREGs for drinking water exposure are calculated from EPAcancer slope factors, based on an adult body weight of 70 kg and an adult water consumption of 2 liters per day.

Toxic Chemical Release Inventory

To identify possible facilities that could contribute to groundwater contamination near WS1, WDOH searched the ToxicChemical Release Inventory (TRI) database for all available years, 1987 through 1992. TRI is developed by EPA frominformation on chemical releases to air, water, or soil, as provided by industries according to law. TRI did not containrecords of tetrachloroethylene releases in Vancouver, Clark County, Washington.

A. On-Site Contamination

Groundwater - WS1 Production Wells and Reservoir

During the Phase I study, groundwater samples were collected in August and October 1989 from two production wellsWell #1 and #10 at WS1. Concentrations of 1,1-dichloroethylene, 1,1,1-trichloroethane, and chloroform were detectedin both production wells. At Well #1, 1,1-dichloroethylene was observed at 2 µg/L, 1,1,1-trichloroethane at 6 µg/L, andchloroform at 6 µg/L. At Well #10, concentrations of 1,1-dichloroethylene were detected at 2 µg/L, 1,1,1-trichloroethaneat 8 µg/L, and chloroform at 8 µg/L. Tetrachloroethylene was not detected at either production well.

The monitoring of the municipal water supply at WS1 and WS4, as well as domestic wells near WS4 consistently revealedtetrachloroethylene in regional groundwater, as well as an increase in the detection of tetrachloroethylene in WS1production wells. However the VOCs previously detected were not consistently found in groundwater samples. Additionally, the recent annual water quality report released by Vancouver for the total municipal water supply confirmedthat concentrations of 1,1-dichloroethylene, 1,1,1-trichloroethane, and chloroform were either not detected or well belowthe MCL.

Since May 21, 1993, WS1 production wells have been pumping groundwater to the air stripping towers for treatment. The treated water is then transferred to the reservoir before distribution to water customers. Vancouver conducts frequent monitoring of tetrachloroethylene in WS1 production wells and reservoir. The monitoring data generated during March 21, 1988 through September 6, 1994 was review for this document. The comparison of tetrachloroethylene concentrations found in production wells and the reservoir before and after air stripping towers were placed on-line to the health comparison value for tetrachloroethylene is presented in Table 1.

Table 1.

Concentration Range for Tetrachloroethylene in On-Site Groundwater
Water Station 1 Concentration Range (µg/L) Comparison Value
µg/L Source
Before Air Stripping Towers Were Placed On-Line
(March 21, 1988 through May 17, 1993)
Well #1 through #10 0.04 - 18.0 0.7 CREG
Reservoir 0.6 - 4.5 0.7 CREG
After Air Stripping Towers Were Placed On-Line
(May 24, 1993 through September 6, 1994)
Well #1 through #10* 0.4 - 30.0 0.7 CREG
Reservoir * 0.4 0.7 CREG

* Tetrachloroethylene not detected or trace level is recorded as 0.4 µg/L.
References - 4, 5, 6, 7

B. Off-Site Contamination

Ground Water - Private Supply Wells

In August and October 1989, groundwater samples were collected from eight private supply wells in the vicinity of WS1and WS3 (Figure 3). Of these wells, three (GW5, GW7, and GW9) were industrial wells and five (GW6, GW8, GW10,GW11, and GW12) were domestic wells. As shown in Table 2, the detected VOCs do not exceed the health comparisonvalues and are not considered contaminants of concern. This study however, is limited as to the number of samples andsample locations to adequately characterize off-site groundwater contamination influencing WS1. Additional off-sitegroundwater monitoring would be necessary to better understand the nature and extent of the groundwater contamination at WS1.

Table 2.

Concentration Range for VOC Contaminants in Off-Site Groundwater
Private Supply Wells Concentration Range (µg/L) Comparison Value
µg/L Source
Industrial and Domestic Wells
Acetone2.0 - 3.0 1000 Child RMEG
Chloroform0.3J - 6.0 6.0 CREG
Chloromethane0.6J 3.0 LTHA
Ethylbenzene2.0 1000 Child RMEG
Tetrachloroethylene 0.3J 0.7 CREG
1,1,1-Trichloroethane0.2J - 4.0J 200 LTHA
Xylenes6.0 2000 Child Inter. EMEG

J - Estimated concentrations: the analyte was analyzed for and positively identified, but the associated numerical value may not be consistent with the amount actually present in the environmental sample.
Reference - 9

C. Quality Assurance and Quality Control

This Preliminary Public Health Assessment relies upon information provided in referenced documents and assumes thatadequate quality assurance and quality control measures were followed regarding chain-of-custody, laboratory procedures,and data reporting. The validity of the analyses and conclusions drawn by this Preliminary Public Health Assessment aredependent on the completeness and reliability of the reference information.

D. Physical and Other Hazards

No physical or other hazards are associated with WS1.


PATHWAYS ANALYSES

To determine whether people are exposed to contaminants associated with WS1, environmental and human componentsof the exposure pathways are evaluated. Pathway analysis consists of five elements: a source of contamination, transportthrough an environmental medium, a point of exposure, a route of exposure, and an exposed population.

Exposure pathways are categorized as completed or potential. Completed exposure pathways contain all five elementsand indicate whether exposure to a contaminant has occurred in the past, is currently occurring, or will be likely occur inthe future. Potential exposure pathways have at least one of the five elements missing, but could possibly exist. Potentialexposure pathways indicate exposure to a contaminant that may have occurred in the past, may be currently occurring,or may occur in the future. An exposure pathway can be eliminated from consideration if at least one of the five elementsis missing and will never be present. The following section discusses exposure pathways relevant to WS1. The completedand potential exposure pathways for WS1 are identified in Table 3.

A. Completed Exposure Pathway

Municipal Water Supply Pathway

Past exposure to contaminated groundwater from the municipal water supply represents a completed exposure pathway. In 1988, tetrachloroethylene was discovered in municipal water supply at WS1. Prior to the operation of the air strippingtowers, water from the WS1 reservoir containing low concentrations of tetrachloroethylene was likely to have beendistributed to water customers. Exposure may have occurred in the past, although the actual duration of exposure isunknown. Since VOC monitoring was not conducted until 1988, it uncertain when the municipal water supply wasimpacted by groundwater contamination and at what contaminant concentrations.

Although past exposure of water customers such as residents, workers, and students to specific tetrachloroethyleneconcentrations is unknown, exposure is anticipated to be lower then concentrations found in the municipal water supplyprior to distribution. Volatilization of tetrachloroethylene from water can occur during storage at WS1 reservoir, as wellas during transfer through the distribution lines to water customers. Water samples need to have been collected at pointsof exposure, such as the drinking water tap to determine concentrations at which people could be exposed to.

Performance tests and monitoring data of the air stripping towers confirm that treatment is effective in removingtetrachloroethylene from water at WS1. Weekly monitoring data from May 24, 1993 through September 6, 1994 showthat tetrachloroethylene concentrations after treatment are consistently below analytic detection limit or not detectable. Therefore, exposure to contaminated groundwater from the municipal water supply is unlikely to be currently occurringor to occur in the future.

Residents, workers, and students may have been exposed to tetrachloroethylene in the past primarily through ingestionof drinking water and inhalation of water vapors. Inhalation exposure can occur as tetrachloroethylene volatilizes fromcontaminated water into indoor air during activities such as showering, bathing, and dish washing. Tetrachloroethylenedoes not readily pass through the skin, therefore dermal contact is not considered a significant route of exposure.

B. Potential Exposure Pathway

Private Supply Well Pathway

Past, present, and future exposure to contaminated groundwater from private supply wells used for industrial and domesticpurposes represent a potential exposure pathway. Eight private supply wells had been identified in the vicinity of WS1and WS3 during the Phase I study. A low tetrachloroethylene concentration of 0.3J µg/L was found in one industrial well(GW9) and tetrachloroethylene was not detected in the domestic wells. The private supply wells have not been resampledsince 1989, therefore current conditions are not known.

Remedial investigations for WS4 indicate widespread tetrachloroethylene contamination in regional groundwater; howeverthe extent and migration is not well defined. In addition, monitoring data from 1988 through 1992 suggest an increasein tetrachloroethylene concentrations in water from WS1 production wells, and more recent data, 1992 through 1994,indicate that these concentrations are remaining steady. Should groundwater contamination migrate and impact existingprivate supply wells, exposure may have occurred in the past, may be presently occurring, or may occur in the future toresidents and workers.

Residents and workers may be exposed to tetrachloroethylene primarily through ingestion of drinking water and inhalationof water vapors. Inhalation exposure can occur as tetrachloroethylene volatilizes into indoor air as a result of activitiessuch as showering, bathing, or dish washing. Dermal contact is not a significant route of exposure for tetrachloroethylene.

Table 3.

Completed and Potential Exposure Pathways
PATHWAY
NAME
EXPOSURE PATHWAY ELEMENTS TIME
SOURCE MEDIA POINT OF EXPOSURE ROUTE OF EXPOSURE EXPOSED POPULATION
Completed Exposure Pathway
Municipal Water Supply Groundwater Groundwater
(WS1)
Residences, Businesses, and Schools (tap) Ingestion and
Inhalation
Users of WS1 Municipal Water Supply Past
Potential Exposure Pathway
Private Supply Wells Groundwater Groundwater
(Residential and Industrial Supply Wells)
Residences and Industries (tap) Ingestion and
Inhalation
Residents and Workers Using Private Supply Wells Past
Present
Future


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Tetrachloroethylene

Past exposure to tetrachloroethylene is likely to have occurred to users of WS1 municipal water supply. Routes ofexposure for tetrachloroethylene are through ingestion of drinking water and inhalation of water vapors during activitiessuch as showering and bathing.

In order to assess health effects resulting from tetrachloroethylene exposure, the daily exposure dose that an individualmay receive is estimated. Since tetrachloroethylene volatilizes readily, the exposure dose through inhalation is assumedto be equivalent to exposure dose through ingestion. The estimated daily exposure dose is compared to health-basedguidelines for the contaminant to evaluate the potential for noncarcinogenic health effects. Noncarcinogenic health-basedguidelines available for tetrachloroethylene exposure include an ATSDR Minimal Risk Level (MRL) and EPA ReferenceDoses (RfD). ATSDR developed an oral MRL for an intermediate exposure duration (15-365 days) of 0.1 milligrams perkilogram of body weight per day (mg/kg/day). EPA derived an oral RfD of 0.01 mg/kg/day for chronic exposure durationof seven years or longer.

Because the actual concentration of tetrachloroethylene that an individual may have been exposed to through the use ofWS1 municipal water supply is not known, assumptions are necessary to calculate the estimate daily exposure. It isassumed that an individual may have been exposed to a concentration as high as the maximum concentration oftetrachloroethylene (4.5 µg/L) observed in water from WS1 reservoir. Using this concentration, the estimated dailyexposure dose calculated for adults and children does not exceed the RfD for chronic exposure or the MRL forintermediate exposure. Therefore, people who use water supplied from WS1 are unlikely to experience adversenoncarcinogenic health effects from short-term or long-term exposure to tetrachloroethylene.

In evaluating carcinogenic health effects, a cancer slope factor is applied with the estimated daily exposure dose for adultsto predict the increased risk of an individual in developing cancer over a lifetime of 70 years. Currently, thecarcinogenicity assessment for tetrachloroethylene is under review by EPA. Studies suggest that tetrachloroethylene cancause kidney and liver cancer in animals; however it has not been shown to cause cancer in humans. A decision as towhether tetrachloroethylene should be classified B2 (as a probable human carcinogen based on evidence from animalstudies and inadequate or not evidence in human, or C (as a possible carcinogen) is pending. The International Agencyfor Research on Cancer classifies tetrachloroethylene as a possible human carcinogen.

The pending EPA cancer slope factor of 0.052 (mg/kg/day)-1 can be used to indicate potential increased cancer risk from tetrachloroethylene exposure. Based upon this cancer slope factor, people exposed to the maximum concentration of tetrachloroethylene in water from the WS1 should experience no increased risk of developing cancer over a lifetime (3, 12).

B. Health Outcome Data Evaluation

The primary health concern expressed by the community is whether exposure to tetrachloroethylene-contaminated drinkingwater will result in cancer. In general, health outcome data can provide information on the health status of the communityliving near a hazardous waste site. In this case, however, state cancer registries do not contain health outcome data forClark County, Washington. Therefore, this community concern cannot be addressed through an evaluation of healthoutcome data.

C. Community Health Concerns Evaluation

Addressed below is the community concern regarding health for WS1.

1. What is the risk of cancer from drinking water contaminated with tetrachloroethylene?

Exposure to low concentrations of tetrachloroethylene in drinking water may have occurred in the past to individuals whoused WS1 municipal water supply. Tetrachloroethylene had been evaluated by EPA for evidence of humancarcinogenicity in 1987. EPA classified tetrachloroethylene on a continuum between B2 (a probable human carcinogenbased on sufficient evidence in animals and inadequate or no evidence in humans) and C (possible human carcinogen);and a cancer slope factor of 0.052 (mg/kg/day)-1 was derived. Studies indicate that tetrachloroethylene can cause liverand kidney cancer in animals, yet it has not been shown to cause cancer in humans. At this time however, the decisionis under review by EPA and the cancer slope factor has been withdrawn (3, 12). Unfortunately, without additionalcarcinogenic data on tetrachloroethylene the risk of cancer from drinking contaminated water cannot be predicted.

Should EPA decide that the pending cancer slope factor for tetrachloroethylene is valid, residents and workers exposedto the maximum concentration of tetrachloroethylene (4.5 µg/L) observed in water at the WS1 reservoir would experienceno increased risk of developing cancer over a lifetime of 70 years.


CONCLUSIONS

WS1 poses no apparent public health hazard. Groundwater treatment has eliminated the possibility of current and futureexposure to tetrachloroethylene to water customers such as residents, workers, and students, who use water provided byWS1 municipal water supply. Past exposure to tetrachloroethylene may have occurred, however concentrations areanticipated to have been minimal and unlikely to cause adverse noncarcinogenic or carcinogenic health effects.

It is uncertain whether exposure to tetrachloroethylene had occurred in the past, is presently occurring, or will occur inthe future to residents and workers who use water provided through private supply wells. Existing data is insufficient toadequately characterize groundwater contamination, and private supply well surveys are too limited to conclusivelyidentify all nearby private supply wells. To determine whether private supply wells are at risk from groundwatercontamination associated with WS1, it is necessary to further characterize groundwater contamination as well as to identifyall nearby private supply wells. Should private supply wells be identified at risk, periodic monitoring of these wells shouldbe conducted to be able to assess exposure to tetrachloroethylene and/or other hazardous substances and to predict associated health risks.


RECOMMENDATIONS

Site Characterization Recommendations:

  1. Further characterize the extent and migration of groundwater contamination associated with WS1.

  2. Conduct a comprehensive private supply well survey within 1-mile radius of WS1.

Cease/Reduce Exposure Recommendations:

  1. Private supply wells (residential and industrial) considered to be at risk from groundwater contamination shouldbe periodically monitored to determine whether exposure to tetrachloroethylene and/or other hazardoussubstances is occurring at levels of health concern. Groundwater monitoring data from these private supply wells should be shared with WDOH and ATSDR for review of public health implications.

  2. Inform private supply wells owners within the vicinity of groundwater contamination of the potential for exposure to contaminated groundwater.

  3. Analyze groundwater from any private supply wells that may be installed in the future within the vicinity of groundwater contamination prior to residential and industrial use.

Health Activities Recommendation Panel Recommendations:

The data and information developed in the WS1 preliminary public health assessment have been evaluated by the ATSDRHealth Activities Recommendation Panel (HARP) for follow-up health actions. No actions are recommended at this time. If data become available suggesting that human exposure to hazardous substances at levels of public health concern isoccurring, WDOH and ATSDR will re-evaluate the site for any indicated follow-up health actions.


PUBLIC HEALTH ACTIONS

The Public Health Action (PHAP) for WS1 identifies actions to be taken by ATSDR and/or WDOH subsequent to thecompletion of this preliminary public health assessment. The purpose of the PHAP is to ensure that this public healthassessment not only identifies public health hazards, but provides a plan of action designed to mitigate and prevent adversehuman health effects resulting from exposure to hazardous substances in the environment. ATSDR, in cooperation withWDOH, has developed the following public health actions based upon recommendations from the WS1 preliminary public health assessment and HARP.

  1. As additional environmental data becomes available, ATSDR and WDOH will re-evaluate the WS1 for necessary follow-up health activities using current environmental data.

  2. ATSDR and WDOH will re-evaluate and may expand the PHAP if additional community health concerns information becomes available. This PHAP will be evaluated annually unless information warrants more frequent evaluation.

PREPARERS OF REPORT

Preparer of Report:

Anne Duffy
Public Health Advisor
Hazardous Waste Section
Washington State Department of Health

Frank Westrum, R.S., M.S., M.P.H.
Supervisor
Hazardous Waste Section
Washington State Department of Health

John Grendon, DVM
Epidemiologist
Hazardous Waste Section
Washington State Department of Health

ATSDR Regional Representative:

Gregory D. Thomas
Senior Regional Representative
Office of the Assistant, Administrator, ATSDR

ATSDR Technical Project Officer:

Richard Kauffman
Toxicologist
Remedial Programs Branch, State Programs Section
Division of Health Assessment and Consultation


CERTIFICATION

This Vancouver Water Station No. 1 Contamination Public Health Assessment was prepared by the WashingtonDepartment of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry(ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessmentwas begun.

Richard R. Kauffman, M.S.
Technical Project Officer
Superfund Site Assessment Branch
Division of Health Assessment and Consultation (DHAC)
ATSDR


The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment, and concurs with its findings.

Robert C. Williams, P.E., DEE
Director, DHAC, ATSDR


REFERENCES

  1. ATSDR. 1992. ATSDR Record of Activity - Vancouver Water Station No. 4 Health Consultation, Document No. 3153. US Department of Health and Human Services, Public Health Services, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia.

  2. ATSDR. 1990 (Draft). Toxicological Profile for Tetrachloroethylene. US Department of Health and Human Services, Public Health Services, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia.

  3. ATSDR. 1992 (Draft). Update Toxicological Profile for Tetrachloroethylene. US Department of Health and Human Services, Public Health Services, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia.

  4. City of Vancouver, Washington. April 1992. Water Station #1 PCE Concentrations - 3/21/88 through 4/20/92. City of Vancouver, Department of Public Works, Vancouver, Washington.

  5. City of Vancouver, Washington. June 1994. Water Station #1 PCE Concentrations - 3/30/92 through 5/31/94. City of Vancouver, Department of Public Works, Vancouver, Washington.

  6. EPA. (Received by) October 1994. Water Station #1 PCE Concentrations - 1/4/93 through 9/6/94. City of Vancouver, Department of Public Works, Vancouver, Washington.

  7. City of Vancouver, Washington. November 1992. Water Station #1 PCE Concentrations Reservoir - 1/7/92 through 9/28/92. City of Vancouver, Department of Public Works, Vancouver, Washington.

  8. City of Vancouver, Washington. April 1989. Blandford Water Station Remedial Action Plan. City of Vancouver, Department of Public Works, Vancouver, Washington.

  9. Ecology and Environment, Inc. under EPA Contract. April 1990. Vancouver Well Field Special Study, Vancouver, Washington. (Well Field 1 and 3) Prepared for EPA Region 10, Seattle, Washington.

  10. Ecology and Environment, Inc. under EPA Contract. February 1990. Volatile Organic Compounds Screening Results, Vancouver Soil Gas Study, Vancouver, Washington. Prepared for EPA Region 10, Seattle, Washington.

  11. Ecology and Environment, Inc. under EPA Contract. October 1991. Vancouver Well Field Study - Phase II, Vancouver, Washington. (Well Field 1) Prepared for EPA Region 10, Seattle, Washington.

  12. TOMES-PLUS electronic data system. Volume 22 Expires 10/31/94. Integrated Risk Information System (IRIS).

  13. US Department of the Interior, Geological Survey. 1990. Quality of Water in Clark County, Washington, 1988. Prepared in cooperation with the Intergovernmental Resource Center of Clark County.

  14. Washington Department of Health. January 1989. Health Consult Regarding The Presence of Unregulated VOCs in Three of the City of Vancouver's Well Fields. Washington Department of Health, Office of Toxic Substances, Olympia, Washington.

APPENDIX

Vancouver Water Station No. 1 Location Map
Figure 1. Vancouver Water Station No. 1 Location Map

Vancouver Water Station No. 1 Vicinity Map
Figure 2. Vancouver Water Station No. 1 Vicinity Map

Groundwater Sample Location Map
Figure 3. Groundwater Sample Location Map



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