PUBLIC HEALTH ASSESSMENT
ORDNANCE PRODUCTS, INCORPORATED
NORTHEAST, CECIL COUNTY, MARYLAND
The tables in this section list the contaminants of concern. We evaluate these contaminants inthe subsequent sections of the public health assessment (PHA) and determine whether exposureto them has public health significance. ATSDR and MDE select and discuss these contaminantsbased upon the following factors:
- Concentrations of contaminants on and off the site.
- Field data quality, laboratory data quality, and sample design.
- Comparison of on-site and off-site concentrations with background concentrations, ifavailable.
In the data tables that follow under the On-site Contamination subsection and the Off-siteContamination subsection, the fact that a contaminant is listed does not mean that it will causeadverse health effects from exposures. Instead, the list indicates which contaminants will beevaluated further in the PHA. When selected as a contaminant of concern in one medium, thatcontaminant will be reported in all media.
- ITM II
|= Maryland Department of the Environment|
|= Maryland Department of Health and Mental Hygiene|
|= Cancer Risk Evaluation Guide|
|= Environmental Media Evaluation Guide|
|= Interim Technical Memorandum II|
|= Ambient Water Quality Criteria|
|= Maximum Contaminant Level|
|= Reference Dose Media Evaluation Guide|
|= Reference Concentration|
|= parts per billion|
|= parts per million|
Comparison values used during the preparation of a PHA are contaminant concentrations inspecific media used to select contaminants for further evaluation. Those values includeEnvironmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs),and other relevant guidelines. EMEGs are calculated from ATSDR's Minimal Risk Levels andprovide a guide to select contaminants for further evaluation of possible non-cancer health effectsupon exposure. CREGs are estimated contaminant concentrations based on one excess cancer ina million persons exposed over a lifetime (considered an insignificant risk). CREGs arecalculated from the U.S. EPA's cancer slope factors. EPA's Maximum Contaminant Level Goal(MCLG) is a drinking water health goal. The Ambient Water Quality Criteria (AWQC) are theU.S. EPA recommended surface water criteria for the protection of human health and aquaticorganisms.
In October 1988, O'Brien and Gere and UXB International, Inc., (UXB) an ordnanceinvestigation and removal company, performed an explosive hazards survey. Areas of concern,identified by geophysical and magnetic surveys, included landfills, solid waste dumping areas(including ordnance products), burn pits, and buried drums of hazardous waste (1). UXBcompleted an exploratory test pit to characterize the nature of subsurface soils in January 1990. The sampling data were collected and presented by O'Brien and Gere in the June 1990 ITM II (2).
In 1992, O'Brien and Gere released additional data which included sampling from on- andoff-site surface water, on-and off-site groundwater, and on- and off-site sediment. The data fromthe O'Brien and Gere sampling were used for health assessment purposes, although data were ofquestionable adequacy because the detection limits for many of the compounds were abovehealth based comparison values used by ATSDR and EPA. The sampling data may be used todemonstrate the presence of a substance which has been detected, but should not be used asindicators of the absence of any compounds which did not appear above the detection limits.
In this PHA, the sampling data collected through 1993 were used to identify contaminants ofconcern and to assess any potential adverse health effects from exposure to these contaminants. Since the initial release version of this PHA was drafted, new sampling data have becomeavailable. O'Brien and Gere have conducted additional sampling of the following media (3): 1)on-site groundwater monitoring wells sampled during January-May 1993 and January 1994; and2) off-site residential wells sampled quarterly during 1993 and again in February 1994. Thesemedia were analyzed for the presence of volatile organic chemicals.
These new data have been reviewed, yielding the following conclusions. No new contaminantsof concern were identified. None of the 1993-1994 samples revealed contaminants at levelsgreater than those detected in earlier years with one exception. One residential well sample (RW28), which was collected before filtration, contained one compound, trichloroethene, in slightlyhigher concentrations in 1994 (180 ppb) than the maximum value detected for that chemical inearlier years (145 ppb; see Table 14). This and other affected residential wells have filtration systems which remove contaminants before the water is used by residents.
The site was divided into 10 areas for evaluation of surface and subsurface soil contamination(see Figure 2). Characterization of contamination in areas A1, A2, B, C, D, E, F, H1, and H2were included in the Interim Technical Memorandum II (ITM II) conducted by O'Brien and Gere,contractors for the potentially responsible parties (PRPs). ITM II describes the aspects of the siteassessment work plan which have been completed. No contamination was found in area G. Maximum levels and the range of levels detected are shown in Tables 1 through 9.
Area A is a wooded area located along the western boundary of the site. Waste found in this areaincluded 32 empty drums, 16 drums containing metal grenade parts, 32 drums containing greensludge-like material, and 4 drums containing grey sludge-like material, all of which wereremoved during the Drum and Material Removal Program of 1988 (4). To characterize thecontaminants, Area A was further divided into Area A 1 and A 2.
Area A 1
During the site assessment work, twenty-nine soil samples were taken from Area A 1(twenty-five surface soil samples plus two duplicate samples, and one subsurface sample plusone duplicate sample). These samples contained levels of antimony and arsenic, which wereabove the ATSDR comparison values. Lead occurs naturally in soil, but several of the levelsfound in Area A 1 are above normal background levels. ATSDR has no comparison value forlead in soil. EPA has established a target cleanup level of 500 to 1000 ppm as an acceptablerange for lead in soil at hazardous waste sites. The highest level of lead found in Area A 1 was2,070 ppm. Arsenic is also a naturally occurring component of soil, and although the levelsfound in Area A 1 exceed the CREG of 0.4 ppm, they do not exceed the mean value of 7.4 ppmfound in the eastern United States (5). Antimony was detected in one of the twenty-nine sampleswhich exceeds ATSDR's comparison value for soil. Antimony is a component of the alloy whichis commonly used in the production of sheet and pipe metal, castings, and ammunition (6). Themaximum concentrations detected of these substances in Area A 1 are presented in Table 1.
Area A 2
Area A 2 is a wooded area on the western boundary of the site adjacent to Area A 1. Eighteensoil samples -- fifteen surface samples plus two duplicate surface soil samples, and onesubsurface sample -- were analyzed for inorganic contamination (see Table 2). Arsenic wasdetected in all eighteen soil samples above ATSDR's comparison value. However, the range oflevels detected does not exceed the mean level of arsenic found to occur naturally in the eastern United States.
Area B is a heavily wooded area located in the north-central portion of the site. Reports list avariety of structures in this area including three test bunkers, a trailer, a storage shed and severalother small structures. Ten soil samples were analyzed for organic and inorganic contaminationand are listed in Table 3. Solid and liquid waste containers, some of which contained titanium,zinc, graphite powder, vermiculite, cement thickener (Napalm), paints, roofing tar, andordnanceparts, were removed (2).
A total of twelve soil samples were taken -- nine surface samples plus one duplicate surfacesample, and one subsurface sample plus one duplicate subsurface sample. Sampling resultsrevealed the presence of arsenic above ATSDR's comparison values. Arsenic was detected in alltwelve samples above ATSDR's comparison value; however, none of the samples exceeded themean soil concentration for naturally occurring arsenic in the eastern United States.
Area C is located at the northernmost section of the site. The area is predominantly open field,covered with low shrubs and grasses and a few trees. Before the removal, a trailer was located inthis area which contained drums of liquid and solid waste, including aluminum powder, ironoxide, milk sugar, an unknown grey powder, and ordnance parts. An area of green sludge thathad a depth of at least twelve feet was found during the excavation of an exploratory test pit. A geophysical survey revealed burn areas with remnants of steel, smoke grenades, and fuses (2).
Twenty-three soil samples from Area C -- nineteen from surface soil, one from subsurface soiland three field duplicates -- were analyzed for organic and inorganic contamination. In one ofthe samples, chromium was detected above ATSDR's comparison value of 300 ppm. Arsenicwas also detected at levels above ATSDR's comparison values in all of the samples but wasbelow the mean soil concentration generally found in the eastern United States.
Areas D and E
Areas D and E cover the wooded, southwestern section of the site. These areas will be discussedtogether as they are small, similar areas within close proximity of each other. Soil from apre-existing hole of size eight feet by four feet in Area D was analyzed for contamination. Thehole is periodically filled with water. The source of the water, whether ponded rainwater orgroundwater, is not known. One surface soil sample was taken from Area D. A total of eightsoil samples -- six surface, one subsurface and one duplicate sample -- were collected from AreaE. In all nine soil samples, arsenic was detected above ATSDR's comparison value for chronicexposure; however, only one exceeded the mean soil concentration found naturally in the easternUnited States. Soil samples from Area E also contained trace amounts of six volatile organiccompounds, none of which approached ATSDR's comparison values. The water from Area Dwas also analyzed for organic and inorganic contamination and will be discussed in the surfacewater section.
Area F is a wooded, two acre piece of land located in the southwest portion of the site adjacent toboth Areas D and E. Aerial photos and excavation of an exploratory test pit revealed threeburned areas within Area F which were formerly used as burn pits. The exploratory test pit alsorevealed the presence of buried debris including steel pipe, cable and banding, blasting caps,grenades and grenade fuses, and spoons, and several badly deteriorated fifty-five gallon drums of grey sludge (2). A total of thirty-three soil samples were taken in Area F, twenty surface, nine subsurface and four duplicate samples.
The analysis of the samples revealed levels of chromium, nickel, and arsenic above ATSDR'scomparison values. Lead was also detected in a sample at 3,300 ppm, which is above EPA'starget cleanup level of 500 ppm. Samples were taken from the bermed areas and areas where thedebris was removed (2). Chromium was detected above the comparison value for non-cancerhealth effects in five of the thirty-three samples, with a maximum detected concentration of1,900 ppm. Nickel was detected above the comparison value for intermediate exposures in threeof the thirty-three samples taken. The maximum concentration of nickel detected was 3,700ppm; ATSDR's comparison value for nickel in soil is 1,000 ppm. Arsenic was detected aboveATSDR's comparison value in all of the thirty-three samples taken; however, none of the samplescontained levels of arsenic above the mean soil concentration for the eastern United States. Trace amounts of six volatile organic compounds were detected in this area, none of whichapproached ATSDR's comparison values (see Table 9).
Area H 1
Area H 1 is located in the central portion of the site, near the surface water impoundments. Atthe time of the Interim Technical Memorandum I in March 1989, Area H was occupied by ScottPowder Company, which tested and stored shotgun ammunition. Twenty soil samples weretaken, fifteen surface, three subsurface, and two field duplicate samples (see Table 7). Thesamples were taken from areas where dumping of general refuse and grenade parts took place.
In one of the twenty samples taken, antimony was detected at 25 ppm, which is above ATSDR'scomparison values. ATSDR's comparison value for chronic exposure to antimony is 20 ppm. Arsenic was detected in all twenty samples above ATSDR's comparison value for chronicexposure but was well below the mean soil concentration for the eastern United States. Two ofthe samples taken from Area H 1 contained trace amounts of several volatile organic compounds,including vinyl chloride, trans-1,2-dichloroethene, TCE, toluene, and xylenes, none of whichexceeded ATSDR's comparison values (see Table 9). The detection limits for these VOCs wereextremely high due to sample dilution. Therefore, the sampling results are not informative onwhether or not low levels of VOCs were present in this area.
Area H 2
Area H 2 is located in the central portion of the site adjacent to area H 1. A total of sixteensamples -- twelve surface and three subsurface samples, and one field duplicate sample -- weretaken from Area H 2. Arsenic was detected above ATSDR's comparison value but was below themean soil concentration for the eastern United States. Although six volatile organic compoundswere detected, they were all well below ATSDR's comparison values (see Table 9). Themaximum concentrations of inorganic contamination from the sampling results are shown inTable 8.
A total of twenty-nine sediment samples taken from the five surface water impoundments locatedin the eastern central section of the site adjacent to Area H 1 and several on-site drainage streamswere analyzed for organic and inorganic contamination. In a later sampling round conducted inJune 1991, two additional sediment samples were taken from each of the surface impoundmentsat depths of zero to one foot and one to two feet to evaluate the vertical distribution ofinorganics.
The surface water impoundments were reported to have been used for collection of platingoperations wastewater, and disposal of organic solvent waste (7). Four sediment samples weretaken from each of the five surface water impoundments, with duplicate samples taken atImpoundments 3 and 4 for a total of twenty-two samples.
Inorganic analysis of the sediment samples revealed the presence of concentrations of antimony,cadmium, and chromium, which exceeded ATSDR's comparison values for soil in three of thefive impoundments. Although there is no ATSDR comparison value for lead in sediment, thelead level in sediment samples from Impoundment 4 exceeds EPA's target cleanup level of 500ppm. Zinc was also detected above ATSDR's comparison value for soil in Impoundment 4. Arsenic was detected above ATSDR's comparison value for chronic exposure in all fiveimpoundments; however, arsenic was only detected above the mean soil concentration for theeastern United States in Impoundment 4. The maximum concentrations of the contaminantsfound in the sediment samples from the surface water impoundments are presented in Table 10.
The data collected from June 1991 sampling regimen indicated that the concentrations ofinorganics decreased significantly with depth.
Analysis of the surface water impoundment sediment samples revealed trace amounts of threevolatile organic compounds (see Table 10). None of these samples contained VOCs whichapproached ATSDR's comparison values. Two other VOCs, vinyl chloride and PCE, were notfound at levels above their detection limits. However, the detection limits for the latter VOCs were well below their respective ATSDR comparison values.
Several small streams cross the site from west to east and eventually drain into Little NortheastCreek. These streams flow intermittently, and during the October/November 1989 sampling, oneof the streams was dry. Seven sediment samples were taken from various locations in theseon-site streams (see Figure 3).
Inorganic analysis of the stream sediment samples revealed concentrations of arsenic whichexceed ATSDR's comparison value; however, these concentrations do not exceed the mean soilconcentrations for arsenic in the eastern United States. The results of the sediment sampling are presented in Table 10.
Surface water samples were taken from the following areas: one sample from each of the fivesurface water impoundments; six samples from the on-site streams (one proposed sampling sitestream was dry); and one sample from the surface water located in Area D (see Figure 4). Thesurface water sampling results are presented in Table 11, Appendix A. Concentrations ofsubstances present in surface water are compared to drinking water comparison values, eventhough these waters are not used for drinking.
Samples taken from the streams were analyzed for thirteen inorganics including copper, zinc, andarsenic. Inorganic analyses of the samples taken from the streams and from the surface waterimpoundments revealed no contamination above the detection limits for arsenic and copper. Zinc was detected above the detection limits but far below ATSDR's comparison value for zincin drinking water. Inorganic analysis of the sample taken from the surface water in Area D wasnot available.
Seven surface water samples were analyzed for the presence of twenty-eight VOCs includingvinyl chloride, t-1,2-dichloroethene, TCE, PCE, toluene, and xylenes (see Table 11). Organicanalysis of the seven surface water samples taken from the on-site streams contained a maximumconcentration of 19 ppb TCE, which exceeds ATSDR's comparison value, in surface watersample 6 (SW-6). SW-6 was taken from a stream at the far eastern border of the site, before thestream flows off-site. PCE was detected in SW-6 at 7 ppb, which exceeds ATSDR's drinkingwater comparison value. Also detected in the SW-6 were low levels of t-1,2-dichloroethene andtoluene, neither of which exceeded ATSDR's comparison values for drinking water.
Organic analysis of the water samples from the five surface water impoundments revealed verylow levels of t-1,2-dichloroethene and toluene, neither of which exceeded ATSDR's comparisonvalues for drinking water. TCE was detected at a maximum concentration of 6 ppb, which doesexceed ATSDR's comparison value for drinking water.
Organic analysis of the surface water from Area D revealed concentrations of TCE and PCEabove ATSDR's comparison values for drinking water and above the AWQC for human health. TCE was detected at a maximum concentration of 79 ppb. The maximum concentration of PCEdetected was 320 ppb.
There are a total of eleven groundwater monitoring wells and two supply wells on the MechanicsValley Trade Center property (see Figure 5). Five of the monitoring wells are shallow and rangefrom 15 to 60 feet deep. The six deep monitoring wells range in depth from 100 to 300 feet. Allof the wells, except for monitoring well 3 (MW-3), were installed as two-well nests, one tosample the deep groundwater and one to sample the shallow groundwater (2). One of the twosupply wells, Supply Well 2, was not functional at the time of the sampling; therefore, onlysupply well 1 (SW-1) was sampled.
The monitoring wells and the supply well were sampled on three occasions during the firstsampling round, October 31 and November 1 and 13, 1989. Analysis of groundwater from themonitoring wells did not detect any significant inorganic contamination. Samples were analyzedfor thirteen inorganics including copper, zinc, and arsenic. Concentrations of copper and zincwere detected at just slightly above the detection limits of 0.01 ppm. Arsenic was detected abovethe 0.005 ppm detection limit. Analysis of the water from Supply Well 1 detected copper, zinc,and arsenic above the detection limits. A concentration of 0.007 ppm arsenic was detected insupply well 1, which exceeds ATSDR's comparison value for children of 0.003 ppm.
A total of sixteen groundwater samples from the monitoring wells were analyzed for organiccontamination: six samples from shallow monitoring wells and ten samples from deepmonitoring wells. The samples were analyzed for twenty-eight VOCs including vinyl chloride,t-1,2-dichloroethene, TCE, PCE, toluene, and xylenes. No organic contamination was foundabove the detection limits in monitoring wells 1, 3, and 6. These monitoring wells are all located along the periphery of the property.
Monitoring wells 2S and 2D are located in the northwestern portion of the site, adjacent to theland owned by the Polo Pallet Company. Analysis of the samples collected from monitoring well2-shallow (MW-2S) detected 16 ppb toluene. ATSDR's comparison value for toluene indrinking water is 2,000 ppb. Monitoring well 2-deep (MW-2D) did not show any organiccontamination above the detection limits.
Monitoring wells 4S and 4D are located on the border of Area H 1, in the western central portionof the site. Analysis of the groundwater samples from MW-4S detected concentrations of vinylchloride (11 ppb), t-1,2-dichloroethene (260 ppb), TCE (720 ppb), and PCE (1,900 ppb), whichexceeded ATSDR's comparison values for drinking water. Maximum concentrations detectedare presented in Table 12. Analysis of the samples from MW-4D revealed low, but consistentlevels of TCE. The levels of TCE detected in MW-4D did not exceed ATSDR's comparisonvalue for TCE in drinking water.
Monitoring wells 5S and 5D are located near Area H 1, between the surface water impoundmentsand the eastern property border. Analysis of the groundwater samples from MW-5D detectedlevels of TCE (2,800 ppb) which exceed ATSDR's comparison values for drinking water. Maximum levels of contaminants are presented in Table 12. Analysis of samples from MW-5Sdid not reveal any inorganic contamination above detection limits.
Supply well 1 is located in the eastern central portion of the site between Area H 1 and Area H 2. Analysis of the water from SW-1 revealed levels of vinyl chloride (57 ppb), t-1,2-dichloroethene(100 ppb), TCE (97 ppb), and PCE (38 ppb), which exceed ATSDR's comparison values fordrinking water. The highest groundwater concentration of vinyl chloride, 57 ppb, was detectedin a sample from SW-1, but the levels of the other organic contaminants found in SW-1 weresignificantly lower than those found in MW-4S and MW-5D. Those concentrations andcomparison values are presented in Table 12.
On-site monitoring wells were sampled again by O'Brien and Gere in January 1992. Thelaboratory methods used dilution with many of their more contaminated samples, thereby raisingalready high detection limits even further for other compounds in the sample. In this round ofsampling, four contaminants were detected above detection limits. These results must beconsidered somewhat unsuitable for detection of many of the contaminants of concern, as thedetection limits are above the health based comparison values.
During this January 1992 sampling of the on-site monitoring wells, 1,2-dichloroethene, PCE,TCE, and vinyl chloride were all detected at concentrations which exceed ATSDR's comparisonvalues. These results are presented in Table 12.
Air monitoring was performed at three locations (upwind, downwind, and within the area) oneach site at Areas A, B, C, D, E, F, and H in October 1989. Areas A and B were analyzed formetals and no airborne releases were detected. Areas C, D, E, F, and H were analyzed for both metals and volatile organics. Areas D, E, and F (D-E-F) weresampled together as one area. Low levels of 1,1,1-trichloroethane were detected in Areas C andH. Low levels of 1,1,1-trichloroethane were also detected in Area D-E-F, but the levels wereconsidered invalid as they were lower than those levels detected in the laboratory blanks. Thelevels detected in Areas C and H were one to two orders of magnitude lower than ATSDR'scomparison value for 1,1,1-trichloroethane in air.
MDE conducted a residential well sampling survey the results of which were released in March1988. In this survey, a total of thirty-nine residential wells were sampled. Several of theresidences already had filtration systems installed. Samples were taken of the raw water before itwas filtered at these residences. Six of these wells showed contamination with organiccompounds. Although this sampling was conducted primarily to identify TCE, PCE, and1,2-dichloroethene, it also identified the presence of methylene chloride in several of the wells. Detected in one of the residential wells sampled (RW-53) were extremely high levels ofmethylene chloride, chloroform, acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone(MIBK). Upon resampling of this well two weeks later, the levels had dropped dramatically andwere gone by the third and fourth rounds of sampling two months later. The conclusion at thetime of the Screening Site Inspection conducted by MDE was that the contamination wasprobably from a source other than the site.
In 1988, after the release of the MDE sampling data, fifty-three residential wells were sampledfor organics contamination in a Well Inventory and Sampling Program conducted by O'Brien andGere. All but one of the wells sampled were located on residences off-site along the boundary ofthe site. The other well was an on-site private well (RW-14), which was used as a drinkingsupply. The residential well survey identified six wells which showed contamination withorganic compounds. All of the off-site wells with contamination were located along the easternborder and downgradient of the site. 1,1-Dichloroethene, 1,2-dichloroethene, PCE, TCE, andvinyl chloride were detected in RW-14. TCE was the only contaminant detected abovecomparison values in the off-site residential wells sampled, with the exception of RW-53. Analysis of a sample taken from RW-53 revealed 9 VOCs, 4 of which were present at levelswhich exceeded ATSDR's comparison values. Many of the contaminants contained in thissample were not found in groundwater from the site. The levels of contamination decreaseddrastically upon the second sampling event and were completely gone within 3 months. Thissuggests that the contamination found in RW-53 was not related to the OPI site.
TCE was detected in four of the five contaminated off-site residential wells. The maximum levelof TCE detected was 160 ppb in RW-14. The highest off-site residential well sampleconcentration was 46 ppb, which exceeds ATSDR's comparison value. 1,1-Dichloroethene wasdetected in RW-14 at 2 ppb, which also exceeds ATSDR's comparison value. 1,2-Dichloroethene was detected in two of the residential wells (one off-site and one on-site), butneither sample exceeded ATSDR's comparison value. PCE was detected in RW-14 at 68 ppbcompared to 0.7 ppb, ATSDR's comparison value for chronic exposure. Vinyl chloride wasdetected at 90 ppb in RW-14. ATSDR's comparison value for chronic exposure to vinyl chlorideis 0.2 ppb.
The five wells which had shown contamination were sampled twenty-two times over the periodfrom October 1988 through April 1990 by O'Brien and Gere. Maximum levels of contaminationfound in both on and off-site residential wells are presented in Table's 13, 14a and 14b.
More recent residential well data obtained from O'Brien and Gere describe thirty-one rounds ofsampling during the period from January 1990 through July 1993. During this period, sixresidential wells were sampled approximately eight to ten times per year. The sampling datafrom O'Brien and Gere record concentrations of contaminants in samples taken from residentialwells, both before filtration and after (see Tables 14a and 14b, respectively). Low levels ofcontaminants, including methylene chloride and TCE, were detected in samples taken fromtapwater during the sampling in 1991. This may have been due to improper functioning of thefiltration systems or inadequate maintenance of the filters. Alternatively, methylene chloride, acommon laboratory reagent, may have been a laboratory contaminant; it was neither detected inthe raw well water nor in the mid-point samples collected between the carbon filters. Thedetected TCE may have alternatively resulted from a raw well water sample that was mislabelledin the laboratory. The levels of contamination detected in these samples are presented in Table15. Residential water systems are currently (as of February, 1995) being sampled at a frequency of every six weeks.
There is no record of off-site soil sampling having been conducted near the Ordnance site. Significant contamination of off-site soils would not be expected based on the identification ofonly sporadic areas of surface soil contamination on the site. Furthermore, off-site soil migrationwould also be minimized by the site topography, which directs surface run-off to streams anddrainage ditches on each side of Mechanics Valley Road. Elevated levels of contaminants werenot detected in the sediment of on-site intermittent streams which drain the site, and which couldpotentially transport contaminants off of the site. A more complete assessment would bepossible if sampling was conducted to document that there has been no contamination of off-sitesoils which might receive surface run-off from the site.
As part of the Ground and Surface Water Sampling Summary conducted in March of 1988, MDEconducted sampling of Little Northeast Creek and several of the drainage ditches originating onthe Ordnance site. The highest levels of contaminants were detected in Little Northeast Creeknear the intersection of Mechanics Valley Road and Stevenson Road adjacent to the property 411Stevenson Road. The maximum level of contamination found in the creek during this time was 5ppb TCE, which exceeds ATSDR's comparison but not the AWQC. Contamination with TCEand 1,2-dichloroethene was also detected in surface water samples taken from a drainage ditchnear Dean's Lane and Little Northeast Creek.
As part of the sampling being conducted by O'Brien and Gere, surface water samples were takenfrom Little Northeast Creek in February 1993. Two sampling points were chosen along LittleNortheast Creek. Another two off-site samples were collected along a stream which flows fromthe site into Little North East Creek. As was the case with all of the 1992 and 1993 samplingcompleted by O'Brien and Gere, detection limits of most of the contaminants were aboveATSDR's comparison values for drinking water, and therefore, many of the contaminants mayhave been present but not detected. One sample from the stream feeding into Little North EastCreek (Site #2) contained 1,2-dichloroethene, TCE, and PCE. The maximum levels ofcontamination were detected adjacent to several properties along Mechanics Valley Road whereresidential well contamination has also been detected. Maximum levels of contaminants foundare presented in Table 16.
In order to characterize off-site migration of contaminants, ten off-site monitoring wells wereinstalled in 1992. The wells are situated in five well nests, each consisting of one deep and oneshallow well (OSW-1S and 1D through OSW-5S and 5D, with S designating shallow and Ddesignating deep). The wells are east of the site between the site boundary and Little NortheastCreek. O'Brien and Gere sampled these wells in January 1993. Because the analytical labdiluted samples highly contaminated with one or two substances, detection limits of many othercontaminants are higher than ATSDR's comparison values. Therefore, it is not possible todetermine whether these contaminants are present at levels which are lower than the detectionlimits but higher than the comparison values.
Of the five well nests, three of the monitoring wells showed contamination in two locations. TCE was detected in OSW-2S, OSW-3S, and OSW-3D. The maximum level of TCE wasdetected in OSW-3D at 2,800 ppb, indicating the greatest contamination in the deep groundwaterin that area. The maximum concentration of contaminants detected are presented in Table 17.
The sediment along Little Northeast Creek was sampled in February 1993 by O'Brien and Gere. Sediment was taken for analysis from the same general area as the surface water samples. Theanalyses detected 1,2-dichloroethene, TCE, and PCE in the sample, SP-2 (taken from the samelocation as surface water sample, Site #2); however, the concentration of contamination wasbelow ATSDR's comparison values for these contaminants in soil.
We have obtained some of the Quality Assurance/Quality Control Summaries from EPA. Firstsubmission of the Interim Technical Memorandum and Site Assessment Work Plan was notaccepted by EPA in August 1989. Recommendations were made by EPA, and a resubmittal ofthe plan was requested. The work plan was resubmitted and accepted in September 1989.
The sampling data submitted by O'Brien and Gere were of limited use because of high detectionlimits. The laboratory used by O'Brien and Gere used dilution methods to quantify a specificcontaminant in a sample, which elevated the detection limits for all other contaminants in thesample above comparison values. This made interpretation of the sampling data impossible formany of the contaminants. The result of employing this dilution method is that the presence ofsome contaminants may have been missed entirely.
A wide variety of potential physical hazards exist for employees at MVTC and for thosetrespassers who gain access to the site. There are approximately 53 building structureson site, one of which contained drums of explosives and grenade fuses. During the site visit,MDE observed that the lock on the door of the building housing the drums of explosives andgrenade fuses had been vandalized and was easily accessible. The drums have subsequently beenremoved from the site for disposal in accordance with local, state, and federal regulations. The site is scattered with abandoned mobile homes, rusting vehicles, and large appliances.
During the site visit, two hummocky areas (hilly areas of mounds) where ordnance products areburied were observed to be unrestricted and unmarked as to any existing hazard. Investigationsby UBX, the subcontractor specializing in pyrotechnics and explosives who assisted in theinventory of site hazards, noted that fuses in pits on the site presented no explosion risk yetcould, if intact, produce a small burst of fire when either detonated or ignited (8).
The five surface water impoundments adjacent to Area H 1 and the ponded water in Area D,where organic and inorganic contamination has been detected, are also unrestricted andunmarked.
The Toxic Chemical Release Inventory (TRI) is a publicly available database that containsspecific toxic chemical release and transfer information from manufacturing facilities throughoutthe United States. Manufacturing facilities that have 10 or more full-time employees and thatmanufacture or process more than 10,000 pounds of any of over 300 listed chemicals must reportto the TRI (9). TRI data were reviewed in order to evaluate if there are any other possiblesources of the contamination found near OPI. All six years of available data were reviewed. Although one wood treatment facility, located about a mile from OPI, reports releases to the airof chromium and arsenic, it is unlikely that these emissions would have contributed to thecontamination at OPI because of the distance between the two sites.
To determine whether nearby residents are exposed to contaminants migrating from the site,ATSDR evaluates the environmental and human components that lead to human exposure. Exposure pathways consist of five elements: A source of contamination, transport through anenvironmental medium, a point of exposure, a route of human exposure, and an exposedpopulation.
ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if theexposure pathway cannot be eliminated. In completed exposure pathways, the five elementsexist and indicate that exposure to a contaminant has occurred in the past, is occurring, or willoccur in the future. In potential exposure pathways, however, at least one of the five elements ismissing, but could exist. Potential exposure pathways indicate that exposure to a contaminantcould have occurred in the past, could be occurring now, or could occur in the future. Anexposure pathway can be eliminated if at least one of the five elements is missing and will never be present.
Completed exposure pathways are summarized in Table 18 and are discussed below.
People who worked and lived on the site are assumed to have been exposed in the past tocontaminants in surface soil because access to contaminated areas was not restricted or posted. Exposures may now be occurring and could continue to occur in the future if access tocontaminated areas is not restricted. The routes of exposure are through inhalation of dust,dermal contact, and incidental ingestion of soil or dust. The number of people likely exposed toon-site soil contaminants cannot be estimated because squatters may have come and gone andbusinesses may vary over time with the number of people employed. Those people living on thesite, especially children, were likely to have come into contact more often with contaminatedsoils than people who worked inside of buildings.
Antimony, chromium, lead, and nickel have been detected in the soil at levels above ATSDR'scomparison values in Areas A 1, C, F, and H 1. Arsenic was also detected at levels which exceedATSDR's comparison values; however, most of the samples did not exceed the mean soilconcentrations for the eastern United States. Therefore, most of the arsenic detected is probablynot related to past activities from the OPI facility. Soil data exist for only small portions of eacharea where contamination was suspected, which leaves most of the on-site soil not yetinvestigated. The soil sampling data that exist characterize sporadic levels of contaminationamong the different areas sampled; therefore, calculation of dose estimates from soil exposure is difficult.
People were exposed to contaminants in the past through use of contaminated groundwater. Present and future exposures are possible from use of groundwater containing contaminants fromthe site if filtration systems fail or if contaminants enter wells that were previously notcontaminated. The first residential well sampling was done by MDE in August 1987. After theresults were returned, a meeting was held with the previous owner of the property. The owneragreed to install four off-site residential well water filter systems and a water treatment systemfor the on-site contaminated wells. In November 1987, a consent order was issued by the Stateof Maryland pertaining to the off-site water filter systems, and a deadline of November 30, 1987,was specified for the filters to be installed. The residences with contaminated well water were supplied with water filtration systems by that date.
The routes of exposure are through ingestion, inhalation of volatilized compounds (whilecooking or showering), and dermal contact. The duration of exposure from contaminatedgroundwater is not known. It can be assumed that, at some point between 1960 and 1987, theresidents (an estimated 12-20 people) of the six residences began drinking, showering, andcooking with contaminated well water. One of the wells, on-site RW-14, is reportedly not in useat this time, although that has not been confirmed. Contamination in another off-site residentialwell was only detected during a three month period and was not believed to be site related. Water filtration systems have been installed for the other four residential wells; these systems aremaintained and sampled every six weeks by O'Brien and Gere. Because the extent of the plumeof contamination has not yet been defined, other residential wells could possibly be or becomecontaminated in the future. From 1990 through 1994, only the four residential wells with knowncontamination were sampled.
In fact, there is evidence that additional contamination of off-site residential wells is possiblyoccurring. As a result of the public availability session held during the public comment periodfor this PHA, residents without prior well contamination living near the site requested to havetheir wells tested. The Cecil County Health Department carried out testing in the spring of 1995. At least two additional off-site wells were found to be contaminated with VOCs, including onewell with PCE at levels exceeding ATSDR's CREG (see Public Comment section of this PHA). It is not clear, at this time, if the newly detected contamination is site-related. The Cecil County Health Department is currently investigating this matter in collaboration with MDE.
People working on the site have been exposed to contaminants through use of contaminatedsupply well water. Current and future exposures are possible if the filtration system does notfunction properly. There are currently two supply wells located on the OPI site: one functionaland one non-functional. The two wells were used in the past for potable water by businesses onthe site; however, bottled water is now reportedly used for drinking water. People were exposedin the past to contaminants in the water through ingestion, inhalation, and dermal contact. Currently, if the treatment system is not functioning properly, people are exposed tocontaminants in the water through inhalation of volatile compounds and dermal contact.
O'Brien and Gere sampled the functional supply well, SW 1, for the 1989 Interim TechnicalMemorandum. Analysis of the sample taken from SW 1 revealed the presence of 57 ppb vinylchloride, 204 ppb TCE, 38 ppb PCE, and 100 ppb 1,2-dichloroethene.
After the sampling, EPA ordered the owner of MVTC to take responsibility for the treatment ofthe water supply from SW 1 (10). During a site visit by MDE Waste ManagementAdministration staff, the well and treatment system, which were installed, were reported to bevandalized. The current condition of SW 1 and the water treatment system is not known, but it isassumed that it is still in use as the only source of supply water, other than the bottled drinking water, on the site.
The air sampling data collected in 1989 did not show any significant air contamination on oraround OPI. Although there was no air sampling completed while OPI was in operation, thereare records of air complaints filed during the 1960s when burning of ordnance occurred on-site. Because of the complaints, people living downwind of the site are assumed to have been exposedby inhaling the products released when ordnance was burned. No data are available to evaluatethose exposures further. No documented exposures have occurred through air releases sinceburning of ordnance stopped.
Potential exposure pathways are summarized in Table 19 and are discussed below.
Sediment samples taken from the on-site surface water impoundments contained concentrationsof antimony, cadmium, chromium, lead, zinc, TCE, and vinyl chloride, which exceed ATSDR'scomparison values. The impoundments are discolored, stagnant, and difficult, but notimpossible, to access. There have been no reports of trespassers or employees using the surface water impoundments. The possible routes of exposure are incidental ingestion of and dermal contact with contaminated sediment.
During excavation of the site by UXB, ordnance parts were removed and other potential burialareas were identified. The number of areas that have buried ordnance parts may not be known;also, the condition of the explosives that may be buried on site is not known. The areas whereburied ordnance has been identified remain unrestricted and unmarked as a hazard.
Although no off-site soil sampling has been conducted, it is possible that some of the on-sitecontaminated soil has migrated off-site due to wind, surface runoff, flooding, and fugitive dustfrom automobile traffic. The five surface water impoundments are located on a hill which, ifoverflowing, could spill toward Mechanics Valley Road and several residences. If people cameinto contact with contaminants in off-site soil, the routes of exposure would be inhalation of dust, incidental ingestion of soil, and dermal contact.
Surface Water - (On-site Surface Water Impoundment and Streams)
There are five permanent surface water impoundments, two intermittent streams, and oneintermittent ponded water area on the OPI site. Surface water samples taken from these sitescontained 1,2-dichloroethene, TCE, and PCE at levels above ATSDR's comparison values fordrinking water. Levels of TCE and PCE detected in the surface water from Area D also exceedAWQC comparison values. There have been no reports of employees of MVTC or trespassersusing any of these surface water sources. However, if people were to come into contact withcontaminants in the surface water, the routes of exposure would be incidental ingestion of water and dermal contact.
Although there have been no studies conducted on fish caught in Little Northeast Creek, analysisof the creek water samples collected in 1993 identified the presence of 1,2-dichloroethene at 4ppb, PCE at 5 ppb, and TCE at 17 ppb. People eating fish from sections of the creek could beexposed to these contaminants in fish tissue; however, these chemicals do not bioconcentrate to a significant degree (11). Because these contaminants do not tend to concentrate in fish tissue, this would not be an important exposure pathway for people who occasionally eat fish from the creek.
In this section, we will discuss the possible health effects in people exposed to specificcontaminants, evaluate state and local health databases, and address specific community healthconcerns.
To evaluate health effects, ATSDR has developed a Minimal Risk Level (MRL) forcontaminants commonly found at hazardous waste sites. The MRL is an estimate of daily humanexposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, such as ingestion and inhalation, and for thelength of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic(greater than 365 days). ATSDR presents these MRLs in Toxicological Profiles. Thesechemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status.
Other health-based criteria are also used to estimate the health risk associated with exposure tocontaminants. One such criterion, called a Reference Dose (RfD), developed by the U.S. EPA,is an estimate of daily human exposure to a contaminant, below which adverse health effects areunlikely to occur. The cancer risk from exposure to a carcinogenic chemical is determined usingassumed exposure scenarios and cancer slope factors, values developed by the U.S. EPA whichindicate the carcinogenic "potency" of chemicals. Cancer slope factors are generally developedfrom studies with laboratory animals in which animals are fed high levels of a chemical overtheir lifetimes. The use of cancer slope factors to predict cancer risk in humans mayoverestimate cancer risk in humans.
In estimating risk from exposure to contaminants from the Ordnance site it is also necessary toassume exposure situations or scenarios. In doing this, "conservative" assumptions are made sothat contaminant exposure, and subsequent health risk, will not be underestimated. It is likely,however, that these assumptions result in an overestimate of contaminant exposure. For theOrdnance site, it was estimated that people would be exposed to contaminants in surface soilstwo days per week for 30 years. It is assumed that during this exposure, people accidentallyingest 50 milligrams per day of soil containing the highest levels of contaminants found at thesite. For contaminants in groundwater it is assumed that people drink 2 liters of the water per day for 30 years.
Antimony is a silvery white metal that occurs naturally in very small amounts in the earth's crust. Antimony is mined as an ore, then changed into a metal or combined with oxygen to makeantimony oxide. Antimony is easily broken by itself, but can form strong alloys when combinedwith metals such as lead and zinc. These alloys are used in solder, sheet and pipe metal,bearings, castings, type metal, and ammunition (6). Antimony is also found in food in very smallamounts. The average person eats and drinks about 5 g of antimony every day (6. Long termexposure to high levels of antimony in the workplace has been linked to heart disease andirritation of the skin and eyes; however, there is no evidence that ingestion of small amounts of antimony causes health problems in humans or laboratory animals.
Antimony was detected above ATSDR's comparison value for soil at 20 ppm in two of the soilsamples taken. In Area A, antimony was detected at 29 ppm and in Area H 1 at 25 ppm. Antimony was also detected in a sediment sample taken from the surface water impoundments ata maximum concentration of 140 ppm in 1989. Exposure to sediment in surface waterimpoundments has not been documented. Based on the assumption that a person incidentallyingests 50 milligrams (mg) of soil per day, two days per week, for thirty years, contaminated with 29 ppm antimony, the estimated exposure dose does not exceed the Reference Dose (RfD) forchronic exposure to antimony (6)
Arsenic is a naturally occurring element in the earth's crust. Pure arsenic is a gray-colored metal,but this form is not common in the environment. Rather, arsenic is usually found combined withone or more other elements such as oxygen, carbon, chlorine, and sulfur, which determine itsform as inorganic or organic. Arsenic combined with inorganic elements is referred to asinorganic arsenic, whereas arsenic combined with carbon and hydrogen is referred to as organicarsenic. It is important to maintain a distinction between inorganic and organic arsenic because the organic forms are usually less toxic than the inorganic forms (12). Data gathered at the OPI site, however, do not give arsenic concentrations by specific forms.
Because arsenic is a naturally occurring element found in soil, detection of arsenic in all soil andsediment samples taken at the OPI site was not unusual. The mean soil concentration for arsenicin the eastern United States is 7.4 ppm. The maximum concentration of arsenic found in anysample taken at the site was 9.3 ppm. Ingestion, based on the assumption that a personincidentally ingests 50 mg of soil per day, two days per week for thirty years, of thisconcentration of arsenic does not exceed ATSDR's chronic MRL; therefore, non-cancer healtheffects are not expected to occur in exposed people (12). Also, the estimated dose would notresult in a significantly increased risk of developing cancer over an individual's lifetime (12).
Chromium is a naturally occurring element of the earth's crust and is an essential nutrient. Allhumans are exposed to low levels of chromium in air and water, but by far the most significantexposure route is through ingestion of food (13).
Chromium can occur in different forms. Hexavalent chromium (chromium VI) is an irritant, andshort-term, high-level exposure can result in adverse health effects at the contact location (forexample, ulcers of the skin, irritation and perforation of nasal mucosa, and irritation of thegastrointestinal tract). Hexavalent chromium may also cause adverse health effects to the kidneyand liver. Hexavalent chromium has also been strongly associated with lung cancer in workerswho were exposed over long periods of time. Because of this, the U.S. EPA has classified it as aknown human carcinogen (Group A). Trivalent chromium (chromium III) does not producethese effects and is in the form thought to be a nutrient. Chromium in food is primarily in thetrivalent form (13). Both forms, depending on ambient water conditions, are toxic to aquatic life (13); however, this section of the PHA focuses on human health issues.
ATSDR has developed a Toxicological Profile for chromium, and has established minimal risklevels for chromium. Also, the EPA has established a RfD for ingestion of chromium VI (13). Analysis of soil samples detected a maximum concentration of total chromium of 1,900 ppm in asample taken from Area F. The total chromium was not broken down by its forms (III and IV). To be maximally protective of public health, we assumed that all of the detected chromium wasin the more toxic hexavalent form. However, because a large proportion of chromium in soil isoften in the trivalent form, this assumption is conservative and may overstate the actual health risk.
Based on the assumptions that the chromium found was predominantly in the hexavalent formand the average person, starting at childhood, ingests 50 mg per day, two days per week, forthirty years, the estimated exposure dose to chromium does not exceed the RfD for chronicexposure (13).
Many epidemiologic studies of chromate production facilities have established an associationbetween chromium VI exposure and lung cancer, with supporting studies from other industries. Long-term inhalation during occupational exposure to low levels of chromium has beenassociated with lung cancer. The form state of the chromium causing cancer in these groups isnot known with certainty; however, experiments with laboratory animals have found that onlyhexavalent chromium is carcinogenic (13).
Although a cancer slope factor has been developed for inhalation, one has not been developed fororal exposure to chromium VI (13). Therefore, it is not possible to estimate cancer risk from oralexposure. Because chromium VI is a known human carcinogen (in some forms), exposure toon-site chromium, may elevate the risk of developing cancer (13). The soil sampling results,however, do not give chromium concentrations by specific form; therefore, risk estimations arelikely to be overestimated.
Lead is a naturally occurring inorganic element that is frequently found in small amounts innature. The maximum level of lead detected in on-site soil samples was 3,300 ppm. Nocomparison value (for non-cancer effects or cancer) has been confirmed as a safe threshold levelfor lead that would not induce a toxic effect. Therefore, a thorough evaluation of exposure tolead at the site is not possible. Current opinion supports the reasoning that toxicity is reducedwith reduced exposure. Until the relationship between toxicity and dose is more clearlyunderstood, all exposure to lead should be avoided to the extent feasible.
Signs and symptoms of lead toxicity depend on lead concentrations in the tissue and the age ofthe individual. Chronic exposure to low levels of lead can interfere with the blood forming andreproductive systems, kidney function and metabolism, and produce subtle effects on personality,memory, learning, reaction time, psychomotor function, and motor coordination. Infants andyoung children are very sensitive to the toxic effects of lead on the nervous system. Impairedneurological development has been observed in children exposed to relatively low concentrationsof lead. At higher concentrations, lead is toxic to the central nervous system and can produceneurological motor dysfunction (14). EPA has classified lead as a probable human carcinogen (14).
Nickel is a tasteless, odorless, naturally occurring element found in the earth's crust and in soil. Nickel is a hard metal which is desirable for combining with other metals such as iron, copper,chromium, and zinc to form alloys. Nickel cannot be destroyed in the environment but it canchange its form or become attached to or separate from particles (15). Most nickel will end up inthe soil or sediment where it is strongly attached to particles containing iron or manganese. Under acidic conditions, nickel is more mobile in soil and may seep into groundwater (15).
The maximum concentration of nickel detected in a soil sample was 3,700 ppm. Based on theassumption that a person, starting in childhood, ingests 50 mg of soil per day, two days per weekover a period of thirty years, the estimated exposure does not exceed the RfD for chronicexposure (15). Therefore, no non-cancer, adverse effects are expected to result from exposure.
Nickel in refinery dust and nickel subsulfide are classified as probable carcinogens (15). However, that type of nickel is not associated with the site; therefore, exposure to nickel in soil at levels found on site is not likely to result in an increased risk of developing cancer upon exposure.
People were exposed to 1,1-dichloroethene (1,1-DCE) contaminated groundwater at 2 ppb,which was the level found in the one on-site residential well, RW-14. Based on the assumptionthat a person, starting in childhood, ingests one liter of water with 2 ppb 1,1-DCE per day, 365days per year, over a thirty year period, the estimated exposure dose does not exceed ATSDR'sMRL for chronic exposure; therefore, non-cancer adverse health effects are not likely to occur. Additionally, exposure to that level would not be expected to significantly increase the estimated risk of developing cancer (16).
1,2-Dichloroethene (cis and trans)
1,2-Dichloroethene (1,2-DCE) is a colorless, highly flammable, man-made liquid with a sharpodor. 1,2-DCE can exist in two forms, cis and trans, and can be present in both forms (17). 1,2-DCE is used most often in the production of solvents and in chemical mixtures. 1,2-DCEhas been found in air, water, and soil as a result of chemical releases from facilities which make or use the chemical, from burning vinyl-containing objects, and from landfills and hazardous waste sites (17).
The maximum concentration detected in a potable source was 200 ppm found in the on-siteresidential well, RW-14. The maximum concentration of 1,2-DCE in off-site residential wellswas 9 ppb. An estimated dose for the described scenario does not exceed the RfD for chronicexposure for those levels. However, the maximum concentration of 1,2-DCE detected in thegroundwater was 820 ppb found in an on-site monitoring well. If a drinking water well were tobecome contaminated with 1,2-DCE at that level, a person, beginning in childhood, ingesting oneliter of water containing that level of 1,2-DCE, 365 days per year over a period of thirty years would receive an estimated exposure dose that slightly exceeds EPA's RfD for chronic exposure (17).
1,2-DCE can be inhaled as a vapor, ingested in contaminated food or water, or absorbed throughthe skin. Neither birth defects or cancer have been reported in humans or animals exposed toover long periods of time to 1,2-DCE (17).
Tetrachloroethylene (PCE) is a nonflammable, sweet smelling, manmade chemical which iswidely used in the dry-cleaning industry and for metal-degreasing operations. PCE evaporateseasily and may get into the air, soil, or water by leaking from storage and waste sites. Once inthe groundwater, PCE can last for several months without being broken down. The use of PCEis widespread and background levels can be found in air and drinking water. One study showedPCE present in 25% of drinking water sources sampled. The effects of breathing in air ordrinking water with low levels of PCE are not known (18).
People were exposed to PCE at 68 ppb found in the on-site supply well, RW-14. Only one otherresidential well, off site, was found to be contaminated with PCE at 1 ppb. Based on theassumption that a person, beginning in childhood, ingests one liter of water every day, 365 daysper year for thirty years, the estimated exposure doses do not exceed ATSDR's MRL for chronicexposure; therefore, non-cancer, adverse health effects are not likely to occur at this thatexposure level (18).
It is estimated that a person's lifetime risk of developing cancer from ingesting 68 ppb of PCEover a 30-year period would be slightly increased (18). The estimated cancer risk forconsumption of water with 1 ppb PCE over a thirty-year period would not be significantlyincreased. PCE was detected in the most recent monitoring well sampling at 4,300 ppb. If adrinking water well were to become contaminated with PCE at that level, a person, beginning inchildhood, ingesting one liter of water containing that level of PCE, 365 days per year over aperiod of thirty years would receive an estimated exposure dose that exceeds the MRL forintermediate exposure (18). A person exposed to this level of PCE for a lifetime might be at risk of illness.
PCE has been used as a general anesthetic, and exposure to high concentrations can cause centralnervous system depression (e.g., dizziness, headache, confusion). Laboratory animals exposed toPCE have shown adverse effects on the central nervous system, liver, and kidney (18). Similareffects have been observed in laboratory animals following repeated oral exposures. PCE hasalso caused cancer (leukemia, liver, and kidney cancer) in laboratory animals followinglong-term oral or inhalation exposures (18).
Trichloroethene (TCE) is a nonflammable, colorless, manmade chemical with a sweet odorsimilar to ether or chloroform. TCE is used in industry as a solvent to remove grease and in theproduction of other chemicals. TCE can also be found in many household products includingpaint remover, adhesives, spot remover, and typewriter correction fluid (19).
People were exposed to TCE detected at 160 ppb in the on-site supply well, RW-14. In one ofthe off-site residential wells, a level of 145 ppb was detected during the 1988-1990 sampling. During the 1994 sampling, the maximum level detected was 180 ppb. Based on the assumptionthat a person would drink water for 30 years containing 160 ppb of TCE, the estimated exposuredose neither exceeds ATSDR's MRL for chronic exposure nor poses a significant lifetime cancerrisk. It should be noted that this and other affected wells are equipped with filtration systems andconsequently exposure to TCE is not expected to occur. The maximum concentration of TCEdetected in the groundwater is 2,800 ppb in an on-site monitoring well. If a drinking water wellwere to become contaminated with TCE at that level, a person who used this water over a 30 yearperiod would receive an estimated exposure dose that exceeds the MRL for intermediateexposure (19). Also, this dose would be expected to result in a slightly increased lifetime cancer risk for the exposed person (19).
TCE can cause depression of the central nervous system (similar to alcohol intoxication), andwas in the past used as a general anesthetic. The health-based comparison value for TCE reflectsits potential carcinogenic activity. TCE has caused leukemia and cancer of the liver and kidneyin laboratory animals (mice and rats) following long-term oral exposures (19). Studies ofhumans exposed to TCE in drinking water have shown a possible association with leukemia andcardiac abnormalities when exposed to several chemicals, including TCE (19).
Vinyl chloride is a colorless, manmade chemical with a mild, sweet odor. Most of the vinylchloride produced in the United States is used in the production of polyvinyl chloride (PVC). PVC is used for the production of a variety of plastic products including furniture, automobileupholstery, housewares, and automotive parts (20).
People occupationally exposed to relatively high levels of vinyl chloride vapors have showndamage to the liver, central nervous system, and peripheral blood circulation. Long-termoccupational exposures through the inhalation route have also been associated with a rare form ofcancer of the liver, angiosarcoma, and possibly cancers of the brain and central nervous system,lung and respiratory system and lymphatic/hematopoietic system (20). Exposure of laboratoryanimals to vinyl chloride vapor has also caused liver cancer (20).
There is no information on the effects of vinyl chloride in people following oral exposure. Oralexposure of laboratory animals to high levels of vinyl chloride has caused liver toxicity andcancer of the liver (20). The lowest daily dose found in studies to produce liver cancer inanimals was 1.7 mg vinyl chloride/kg/day. Based on the consistent animal evidence ofcarcinogenicity through ingestion, ATSDR has concluded that "it would be prudent to considerthe potential for carcinogenic effects in humans by this route as well" (20).
People were exposed to vinyl chloride in the on-site supply well, RW-14. Vinyl chloride has notbeen detected in any of the off-site residential wells. Based on the assumption that a person,beginning in childhood, ingests one liter of water with 90 ppb vinyl chloride per day, 365 daysper year, for thirty years, the estimated exposure dose to vinyl chloride significantly exceedsATSDR's MRL for chronic exposure. Exposure to vinyl chloride at this level might slightlyincrease a person's lifetime risk of developing cancer (20).
Birth defects rates are not available for the census tracts or zip codes in the immediate vicinity ofthe OPI site. The smallest geographic unit for which such data are available is Cecil County. The County population is seven times larger than that for the zip code, which includes the site(71,347 versus 10,363 in 1990, respectively) (Source: U.S. Census, 1990). The County alsospans a significantly larger geographic area than the zip code of interest. Thus, it is very difficultto assess whether or not an excess rate of birth defects exists near the site by using countystatistics. Even if local statistics were available, they are of limited value to establish a linkbetween birth defects and exposure to the contaminants of concern: no such exposureinformation is collected from the individual parents who give birth to infants withmalformations. Nonetheless, a high rate of birth defects in the county would suggest that furtherstudies be done to determine where within the county the defects are occurring, and whether theparents who gave birth to infants with defects were exposed to significantly higher levels of the contaminants than parents who had offspring without such defects.
The preliminary data available from the Birth Defects registry show that from 1984-1988, theaverage annual birth defect rate for all sentinel birth defects combined in Cecil County (107.1 per10,000 live births) was nearly 50% higher than the overall Maryland State rate (73.1 per 10,000live births). Cecil County birth defect rates were higher than Maryland rates for eight of the 12sentinel birth defects measured. The Cecil County birth defect rate for non-sentinel birth defectswas 30% higher than the Maryland rate in the same years (25.4 versus 19.5 per 10,000 births,respectively).
The causes of these birth defects are largely unknown. There are many difficulties, previouslydiscussed, in trying to use data such as that available to establish cause and effect. It is notpossible, with these data, to link the observed excess birth defect rates to any particular causes,including potential exposures from the OPI site. However, future analytical epidemiologicalstudies would be of use in determining if the birth defects in Cecil County were localized toresidents living near hazardous waste sites. Such studies could also help elucidate the causes of the birth defects observed in the County and any near the site.
Unlike birth defects data, cancer death statistics are available for the zip code in which the site islocated. However, the same caution used to interpret birth defects data applies to using cancerdata to draw conclusions about residents near the site: the available statistics do not includeinformation on whether the individuals who died of cancer were exposed to unusually high levelsof the contaminants of concern. An additional caveat is that cancer generally takes 10 to 20 yearsto develop after exposure to a cancer-causing agent. Thus, those who die of cancer in the areaaround the site (and thus become part of the cancer mortality statistics) may not have lived in thesame area when they were exposed to any causative agent(s). These considerations make itdifficult to draw solid conclusions about the cancer risk to residents around the site. Nonetheless, a high rate of cancer deaths in zip code 21901 would suggest that further studies be done to evaluate whether or not OPI is posing an excess cancer risk to residents near the site.
There were 57 total cancer deaths among people living in zip code 21901 at the time of deathover the period 1987-1989. Of these 57, 14 deaths were from lung and bronchus cancer, six frompancreatic cancer, five from colon cancer, four from female breast cancer, and four from prostate cancer. The remaining cancer deaths were from a variety of cancer types, each with less than four cases per type.
Age-adjusted, standardized mortality ratios (SMRs) for cancer deaths occurring in zip code21901 over 1987-89 were computed for all races and sexes combined for the following sites: allsites combined, lung and bronchus, and pancreas. SMRs are the ratio of observed over expecteddeaths. The expected number of cancer deaths was determined using age-adjusted cancer ratesfor the population of the United States for the period of 1985-1989. SMRs greater than 1.00indicate that there are more observed cancer deaths than would be expected from the populationof interest, and thus, there is an elevated cancer risk. SMRs less than 1.00 suggest that there arefewer observed cancer deaths than expected, while an SMR equal to 1.00 means that the cancerdeath rate is not higher or lower than expected.
The age-adjusted SMR for all cancers combined was 1.03 -- that is, the deaths from all cancerswas 3% higher than expected. However, this small excess was not statistically significant; the95% confidence interval ranged from 0.78 to 1.34. In other words, one can only say with 95%certainty that the true risk from all cancers combined is somewhere between 22% less thanexpected to 34% higher than expected. The age-adjusted SMR for cancers of the lung andbronchus was 0.90 with a 95% confidence interval of 0.49 to 1.52. This means that there were10% fewer lung and bronchus cancer deaths than expected, although again this finding was notstatistically significant (i.e, the 95% confidence interval includes 1.00).
The age-adjusted SMR for pancreatic cancer was 2.23 with a 95% confidence interval of 0.82 to4.86. Thus, although there appears to be 123% more pancreatic cancer deaths than expected, thisexcess is not statistically significant. This lack of statistical significance may be due to the smallnumber of pancreatic cancer deaths (N=6) rather than a true lack of excess risk. However, it isunlikely that these cancers are linked to exposures from living near the site for the followingreasons: five of the six people who died from pancreatic cancer lived at least two miles from thesite (two lived about five miles from OPI) at the time of death; the residential location for thesixth person who died could not be determined; none of the contaminants of concern have beendemonstrated to cause pancreatic cancer in either humans or test animals; and finally, theseSMRs were not adjusted for smoking habits because that information was not available. Thatlack of information may confound the true cancer risk because smoking is known to cause bothlung and pancreatic cancer.
In sum, the available cancer data are insufficient to conclusively determine whether or notcontamination from the site has been or will be associated with an excess risk of cancer toresidents. More extensive analytical epidemiology studies, with a longer follow-up period (i.e.,years beyond 1989), would be required to provide more definitive answers. Even rigorous,analytical epidemiology studies would be of limited value for the community surrounding thesite, however, because they would be unlikely to reveal any excess cancer cases attributable tothe site. This is because only a small number of people have potentially been exposed to the site and its contaminants, and the potential cancer risks posed by the contamination levels at the site are low.
In July of 1973, the blood of 27 persons employed at OPI was tested for lead. The resultsindicated many people had elevated levels of lead in their blood. The levels ranged from 12-50 glead/dL blood. Seventeen people had lead levels higher than 20 µg/dL, and three people had levelsthat exceeded 40 µg/dL. It is unclear from currently available Cecil County Health Departmentrecords how these results were obtained and used.
Many of the past community health concerns appear to have been addressed to the satisfaction ofthe residents in the vicinity of the site. The air pollution caused by the burning of ordnance wasteproducts was at first reduced by changes in burning procedures and then eliminated when OPIceased operations. On- and off-site drinking water wells known to be chemically contaminatedhad water treatment systems installed. O'Brien and Gere samples these four residential wellsperiodically for contamination and maintains the filtration systems. The leaking septic tankproblem was ameliorated.
MDE identified two outstanding issues. The first issue is whether or not potential healthproblems in OPI workers, such as elevated blood leads or cancer, were investigated andaddressed. The second issue is whether there remain any outstanding community health concernsat the present time.
MDE held two public availability sessions on March 21, 1995 to solicit community opinions andto answer questions on potential health hazards associated with the site. No additionalinformation on the potential adverse effects of occupational exposure was provided byattendants. The health concerns raised by community members are summarized in the PublicComments section of this PHA.