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1. ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

BOOMSNUB/AIRCO
VANCOUVER, CLARK COUNTY, WASHINGTON

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

This section lists the contaminants of concern. These contaminants are evaluated in the subsequent sections of the Public Health Assessment to determine if exposure to them has public health significance. ATSDR selects and discusses these contaminants based upon the following factors:

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 values for (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-site Contamination subsection, the listed contaminant does not mean that it will cause adverse health effects from exposures. Instead, the list indicates which contaminants will be evaluated further in 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 to be without adverse health effects upon exposure. Those values are developed by health and regulatory agencies to provide estimates of levels below which health effects would not be observed. Those values, in many cases, have been derived from animal studies. Health effects are related not only to the exposure dose, but to the route of entry into the body and the amount of chemical absorbed by the body. For those reasons, comparison values used in public health assessments are contaminant concentrations in specific media and for specific exposure routes. Several comparison values may be available for a specific contaminant. ATSDR generally selects conservative exposure assumptions in order to protect the most sensitive segment of the population. The potential for adverse health effects from exposure to contaminants will be discussed 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. The NPL site closest to Boomsnub/Airco is Bonneville Power Administration's (BPA) Ross Complex which is about two miles to the southwest. The BPA Ross Complex is an active power distribution facility that coordinates the distribution of hydroelectric power to areas throughout the Pacific Northwest. During the course of past operation at the Ross Complex heavy metals and 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 any other industrial facilities in the same zip code as the Boomsnub/Airco site have contributed to area contamination. The information contained in TRI is submitted to EPA by facilities that release hazardous materials to the environment. During the years reported, spills of chromium occur on the average about every three to four months. Table 1 lists the spills.

TABLE 1
REPORTED SPILL EPISODES IN SITE ZIP CODE

A. On-Site Contamination

Chromium

In 1994, Ecology's contractor estimated that prior to 1978 in excess of ten tons of chromium were discharged to the soil at Boomsnub (22). On March 18, 1994, Ecology took groundwater samples from on-site monitor well MW11A. The unfiltered sample contained 120 ppm total chromium (3). In June 1994, the total chromium level in MW11A was 2,400 ppm. That is the highest concentration of total chromium in groundwater ever detected at Boomsnub (24). During April 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 floors containing 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 total chromium sludge from the containment vault and some concrete debris outside of the vault's steel lining. EPA found the highest levels of chromium in soils directly under the containment vault (2). Sludge from the containment vault contained 445,000 ppm total chromium. The outer concrete wall debris contained 152,000 ppm chromium (3).

Following these findings EPA took soil borings under and around Boomsnub's building. The soil samples taken from under and around the western end of the containment vault and building commonly exceeded 2,000 ppm of chromium and were as high as 9,270 ppm at depths of 28 feet below ground surface where groundwater was encountered. Soil samples taken from borings 30 to 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 ppm chromium (11). The background levels of chromium in the area soils are between 10 and 25 ppm (19).

In December 1989, a water line break at Boomsnub released over 300,000 gallons of water. The water 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 the water 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 Airco Gases, a plant adjacent to Boomsnub, as a source of the VOCs (4). The VOCs detected in groundwater include trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), tetrachloroethylene (PCE), trichlorofluoromethane (Freon 11), 1,1-dichloroethene (DCE), carbon tetrachloride, and acetone (6). On September 11, 1992, the five VOCs detected in groundwater samples collected from Airco monitor wells were present at concentrations exceeding Washington State cleanup standards or EPA drinking water standards. Compounds exceeding Washington State cleanup standards include TCE, TCA, and PCE. Compounds exceeding EPA drinking water standards include DCE and carbon tetrachloride (6).

On the western portion of the Airco property there are two dry wells which collect storm water and plant condenser water. The VOCs detected at the highest concentrations in the south dry well 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 unconfined alluvial aquifer which overlies the confined Troutdale aquifer. A clay and silt aquitard separates the two aquifers, but there are known breaks in the aquitard.

Chromium has not been detected in the Upper Troutdale. Low concentrations of TCE (less than 0.011 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. Water samples 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, Ecology collected unfiltered groundwater samples from the off-site monitor wells. The total chromium found in these samples ranged from 0.12 to 52 ppm (3). By May 1994, the chromium plume reached over 3,300 feet west of Boomsnub. That is the direction of groundwater flow in the unconfined alluvial aquifer (3).

Chromium was discovered in five private wells near Boomsnub. During 1991, the chromium in private wells ranged from 0.0112 ppm to 0.292 ppm. In 1993, the well with 0.292 ppm was tested at 0.030 ppm. Another private well over 3,000 feet from the Boomsnub plating facility has had chromium levels of 0.014 ppm. These private wells have been closed and the residences have been connected to the available municipal water supplies. On July 20, 1994, the Washington State Department of Health issued a news release which recommended that people in 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 chromium plume 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 the groundwaterextraction system to remove VOCs. TCE has been detected in one off-site private well. The level of TCE has ranged from 0.001 to 0.0029 ppm. That private well is completed in the upper Troutdale aquifer (29).

C. Quality Assurance and Quality Control

In preparing this Public Health Assessment, The Washington State Department of Health relies on the information provided in the referenced documents and assumes that adequate quality assurance and quality control measures were followed with regard to appropriateness of testing procedures, chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn for this Public Health Assessment is determined by the availability 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 fenced facilities, not easily accessible to the public.

PATHWAY ANALYSES

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, ATSDR and WDOH evaluate the environmental and human activities that lead to human exposure. This pathway 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 the exposure pathway cannot be eliminated. Completed pathways have all five elements and indicate that exposure to a contaminant has occurred in the past, could be occurring now, or could occur in the future (Table 2). Potential pathways, however, have at least one of the five elements missing. Potential pathways indicate the exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future (Table 2). An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present.

A. Completed Exposure Pathways

Boomsnub's Workers

In the past, Boomsnub represented a health hazard to on-site workers exposed to chromium. The health assessors believe that these workers came in contact with heavily contaminated soils and chromic product which may cause adverse health effects by incidentally ingestion, inhalation of dust or vapor, and/or dermal exposed. High levels of chromium contamination were found in sludges, debris, and soils on-site. Analyses of surface concrete debris and sludges found near the plating 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 surface where groundwater was encountered. EPA has removed the plating building and is now removing contaminated soil.

Boomsnub claimed to have a work force of thirty employees. This would be the maximum number of persons exposed through this pathway. Probably no more than three employees worked 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 in situations of exposure to chromium which EPA considered not safe. No test data pertaining to employee exposure to chromium or adverse health consequences were found.

Private Wells

Chromium was detected in five private wells near Boomsnub. The level of chromium ranged from 0.0112 parts per million (ppm) to 0.292 ppm. Monitoring of the private well with chromium at a level of 0.292 ppm in 1991 revealed the level had dropped to 0.03 ppm in December 1993. One private well over 3,000 feet downgradient from Boomsnub had chromium levels 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 been exposed for 27 years. The total number of people with water wells in groundwater contaminated by 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 is about 150 feet below ground surface. The plume of contamination is in the unconfined alluvial aquifer which overlies the confined Troutdale aquifer. A clay and silt aquitard separates the two aquifers, but there are known breaks in the aquitard. Clark County and Vancouver take water from a well field which is about one mile southwest and downgradient of the site. The rate of flow in the Troutdale ranges from 15 to 200 feet per day. By May 1994, the 2.0 ppm edge of the chromium plume in the surface aquifer was over 3,300 feet west of Boomsnub. The municipal wells at risk provide water to more than 50,000 people. Thus far neither chromium or VOCs have been detected in the at risk municipal wells.

TABLE 2
Completed and Potential Exposure Pathways

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

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

Where estimated daily exposure doses exceed MRLs or RfDs, we further compare with values called 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 to indicate possible human health effects. It should be noted that there are uncertainties when using these estimated doses and NOAELs, and in some cases the exposure may be above or below by a small margin. That small difference may or may not be protective for sensitive individuals or populations.

The assumptions used in calculating the estimated daily exposure dose from exposure to surface soil contaminants include an adult body weight of 70 kilograms (kg) and soil ingestion rate of 50 milligrams (mg) per day, and a child body weight of 16 kg and soil ingestion rate of 100 mg per day. Exposure for an adult worker was assumed to be five days per week for 20 years. Water ingestion 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 carcinogenic potential of specific chemicals. For many carcinogens, EPA has derived cancer slope factors or unit 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 the increased risk of developing cancer over a lifetime of exposure (70 years). Normally, as high as 300,000 people out of 1,000,000 develop cancer over their lifetime; in this section cancer risk is related as anticipated increase above this rate. Rates of cancer risk are qualitatively expressed in Table 3.

TABLE 3
Qualitative Cancer Risk

Chromium

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 that all exposure occurs to hexavalent chromium. Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. The most common forms of chromium are chromium (0), chromium (III) or trivalent, and chromium (VI). Chromium (III) occurs naturally, but Chromium (0) and Chromium (VI) are generally produced by industrial processes. 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 food containing 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 over land and water. Rain and snow help remove chromium from air. Chromium compounds will usually remain in the air for less than 10 days. Chromium VI is classified by EPA as a carcinogen when exposure is through inhalation. Long-term exposure to chromium has been associated with lung cancer in workers exposed to levels in air that were 100 to 1,000 times higher than those found in the natural environment. Lung cancer may occur long after exposure to chromium has ended (10).

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

TABLE 4
EPA's Chromium Health Advisory for Drinking Water

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

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

Without factual data for concentrations and specific knowledge of plating operations, it was not possible 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 been exposed 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 chromium exposure as a result of the completed pathway. The 1992 age-adjusted lung cancer incidence rate for Clark county (48.6 cases per 100,000 residents) was lower than the 1992 rate of the comparison population, all Washington residents (58.1 cases per 100,000 residents). This comparison 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 data may not detect an excess of lung cancer in a smaller population such as residents living near the site or the worker population. In addition, the 1992 Washington State Cancer Registry data may represent an under count of cases because case ascertainment from some participating hospitals is not complete.

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

The findings of the cancer cluster investigation included: the Clark County county-wide childhood cancer incidence rate is higher than expected for the period of 1980-1985, and the cancer incidence is primarily increased in persons aged 10-14 years for non-Hodgkin's lymphoma. Although the contaminant at this site (chromium) has no known relation to the non-Hodgkin's lymphoma, the cancer cluster investigation results were included because it was available 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 cooperation with the Southwest Washington Health District, the Department of Ecology, the City of Vancouver, Clark Public Utilities and the EPA, advised residents using private drinking water wells in the Boomsnub/Airco area to connect to a public water supply. Although most private wells are not affected at this time, the recommendation is made to ensure a continuing safe water supply, 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 during the period of May 1, 1995 through June 1, 1995. The document was made available at the Fort Vancouver Regional Library in Vancouver. A news release was sent to the Vancouver newspaper which published an article about the assessment. A fact sheet was prepared and sent to over two hundred parties on EPA's mailing list. No comments were received from the public on the health assessment.

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