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DISCUSSION

The sampling results discussed in this consultation were taken from the available data produced by the investigations of the property, and are not adjusted for limitations or bias in the sampling programs. The Tables presented in this consultation include maximum and median concentrations in the samples collected. Health discussions are based on the maximum concentrations reported and long-term, frequent exposure scenarios, which are reasonably conservative assumptions.

The type and severity of health effects associated with exposure to chemicals in the environment depend on the level, duration, and route of exposure. The age, sex, weight, preexisting health condition, and overall susceptibility of the individual also influence the health effects he or she may experience. Individuals show a wide range of variability in their tolerance of chemical exposure.

During the BFRA in October 1997, the MDEQ collected 28 surface soil samples (depth 0-3 inches) from the property1. They analyzed 23 samples for the full suite of inorganic and organic chemicals, one for metals, cyanide, and volatile organic chemicals (the fraction of that sample submitted for analysis for semi-volatile organic chemicals, pesticides, and PCBs was broken when it arrived at the laboratory) one for metals, cyanide, semi-volatile organic chemicals, pesticides, and PCBs, and three for only metals and cyanide. As shown in Table 1, one sample (MDEQ designation SS-29) contained a lead concentration above the MDEQ Generic Cleanup Criteria for Industrial, Commercial, or Residential Use.2  Another sample (SS-37) contained a chromium concentration above the MDEQ Residential Use Criteria (6, 7). These two concentrations were far above the typical values found in the samples, the second-highest chromium concentration (in SS-29) being 668 parts per million (ppm), the second-highest lead (in a third sample, SS-20) being 256 ppm. Sample SS-29 was described as a "composite of . . . dark brown to black soil, some moisture, some neon orange paint flakes, pieces of dead weed stems . . . from between concrete pad slabs . . . storage cubicle full of various chemicals, staining of concrete observed." Sample SS-29 also contained the highest antimony, arsenic, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, butylbenzylphthalate, cadmium, chrysene, cobalt, copper, 4,4'-DDE, dieldrin, fluoranthene, manganese, nickel, pyrene, selenium, silver, and zinc concentrations found in the surface soil samples. All of these concentrations were below the MDEQ Residential Criteria. Sample SS-37 was collected at the end of a drain pipe from a building on the property, and the MDEQ did not observe any stained soil in the area. Samples collected in an area of alleged chromate and hydrocarbon dumping north of the property fence did not contain any concentrations of chemicals substantially above those found in background samples (5).

Based on the maximum concentration found, a child subject to pica behavior 3might ingest more chromium each day per body weight, from the surface soil on the property than did people whose well water was contaminated with hexavalent chromium compounds and who suffered gastrointestinal problems after long-term exposure. Any child might incidentally ingest as much total chromium each day per body weight, from the surface soil on the property as did chromium-sensitive people whose dermatitis was exacerbated by ingesting one capsule containing a hexavalent chromium compound. Under current conditions, children are not likely to be on the property without supervision, however, MDCH has no information about planned redevelopment of the property. No information is available on what valence state the chromium in the surface soil on the property is in, but naturally-occurring chemical reactions in the environment tend to reduce hexavalent chromium compounds to much less toxic trivalent chromium compounds. Some workers in chromium-using industries and laboratory animals who inhaled hexavalent chromium compounds developed elevated rates of lung cancer. The U.S. EPA has classified hexavalent chromium compounds as known human carcinogens (U.S. EPA Class A). The available information does not allow an evaluation of the increased cancer risk from ingesting hexavalent chromium compounds or link exposure to trivalent chromium compounds with cancer (8).

Based on the maximum concentration found, anyone might incidentally ingest as much lead per body weight, each day from the soil on the property as did volunteers who showed changes in their blood chemistry after seven weeks of daily dosing with lead acetate. Lead is a cumulative poison, and long-term low-level exposure might cause as much harm as a single high dose. Some laboratory animals whose food or water contained lead developed elevated rates of cancer of the kidneys. The U.S. EPA has classified lead as a probable human carcinogen (U.S. EPA Class B2). The available information on lead exposure does not allow an evaluation of the risk of contracting cancer from ingesting the metal (9).

During the Remedial Investigation (RI) of the property in 1995, a U.S. Army CoE contractor collected 33 samples of subsurface soil from the 19 borings where they later installed temporary or permanent monitoring wells. One to four samples were collected from each boring, one at a depth of 0-2 feet 4 and as many as three deeper ones, as deep as 50-52 feet. They analyzed the samples for arsenic, cadmium, chromium, lead, mercury, cyanide, and organic chemicals. As seen in Table 2, none of the samples contained any chemicals at concentrations above the MDEQ Industrial, Commercial, or Residential Criteria (2, 6, 7).

During the BFRA in October 1997, the MDEQ collected a total of 54 subsurface soil samples from the property. These samples included 10 deep grab samples (depths ranging from 0-12 inches 4 to 24-36 inches) and two samples apiece (at different depths, typically 2-5 feet and 7-10 feet) from 22 borings. As seen in Table 2, none of the samples contained any chemicals at concentrations above the MDEQ Industrial, Commercial, or Residential Criteria (5, 6, 7).

During the RI in May 1995, a contractor for the U.S. Army CoE constructed 15 temporary and 4 permanent monitoring wells, depths ranging from 23 to 54 feet, on the property. They analyzed samples of groundwater collected from these wells for arsenic, cadmium, chromium, lead, mercury, cyanide, and organic chemicals. They analyzed filtered and unfiltered splits of each sample to obtain dissolved and total concentrations of the metals. The results are summarized in Tables 3 (temporary wells) and 4 (permanent wells). Some samples from the temporary monitoring wells contained total arsenic, total cadmium, total chromium, total and dissolved lead, and methylene chloride at concentrations above the MDEQ/U.S. EPA drinking water standards. Water from two of the permanent monitoring wells contained methylene chloride concentrations above the MDEQ/U.S. EPA drinking water standards (2, 7). One pair of samples had a much higher lead concentration in the filtered sample (61 ppb, the maximum concentration in filtered samples listed in Table 3) than in the unfiltered sample (1.1 ppb). This suggests that the lead detected in the filtered sample may have been an artifact of the analysis. Methylene chloride is a common laboratory contaminant.

During the BFRA, the MDEQ collected groundwater samples from the 4 permanent monitoring wells installed during the RI. One sample contained lead and thallium and another sample contained thallium at concentrations above the MDEQ/U.S. EPA drinking water standards (5, 7).

The dissolved metals concentrations, from the analysis of filtered water samples, might represent the concentration a person using the water as drinking water would be exposed to more accurately than the total concentration from unfiltered samples. A drinking water system might contain a filter or settling tank that would remove some of the suspended particles as the filter in the analysis did. In addition, the dissolved metals might be more easily absorbed by the body than would be metals retained in suspended particles.

No one is likely to ingest as much arsenic each day per body weight for body weight, from the groundwater, filtered or unfiltered, on the property as has been observed to be linked with adverse health effects in epidemiologic studies of humans or laboratory studies of animals. Some people whose drinking water contained high levels of arsenic for years suffered elevated rates of cancer of the skin, lung, liver, and bladder. The U.S. EPA has classified arsenic as a known human carcinogen (U.S. EPA Class A). Lifetime consumption of unfiltered groundwater on the property might result in a high increased risk of contracting cancer. Lifetime consumption of filtered groundwater on the property might result in a low increased risk of contracting cancer (11).

No one is likely to ingest as much cadmium each day per body weight, from the groundwater, filtered or unfiltered, on the property as has been observed to be linked with adverse health effects in epidemiologic studies of humans or laboratory studies of animals. Some workers in cadmium-using industries and laboratory animals who breathed cadmium dust developed cancer of the lung. The U.S. EPA has classified cadmium as a probable human carcinogen (U.S. Class B1). The available information does not allow an evaluation of the increased cancer risk from ingesting cadmium (12).

A child might ingest as much total chromium each day per body weight, from the unfiltered groundwater on the property as did chromium-sensitive people whose dermatitis was exacerbated by ingesting one capsule containing a hexavalent chromium compound. The filtered groundwater contained no detectable chromium. No information is available on what valence state the chromium in the groundwater on the property is in. Naturally-occurring chemical reactions in the environment tend to reduce hexavalent chromium compounds to much less toxic trivalent chromium compounds. Some workers in chromium-using industries and laboratory animals who inhaled hexavalent chromium compounds developed elevated rates of lung cancer. The U.S. EPA has classified hexavalent chromium compounds as known human carcinogens (U.S. EPA Class A). The available information does not allow an evaluation of the increased cancer risk from ingesting hexavalent chromium compounds. The available information does not link exposure to trivalent chromium compounds with cancer (8).

Anyone using the unfiltered groundwater at the property for drinking water might ingest per body weight, as much lead each day as did volunteers who showed changes in their blood chemistry after seven weeks of daily dosing with lead acetate. No one using filtered groundwater from the property is likely to ingest as much lead per body weight, from the groundwater at the property as has been observed to be linked with adverse health effects in epidemiologic studies of humans or laboratory studies of animals. Lead is a cumulative poison, and long-term low-level exposure might cause as much harm as a single high dose. Some laboratory animals whose food or water contained lead developed elevated rates of cancer of the kidneys. The U.S. EPA has classified lead as a probable human carcinogen (U.S. EPA Class B2). The available information on lead exposure does not allow an evaluation of the risk of contracting cancer from ingesting the metal (9).

No one is likely to ingest as much methylene chloride per body weight, from the groundwater at the property as has been observed to be linked with adverse health effects in epidemiologic studies of humans or laboratory studies of animals. Some laboratory animals who breathed or ingested methylene chloride developed increased rates of cancer of the liver, lung, or breast. The U.S. EPA has classified methylene chloride as a probable human carcinogen (U.S. EPA Class B2). Using water containing the methylene chloride concentration found in the groundwater on the property for drinking water is not likely to result in any apparent increased risk of contracting cancer (13).

No one is likely to ingest as much thallium per body weight, from the groundwater at the property as has been observed to be linked with adverse health effects in epidemiologic studies of humans or laboratory studies of animals. The available information does not link exposure to thallium with cancer (14).

During the BFRA, the MDEQ also collected samples of sediment from two manholes on the property. As seen in Table 5, none of the samples contained any chemicals at concentrations above the MDEQ Industrial, Commercial, or Residential Criteria (5, 6, 7). The MDEQ also collected five paint chip samples from in or around three buildings on the property, for analysis for lead. The paint chip samples contained up to 4,030 ppm lead. MDEQ staff also observed asbestos-containing materials (ACMs), with asbestos content ranging from 2% in vinyl floor tiles to 90% in furnace insulation, within the buildings on the property. MDEQ staff estimated that the amounts of ACMs present on the property exceeded the limits set in the U.S. EPA's National Emission Standards for Hazardous Air Pollutants (NESHAP), Asbestos Revision 5, above which removal of the ACMs is required before a structure is demolished. NESHAP also prescribes the appropriate techniques to be used while removing ACMs to minimize release of asbestos fibers and human exposure to the materials. The buildings were built at a time when lead-based paint and asbestos-containing construction materials and insulation were extensively used. A piece of green-stained wood collected from the property contained 2,380 ppm chromium (5).

Any child might incidentally ingest more lead each day per body weight, from soil containing the same concentration of lead as the paint chips collected from the property (for example, dust weathered off the paint) as did volunteers who showed changes in their blood chemistry after a few days of daily dosing with lead acetate. Lead is a cumulative poison, and long-term low-level exposure might cause as much harm as a single high dose. Some laboratory animals whose food or water contained lead developed elevated rates of cancer of the kidneys. The U.S. EPA has classified lead as a probable human carcinogen (U.S. EPA Class B2). The available information on lead exposure does not allow an evaluation of the risk of contracting cancer from ingesting the metal (9).

People who worked with asbestos have suffered from a lung disease called asbestosis and from lung cancer more often than other people. These effects are attributed to inhalation of free asbestos fibers. Some laboratory animals exhibited minor changes in their gastrointestinal systems when their feed contained asbestos fibers, and some studies of laboratory animals or humans who ingested asbestos have found a connection between ingestion of asbestos and cancer of the stomach, colon, and pancreas. However, the evidence for a connection between ingestion of asbestos and adverse health effects, including cancer, is considered extremely weak, because other studies of laboratory animals and humans have found no relationship between ingestion of asbestos and adverse health effects. The U.S. EPA has classified asbestos as a known human carcinogen by inhalation (U.S. EPA Class A) (15). Properly installed and intact asbestos-containing materials (ACMs) confine the asbestos fibers within a matrix or other containment system that prevents human exposure to the fibers. Degradation of ACMs over time or fracture of the materials during demolition of the buildings might release asbestos fibers into the environment. As mentioned above, NESHAP describes appropriate techniques to be used while removing ACMs to minimize release of asbestos fibers and human exposure to the materials. The available information on the KMC property does not report the concentration in any medium of loose asbestos fibers that might be inhaled or ingested.

A child subject to pica behavior might ingest more chromium each day per body weight, from soil containing the same chromium concentration as the wood sample (for example, dust weathered off the wood) than did people whose well water was contaminated with hexavalent chromium compounds and who suffered gastrointestinal problems after long-term exposure. Any child might incidentally ingest as much total chromium each day per body weight, from such soil as did chromium-sensitive people whose dermatitis was exacerbated by ingesting one capsule containing a hexavalent chromium compound. Under current conditions, children are not likely to be on the property without supervision, however, MDCH has no information about planned redevelopment of the property. No information is available on what valence state the chromium in the stained wood on the property is in. Naturally-occurring chemical reactions in the environment tend to reduce hexavalent chromium compounds to much less toxic trivalent chromium compounds. Some workers in chromium-using industries and laboratory animals who inhaled hexavalent chromium compounds developed elevated rates of lung cancer. The U.S. EPA has classified hexavalent chromium compounds as known human carcinogens (U.S. EPA Class A). The available information does not allow an evaluation of the increased cancer risk from ingesting hexavalent chromium compounds. The available information does not link exposure to trivalent chromium compounds with cancer (8).

The property is fenced, though the MDEQ observed large gaps in the fence during the field work for the BFRA and, as mentioned above, there are signs that trespass and vandalism has occurred (1, 3). The Army CoE contractors carrying out the RI in 1995 observed ordnance and explosive waste on the ground surface in a former target range north of the property and concluded that buried unexploded ordnance (practice 40-millimeter mortar rounds) might also be present (2). MDEQ staff observed unexploded ordnance and explosive waste in the area during the BFRA field work in October 1997 (16).




1 The MDEQ collected a total of 38 samples that they considered surface soil and labeled SS-01 through SS-34 and SS-36 through SS-39. These samples ranged in depth from 0-3 inches to 24-36 inches (5). Only 28 of these samples were in the range that ATSDR and MDCH consider appropriate to evaluate the concentrations people who come into contact with the soil are likely to encounter, not deeper than 6 inches. The remaining 10 samples are discussed below as subsurface soil samples. WW-35 was a sample of stained wood, discussed separately below.

2 The MDEQ Industrial and Commercial Clean-Up Criteria for lead were developed using the U.S. EPA Integrated UPtake Biokinetic MOdel for children, and are equal to the Residential Criteria. No risk assessment methods are currently available to evaluate lead toxicity in adults.

3 Pica behavior is an abnormal consumption of non-food materials, such as soil, most often seen in children under 5 years of age.

4 By ASTDR and MDCH policy, policy, soil samples that include surface material but are deeper than 6 inches are considered subsurface soil samples.

5 40 CFR Part 61, Section 61.145(a)


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