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A. Introduction

This section presents the contaminants of concern in each environmental medium. Surface soils,subsurface soils, surface water, sediments, air, and groundwater have been tested for a largenumber of chemical contaminants. The following sections will address whether individuals havebeen exposed or could be exposed to the contaminants of concern and whether those exposuresare of public health significance. Those contaminants most likely to pose a health threat areevaluated further in the Public Health Implications section of this public health assessment.

ATSDR selects and discusses contaminants of concern using criteria such as the following:concentrations and locations of contaminants on site and off site, field data quality, laboratorydata quality, frequency of detection, and comparison of concentrations of contaminants tocomparison values for cancerous and noncancerous health effects.

Comparison values for ATSDR public health assessments are contaminant concentrations inspecific media that are used to determine which contaminants exist at levels of contaminationthat could potentially cause adverse human health effects. Standard body weights and dailyingestion rates for both adults and children are assumed for deriving these values.

ATSDR and other agencies have developed comparison values to provide guidelines foridentifying levels of contaminants in environmental media that might pose public health hazards. These values include Cancer Risk Evaluation Guidelines (CREGs), Environmental MediaEvaluation Guidelines (EMEGs), EPA's Reference Doses (RfDs), Reference Concentrations(RfCs), and Lifetime Health Advisories (LTHAs). ATSDR derives CREGs from EPA's cancerslope factor, which allows for no more than one excess cancer in a million persons exposed overa lifetime (70 years). EMEGs are concentrations in water, air, or soil at which daily humanexposure is unlikely to cause adverse noncancerous effects. EMEGs are calculated from ATSDRMinimal Risk Levels (MRLs). Both MRLs and RfDs are estimates of the daily exposure tocontaminants that are unlikely to cause adverse noncarcinogenic health effects over a lifetime. EPA LTHAs are drinking water concentrations at which adverse noncancerous health effects arenot expected to occur. EPA also has Maximum Contaminant Levels (MCLs), which areenforceable drinking water regulations and are protective of human health to the "extent feasible"over a lifetime.

ATSDR searched the Toxic Chemical Release Inventory (TRI) database to determine whetherany other industrial facilities in the Vancouver area have contributed to any of the contamination,particularly groundwater, found near the Ross Complex. Facilities that release hazardousmaterials to the environment submit the information for the database to EPA to comply withSection 313 of the Emergency Planning and Community Right-To-Know Act of 1986. Theresults of the TRI search identified approximately 20 facilities in the Vancouver area that havehad releases of manganese, nickel, chloroform, chromium, and 1,1,1-TCA from the years 1987 to1990 (10).

In addition to the facilities identified in the TRI, the Remedial Investigation (RI) for OperableUnit B (OUB) identified industrial facilities upgradient of the Ross Complex that have releasedor might have released hazardous wastes. The facilities are located in an industrial andcommercial area within 2 miles northeast of the complex. The facilities include an ARCOService Station, the Colf Landscaping firm, an AIRCO Industrial Gas facility, and BoomsnubPacific Northwest Plating. Contaminants identified in environmental media surrounding thesefirms include metals, pesticides, chlorinated and nonchlorinated solvents, petroleum products,and other organic compounds (3). EPA has begun a removal action at the Boomsnub facility toprevent further contamination of the groundwater.

The presence of a listed contaminant in the data tables that follow does not necessarily indicatethat exposure to the contaminant will cause adverse health effects. Contaminants might not bepresent in the environmental media in sufficiently high concentrations to cause adverse healtheffects. Instead, the listing in the tables indicates which contaminants will be evaluated further inthe public health assessment.

B. On-Site Contamination

The RIs conducted at the Ross Complex identified 21 potentially contaminated areas on site. During the RIs, surface soil, subsurface soil, sediment, surface water, and groundwater wereanalyzed for metals, VOCs, semivolatile organic compounds, PCBs, and pesticides. Groundwater samples were also analyzed for total and dissolved (filtered) metals. Air samplingwas limited to PCB analysis. Limited environmental data were collected on site before the RIs. The RIs contained summaries of that data. Sediment and surface water samples, although takenon site in the creeks, will be addressed in the Off-Site Contamination section because workerswould not be expected to come in contact with the creeks during normal work activities.

Surface Soil

The RI for OUA characterized surface (less than or equal to 3 inches in depth) soil contaminationon site. Surface soils at all seven waste units were extensively sampled. Table 3 presents thecontaminants of concern in on-site surface soils and their respective concentrations. Concentrations of PCBs, PAHs, pentachlorophenol, and lead above their comparison values werefound in specific areas throughout the site. The contamination was in hot-spot areas near specificbuildings or areas of operation rather than in large-scale horizontal or vertical migration patterns.

In July 1986, a maximum concentration of PCBs at 1,640 mg/kg (milligrams of PCBs perkilogram of soil) was identified in surface soil samples collected from the Capacitor TestingLaboratory (6). Two removal actions were performed before the RI. In surface soil samplestaken during the RI, PCB concentrations ranging from 0.16 mg/kg to 38.9 mg/kg were identified. The maximum PCB concentration detected was located south of a previous soil removal area (6).

Previous investigations showed that the Utilization and Disposal Yard (U&D Yard) containedPCBs, including a maximum concentration of 85.3 mg/kg (4). During the RI, PCBs were alsofound in surface soils in the U&D Yard. Sampling performed during the RI found traceconcentrations of PCBs below comparison values.

Previous investigations also identified high concentrations of PCBs in the Ross Substation &Capacitor Yard (RS&CY). In 1989, maximum concentrations of PCBs were found at 225 mg/kg(4). During the RI, soil samples were collected from the RS&CY, and a maximum total PCB concentration of 368 mg/kg was detected (4).

Surface soils were tested for up to 15 PAH compounds. Table 3 presents the range of the total PAHs reported from different sampling locations. The Wood Pole Storage East area containedthe highest total PAH concentration, approximately 505 mg/kg. The primary PAH identified inthis sample was fluoranthene, at an estimated concentration of 350 mg/kg. However, thecarcinogenic portion of the sample was 112 mg/kg. Benzo(a)pyrene is included in the tablebecause this PAH is the carcinogenic component of greatest health concern.

The Wood Pole Storage East area is also the site of the maximum pentachlorophenolconcentration measured on site. Previous investigations before the RI identified a maximumconcentration of 405 mg/kg (4). During the RI, the maximum pentachlorophenol concentration in this area was detected at 62 mg/kg (4).

Lead was detected in areas across the site. The RS&CY had a maximum lead concentration of2,360 mg/kg; the Sandblasting Area, 2,250 mg/kg; and the Top Coat Test Area, 3,000 mg/kglead.

Seven areas on site were cleaned up in the summer of 1992. Eleven areas did not requirecleanup. The Ross Substation & Capacitor Yard and Wood Pole Storage East areas remaincontaminated.

Table 3.

On-Site Surface Soil Concentrations
ContaminantConcentration Range
1986 - 19881991
RI results
Lead1.6 - 3,0008.15 - 2,360B2 Carcinogen
Total PAHs7.35 - 138.61.66 - 505B2 Carcinogen
Benzo(a)pyrene0.7 - 13.20.002 - 240.12 CREG
Pentachlorophenol199 - 4050.002 - 625.8CREG
Total PCBs0.01 - 1,640
* 47,000
0.13 - 3680.09CREG

mg/kg = milligrams per kilogram
B2 Carcinogen = EPA's classification for probable human carcinogen
CREG = Cancer Risk Evaluation Guide
EMEG = Environmental Media Evaluation Guide
* = Concentration found in concrete


The maximum concentration of PCBs found on site was in the Capacitor Testing Laboratory. Concrete samples were taken from the floor of the Capacitor Laboratory in 1986, and the totalPCB concentration ranged from 30.5 mg/kg to 47,000 mg/kg. The building is currently beingused for storage purposes.

Subsurface Soils

Three areas on site were identified as having subsurface soil (greater than 3 inches in depth)contamination. These areas include the Fog Chamber Dump Trench 1 and Fog Chamber DumpTrench 2 (designated as FCDT1 and FCDT2, respectively), and the Cold Creek Fill Area. ColdCreek Fill Area soils were analyzed only for VOCs and PCBs.

Concentrations of PCBs, specifically Aroclors 1254, 1242, and 1260, were detected in theFCDT1 to the maximum depth sampled at 25 feet. The maximum concentration of PCBs(primarily Aroclor 1254) was 30,000 mg/kg, detected at a depth of 8 feet. Lead was found at 1.5feet below the surface at a maximum concentration of 16,700 mg/kg. VOCs were not detected inany of the soil boring samples. Carbazole and dibenzofuran, both base neutral acids (BNAs),were detected at maximum concentrations of 0.45 mg/kg (milligrams per kilogram of soil) and0.036 mg/kg, respectively.

Various organic compounds were found in FCDT2 subsurface soils between 1.5 feet and 11 feet,but all were found at levels less than health-based soil comparison values. A maximum leadconcentration of 10,200 mg/kg was detected in FCDT2 at 3.5 feet.

The Cold Creek Fill Area, a former landfill, has been used since 1960 to dispose of site-relateddebris and soils. Ninety-four subsurface soil samples were collected from five soil borings. PCBs were detected in this area between 5 and 10 feet at concentrations ranging from 0.12 mg/kgto 6.4 mg/kg. 1,1,1-TCA was the only VOC detected, and the concentration was estimated to be0.015 mg/kg at a depth of 70 feet.

The paint shop area had VOC contamination in the subsurface soils. A maximum total VOCconcentration of 6,413 mg/kg was detected at 3.5 feet in this area.


During the RI, groundwater samples from both the shallow and deep (Troutdale) aquifers werecollected from 32 monitoring wells throughout the site, including the Dittmer well. BPA hascontinued to collect groundwater samples quarterly. Samples are analyzed for EPA's TargetAnalyte List (TAL). Metal concentrations are presented in total (unfiltered) and dissolvedconcentrations. Dissolved metal concentrations are obtained from water samples that have hadsuspended particulates and sediments filtered out. Table 4 lists the contaminants of concern ingroundwater with their respective concentrations. Figure 3 in Appendix A identifies thelocations of the 32 monitoring wells.

Perched Water

Contaminants of concern in the shallow perched water table include 1,1-DCE; 1,1,1-TCA;chromium; nickel; manganese; and vanadium. Higher concentrations of 1,1-DCE and 1,1,1-TCAwere found in the western portion of the site, near the old chemistry lab, than in other areas. However, the maximum concentration of 1,1,1-TCA was identified in monitoring well 4A. Sampling performed in July 1992 identified maximum concentrations of 1,1,1-TCA and 1,1-DCE in well 4A at 210 g/L (micrograms per liter) and 14 g/L, respectively. The total anddissolved concentrations of manganese exceeded drinking water comparison values inmonitoring wells 3, 7, 12, and 18. Total vanadium was detected in monitoring well 6 at 226g/L, and all dissolved vanadium concentrations were below the drinking water comparisonvalue.

Monitoring well 3 was the only shallow well where total chromium and total nickel weredetected above comparison values. The RI noted possible sampling errors at monitoring well 3because, in a few samples collected between September 1991 and April 1992, the concentrationsof dissolved metals were higher than the concentrations of total metals. The maximumconcentration of total chromium detected during that time was 286 g/L. Later samples collectedshowed dissolved chromium at 275 g/L, while the concentration for total chromium was 209g/L. The same problems were encountered with nickel concentrations. A filtered samplecontained a concentration of dissolved nickel at 149 g/L, while the concentration of total nickelwas 112 g/L.

Deep Aquifer

Contaminants of concern in the deep aquifer include chloroform; 1,1-DCE; 1,1,1-TCA;manganese; nickel; chromium; and vanadium. Chloroform has been detected frequently in thedeep monitoring wells. The maximum concentration of chloroform was detected in monitoringwell 4B at 32 g/L in April 1989. However, analyses performed on samples collected at well 4Bin November 1989 and from September 1991 to July 1992 did not detect chloroform. Chloroform and 1,1-DCE were identified at levels above comparison values in monitoring well16 near the southwestern boundary of the site. Concentrations of 1,1-DCE in monitoring well 16 increased from 3 g/L to 5 g/L from September 1991 to July 1993. Chloroform concentrations also increased in the same well from 7 g/L in July 1992 to 11 g/L in July 1993. 1,1-DCE has been detected in monitoring well 13 and the Dittmer well at concentrations of 14 g/L and 11.8 g/L, respectively. These wells are located next to the District Office Building (DOB) -1 drain field, where the old chemistry lab was located.

The maximum concentration of manganese was identified in monitoring well 11, which is onsite, upgradient of site activities. Just north of the Dittmer control building, maximumconcentrations of nickel and chromium were identified in well 24 at 2,160 g/L and 1,720 g/L, respectively. Groundwater samples taken from the Dittmer well in September 1991 containedPAHs, but none were detected before or after this date.

Bis(2-ethylhexyl)phthalate, a common laboratory chemical, has been detected inconsistentlyduring monitoring in both shallow and deep water monitoring wells (11). Bis(2-ethylhexyl)phthalate was also detected in a blank sample at 480 g/L, suggesting that samples might have become contaminated through contact with the plastic components of the sampling equipment. Bis(2-ethylhexyl)phthalate is not considered to be a contaminant of concern and will not be discussed further.

Table 4.

Groundwater Contaminant Concentrations in On-Site Monitoring Wells for the Period May 1988-July 1992
ContaminantShallow Water
Concentration Range (g/L)
Deep Aquifer
Concentration Range (g/L)
Comparison Value
Chloroform ND - 0.3 ND - 32 6CREG
1,1-DCE ND - 78 ND - 140.06CREG
1,1,1-TCA 0.5 - 820 0.3 - 21200MCL
Pentachlorophenol ND - 0.95 ND0.3CREG
t Manganese 12 - 14,500 ND - 1,27050RMEG
d Manganese ND - 13,300 ND - 15650RMEG
t Nickel ND - 152 ND - 2,160100LTHA
d Nickel ND - 14.3 ND - 40100LTHA
t Chromium ND - 286 ND - 4,38050RMEG
d Chromium ND - 25 ND - 6.650RMEG
t Vanadium 14.8 - 226 ND - 11220LTHA
d Vanadium ND - 19.2 ND - 18.820LTHA

      g/L = micrograms per liter
      ND = Not detected
      CREG = Cancer Risk Evaluation Guide
      MCL = Maximum Contamination Level for drinking water (EPA)
      RMEG = Reference Dose Media Evaluation Guide
      LTHA = Lifetime Health Advisories for drinking water (EPA)
      t = total (unfiltered sample)
      d = dissolved (filtered samples)


Air monitoring was conducted on site to determine PCB concentrations in ambient air. The method used for sampling allowed the compound to be collected whether it was a vapor, an aerosol, or a particulate (1). Ambient air monitoring was conducted at three stations on site. Monitors were located in areas where levels of contamination were believed to be the highest. Analysis was limited to PCBs (Aroclors 1232, 1242, and 1248) and was conducted for 20 days in August and September of 1991. Continuous daily monitoring (24 hour) was performed at all three stations. Eighty samples were collected and analyzed. Only one of the three sampling stations had detectable concentrations of PCBs. Results showed maximum concentrations of combined Aroclors at 0.066 g/m3. The highest concentration for a single Aroclor (1232) was 0.043 g/m3. Concentrations at the upwind and downwind on-site monitoring stations were below detection limits.

C. Off-Site Contamination

Surface and subsurface soils were analyzed for metals and PCBs. Sediment and surface watersamples were analyzed for VOCs, PAHs, PCBs, BNAs, metals, and various herbicides andpesticides.


During the RI, off-site surface and subsurface soil samples were collected for comparison of soilchemical concentrations with those of samples from the site. Sampling stations were locatedapproximately 300 to 400 feet away from the site to determine whether areas had been affectedby site activities and development. Soil samples were collected from 21 surface locations inareas that were related to urban development, 10 surface locations that have not been affected byurban and/or industrial development, and one subsurface soil boring location off site andhydraulically upgradient.

Among the contaminants of concern on site, only lead was found off site at levels that might beof public health concern. ATSDR does not have a comparison value for lead but, because it hasbeen classified as a probable human carcinogen, it was selected for further analysis. Results ofthe monitoring revealed surface soil lead concentrations ranging from 5.7 mg/kg to 378 mg/kg. The maximum concentration of lead was detected in a sample taken from a residential yardsoutheast of the site. This sample result appears to represent an isolated occurrence. PCBs werenot detected in any of the samples analyzed.


No off-site monitoring wells were installed during the RI. However, monitoring data for theVancouver Water Station No. 3 for the years 1989 to 1992 showed the following levels ofcontamination: 2.8 to 9.9 g/L 1,1,1-TCA; 0.7 to 3.5 g/L 1,1-DCE; and 1.5 to 14.4g/Ltrihalomethanes. Trihalomethane and 1,1-DCE levels were above health-based drinking watercomparison values for 1989 and 1990. No 1,1-DCE was detected in any of the groundwatersamples taken in 1992.

During the RI for OUB, BPA officials and the EPA representatives performed modeling of 1,1-DCE and chloroform migration to estimate off-site concentrations of these contaminants. Twohypothetical wells (HW) were located downgradient from the DOB Drainfield (HW-1) and theFog Chamber Dump Trench Area 1 (HW-2). The calculations performed predictedconcentrations of 1,1-DCE and chloroform at 1.8 g/L and 3 g/L, respectively, at HW-1; HW-2had similar results.

According to officials at the Clark County Department of Public Services Water QualityDivision, there has been widespread tetrachloroethylene (PCE) contamination in Clark County'sdrinking water supply since the mid-1980s (12).

Surface Water

Surface water samples were collected in mid-June and early August of 1991 from eight samplingstations along Burnt Bridge Creek and Cold Creek. Samples collected in June 1991 were takenfrom both creeks during periods of high flow rates. The high flow rates were caused by stormwater runoff from on-site and off-site sources. Additional surface water samples were collectedfrom Cold Creek in June 1992, September 1992, and twice in October 1992. Figure 4 in Appendix A identifies the locations of the surface water and sediment sampling stations. Table 5 presents the contaminants of concern in surface water.

Cold Creek

Surface water samples were obtained from four permanent monitoring stations installed along the1.5-mile watershed area of the creek. Eleven surface water samples were taken from seeps alongthe bank of Cold Creek near the Wood Pole Storage East area. Chloroform was detected in only one sample. The concentrations of 1,1,1-TCA and 1,1-DCE in seep samples along Cold Creek were consistently greater than their comparison values. These contaminants were detected in one or two surface water samples from Cold Creek at levelsless than their comparison values.

Except for manganese and vanadium, the maximum concentrations of metals were detected insamples collected during the time of high flow rates in the June sampling period. Manganesewas consistently detected in the surface water samples at levels greater than the drinking watercomparison value. The maximum levels of manganese found in Cold Creek were 1,320 g/Ltotal manganese and 99 g/L dissolved manganese. A few samples contained total vanadium atconcentrations above the drinking water comparison values.

The maximum concentrations of benzo(a)pyrene and benzo(b)fluoranthene were detected in astorm water sample collected in June 1991 during a time of high flow rates. The maximumconcentration of total carcinogenic PAHs was 0.63 g/L. PAHs were not detected in samplescollected from the seeps.

Burnt Bridge Creek

Three permanent sampling stations were used along the watershed of Burnt Bridge Creek. Fourteen surface water samples were collected during the investigation. The maximumconcentrations of lead and benzo(a)pyrene were identified during times of high flow rates inBurnt Bridge Creek. Chloroform was the only VOC detected, and it was found at an estimatedlevel in only one sample. The maximum concentrations of nickel, manganese, chromium, andvanadium shown in Table 5 were not validated. Later sampling at the same station did not detectany of these metals. PAHs were detected at a maximum total concentration of 0.407 g/L inBurnt Bridge Creek at sampling point BB-SWSW1. The surface water samples collecteddownstream from the site after the confluence with Cold Creek did not contain contaminants ofconcern at concentrations greater than their respective drinking water comparison values.

Table 5.

Off-Site Surface Water Contamination
ContaminantBurnt Bridge Creek Concentration Range (g/L)Cold Creek Concentration Range (g/L)Comparison Value*
ChloroformND - 0.2ND - 96CREG
1,1-DCENDND - 30.06CREG
1,1,1-TCANDND - 87200MCL
Nickel ND - 108ND100LTHA
ManganeseND - 90.7ND - 1,32050RMEG
ChromiumND - 208ND - 11.250RMEG
VanadiumND - 11.9ND - 3620LTHA
LeadND - 12ND - 11.6None
CadmiumND - 11 ND - 4.52EMEG
Benzo(a)pyreneND - 0.03ND - 0.060.006CREG
Benzo(b)fluorantheneND - 0.07ND - 0.250.2PMCL
DiuronND - 2.3ND - 5410LTHA
    * = Comparison value based on human ingestion of contaminants
    g/L = micrograms per liter
    ND = Not detected
    CREG = Cancer Risk Evaluation Guide
    MCL = Maximum Contaminant Level for drinking water (EPA)
    LTHA = Lifetime Health Advisories for drinking water (EPA)
    RMEG = Reference Dose Media Evaluation Guide
    PMCL = Proposed Maximum Contaminant Level for drinking water (EPA)


Sediment samples were collected in June 1991 from both creeks in the same locations wheresurface water samples were collected. Cold Creek was resampled in June 1993. Contaminantsof concern found on site were not found above comparison values in the sediments found in ColdCreek and Burnt Bridge Creek. Only one sediment sample contained arsenic (58.1 mg/kg) aboveits health comparison value. This sample was collected at station 3 along Burnt Bridge Creek,just west of the confluence with Cold Creek.


No air sampling was conducted off site. The air monitors located on site at the upwind anddownwind monitoring stations did not detect any PCB concentrations.


An ecological and aquatic risk assessment was performed during the RI. Three indicator species-- the American robin, the black-tailed deer, and the raccoon-- were selected for the ecologicalportion of the assessment. Use of indicator species was not required for the aquatic portionbecause EPA's Ambient Water Quality Criteria were used and these are designed to protect allaquatic life. However, no biota samples were collected during the RI. A representative from theWashington State Department of Ecology informed ATSDR that he was not aware of any fishsampling ever being conducted in either creek (13).

D. Quality Assurance and Quality Control

In preparing this public health assessment, ATSDR relies on the information provided in thereferenced documents. The Agency assumes that adequate quality assurance and quality controlmeasures were followed with regard to chain-of-custody, laboratory procedures, and datareporting. The validity of analyses and conclusions drawn for this public health assessmentdepends on the completeness and reliability of the referenced information. As previously noted,there was possible sampling error at monitoring well 3 because the concentrations of dissolvedmetals were higher than the concentrations of total metals.

E. Physical and Other Hazards

Maintenance operations and training activities conducted on site have inherent hazards, such ashandling transformers and working on overhead power lines. Observations made by ATSDRstaff members during the site visit did not detect any physical hazards that would be a threat tothe general public's health.


To determine whether workers and nearby residents are exposed to contaminants on site or offsite, ATSDR evaluates the environmental and human components that could lead to an exposure. The pathways analysis consists of the following five elements: a source of contamination,transport through an environmental medium, a point of exposure, a route of human exposure, andan exposed individual or population. ATSDR characterizes an exposure pathway as completedor potential if it cannot be eliminated. Completed pathways occur when all five elements arepresent and there are indications that exposure to a contaminant has occurred in the past, iscurrently happening, or will occur in the future. A potential exposure pathway exists whenevidence of one or more of the five elements is missing, but the missing elements are plausible. Potential pathways indicate that exposure to a contaminant could have occurred in the past, couldbe occurring now, or could happen in the future. An exposure pathway can be eliminated if atleast one of the five elements is missing and is not likely to be present. Exposure is defined byATSDR as "contact at a boundary between a human being and the environment with acontaminant of a specific concentration for an interval of time" (14). Table 6 summarizes thepotential pathways of concern at BPA and the time frame associated with them.

A. Completed Exposure Pathways

Surface Soil/Equipment

A past completed exposure pathway existed for workers who came in contact with surface soilsand equipment containing lead, PCBs, PAHs, and pentachlorophenol in the following areas: theRoss Substation & Capacitor Yard (RS&CY), the Utilization & Disposal (U&D) Yard, theCapacitor Testing Laboratory (CTL), the Sandblasting Area, the Top Coat Test Area, the WoodPole Storage East (WPSE) and Wood Pole Storage South (WPSS), the Hazardous Waste StorageBuilding, and the PCB Storage Building. In the following discussion, each contaminant and theassociated exposure pathways are evaluated.

Surface soils, drums, and capacitors were contaminated with oils containing PCBs in the CTL,the RS&CY, the U&D Yard, and the PCB Storage Building. Capacitors in the CTL werestressed to the point of rupturing, which resulted in the release of PCBs inside the building. Concentrations of PCBs detected in the CTL ranged from 30.5 mg/kg to 47,000 mg/kg (4). Capacitors in the RS&CY underwent considerable vibration during operation and leaked PCBsonto surrounding soils, which are covered with gravel. The maximum concentration of PCBsdetected in the RS&CY soil was 225 mg/kg. The capacitors were dismantled in the U&D Yard,and surface soil sampling in this area detected a maximum concentration of PCBs at 85.3 mg/kg. Drums containing oils with PCBs were stored in the PCB Storage Building. Surface soilsampling during the RI identified a maximum concentration of PCBs in the building at 32.7mg/kg. The route of exposure to PCBs in surface soils, drums, and capacitors most likelyoccurred by incidental ingestion of soil or oil or dermal (skin) contact with soil or oil. Thepopulation exposed to PCBs in these areas would have been on-site workers.

Surface soils in the Sand Blasting Area and the Top Coat Test Area were contaminated with leadas a result of sandblasting and painting operations performed on capacitors and transformers inthese areas. Maximum surface soil lead concentrations in the Sand Blasting Area and the TopCoat Test Area were 2,250 mg/kg and 3,000 mg/kg, respectively. The RS&CY surface soils alsocontained lead concentrations, with a maximum of 2,360 mg/kg. On-site workers were likelyexposed to lead by incidental ingestion of soil.

The primary source of PAHs and pentachlorophenol in on-site surface soils is the leaching ofcreosote from treated wooden transmission poles in the WPSE area. Only workers have accessto the wood pole storage areas. Maximum concentrations of total PAHs and pentachlorophenoldetected in the WPSE were 505 mg/kg and 405 mg/kg, respectively. Workers and trespasserswere likely exposed to PAHs and pentachlorophenol via incidental ingestion of soil, dermalcontact with soil and transmission poles, or inhalation of vapors.

B. Potential Exposure Pathways

Table 6 lists the potential exposure pathways.

Soil Pathway

In the summer of 1992, surface soil remediation of all but three areas reduced the possibility of exposure to contaminated soils. The RS&CY, WPSE, and CTL have not been remediated. Sinceaccess is restricted in these three areas, present and future exposures to contaminated surfacesoils in these areas are expected to occur only during remediation. A Record of Decision (ROD)was signed in May 1993 to address the contamination in the three unremediated areas. Potentialexposures can be minimized if qualified personnel take appropriate precautions by wearingpersonal protective equipment and complying with applicable health and safety guidelines.

Exposure to subsurface soils could occur when workers perform excavation, construction, orremedial activities in the Cold Creek Fill area. The future redevelopment of the site forresidences is unlikely because the complex is expected to continue to supply energy throughoutthe Pacific Northwest.

Groundwater Pathway

An on-site groundwater pathway does not exist at this site because groundwater is not used fordrinking or irrigation purposes. Groundwater at the site is located in a shallow perched watertable and in the deeper Troutdale aquifer. The groundwater contaminants detected in on-sitemonitoring wells are not the same as those found in the on-site soil samples. Contaminants in thesoil have not migrated to the groundwater because of their adsorption to the first few feet of thesoils.

The groundwater in the shallow perched water table is contaminated with VOCs and metals. However, no on-site private or public wells are located in the perched water, and the groundwaterfrom this perched water table is not used as a source of potable water. A layer of impermeableclay separates the perched water table and the deep aquifer. The shallow perched groundwaterflow is towards Cold Creek and is in communication with the creek through a series of seeps.

The groundwater in the Troutdale aquifer is contaminated with chloroform; 1,1-DCE; 1,1,1-TCA; manganese; nickel; chromium; and vanadium. The only on-site deep aquifer well thatmight be used for drinking water is the Dittmer well. This well is an emergency supply well thathas never been used but could be used as a source of potable water in the future. All operationsperformed at the complex use city water; therefore, on-site personnel have not been exposed tocontaminants in the on-site groundwater.

Chloroform; 1,1-DCE; manganese; nickel; chromium; and vanadium were detected atconcentrations above comparison values in monitoring wells near the southwestern edge of thesite. However, there appear to be no private wells that are in use downgradient of the site. Thereare two private wells on the northwestern end of Alki Road; however, these do not appear to bein the pathway of groundwater flow from the site. Another private well southeast of the site (NE18th Court) is currently not in use and also appears to be outside the pathway of groundwaterflow from the site. A future potential exposure pathway would exist if a resident were to install aprivate well within a half mile downgradient (southwest) of the site and the concentrations ofcontaminants on site remained the same or increased.

The total (dissolved and undissolved) concentrations of nickel, chromium, vanadium, andmanganese were above comparison values in the deep aquifer on site in some samples. (SeeTable 4.) However, the dissolved portions of three of these metals (nickel, chromium, andvanadium) were measured below comparison values; dissolved manganese was measured slightlyabove the comparison value for manganese. Because metals adhere to soil and often migratevery slowly (on the order of a few feet or less per year), concentrations of these metals in theaquifer are not expected to be above comparison values downgradient of the site. Therefore,ATSDR will not consider this hazard further.

Commercial, industrial, and public facilities in the Vancouver area have contributed to VOCcontamination of the city's drinking water supply. Figure 5 in Appendix A shows the facilitieslocations in relation to the Ross Complex. Trihalomethanes; 1,1-DCE; and 1,1,1-TCA have beenidentified in the groundwater from wells in well field 3. The Washington State Department ofTransportation motor pool was identified as the source of 1,1-DCE and 1,1,1-TCA in thegroundwater at this well field. The water at well field 3 is treated with chlorine and fluoride priorto sampling (15). The presence of trihalomethanes in the groundwater samples is most likely dueto the chlorination process.

Contamination from other sources upgradient of the site might have had an impact ongroundwater southeast of the Ross Complex. Public and private wells that are east of the site anddraw groundwater from the Troutdale aquifer could potentially expose people to contaminantsfrom these other sources. No sampling data are available on groundwater from private wells. Exposure could occur through ingestion of groundwater, dermal contact with groundwater, andinhalation of VOCs from the groundwater.

Surface Water & Sediment Pathways

People using the Burnt Bridge Creek for recreational purposes might be exposed to metals andPAHs in the surface water. The extent of recreational activities in either Burnt Bridge or ColdCreek is not known; however, Burnt Bridge Creek is more accessible than Cold Creek. Ingestionof and dermal contact with water from Burnt Bridge Creek represent past, present, and futurepotential exposure routes.

The potential for exposure would be greater for children than adults because children are morelikely to spend more time playing near the creek beds.

Public access to Cold Creek (and the seeps along Cold Creek) is limited because of the steepwalled canyon--approximately 100 feet--in which the creek flows and because the western half ofCold Creek flows underground in a culvert. Therefore, exposures are unlikely in Cold Creek. BPA workers would not likely come in contact with either Burnt Bridge Creek or Cold Creekduring normal work activities.

The elevation of the site ranges from greater than 250 feet to about 40 feet mean sea level. Thesite slopes moderately to steeply toward the southwest. Runoff from the site drains into eitherBurnt Bridge Creek or Cold Creek. The facility has nine oil-water separators, ranging in sizefrom 500 to 24,300 gallons, that serve to reduce the amount of equipment oil being released intoboth creeks (1). VOCs in the shallow perched water table are transported to seeps in the banks ofCold Creek, mainly in the eastern portion of the site. The VOCs are diluted, and they volatilizeonce they are discharged into the creek.

PAHs measured in Burnt Bridge Creek were below levels of concern. Higher concentrations oftotal metals in the surface water in both creeks could be accounted for by high flow rates. Highflow rates of the surface water resuspend sediments containing metals. Upgradient surface waterand sediment samples contained both metals and PAHs at concentrations equal to or higher thanthose found in samples downstream of the site.

Ambient Air / Soil Dust Pathway

No present or future potential ambient air exposure pathway exists for the public at the site. Thecontaminated surface soils have been remediated in all but three areas. The potential for dustgeneration in these three areas is minimal, because two areas are covered with coarse gravel andthe third is indoors.

Since no PCBs were found at detectable levels in either the upwind or downwind monitoringstations on site, it can be concluded that PCBs did not migrate into the surrounding communities. Off-site soil sampling did not detect any PCBs.

In the past, workers might have been exposed to volatile organic compounds and metals, butbecause of the lack of ambient air and personal air monitoring data, it is not possible to determinewhether exposure occurred and if so, to what extent. VOCs do not appear to have been aproblem, as evidenced by the low concentrations reported in the RI, but the potential for pastexposures can not be ruled out. Whether there were particulate air emissions into the surroundingcommunity in the past is not known because of the lack of air monitoring.

Workers in the Sand Blast Area have been required to wear full-face respirators since 1979. Before 1979, only half-face respirators were worn. During operations in the Top Coat TestingArea, on-site workers were likely exposed via inhalation of organic vapors.


According to the RI, Cold Creek is unable to support fish or shellfish most of the year (1). Burnt Bridge Creek has been classified for fishing use by the Washington State Department of Ecology. The extent of fishing in Burnt Bridge Creek is unknown. As previously stated in the Off-SiteContamination section, no biota sampling has been conducted in either of the two creeks. Thecontaminants of concern in the surface waters and sediments of both creeks are not likely tobioaccumulate at levels of public health concern.


Past, present, and future ingestion of vegetation grown off site is a potential exposure pathway. Vegetation might have been irrigated with contaminated water or planted in contaminated soil, ordusts might have deposited on plant surfaces. Ingestion of homegrown fruits or vegetables couldbe a potential exposure route. Certain leafy green vegetables bioaccumulate various heavymetals in their tissues. No data exist on how many gardens are in the vicinity of the site andwhether they are irrigated with contaminated water.

Table 6.

Potential Exposure Pathways
Contaminated Environmental MediumTime Frame Exposed PopulationPoint of ExposureRoute of Exposure
Surface SoilsFuture RemediationWorkers (<20) Wood Pole Storage East
Capacitor Testing Lab
Ross Substation & Capacitor Yard
Ingestion & Dermal Contact
PastTrespassers (<20)Wood Pole Storage East
Wood Pole Storage South
Surface WaterPast
Persons using the creeks (unknown)Burnt Bridge CreekIngestion & Dermal Contact
AirPastWorkers (<100)Van's Way Oil Storage
Old Chemistry Lab
SedimentsPastPersons using the creeks (unknown)Burnt Bridge CreekDermal Contact
Residents surrounding the Ross Complex (<1000)Gardens irrigated with surface water and groundwaterIngestion
GroundwaterPast Future Residents downgradient of the Ross Complex (<100) Off-site private wellsIngestion &
Dermal Contact
Subsurface SoilsFuture RemediationWorkers (<20)Fog Chamber Dump Trenches 1 and 2
Cold Creek Fill Area
Ingestion &
Dermal Contact


A. Toxicological Evaluation


The evaluation of toxicological properties of contaminants and their effects on human healthtakes a variety of factors into account. First, a person must be exposed to a chemical by comingin contact with it. Second, the type and severity of adverse health effects resulting from anexposure to a contaminant depend on the concentration of the chemical, the frequency andduration of exposure, the route of exposure, a determination of whether the exposure was to asingle contaminant or a mixture of contaminants, and an assessment of whether there weremultiple exposures.

The routes of exposure can include breathing, drinking, eating, or dermal contact with asubstance that contains the contaminant. A combination of contaminants can result in thechemicals acting synergistically, where the simultaneous action of the separate compoundstogether have a greater total effect than the sum of their individual effects (16).

The opposite is also a possibility. The combination of contaminants can act antagonistically,with one contaminant acting in opposition to or counteracting another contaminant. A thirdsituation, in which the contaminants have no effect on each other, could also result.

Once an exposure has occurred, characteristics such as age, sex, race, socioeconomic status,genetics, lifestyle, and health status of the exposed individual influence how the individualabsorbs, distributes, metabolizes, and excretes the contaminant. All these factors andcharacteristics are considered when determining the health effects that might occur as a result ofexposure to a contaminant.

The following formula is used in determining an exposure dose:

    ED = (C X IR X EF) / BW
where, ED = exposure dose (mg/kg/day)
C = contaminant concentration
IR = intake rate
EF = exposure factor
BW = body weight

A standard intake rate is used for the ingestion of soil and water. For incidental soil ingestion,the intake rate for adults is 100 mg/day; for children, 200 mg/day; and for children with picabehavior, 5,000 mg/day. Pica behavior is characterized by an abnormal craving to eat substancesnot fit for food. Examples of these substances include dirt, chalk, paint chips, and mothballs. Aconservative estimate of 0.5 liter per day for incidental surface water ingestion was used incalculating an estimated exposure dose. Standard body weights are 40 kg for children and 70 kgfor adults.

The maximum concentration for a contaminant is used to calculate an exposure dose mostprotective of public health. Exposures might vary, because different groups of the populationwill be exposed at different frequencies. An exposure factor is used in certain situations, becauseexposures can be intermittent and not continuous.

The exposure frequency for workers is expected to be less than daily because most workers workonly 5 days a week. When ATSDR calculates an exposure dose for workers, it is assumed thatthe worker works an 8-hour work day, 5 days a week, 50 weeks per year, for 30 years. ATSDRhas evaluated exposures on an individual contaminant basis in this public health assessmentbecause of the limited amount of toxicologic information on mixtures.

Minimal risk levels (MRLs) have been derived from animal data for both short- and long-termexposure and are used to provide a basis for hazard in humans, based upon all known experimental data on the chemical. Since themethod for deriving MRLs does not use any information about cancer, an MRL does not implyanything about the presence, absence, or level of risk of cancer. For carcinogenic substances,EPA has established the Cancer Slope Factor (CSF) as a health guideline. The CSF is used todetermine the number of excess cancers expected from exposure to a carcinogenic contaminant.


1,1-Dichloroethene (1,1-DCE) is a manufactured chemical and is not found naturally in theenvironment. The EPA has classified 1,1-DCE as a possible human carcinogen (17). However,because of insufficient data, the International Agency for Research on Cancer (IARC) hasdetermined that 1,1-DCE is not classifiable as to its carcinogenicity to humans (17).

Occupational exposures to 1,1-DCE have resulted in possible damage to the liver, kidney, lungs,and nervous system.

Levels of 1,1-DCE were detected on site at a maximum concentration of 14 g/L in the deepaquifer. At this concentration, a public health concern would exist only if lifetime exposureswere to occur. No private groundwater monitoring has been performed off site, and off-sitegroundwater concentrations of 1,1-DCE are not known. The predicted concentrations at two off-site hypothetical well locations exceed the cancer risk evaluation guideline (CREG) for 1,1-DCE. If people were to consume water from private wells at the predicted concentrations, they wouldhave an increased risk of developing cancer from oral ingestion of 1,1-DCE. ATSDR does notconsider model calculations to be sufficient in making public health conclusions.


Chloroform was detected in the deep aquifer on site in concentrations up to 32 g/L. However,not all deep aquifer water samples contained chloroform.

Chloroform was used as an anesthetic during surgery for many years before its harmful effects onthe liver and kidneys were recognized. Chloroform affects the central nervous system, liver, andkidneys of humans who breathe air or drink liquids that contain large amounts of the chemical. Chloroform might also cause sores when it comes in contact with the skin (18). However, at 32g of chloroform per liter of water, noncancerous adverse health effects are not expected.

Cancer of the liver and kidney developed in rats and mice that ate food or drank water with smallamounts of chloroform in it for a long time. Little information exists about the development ofcancer in people who have been chronically exposed to chloroform. However, based on theanimal studies, EPA has classified chloroform as a probable human carcinogen (18). Nevertheless, based on a calculated dose using 32 g/L, there is no apparent increased risk ofdeveloping cancer from chronic ingestion of the groundwater. The inconsistency with whichchloroform was detected further supports this conclusion.

Polycyclic aromatic hydrocarbons (PAHs)

PAHs are a class of compounds that are formed during the incomplete burning of coal, oil, gas,or other organic compounds. According to IARC and EPA, the following PAHs are considered probable or possible human carcinogens: benz(a) anthracene; benz(a)pyrene;benzo(b,j,k)fluoranthene; indeno(1,2,3-c,d)pyrene; chrysene; and dibenz(a,h)anthracene (28). Most PAHs occur as mixtures in the environment. Cancer is the most important result oftoxicity resulting from exposure to PAHs. Evidence of carcinogenicity in humans comesprimarily from occupational (inhalation or dermal) exposure studies. The types of cancersassociated with PAHs include skin, lung, laryngeal, and pharyngeal. No studies were locatedregarding cancer in humans from oral exposure.

The maximum concentration of total PAHs detected in on-site soils was approximately 505mg/kg (Wood Pole Storage East area). However, the carcinogenic portion of this total wasapproximately 112 mg/kg. Benzo(a)pyrene (B[a]P) makes up approximately 20 percent of thismixture (24 mg B[a]P per kg of soil). An estimated exposure dose based on this concentrationdoes not exceed the acute (less than or equal to 14 days) oral MRL for B(a)P. A chronic MRLhas not been determined for this compound. Using EPA's CSF for ingestion of B(a)P, exposureat the maximum concentration detected in on-site surface soil over a lifetime could result in alow increased risk of cancer; however, lifetime exposures to the maximum concentrations in soilare not expected to occur. In addition, BPA plans to reduce its wood pole inventory and initiateenhanced bioremediation at this location.


Pentachlorophenol was detected in surface soil in the Wood Pole Storage Area at a maximumconcentration of 405 mg/kg. Exposures to pentachlorophenol might have occurred in the pastfrom ingestion, inhalation, and dermal contact with contaminated soil.

The acute oral MRL is 0.005 mg pentachlorophenol per kg of body weight per day (0.005mg/kg/day), established for developmental effects, and the intermediate (15-364 days) oral MRLis 0.001 mg/kg/day, established for hepatic effects (19).

The exposure dose calculated from the maximum surface soil concentration does not exceed theacute or intermediate MRL; therefore, noncancerous effects are unlikely to occur from soilingestion.

EPA has classified pentachlorophenol as a probable human (B2) carcinogen based on animalstudies. ATSDR has estimated the cancer risk from ingestion of soils contaminated withpentachlorophenol using EPA's CSF. If chronic oral exposures occurred at the maximum soilconcentration, there would be no apparent increased risk of developing cancer.

Since pentachlorophenol was used as a wood preservative, workers were much more likely tohave been exposed to pentachlorophenol through dermal contact or inhalation than through oralingestion of contaminated soils. Although there are occupational guidelines for maximum air exposure to pentachlorophenol, there are no air data indicating to what concentrations workers were exposed. There are also no data describing actual dermal exposures, although workers might have experienced acute exposures to pentachlorophenol through direct dermal contact.

Pentachlorophenol is readily absorbed from the lung and through the skin. Health effects varywith the duration and frequency of exposure and include harm to the liver, kidney, skin, blood,lungs, nervous system, and gastrointestinal tract; high doses for an acute exposure can causedeath (19). Short-term inhalation exposures can cause irritation to the eyes and nose (19). Chronic exposure to low levels of pentachlorophenol can cause damage to the liver, kidney,blood, and nervous system (19).

Pentachlorophenol is believed to interact synergistically with PAHs as well as with PCBs. Therefore, workers might have been exposed in the past to combinations of these chemicals atlevels of health concern. However, BPA is no longer purchasing wood poles treated withpentachlorophenol. As a result of operational changes and soil remediation activities, thecontamination levels, and consequently the health hazard, are expected to diminish.


Lead was detected in soils on and off site. Workers were exposed to lead dermally, orally, andby inhalation. Lead exposure studies have shown that a variety of adverse health effects canoccur regardless of the route of exposure. However, the degree of absorption varies according tothe route of exposure (20). The greatest amount of absorption occurs via the inhalation route. Dermal absorption is much less significant than the absorption through the inhalation oringestion routes (20).

Investigations done prior to the RI identified a maximum concentration of lead, in on-site soils inthe Top Coat Test Area, at 3,000 mg/kg. The National Academy of Sciences has established anacceptable daily intake (ADI) for lead of 3 mg/week for adults (20). If absorption in thegastrointestinal tract is assumed to be 100 percent, then the daily estimated exposure to workersover a lifetime from incidental ingestion of soil at this concentration is 0.00124 mg lead per kgbody weight per day (0.00124 mg/kg/day). This dose is about 20% of the ADI. Therefore, dailyexposure of workers to lead-contaminated soil at the site is not expected to result in adversehealth effects.

The maximum concentration of lead detected in soils off site was 378 mg/kg. Residents whoincidentally ingest soil containing 378 mg lead per kg of soil would be exposed to 0.00054mg/kg/day over a lifetime; this dose is less than 1 percent of the ADI.

Blood levels of lead might increase by 10 g lead/deciliter (dL) blood in children whochronically ingest soil containing 378 mg lead per kg of soil. Lead toxicity in children mightoccur at blood lead levels as low as 10 g/dL (21). This increase in blood lead and possibleincreases from other sources might result in adverse health effects. Effects might includeimpaired mental and physical development, decreased heme biosynthesis, elevated hearingthreshold, and decreased serum levels of vitamin D. Neurotoxicity of lead is of particularconcern because effects such as impaired academic performance and deficits in motor skillsmight persist even after blood lead levels return to normal (21).

Some animal studies have linked exposure to lead with cancer; as a consequence, EPA hasclassified lead as a probable human (B2) carcinogen (20). However, the cancer risk in humansassociated with exposure to on- and off-site lead-contaminated soils can not be evaluated becausethere are no cancer related environmental comparison values for lead.

Polychlorinated biphenyls (PCBs)

PCBs are manufactured chemicals that are used as coolants and lubricants in transformers, capacitors, and other electrical devices. PCBs are no longer made. PCBs, which are very insoluble in water and bind readily to soil and sediment, usually persist in the environment. The ability to bind or adsorb to soils increases as chlorination of the compound and organic carbon content of the soil increase (4). The highly chlorinated PCBs (Aroclors 1248, 1254, and 1260) resist both chemical and biological degradation in the environment.

Based on animal studies, the EPA has classified PCBs as B2 carcinogens (4). There is sufficient evidence that commercial PCB mixtures are carcinogenic in rats and mice. Results of occupational studies, which involve inhalation and dermal exposure, provide indications that liver, skin, and thyroid might be targets of PCBs in humans (22).

Dermal exposure to PCBs can result in skin rashes, erythema, and chloracne. No data are available to determine the extent of dermal contact to PCB-contaminated soils and equipment. Air monitoring data collected during the RI identified PCBs that were not at levels of public health concern. However, air monitoring data are not available to determine what PCB air concentrations existed during laboratory operations in the past. Therefore, the possible health effects that might have occurred because of dermal and inhalation exposures can not be evaluated.

The maximum PCB concentration detected on site was found in the Capacitor Testing Laboratory at 47,000 mg/kg (23). This concentration was detected in a concrete sample and is not likely to be ingested; however, concrete deterioration could result in exposures to contaminated airborne particulates through inhalation and incidental ingestion of dust.

B. Health Outcome Data Evaluation

Officials at the Southwest Washington Health District conducted a childhood cancer incidencestudy of Clark County covering the years 1963 through 1985. The study focused on thosechildren who had a diagnosed malignancy, were aged 14 or younger at the time of diagnosis, andhad lived in Clark County at the time of diagnosis. The information gathered was obtained fromseveral sources: the Southwest Washington hospital tumor registry, the Oregon Health SciencesCenter tumor registry, the Kaiser Permanente tumor registry in Portland, and death certificatesfor Clark County residents aged 19 and younger who died in Washington or Oregon.

Results from the study indicated a higher-than-expected number of cancers for the period 1980 to1985 (57 observed versus 41 expected) (24). The excess occurred primarily in the 10 -to- 14-year age group (21 observed versus 10.5 expected); within this group, the number of non-Hodgkin's lymphomas was the most remarkable, with 3 observed versus 0.2 expected (24). Thecause for the elevated cancer cases in Clark County has not been determined; however, childhoodcancer does not seem to represent a plausible health outcome for exposures related to the RossComplex, based on the identified contaminants of concern and an analysis of the known andpotential exposures.

C. Community Health Concerns Evaluation

The following are concerns expressed by members of the community surrounding the RossComplex and ATSDR's responses to the concerns:

1. If the Fog Chamber Dump Area is a dangerous waste area, why isn't it fenced off?

The remedial investigation revealed that all of the contamination is buried several feet below thesurface. The area has since been fenced off to prevent any entrance. The preferred alternative inremediating the area is capping the area to prevent any human contact and to minimize theinfiltration of water into the contaminated medium.

2. Does the Ross Complex receive hazardous waste from sources off site, and has BonnevillePower met all handling and storage requirements?

The Ross Complex does receive hazardous waste from other BPA facilities, but no treatment ordisposal is done on site (25). However, the site has a Resource Conservation and Recovery Act (RCRA) permit to store hazardous materials and wastes. A hazardous and toxic materials handling facility, which will better accommodate the wastes that are generated, has recently been constructed. The facility is on site and is required to meet state and federal regulations.

3. Could the foul air from the Wood Pole Storage East area contain concentrations of chemicals that are hazardous to the public's health?

The smell comes from the chemicals used in treating the wood poles to preserve their longevityin the environment. The major chemicals in the coal-tar creosote mixture that can cause harmful health effects are PAHs, phenols, and cresols. Short-term inhalation exposure to low levels of pentachlorophenol can cause irritation to the eyes and nose. Studies of the inhalation toxicity of PAHs and cresols have not been adequately detailed to determine what concentrations are considered harmful to human health.

4. Are digging up the asphalt and remediating the contaminated soils on site going to causeconsiderable dust generation, possibly leading to migration of contaminants off site?

During the remediation process, the soils are kept wet to reduce the chances of dust beinggenerated. Any surface water runoff is collected in the dikes that are constructed around theremediation areas.

5. If groundwater monitoring does show any contamination in OUB, will site officials be ready to deal with that problem?

ATSDR staff members believe that results from the OUB investigation indicate thatconcentrations of VOCs in the on-site groundwater could potentially cause adverse effects ifsomeone on site were to drink the water over a lifetime. However, all water consumed on site iscity water. Monitoring performed at the well station no. 3 (the station that serves the areasurrounding and including the Ross Complex), has identified slight to no detectableconcentrations of these compounds. No downgradient private wells that would be affected by thecomplex are being used.

6. Is the drinking water safe? Should the residents take any precautions?

Residents who use city water from the municipal well field 3 have been exposed to VOCs andtrihalomethanes in the past. However, the concentrations were not of public health concern. Thecontaminants detected in the well field were not caused by the Ross Complex. Residents whouse private wells in the vicinity of the site, especially upgradient, for sources of potable watermight be exposed to metals and VOCs at levels of public health concern from sources other thanthe Ross Complex. In the future, if persons within a half mile downgradient (southwest) of thecomplex are going to use private wells for potable water or irrigation purposes, they should havetheir water tested for VOCs.

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