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Sampling data and supporting site-related information show that metals associated with process materials and wastes were present at the facility and accumulated in soils and groundwater, including some limited amounts in public and private drinking water. Liquids released by the facility to the tributary would be expected to have deposited metals in the channel but no substantive evidence of them has been found in sampling activities.

This section identifies contaminants ATSDR staff have selected for evaluation in later sections of this public health assessment to determine whether exposure to them has public health significance. However, ATSDR's identification of contaminants here does not imply that human exposure has occurred or that exposure would actually result in adverse health effects.

Contaminant selection considered the following factors:

  • Concentrations of contaminants in media
  • Relationship of concentrations to ATSDR's public health assessment comparison values; and the absence of valid comparison values.
  • Community health concerns

The EPA's Toxic Chemical Release Inventory (TRI) (12) does not contain information about industrial releases of toxic chemicals to the environment for the site vicinity.

Selected contaminant information is summarized in Tables 1 and 2 (Appendix B). Those tables include, where available, the public health assessment comparison values ATSDR used for selection. Reference Dose Media Evaluation Guide (RMEGs) comparison values are based on EPA's estimate of the daily dose below which exposure to a contaminant is unlikely to cause adverse noncancer health effects. Action Levels (ALs) are concentrations in drinking water, which, when exceeded, require implementation of a regulatory-based response protocol. EPA's Maximum Contaminant Levels (MCLs) represent contaminant concentrations that agency deems protective of public health (considering the availability and economics of water treatment technology).

Laboratory data presented in site-related documents report results for chromium either as chromium (VI) or as total chromium. Chromium occurs in the environment in several different forms. Two of the most common forms are trivalent [chromium (III)] and hexavalent [chromium (VI)]. Chromium (VI) is generally produced by industrial processes. Chromium (III) occurs naturally in the environment but can also be produced by industrial processes. The chromium (VI) form is associated with plating processes. KDHE staff told ATSDR that discussions with the city had shown that the person who analyzed groundwater from Colby public and private wells for Chromium (VI) from 1985 to 1988 used a colorimetric technique. KDHE has been unable to verify that groundwater samples have ever been analyzed for Chromium (VI) at the Kansas Health and Environmental Laboratory or other contract laboratory. Thus, the concentration data presented for Chromium (VI) in groundwater in this document may not be as accurate as laboratory analyses would provide.

A. On-Site Contamination

Conditions Prior to the 1992 and 1994 Removals

    Process Materials, Wastes, in Buildings

Sampling conducted in the plating and wastewater treatment buildings in the 1990s, after operations ceased, shows that accumulated solids contained elevated concentrations of total chromium and lead (Table 1). The highest concentrations (154,000 parts per million [ppm] and 38,500 ppm, respectively) were found in the wastewater treatment building. Liquids contained within these buildings were shown to contain total chromium at levels up to 441,000 parts per billion (ppb). In the plating building, sampling showed elevated concentrations of metals in concrete samples [chromium (VI), 21,100 ppm; lead, 6,020 ppm] taken from the plating troughs and the building floor. Dust residues that had accumulated in the plating building also were shown to contain high concentrations of metals (total chromium, 62,100 ppm; lead 24,300 ppm). No information is available about air quality in the wastewater treatment building and also the plating building (until after the 1994 removal), and metals concentrations have not been quantified for any media within the machine shop building and the chemical storage building (2, 7, 13).

    Media Outside Buildings

Samples of wastewater being discharged into the tributary during operations were shown in 1971 to contain total chromium at levels as high as 21,000 ppb (14) (Table 1).

Samples of surficial materials taken within the lagoon (could be either contaminated soil or sludge) in 1989 and 1993 showed total chromium present as high as 19,100 ppm and lead at 29,100 ppm. Surface soil samples taken elsewhere on the property showed total chromium present at less than 1,000 ppm and lead less than 300 ppm – except for a sample taken next to the chemical storage unit where total chromium was 79,200 ppm and lead was 81,800 ppm. Samples of subsurface soils taken down gradient from the lagoon in 1980 and 1990 showed total chromium and lead present at about 3,000 and 2,000 ppm, respectively. Subsurface soils elsewhere showed metals were at concentrations that appear to be typical of background levels (2,13,15).

Groundwater samples taken in the 1980s from the on-site recovery well showed chromium (VI) to vary up to nearly 1,000 ppb. Lead was found in 1991 to be less than 5 ppb (2,3).

Plating Building Air Quality Shortly After 1994 Removal

Two air samples taken in the plating building two weeks after the 1994 removal activities in that structure were completed showed the following maximum concentrations: total chromium, 37.4 g/M3; and lead, 6.7 g/M3 (7). EPA staff advised our personnel that eight-hour samples were taken. The doors were closed to exclude effects of ongoing removal activities outside the building. About once an hour during the tests, workers swept the floor to simulate a work-type air environment.

Residual Contaminants – After Latest (1994) Removal

    Interior Plating Building – Concrete Floor

Sampling data are not available to evaluate whether chemical washing of the plating building concrete floor was effective in converting chromium (VI) to chromium (III) (7).

    Beneath Plating Building Floor – Subsoils

Samples taken beneath the plating building during the 1994 removal show that metals were present at substantive concentrations in some soils that could not be excavated without endangering building stability; those concentrations are as much as: total chromium, 2,600 ppm; and lead, 120 ppm. Elsewhere beneath the building, residual levels in the subsoils are substantially less. Areas where contaminated soils remain beneath the building were covered with imported soil, and concrete was poured to reform the floor (7).

    Lagoon – Surface Soils and Subsoils

The lagoon area was excavated, covered with imported fill soil, and graded in 1994 (7). Sampling data for the imported fill show total chromium, 11 ppm and lead, 12 ppm (16). Samples were taken on a grid network prior to excavation in 1993 to identify the expected lateral extent of the affected area (15). An x-ray fluorescence (XRF) instrument was used during the removal to guide the lateral and vertical extent of excavation (8).

Some subsoils remaining in the lagoon area after excavation contain metals at low concentrations. Those materials are now covered with imported fill materials. Sampling data show maximum residual concentrations of total chromium, 560 ppm; and lead, 380 ppm (7, 16).

    Unexcavated Surface Soils Beyond Lagoon and Plating Building

Surface soil sampling in 1988 and 1993 extended beyond the area that was excavated during the 1994 removal. The maximum concentrations for samples taken in unexcavated areas are total chromium, 742 and lead 418 ppm. Almost all of the sampling results are less than half of these maximums (2, 15).

B. Off-Site Contamination

Tributary Soil/Sediment

Samples of surface soils or sediment taken within the unnamed tributary in 1989 both upstream and downstream from the facility showed about the same low levels of total chromium and lead (Table 2, Appendix B). Concentrations varied up to about 14 and 60 ppm, respectively (2).


    Monitoring Well Near ACE

An off-site groundwater monitoring well located a short distance east of the tributary showed total chromium to be as much as 1,910 ppb and lead 3 ppb from 1990 to 1991 (2). In 1995, sampling showed total chromium to be much lower, 345 ppb (17).

    Monitoring Wells at County Landfill

In 1995, a monitoring well at the county landfill immediately down gradient from the pit where the ACE sludge was deposited in 1981 showed total chromium and lead to be 20 and 5 ppb, respectively. At two other monitoring wells on landfill property, total chromium and lead were not detected (18).

    Public Water Wells

Water samples taken in 1980 from Well #8, located about 1,000 feet east of the ACE property, were found to contain total chromium up to 1,800 ppb (Table 2, Appendix B). That well was taken out of service later in 1980. A much earlier analysis in 1973 for chromium (VI) showed none was present (3). In 1995, total chromium at the former public well was shown to be 64 ppb (17). No data for lead have been reported.

Sampling of other public wells in the community in the 1970s, 1980s, and 1990 showed chromium (VI) up to 13 ppb, total chromium up to 40 ppb, and lead up to 6 ppb. Analysis in 1990 for nitrate (reported as N [nitrogen]), which is not associated with site activities, showed it to be at levels up to 4,400 ppb (2, 3). Sampling of public wells toward the mid 1990s showed low levels of total chromium and lead (a maximum of 10 ppb and less than 1 ppb, respectively). Chromium (VI) was not analyzed (19).

    Private Water Wells

During the mid to late 1980s and 1990, several private water wells as far as 9,000 feet down gradient (eastward) were sampled at least once. Most of those wells were located near, or along, U.S. Route 24. Those data showed chromium (VI) as high as 4,100 ppb for the nearest well, located 2,000 feet east of the site, near the city limits. Two months later, the concentration for that same well was 610 ppb and a few months later, none was detected. That well, and one on adjacent property, have been capped; those residents now use municipal water. Total chromium levels reported for the other private wells ranged from nondetect to 17 ppb. Lead results have not exceeded 6 ppb. In 1992, nitrate (reported as N), which is not associated with the site, was reported at elevated levels (up to 28,000 ppb) in two private wells in the site area within the city limits. KDHE advised those owners to discontinue use of the wells. (2, 3). Based on water department personnel descriptions of current private well usage in the area, ATSDR concludes that those well owners are now connected to the city water system. NorthWest Local Environmental Protection Group [NWLEPG] (a state-funded group) has been conducting "screening" analyses of private well water, upon request, since 1991 within a 16-county area. The group director reports that 7 of the 167 wells sampled (about 4 percent) in Thomas County to date have shown nitrate (reported as N) at levels greater than 10,000 ppb. The maximum level shown to date is 21,000 ppb. The director mails laboratory results to each well owner; the form mailed also identifies possible health effects of elevated nitrate on infants, indicates that nitrate cannot be easily removed from water, reports that the laboratory is not certified, and recommends that the owner have the water reanalyzed for verification (20).

In December 1995 and January 1996, eight private wells located east of the site along U.S. Route 24 at and beyond the city limits (which is about 3,000 feet east of site) were analyzed for total chromium and lead. Total chromium was not detected in any of the four wells on the north side of the highway. On the south side, the three wells nearest the city limits were shown to contain total chromium at levels of 14 to 24 ppb – total chromium was not detected in the well farthest from the city limits on that side of the road (17). There is uncertainty whether the chromium noted at those locations is site-related.


Discussion of specific human exposure pathways in this section does not imply that adverse health effects are associated with them; any health issues that may be associated with exposure pathways are discussed in the Public Health Implications section. ATSDR identifies human exposure pathways by examining environmental and human components that might lead to contact with contaminants. A pathway analysis considers five elements: a source of contamination, the presence or transport of contaminants in an environmental medium, a point of exposure, a route of human exposure, and an exposed population. Completed exposure pathways are those for which the five elements are evident, indicating that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. ATSDR regards people who come in contact with contamination as exposed: for example, people who drink contaminated water, or who reside in an area with contaminated air, or who work or play in contaminated soil are considered exposed. Potential exposure pathways are those for which one or more of the elements is not clearly defined but through which exposure is plausible. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. Elements of completed and potential exposure pathways are summarized in Tables 3 and 4 (Appendix B). Although the information available is ample for identifying several specific completed and potential human exposure pathways, data for confirming the degree and duration of exposure are not fully available.

A. Completed Exposure Pathways

Plating Chemicals, Residues, Building Components, Soils, Public Water Supply: On Site

ATSDR staff's observations and evaluations at active plating plants lead to a conclusion that ACE workers, during operations, were likely to have been substantively exposed to contaminants in plating chemicals, plating wastes, dust, building components, and, to a lesser extent, surface soils on site (Table 1) through incidental ingestion via hand-to-mouth activity, dust inhalation, and skin contact. Ace workers, while on the job, also were exposed by ingestion to some metals present in the public water supply. The general public water system pathway is described in the next subsection.

Public and Private Water Supply: Off-Site

In 1980, Well #8 (located 1,000 feet east of the site) was found to be introducing contaminated water (Table 2) into the public distribution system and was disconnected from service. Water from that well was being blended in the storage tank with whatever water remained in the tank from other supply wells that had been pumped on preceding days. Thus, the community was exposed to contaminant concentrations principally through ingestion at levels that, because of dilution, were less than Well #8 delivered to the tank. Because of blending effects, actual exposure concentrations cannot be identified. The available data suggest that exposure associated with that well might have occurred for several years. Concentrations reported in other municipal wells (Table 2) have been quite low and result in only nominal levels of exposure.

In private well sampling (Table 2) conducted eastward from the site through 1990 within and beyond city limits, one well was found to have elevated chromium (VI) for several months, and another had low levels of chromium (VI) for a short time. A few of the others sampled at that time had low levels of total chromium. City and EPA staff indicate that the residents whose well water once contained elevated chromium (VI) now are connected to public water. By 1995, everyone down gradient (eastward) within the city limits had been connected to the public water system except for one residence about 2,500 feet from the site. That well has not been sampled. Sampling in 1995 at several private wells east of the city limits showed that water from two wells has low levels of total chromium. The early and recent sampling information show that some residents have been and/or are being exposed to chromium principally through ingestion.

Two wells within the city limits in the site area were shown to have elevated nitrate in the past. However, recent information about water users indicates that those well owners now are connected to the city water. The director of NWLEPG, which samples private wells in the region, has reported that about 4 percent of the wells sampled to date in Thomas County contain elevated nitrate levels. Those well owners have been provided a form that shows the nitrate levels in their water, reports the difficulty of removing nitrate, and recommends resampling for verification. ATSDR believes that at least a few of the many county residents who have not had their wells tested are likely to have elevated nitrates in their water supply; also, some who have been notified of elevated nitrate levels may not respond appropriately. Therefore, it is likely that some county residents continue to be exposed to elevated nitrate levels and will be exposed in the future, principally through ingestion.

B. Potential Exposure Pathways

Facility Reuse: On Site

If the plating building is reused for recycling or other activities without further remediation, persons in the plating building are expected to be exposed to residual contamination principally through dust inhalation and by incidental ingestion. Sampling data are not available for either the small office area or for the entire machine shop building to evaluate whether potential exposures there might be substantive.

Ace Workers at Home: Off Site

Any of the former Ace employees that wore work clothes home were likely to have transported contaminants into their residences where family members would have been exposed in the past principally through inhalation and incidental ingestion. The extent of that potential past exposure cannot be evaluated.

Remedial Workers – 1981 Removal: On Site

Information about health and safety practices and protection for workers involved in the 1981 removal is not available. Without evidence of such practices, ATSDR presumes there was a potential for exposure to have occurred at that time at substantive concentrations principally through incidental ingestion and inhalation. The extent of that potential past exposure cannot be evaluated.

C. Other Exposure Considerations

The 1992 and 1994 removals were conducted under terms of health and safety plans, which required that workers wear protective clothing and respirators. KDHE and EPA staff indicate that those requirements were fulfilled. Therefore, ATSDR believes that substantive exposure is not likely to have occurred through any route.

The information obtained through the site visit and review of reference documents suggests that there has not likely been, nor will likely be, any substantive nonworker exposures through contact with surface soils, wastewater that formerly discharged to the tributary, tributary sediments, and tributary surface water.




This section discusses pertinent health effects in persons exposed to specific contaminants, evaluates state and local health databases, and addresses any specific community health concerns. To evaluate health effects, ATSDR has developed a Minimal Risk Level (MRL) for many contaminants commonly found at hazardous waste sites. The MRLs are similar to the reference dose (RfD) and the Reference Concentration (RfC) developed by the U.S. Environmental Protection Agency (EPA). The MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for specific routes of exposure, such as ingestion and inhalation, and for specific lengths of exposure, such as acute (less than 14 days), intermediate (15- 364 days), and chronic (greater than 365 days). ATSDR presents its MRLs in Toxicological Profiles. These chemical-specific profiles provide information about health effects, environmental transport, human exposure, and regulatory status. In the following discussion, ATSDR Toxicological Profiles for chromium and lead were used.

At EPA's request, ATSDR prepared public health consultations (November 28, 1995, and January 30, 1996) that addressed several specific types of future facility use: recycling, athletic practice, equipment maintenance, student dormitory (10,11). Key issues developed in those consultations about those uses, and also reuse in general, are provided in the Conclusions and Recommendations sections of this assessment.


Chromium exposure has occurred to former workers through inhalation and incidental ingestion of plating chemicals, plating wastes, soil, and dust. While on site, workers also ingested some metals in water provided by the public distribution system. Some residents that have used, or are currently using, wells for potable water in the general area have been exposed to chromium via that water.

Total chromium reported by investigation documents consists of two major chemical forms: the toxic chromium (VI) and the relatively non-toxic chromium (III). The specific ratios of these two forms have not been measured in the environmental media. However, some generalized species information is available for the concrete floors where analyses of separate samples suggest that the chromium in that medium is principally chromium (VI). Other separate samples of miscellaneous waste solids and sludge analyzed do not help identify the specific form of chromium present.

    Worker Exposure

Before the removal activities, chromium (VI) concentrations up to 23,900 ppm were found in the waste solids, sludge, and concrete floors in the plating building. ATSDR'S estimate of the former workers' exposure dose from ingestion of those contaminated media is five times greater than EPA's health criteria, based on a five-day work week.. The exposure dose is less than what might cause stomach upset and ulcers, but is comparable to the dose that has caused skin rashes in people sensitive to chromium (22).

Health effects associated with worker incidental ingestion of chromium in floor dust and soil cannot be estimated with certainty. If the chromium was entirely chromium (VI), then the ingested dose was high enough to have caused skin rash for people sensitive to chromium. However, if the chromium was entirely chromium (III), ingestion would not be expected to have caused any adverse effects.

If the chromium that Well #8 had added to the public water system from the late 1970s to 1980 was largely chromium (VI), that incremental chromium in the worker's drinking water would have been an added burden to those sensitive to chromium.

Air monitoring data are not available for the period the facility operated. Shortly after the most recent removal action some air samples were taken in the plating building; those data might represent levels to which the former workers could sometimes have been exposed. That sampling showed total chromium concentrations up to 37.4 g/M3. The ratio of the chromium (VI) to chromium (III) was not measured. If the chromium was largely chromium (VI), worker exposures would have been in the range that would have caused an increased risk of cancer and also noncancer effects. If chromium (III) predominated, worker effects would have been less likely.

    Resident Exposure

Some private wells once supplied residents with potable water containing chromium (VI) at levels up to 4,100 ppb. Locations formerly serviced by those specific wells are now connected to the public water system. Residents' exposures resulting from ingestion of such elevated levels are likely to have caused skin rash or stomach upset (22). In other private wells sampled, total chromium levels were found to be very low.

Well #8 once was shown to have contained total chromium at levels as high as 1,800 ppb. Chromium (VI) concentrations were not reported. The elevated chromium concentration in water from that well was reduced by an uncertain amount through dilution in the storage and distribution system. If the ratio of chromium (VI) to total chromium for Well # 8 at that time was the same as the ratio shown for other public wells, it seems likely that water distributed by the system in the late 1970s and in 1980 could have caused skin rash, especially in children sensitive to chromium.


Lead exposure has occurred to former ACE workers through contact with several media.

    Worker Exposure

Lead exposure occurred to former workers through inhalation and incidental ingestion of dust, waste solids, sludge, and soils.

During investigations associated with the removal actions, lead was found at concentrations up to 24,300 ppm in dust on the plating room floor. Levels in waste solids or sludge and the on-site soils were as much as 38,500 and 81,000 ppm, respectively. The estimated worker exposure to lead through incidental ingestion of building dust, the most frequent exposure likely, exceeds the harmful dose found in animal experiments. At this estimated exposure dose from dust, lead can increase blood pressure in laboratory rats. In addition, exposure to the greater lead levels that were present in on-site soil and sludge has been found to harm adult nerve, kidney, and reproductive systems. Those exposure levels also can increase blood pressure in men, but it is not known whether women are similarly affected. (21)


Two private wells within the city limits near the site were found to contain nitrate at levels that exceed drinking water standards; this nitrate is not related to ACE operations. The nitrate concentration (maximum 28,000 ppb) is great enough to interfere with the ability of the blood to transport oxygen and could cause "blue baby" symptoms if the contaminated well water was consumed by infants (23). The two well owners were advised to stop using well water, and ATSDR learned that those owners are now connected to the city water system. Information from the private well screening program conducted by NWLEPG shows that a few of those tested in the county have elevated nitrate levels and those owners have been notified. As part of a pregnancy testing program, the Thomas County Health Department notifies the NWLEPG to analyze nitrate levels in well water at the homes of participating women. Some private wells where elevated nitrates have been reported could still be in use. Also, some of the many private wells in the county that have not been tested are likely to yield elevated nitrates. Thus, ATSDR concludes that some private well owners currently consume elevated nitrates in their potable water and may experience adverse effects. Nitrate levels in the public water system are not elevated.

Under a professional health education program ATSDR sponsored earlier, nitrate toxicity information has been provided to some of the doctors in the state, including some in Thomas County.

B.     Health Outcome Data Evaluation

The Kansas Department of Health and Environment compiles summaries of vital statistic data from health records each calender year. ATSDR's review of data for 1986-1990 did not identify any abnormal rates of cancer or other cause of death in Thomas County, when compared to its surrounding counties and the state. A cancer registry for the state was started some 20 years ago. However, cancer incidence data relevant to the exposed populations addressed in this assessment are not available. A birth defect record begun in 1983/84 has not yet accumulated enough data for adequate evaluation.

C.     Community Health Concerns Evaluation

None of the few persons that attended the ATSDR public availability sessions that were advertised and held in Colby in September 1995 voiced any concerns that were health-related.

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