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This section lists the contaminants of concern. These contaminants are evaluated in thesubsequent sections of the Public Health Assessment to determine if exposure to them has publichealth significance. ATSDR selects and discusses these contaminants based upon the followingfactors:

  1. Concentrations of contaminants on and off the site.

  2. Field data quality, laboratory data quality, and sample design.

  3. Comparison of on-site and off-site concentrations with background concentrations, if available.

  4. Comparison of on-site and off-site concentrations with health assessment comparison valuesfor (1) noncarcinogenic endpoints and (2) carcinogenic endpoints.

  5. Community health concerns.

In the data tables that follow under the On-site Contamination subsection and the Off-siteContamination subsection, the listed contaminant does not mean that it will cause adverse healtheffects from exposures. Instead, the list indicates which contaminants will be evaluated furtherin the Public Health Assessment. When selected as a contaminant of concern in one medium,that contaminant will be reported in all media.

Contaminant concentrations detected on-and off-site are compared to values that are believed tobe without adverse health effects upon exposure. Those values are developed by health andregulatory agencies to provide estimates of levels below which health effects would not beobserved. Those values, in many cases, have been derived from animal studies. Health effectsare related not only to the exposure dose, but to the route of entry into the body and the amountof chemical absorbed by the body. For those reasons, comparison values used in public healthassessments are contaminant concentrations in specific media and for specific exposure routes. Several comparison values may be available for a specific contaminant. ATSDR generallyselects conservative exposure assumptions in order to protect the most sensitive segment of thepopulation. The potential for adverse health effects from exposure to contaminants will bediscussed in the Toxicological Evaluation section of this document.

Clark County

There are seven NPL sites in Clark County. The sites are: BPA Ross, Frontier Hard Chrome,Water Station 4, Water Station 1, Alcoa Smelter, Tofdahl Drums, and Boomsnub/Airco. TheNPL site closest to Boomsnub/Airco is Bonneville Power Administration's (BPA) Ross Complexwhich is about two miles to the southwest. The BPA Ross Complex is an active powerdistribution facility that coordinates the distribution of hydroelectric power to areas throughoutthe Pacific Northwest. During the course of past operation at the Ross Complex heavy metalsand organic compounds were disposed of into trenches and storm drains.

A search was made of the Toxic Chemical Release Inventory (TRI) database to determine if anyother industrial facilities in the same zip code as the Boomsnub/Airco site have contributed toarea contamination. The information contained in TRI is submitted to EPA by facilities thatrelease hazardous materials to the environment. During the years reported, spills of chromiumoccur on the average about every three to four months. Table 1 lists the spills.

Table 1.

YearNo. of SpillsNo. of FirmsNo. of chromiumspills

A. On-Site Contamination


In 1994, Ecology's contractor estimated that prior to 1978 in excess of ten tons of chromiumwere discharged to the soil at Boomsnub (22). On March 18, 1994, Ecology took groundwatersamples from on-site monitor well MW11A. The unfiltered sample contained 120 ppm totalchromium (3). In June 1994, the total chromium level in MW11A was 2,400 ppm. That is thehighest concentration of total chromium in groundwater ever detected at Boomsnub (24). DuringApril 1994, EPA found extremely high levels of chromium in Boomsnub's buildings and soil. EPA found that Boomsnub's plant was in a deteriorated condition with pitted, stained floorscontaining yellow plating solution, corroded equipment and chromic acid present in many places(2).

Several plating tanks were located directly over a large sump, called the containment vault,which collected rinse water and spilled plating solutions. During 1994, EPA sampled for totalchromium sludge from the containment vault and some concrete debris outside of the vault'ssteel lining. EPA found the highest levels of chromium in soils directly under the containmentvault (2). Sludge from the containment vault contained 445,000 ppm total chromium. The outerconcrete wall debris contained 152,000 ppm chromium (3).

Following these findings EPA took soil borings under and around Boomsnub's building. Thesoil samples taken from under and around the western end of the containment vault and buildingcommonly exceeded 2,000 ppm of chromium and were as high as 9,270 ppm at depths of 28 feetbelow ground surface where groundwater was encountered. Soil samples taken from borings 30to 50 feet from the western end of the containment vault contained about 100 ppm chromium (3). During the removal action EPA's cleanup goal is to reduce soil contamination levels to 100 ppmchromium (11). The background levels of chromium in the area soils are between 10 and 25ppm (19).

In December 1989, a water line break at Boomsnub released over 300,000 gallons of water. Thewater flushed chromium from site soil into the groundwater. An on-site monitor well, MW-4B,which is downgradient, had 0.17 ppm chromium in October 1989. In January 1990, after thewater line break the level of chromium in that well jumped to 749 ppm.

Volatile Organic Compounds (VOCs)

In 1990, VOCs were detected in the monitor wells at Boomsnub. Ecology identified AircoGases, a plant adjacent to Boomsnub, as a source of the VOCs (4). The VOCs detected ingroundwater include trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), tetrachloroethylene(PCE), trichlorofluoromethane (Freon 11), 1,1-dichloroethene (DCE), carbon tetrachloride, andacetone (6). On September 11, 1992, the five VOCs detected in groundwater samples collected from Aircomonitor wells were present at concentrations exceeding Washington State cleanup standards orEPA drinking water standards. Compounds exceeding Washington State cleanup standardsinclude TCE, TCA, and PCE. Compounds exceeding EPA drinking water standards includeDCE and carbon tetrachloride (6).

On the western portion of the Airco property there are two dry wells which collect storm waterand plant condenser water. The VOCs detected at the highest concentrations in the south drywell sediment are TCE at 250,000 ppm and Freon 11 at over 800,000 ppm (22).

B. Off-Site Contamination

The plume of contamination has migrated over 3,000 feet. The plume is in the unconfinedalluvial aquifer which overlies the confined Troutdale aquifer. A clay and silt aquitard separatesthe two aquifers, but there are known breaks in the aquitard.

Chromium has not been detected in the Upper Troutdale. Low concentrations of TCE (less than0.011 ppm) were detected in several Upper Troutdale wells located west-southwest of the site(29).

The first off-site downgradient monitor well, MW5A was installed in November 1989. Watersamples from that well in 1989 found total and hexavalent chromium at 4.08 and 2.86 ppm (18). Thus far, more than fifty monitor wells have been installed. On March 18, 1994, Ecologycollected unfiltered groundwater samples from the off-site monitor wells. The total chromiumfound in these samples ranged from 0.12 to 52 ppm (3). By May 1994, the chromium plumereached over 3,300 feet west of Boomsnub. That is the direction of groundwater flow in theunconfined alluvial aquifer (3).

Chromium was discovered in five private wells near Boomsnub. During 1991, the chromium inprivate wells ranged from 0.0112 ppm to 0.292 ppm. In 1993, the well with 0.292 ppm wastested at 0.030 ppm. Another private well over 3,000 feet from the Boomsnub plating facilityhas had chromium levels of 0.014 ppm. These private wells have been closed and the residenceshave been connected to the available municipal water supplies. On July 20, 1994, theWashington State Department of Health issued a news release which recommended that peoplein the area of the site who used private wells should connect to available public water supply.

Late in 1990, Ecology found volatile organic compounds (VOCs) commingled in the chromiumplume in on-site monitor wells. The VOCs found included: trichloroethylene (TCE),1,1,1-trichloroethane (TCA), tetrachloroethane (PCE), and trichlorofluoromethane (Freon 11)(6). During March 1993, an air stripper and an activated carbon unit were added to thegroundwaterextraction system to remove VOCs. TCE has been detected in one off-site privatewell. The level of TCE has ranged from 0.001 to 0.0029 ppm. That private well is completed inthe upper Troutdale aquifer (29).

C. Quality Assurance and Quality Control

In preparing this Public Health Assessment, The Washington State Department of Health relieson the information provided in the referenced documents and assumes that adequate qualityassurance and quality control measures were followed with regard to appropriateness of testingprocedures, chain-of-custody, laboratory procedures, and data reporting. The validity of theanalyses and the conclusions drawn for this Public Health Assessment is determined by theavailability and reliability of the referenced information.

D. Physical and Other Hazards

The site physical hazards are typical of heavy industry. Both Boomsnub and Airco are fencedfacilities, not easily accessible to the public.


This section will focus on the migration of contaminants and how human exposure may occur.To determine if human populations are exposed to contaminants migrating from the site, ATSDRand WDOH evaluate the environmental and human activities that lead to human exposure. Thispathway analysis consists of five elements:

  1. A source of contamination
  2. Environmental media and transport mechanisms
  3. Point of exposure
  4. Route of exposure
  5. Receptor population

ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if theexposure pathway cannot be eliminated. Completed pathways have all five elements andindicate that exposure to a contaminant has occurred in the past, could be occurring now, orcould occur in the future (Table 2). Potential pathways, however, have at least one of the fiveelements missing. Potential pathways indicate the exposure to a contaminant could haveoccurred in the past, could be occurring now, or could occur in the future (Table 2). An exposurepathway can be eliminated if at least one of the five elements is missing and will never bepresent.

A. Completed Exposure Pathways

Boomsnub's Workers

In the past, Boomsnub represented a health hazard to on-site workers exposed to chromium. Thehealth assessors believe that these workers came in contact with heavily contaminated soils andchromic product which may cause adverse health effects by incidentally ingestion, inhalation ofdust or vapor, and/or dermal exposed. High levels of chromium contamination were found insludges, debris, and soils on-site. Analyses of surface concrete debris and sludges found near theplating building, which has been removed, detected 152,000 ppm and 445,000 ppm chromium,respectively. Subsoil on-site contained as much as 9,270 ppm at 28 feet below ground surfacewhere groundwater was encountered. EPA has removed the plating building and is nowremoving contaminated soil.

Boomsnub claimed to have a work force of thirty employees. This would be the maximumnumber of persons exposed through this pathway. Probably no more than three employeesworked at a time in the plating operation where the highest level of exposure may have occurred. Also, when EPA began the removal action at Boomsnub they observed employees working insituations of exposure to chromium which EPA considered not safe. No test data pertaining toemployee exposure to chromium or adverse health consequences were found.

Private Wells

Chromium was detected in five private wells near Boomsnub. The level of chromium rangedfrom 0.0112 parts per million (ppm) to 0.292 ppm. Monitoring of the private well withchromium at a level of 0.292 ppm in 1991 revealed the level had dropped to 0.03 ppm inDecember 1993. One private well over 3,000 feet downgradient from Boomsnub had chromiumlevels of 0.014 ppm. Since 1991, six houses have been hooked up to city or county water. Because Boomsnub has lost chromium to the environment since 1968 people may have beenexposed for 27 years. The total number of people with water wells in groundwater contaminatedby this site is unknown.

B. Potential Exposure Pathways

Municipal Wells

The primary supply of potable water for the Vancouver area is the Troutdale aquifer which isabout 150 feet below ground surface. The plume of contamination is in the unconfined alluvialaquifer which overlies the confined Troutdale aquifer. A clay and silt aquitard separates the twoaquifers, but there are known breaks in the aquitard. Clark County and Vancouver take waterfrom a well field which is about one mile southwest and downgradient of the site. The rate offlow in the Troutdale ranges from 15 to 200 feet per day. By May 1994, the 2.0 ppm edge of thechromium plume in the surface aquifer was over 3,300 feet west of Boomsnub. The municipalwells at risk provide water to more than 50,000 people. Thus far neither chromium or VOCshave been detected in the at risk municipal wells.

Table 2.

Completed and Potential Exposure Pathways
PathwayNameExposure Pathway ElementsTime
SourceMediaPoint ofExposureRoute of ExposureExposed
BoomsnubWorkersBoomsnubSoil & AirBoomsnubingestion inhalation
Boomsnub Workers
# = 30
PrivateWells BoomsnubAircoGroundwater tap wateringestion inhalationPeople on private wells inshallow aquifer
# = unknown
Past Present Future
MunicipalWellsBoomsnubAirco Groundwater tap wateringestion
50,000 in Vancouver and ClarkCountyFuture


A. Toxicological Evaluation

The Public Health Implications section discusses the potential health effects resulting fromexposure to contaminants of concern associated with the completed exposure pathway. To assesshealth effects that could result from exposure to site contaminants, daily exposure doses whichan individual may receive are estimated. The estimated daily exposure dose is compared to ahealth-based guideline which defines a level of exposure at which adverse health effects areunlikely to occur. ATSDR has developed Minimal Risk Levels (MRLs), health-based guidelinesused to evaluate noncarcinogenic adverse health effects for routes of exposure such as ingestionand inhalation, and for exposure durations including acute (less than 14 days), intermediate (15days to 364 days), and chronic (greater than 365 days). When MRLs are not available, EPAhealth-based guidelines are used. EPA has developed reference doses (RfDs) and referenceconcentrations (RfCs) for ingestion and inhalation exposure, respectively.

Where estimated daily exposure doses exceed MRLs or RfDs, we further compare with valuescalled No Observed Adverse Effect Level (NOAEL) and Lowest Observed Adverse Effect Level(LOAEL). Data from human studies are used preferentially, but animal studies can be used toindicate possible human health effects. It should be noted that there are uncertainties when usingthese estimated doses and NOAELs, and in some cases the exposure may be above or below by asmall margin. That small difference may or may not be protective for sensitive individuals orpopulations.

The assumptions used in calculating the estimated daily exposure dose from exposure to surfacesoil contaminants include an adult body weight of 70 kilograms (kg) and soil ingestion rate of 50milligrams (mg) per day, and a child body weight of 16 kg and soil ingestion rate of 100 mg perday. Exposure for an adult worker was assumed to be five days per week for 20 years. Wateringestion rates are assumed to be 2L/day for adults and 1L/day for children.

EPA has reviewed available data from human and animal studies to determine the carcinogenicpotential of specific chemicals. For many carcinogens, EPA has derived cancer slope factors orunit risks for oral and inhalation exposure routes. In evaluating carcinogenic health effects,cancer slope factors or unit risks are used with the estimated daily exposure dose to predict theincreased risk of developing cancer over a lifetime of exposure (70 years). Normally, as high as300,000 people out of 1,000,000 develop cancer over their lifetime; in this section cancer risk isrelated as anticipated increase above this rate. Rates of cancer risk are qualitatively expressed inTable 3.

Table 3.

Qualitative Cancer Risk
Qualitative Cancer Risk1 to 9 excess cancers per
no increased risk1,000,000
no apparent increased risk100,000
low increased risk10,000
moderate increased risk1,000
high increased risk100
very high increased risk10


Analytical results indicate that most chromium in groundwater at this site occurs in hexavalent(Chromium VI) form (29). Discussions related to drinking water health effects will assume thatall exposure occurs to hexavalent chromium. Chromium is a naturally occurring element foundin rocks, animals, plants, soil, and in volcanic dust and gases. The most common forms ofchromium are chromium (0), chromium (III) or trivalent, and chromium (VI). Chromium (III)occurs naturally, but Chromium (0) and Chromium (VI) are generally produced by industrialprocesses. No taste or odor is associated with chromium compounds (10).

In general, you can be exposed to chromium by breathing air, drinking water, or eating foodcontaining chromium, or through skin contact with chromium or chromium compounds. In air,chromium compounds are present mostly as fine dust particles. This dust eventually settles overland and water. Rain and snow help remove chromium from air. Chromium compounds willusually remain in the air for less than 10 days. Chromium VI is classified by EPA as acarcinogen when exposure is through inhalation. Long-term exposure to chromium has beenassociated with lung cancer in workers exposed to levels in air that were 100 to 1,000 timeshigher than those found in the natural environment. Lung cancer may occur long after exposureto chromium has ended (10).

In studies, workers handling liquids or solids that have Chromium (VI) in them have developedskin ulcers. Because some Chromium (VI) compounds have been associated with lung cancer inworkers and caused cancer in animals, the Department of Health and Human Services hasdetermined that certain Chromium (VI) compounds (calcium chromate, chromium trioxide, leadchromate, sodium dichromate, strontium chromate, and zinc chromate) are known carcinogens.The International Agency for Research on Cancer (IARC) has determined that Chromium (VI) iscarcinogenic to humans, based on sufficient evidence in humans for the carcinogenicity ofChromium (VI) compounds as found in chromate production, chromate pigment production andchromium plating industries. IARC has also determined that Chromium (0) and Chromium (III)compounds are not classifiable as to their carcinogenicity to humans (10). However, therepresently is no cancer slope factor available, which is a necessary mathematical figure to estimatethe possible excess risk of cancer.

Table 4.

EPA's Chromium Health Advisory for Drinking Water
One day10 kg (22 lb.)childOne liter1.4
Ten days10 kg (22 lb.)childOne liter1.4
*Long-term10 kg (22 lb.)childOne liter0.24
Long-term70 kg (155 lb.)adultTwo liters0.84

(Adapted from Refs. 10 & 12) # = Chromium (III) and Chromium (VI) * = 7 years. One liter isabout one quart.

The authors estimated "worst case scenario" exposure doses for adult and children residentsusing off-site groundwater wells. During the years 1990 and 1991, and possibly prior to thoseyears, when concentrations were as high as 0.292 ppm, estimates are that adult doses were at, orslightly higher than, the EPA established RfD. Estimated doses for children during the sameperiod were substantially higher than the RfD. After 1991, when the chromium concentrationswere found to be at 0.03 ppm, the estimated doses for both adult and child were less than theRfD. During the years when the dose is estimated to be above the RfD, the levels of exposurewere still below oral NOAEL's and LOAELs. Therefore, we would not expect to see adversehuman health effects from estimated groundwater exposure.

Without factual data for concentrations and specific knowledge of plating operations, it was notpossible for authors to estimate exposure doses for people who worked in the facility. However,from information gained during the site visit, it appears that some workers could have beenexposed to acute levels of contaminants through dermal contact and incidental ingestion.The information on site workers leads to no conclusions.

B. Health Outcome Data Evaluation

Lung cancer was determined to be the only possible health outcome associated with chromiumexposure as a result of the completed pathway. The 1992 age-adjusted lung cancer incidence ratefor Clark county (48.6 cases per 100,000 residents) was lower than the 1992 rate of thecomparison population, all Washington residents (58.1 cases per 100,000 residents). Thiscomparison does not indicate an excess of lung cancer for residents of Clark County as a whole,when compared to the state lung cancer rate; however, the use of county-wide lung cancer datamay not detect an excess of lung cancer in a smaller population such as residents living near thesite or the worker population. In addition, the 1992 Washington State Cancer Registry data mayrepresent an under count of cases because case ascertainment from some participating hospitals isnot complete.

No specific health outcome data is available for the residential population living near the site orfor the worker population.

The findings of the cancer cluster investigation included: the Clark County county-widechildhood cancer incidence rate is higher than expected for the period of 1980-1985, and thecancer incidence is primarily increased in persons aged 10-14 years for non-Hodgkin'slymphoma. Although the contaminant at this site (chromium) has no known relation to thenon-Hodgkin's lymphoma, the cancer cluster investigation results were included because it wasavailable health outcome data for Clark County.

C. Community Health Concerns Evaluations

In a news release of July 20, 1994, the Washington State Department of Health, in cooperationwith the Southwest Washington Health District, the Department of Ecology, the City ofVancouver, Clark Public Utilities and the EPA, advised residents using private drinking waterwells in the Boomsnub/Airco area to connect to a public water supply. Although most privatewells are not affected at this time, the recommendation is made to ensure a continuing safe watersupply, as some wells may be subject to future problems as the contamination migrates (28).

The public was officially invited to review and comment on this draft health assessment duringthe period of May 1, 1995 through June 1, 1995. The document was made available at the FortVancouver Regional Library in Vancouver. A news release was sent to the Vancouvernewspaper which published an article about the assessment. A fact sheet was prepared and sentto over two hundred parties on EPA's mailing list. No comments were received from the publicon the health assessment.

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