assessment of potential environmental health risks of residue of high-explosive munitions on...

Federal Facilities Environmental Journal/Spring 2002 7

Loren Phillips and Bernard Perry

© 2002 Wiley Periodicals, Inc.* This article is a U.S. Government work and, as such, is in the public domain in the United States of America.Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/ffej.10021

Assessment of PotentialEnvironmental HealthRisks of Residue ofHigh-ExplosiveMunitions on MilitaryTest Ranges—Comparison in a Humidand Arid Climate

Loren Phillips and Bernard PerryThe U.S. Army Developmental Test Command (DTC) manages active rangesin a wide variety of environmental settings where personnel fire munitions of allcalibers. Over time, physical, chemical, and biological processes may distributemunition fragments and residue on the range. Estimating the human health andecological risks of these residues is a challenge because little information existsfor evaluating the health effects of military-unique releases. A human health andecological risk assessment at two DTC munition ranges (one in a humid,temperate climate (Aberdeen Proving Ground, Maryland), and one in a hot, aridclimate (Yuma Proving Ground, Arizona) has been completed. The objectivewas to estimate health risks associated with exposure to munition residues. Thescope included identifying the nature and extent of munition residue at firingpoints and in impact areas from firing munitions, analyzing exposure path-ways, estimating the dose to living organisms and the response to the dose, andestimating risk from exposure. Where appropriate, water, soil, sediment, air, andbiota samples were collected from the range area and reference areas. Sampleswere tested for explosives and metals. Risk to humans and ecosystem species wasmodeled. Results show that munition residue is not getting into the food chainor being transmitted by direct or indirect exposure in either climate despite low-level detections in some media. © 2002 Wiley Periodicals, Inc.*

Loren Phillips is a senior geologist with the U.S. Army Center for Health Promotion andPreventive Medicine (CHPPM), at Aberdeen Proving Ground (APG), in Maryland. He has beenconducting environmental investigations at munition firing ranges for the past 14 years.Bernard Perry is chief of the Environmental Quality Division of the U.S. Army DevelopmentalTest Command (DTC), at APG. He is responsible for the environmental management of about 3.4million acres of Army range land for munition testing.

8 Federal Facilities Environmental Journal/Spring 2002

Assessment of Potential Environmental Health Risks of Residue of High-Explosive Munitions on Military Test Ranges

INTRODUCTIONThe U.S. Army Developmental Test Command (DTC) manages active

test ranges where munitions of all sizes are fired. These test ranges arelocated at Aberdeen Proving Ground (APG), in Maryland; DugwayProving Ground (DPG), in Utah; Yuma Proving Ground (YPG), inArizona; and White Sands Missile Range (WSMR), in New Mexico.

These test ranges occupy large land areas (some > 500,000 acres) in awide variety of environmental settings. Together they comprise about3.4 million acres. The ranges at APG have been operating for approxi-mately 84 years; DPG, YPG, and WSMR ranges are about 55 years old.

A wide variety of munitions are tested at these locations, includingconventional high-explosive munitions, depleted uranium (DU), smokes,pyrotechnics, and propellants. Conventional munitions tested includebombs, grenades, mines, rockets, mortars, and projectiles of all calibers.In the 1980s, environmental monitoring plans for DU testing operationswere developed and implemented. Monitoring for DU in soil, sediment,water, air, plants, and animals is routinely conducted. However, envi-ronmental issues related to conventional munitions were not addressed.

A project was proactively initiated to assess risk from testing conven-tional munitions. The objective was to estimate the human health andecological risks associated with exposure to range-related residues fromconventional high-explosive munitions. The scope of the project in-cluded identifying the nature and extent of conventional-munitionresidues on the range, analyzing potentially completed exposure path-ways, estimating the dose of the residues to living organisms and theresponse to the dose, and estimating risk from exposure to the residues.Based on the scope of the project, plus the size, testing history, and widevariation in environmental settings of the ranges, accomplishing theobjective was a major challenge.

APG was the first installation to be investigated. From 1989–1997,ranges in the APG Aberdeen Area were assessed and several reportswere written (Phillips & Bouwkamp, 1994; Phillips & Lee, 1995;Tannenbaum, 1996 and 1998a). Beginning in 1995, preliminary workstarted at DPG, WSMR, and YPG. Based on an analysis of this prelimi-nary work and on funding limitations, only one range at YPG wasselected for follow-up sampling and health risk evaluation. The YPGinvestigation ended in 1999 with the publication of three reports(Tannenbaum, 1998b; Phillips, 1998 and 1999). The purpose of this articleis to explain the methods and results of the major field investigations atAPG and YPG, and to identify three lessons learned from the experience.

ENVIRONMENTAL SETTING AND MUNITION USAGECOMPARISON

There could not be a greater difference in environmental settings thanthat exhibited by YPG and APG. YPG is in hot, arid southwest Arizona,where precipitation averages less than three inches a year, no surfacewater exists, ground water is deep, and almost all nonhuman life sticks,stings, or bites. APG is located in humid, temperate eastern Maryland,

There could not be agreater difference inenvironmental settingsthan that exhibited byYPG and APG.



with abundant precipitation and surface water, wetlands, shallow depthto ground water, thick vegetative cover, thick soil profile, and a thrivingforest ecosystem. Exhibit 1 shows this remarkable contrast. Perhaps theonly thing similar in the two places is the mission of the installations.Both of these installations test high-explosive munitions.

MUNITION LOADING TO THE LANDAn attempt was made to quantify the munition loading (the total

number of munitions fired into an impact area) at each range studied.This was done at both APG and YPG. However, these were separate andindependent efforts.

At APG, a mostly complete set of firing records from 1918–1997 exists.These records were searched to determine the number, types, andlocations of projectiles fired throughout the history of the post. This wasan independent effort not connected with the APG and YPG risk assess-ments. It was separately funded and took over three years to complete.Based upon the records searched, an estimate of the total number of 75,105, and 155 mm projectiles fired and the munition loading to APG wasmade (Conloy et al., 1997).

From 1918–1997, a total of 2,343,747 projectiles (75, 105, and 155 mmcaliber) were fired at APG (Conloy et al., 1997). Dividing the totalnumber of projectiles by the number of years of firing gives the averagenumber of projectiles fired per year: 2,343,747 / (1997 - 1918) = 29,667projectiles/year. Of the total number of projectiles that were fired,1,659,618 projectiles did not detonate and are estimated to be remainingon the range—on the ground, under the ground, or in the water (Conloy

Exhibit 1. Characteristics of YPG and APG

CHARACTERISTIC YPG (AZ) APG (MD)Location Sonoran Desert, Southwest AZ Peninsula on Chesapeake BayClimate Hot, arid Humid, temperate

Precipitation (in/yr) < 3 > 35Physiography Basin and range Coastal plainTopography Flat (some mts.) Flat

Geology Alluvial basins with fault block mts. Unconsolidated sedimentSoil Thin—desert pavement Thick—forest, wetland soil

Mineral mines Many NoneSurface water None Abundant

Drainage Dry washes Perennial streamsGround water Deep (> 100 ft) Shallow (< 25 ft)

Habitat Sparse AbundantVegetation Grasslands, cacti, creosote in washes Forested, some cleared areas

Mission Munition testing Munition testingMunition usage High explosive High explosive

Impact areas Many, large land areas Many, some in waterFiring history 55 years 84 years



et al., 1997). Some of the projectiles remaining were designed not todetonate on impact (they had an inert nonexplosive charge) and somewere duds (they had a high-explosive charge that did not detonate).

At YPG, the firing records were not as complete. A complete set of firingrecords for fiscal year 1974 was found to exist for the Kofa range. Inaddition, records in the Range Usage Management System (RUMS, aUNIX computer database managed by range operations personnel) showthat 41,281 munitions were fired on the Kofa range from 1992 to 1997, withan average of 6,885 rounds fired per year. Based upon known records ofrange utilization and assumptions about firing during other years, theestimated total number of munitions that were fired on the Kofa range atYPG from 1965 to 1997 is 909,321. The average number of projectiles firedper year at this range is: 909,321 / (1997 - 1965) = 28,416 projectiles/year(Phillips, 1999). The estimated average projectiles fired per year for APG(29,667) and for YPG (28,416) is very close. This lends credence to thevalidity of the assumptions used in making the YPG estimate.

The munition loading efforts at both APG and YPG produced mapsestimating where the munitions impacted on the range (Phillips, 1998and 1999; Conloy et al., 1997). These maps were used to identify areas(acres to tens of acres in size) within the larger range area (hundreds tothousands of acres in size) where high munition density would mostlikely be found. Some of these areas of high munition density becameenvironmental sampling sites.

EVOLUTION OF TECHNICAL APPROACHThe initial phase at APG focused on chemical characterization of

residues of high-explosive munitions (dust-sized particles of conven-tional high and low explosives, explosive degradates, and heavy metals)in soil, water, and sediment in the range area (Phillips & Bouwkamp,1994; Whaley, 1995). Human and ecological exposure scenarios were notconsidered. The results of this phase could not answer some basicquestions: Are the workers being exposed? Is it safe to eat the deer fromthe range area? Is it safe to eat the fish and shellfish? Rethinking thetechnical approach in light of these questions and concerns led toenvironmental risk assessment. All remaining work (the remainingphases of the APG investigation plus the YPG investigation) used riskassessment as the technical approach. Changing the technical approachfrom chemical characterization to risk assessment became the first majorlesson learned during the study.

Risk AssessmentRisk assessment, as used here, is defined as a measure of the potential

for munition residue to cause adverse health effects to biological receptorssuch as people, plants, and animals. The National Academy of Sciencesformalized the procedures for risk assessment in 1983 (National Academyof Sciences, 1983). In addition, the procedures were approved by the U.S.Environmental Protection Agency (see USEPA, 1988, 1989a, 1989b, 1991a,1991b, 1992, 1996, 1997, 1998a, 1998b; Wentsel et al., 1996). Hazard identi-

Changing the technicalapproach from chemicalcharacterization to riskassessment became thefirst major lesson learnedduring the study.



fication, exposure assessment, toxicity assessment, and risk characteriza-tion have become the litany of environmental risk assessment since 1983.

Conceptual modelThe conceptual model for the project is shown in Exhibit 2. The model

shows an artillery range with a firing point and an impact area (Exhibit2a). The major components of the model are a source of munition residue,pathways to transport residue, and receptors (people, plants, and ani-mals) that may be exposed to the residue (Exhibit 2b).

The model describes the relationship between firing munitions andenvironmental exposure pathways. When munitions are fired, chemicalreactions occur, and compounds used in munitions interact with environ-mental media (air, water, soil, sediment). These media provide a transportpathway or route through the environment for these compounds. People,plants, and animals interacting with these media containing munitioncompounds may potentially be exposed and incur health effects.

When the weapon is fired at the firing point, the munition and a largesmoke cloud (containing propellant gases) discharge from the muzzle. Someof these emissions have been identified and quantified (Szostak & Cleare,2000). Blast overpressure from the weapon may mobilize the surficial soil inthe immediate area, creating dust. Residue in the smoke cloud and dust canpotentially be inhaled by people at the firing point. In addition, peopleopening the breech after the test are potentially exposed to exiting gases.

Munitions discharging from the muzzle travel downrange. Uponhitting a target or impact area, they may undergo high-order detona-tion and explode, sending fragments into the local area. Other muni-tions may impact, undergo low-order detonation, stay on the surface ofthe ground, bounce, crack, and break apart into fragments. High andlow explosives in the munition and metals in the casing may be locallydistributed in the surrounding range area. Some munitions are sup-posed to explode, but do not. These are called unexploded ordnance(UXO). UXO can be found on the surface or at a shallow depth belowthe surface. UXO may contain ounces to pounds of undetonated highexplosives. Casing corrosion or cracks may release the explosives intothe surrounding range/impact area.

Over time (years to decades), physical, chemical, and biological processesoperating in the natural environment (mainly from the sun, wind, and water)may degrade conventional munitions and fragments into residues. Soldiers,workers, and other people traversing the range area may ingest dust-sizedparticles or get soil on their skin through the soil exposure pathway.

Plants living in the range and impact area may be exposed to muni-tion residue by direct soil contact. Their roots may extract residue fromthe soil. Animals (for example, deer) may be exposed to residue that isretained in the plant tissue or on the outer surfaces. In addition, rodentsand other animals that live in the soil throughout the range and impactarea may be exposed to munition residue by direct soil contact. Whenpredators eat these animals, the predators may be exposed to munitionresidue retained in the bodies of their prey.

The major components ofthe model are a source ofmunition residue,pathways to transportresidue, and receptors(people, plants, andanimals) . . .



Exhibit 2. Conceptual Model of Munition Residue Transport through Environmental ExposurePathways at Firing Ranges

2a.

2b.



Infiltrating precipitation can potentially cause the vertical migrationof munition residue through the soil profile. Munition residue poten-tially could migrate to groundwater and affect the water quality. Ifgroundwater is used as a drinking water source, it may represent apotential exposure pathway.

Stormwater processes may move munition fragments and residuefrom their original resting location. Surface water channels are potentialconduits for migration of munition residue and fragments throughrunoff and sediment transport. Depending on storm duration andvelocities, munition fragments and residue can potentially be trans-ported off-range or off-post. In addition, munitions that land in surfacewater can potentially leach their contents into the water column or thebottom sediment. People using surface water as drinking water, aquaticlife living in the streams, and animals using the stream may potentiallycontact the residue from munitions and be exposed.

Therefore, the potential exists for munitions to degrade into residue,and for the residue to be distributed on the ranges. The potential alsoexists for people, plants, and animals to be exposed to the residue, andpossibly suffer health effects. The model represents a hypothesis of howpeople, plants, and animals can potentially interact with residue frommunitions. To find out if this is actually happening and to estimate towhat degree, the model was tested at APG and YPG.

DATA COLLECTION AND EVALUATIONData Collection

Since the objective was to estimate health risks to people, plants, andanimals, a number of different environmental media were sampled. The typeand number of media sampled at YPG and APG are shown in Exhibit 3.

Exhibit 3. Type and Number of Media Sampled at YPG and APG

MEDIA SAMPLED YPG (AZ) APG (MD)

Groundwater 8 20Surface water — 52Sediment — 52Soil 239 * 90Air 30 —Rodents 100 —Vegetation 12 —Insects 12 —Benthic invertebrates — 47Clams — 12Deer (previous study)1 — 150

an asterisk (*) indicates washes and desert pavementa dash (—) indicates media was not sampled1 See Whaley (1995).



The samples were analyzed for munitions-related compounds (Ex-hibit 4). Air samples were also analyzed for 18 polynuclear aromatichydrocarbons (PAHs) and 34 volatile organic compounds (VOCs). Wedid not analyze every sample for this entire suite of compounds. Weanalyzed some samples for indicators of munitions-related compounds,which was an abbreviated list. Both field and laboratory proceduresfollowed standard, published EPA protocols.

The area around the gun positions, downrange in the impact area, thechannels draining the range and impact area, plants and animals livingin the range, and groundwater underneath the impact area were sampled.Off-site reference areas uninfluenced by all military activities were alsosampled for comparison purposes. The climate, geology, soils, vegeta-tion, ecosystem, and other relevant aspects of each respective range andreference area were matched for similarity. The sampling effort was notdesigned to provide a detailed and comprehensive chemical character-ization of the range and impact area. In addition, it was not designed tolocate and characterize “hot spots.” This type of sampling was deter-mined to be cost prohibitive. Rather, it was designed to provide a broadoverview of the range and impact area for assessing overall health riskfrom conventional-munition residue on the range.

Environmental media and sampling locations were chosen based onpotentially complete exposure pathways, exposure patterns, and muni-

Exhibit 4. Analyte List for Environmental Investigations of High-Explosive-Munition Ranges at APG and YPG

Explosives Metals Other

HMX Antimony pHRDX Arsenic Conductivity2,4,6-TNT Barium TOC1,3,5-TNB Cadmium TOM1,3-DNB Chromium VOC (air only)Tetryl Copper PAH (air only)NB Lead2A-4,6-DNT Manganese4A-2,6-DNT Mercury2,6-DNT Molybdenum2,4-DNT Nickel2-NT Selenium3-NT Silver4-NT TungstenNitroglycerin Zinc

TOC: total organic carbonTOM: total organic matterVOC: volatile organic compoundsPAH: polynuclear aromatic hydrocarbons



tion density. For human health, groundwater was a pathway for drinkingand showering in most situations. Soil (or dust) was a pathway forunintentional ingestion and dermal contact. Air was a pathway for breath-ing at gun positions during firing. Clams and deer (at APG) were path-ways for eating and accumulation in the food chain. Additionally, clamsprovided an indication of munition residue migration. For ecological risk,surface water and sediment were direct contact pathways for the aquaticcommunity. Benthic macroinvertebrates provided an indication of gen-eral aquatic health. Rodents, vegetation, and insects provided an indica-tion of accumulation in the food chain. The sampling density was ad-equate to characterize the potentially completed exposure pathways.

During the initial stages of the project, we discovered many con-founding influences when identifying sampling locations. Sources ofcontamination were known to exist in and around the range areas.Considerable effort was needed to map these areas in relation to loca-tions of high munition density and potentially completed exposurepathways. Areas identified as contaminated (through past samplingstudies and efforts) were considered confounding influences and wereavoided. At these ranges wanted to assess risk only from testing conven-tional munitions. Therefore, we focused the sampling and risk assess-ment on health risks from firing conventional munitions, which in-cluded potential exposures associated with firing munitions at the gunposition and potential exposures from the residue of detonating orimpacting munitions downrange in the impact area. All other forms ofpotential or known contamination on the range (other waste disposalsites, garbage areas, industrial sites, metallic mineral mines, sewagelagoons, buildings, Resource Conservation and Recovery Act (RCRA)sites, Solid Waste Management Units (SWMUs), open burning/opendetonation (OB/OD) areas, landfills, and open pits) were consideredconfounding influences and were avoided. We tried to exclude all ofthese from consideration and evaluate the risk contribution from muni-tion testing only. Reducing the confounding influences and focusing therisk assessment on munition testing was the second lesson learned.

Data EvaluationData evaluation began when the sample results came back from the lab.

We evaluated exposure of people, plants, and animals to explosives, heavymetals, and other residue from conventional high-explosive munitions.We did not evaluate the physical safety or explosion risks of encounteringUXO; it was outside the scope of the project. We analyzed the data andlooked for indications of human health and ecosystem effects. Cancer riskmodeling, chemical exposure modeling, and health standard screeningwere conducted for humans. Chemical exposure modeling and healthstandard screening were conducted for ecological organisms. Healthstandard screening was the main type of evaluation used.

For humans, data were evaluated for cancer risk. For cancer riskmodeling, individual exposure scenarios and individual carcinogeniccompounds from munition residue were evaluated separately. An esti-

Reducing the confoundinginfluences and focusingthe risk assessment onmunition testing was thesecond lesson learned.



mate of the amount of a compound entering the body was calculated basedon a realistic exposure scenario. This dose was then multiplied by a cancertoxicity factor for the compound, producing a compound-specific cancerrisk. A similar calculation was done for each detected compound in thesampled media. The risk from all detected compounds and all of theexposure scenarios was added together for a final cancer risk. Backgroundcancer risk is about one person in four, or 0.25 (USEPA, 1989b). Thus,under normal circumstances humans have a 25 percent chance of gettingcancer. The EPA has established an acceptable range of cancer risk abovebackground to be 1 in 10,000 to 1 in 1,000,000 people (USEPA, 1989b). Ifcancer risk (above natural background) is within this range, then this isconsidered an acceptable level and there is no need to take action.

Chemical exposure modeling is similar to cancer risk modeling, butit is for noncarcinogenic compounds only. Individual exposure sce-narios and individual compounds were evaluated separately. For eachexposure scenario, an ingestion hazard for each compound was calcu-lated by taking the chronic daily intake of the compound and dividingit by a reference dose. This produced a compound-specific hazard. Therisk from noncarcinogenic compounds was added together to obtain ahazard index.

In addition, we also conducted health standard screening for bothhumans and ecosystem organisms. For human health, the data werecompared to relevant, known health standards. For soil, water, and air,background concentrations from reference sites, EPA risk-based concen-trations (RBCs), and maximum contaminant levels (MCLs) for drinkingwater were used. Health standard screening for ecological organisms isvery similar. We compared site concentrations to background as well asother standards. For example, we compared the surface water sampleresults from the range area to the Ambient Water Quality Criteria(AWQC). In addition, we compared the sediment sample results tosediment quality benchmarks (SQBs). The AWQC and the SQBs areconservative concentration standards for protection of aquatic life. Forbiological tissue samples—deer, rodents, vegetation, insects, and clams—we compared site results to background levels from reference sites. Forbenthic macroinvertebrates, we compared site metrics (species diversityand richness, percent contribution of dominant taxa, and communitysimilarity) to background metrics from reference areas.

At YPG, rodent histopathology tests were also conducted. Theyprovided collateral data about ecological risk. The histopathology testsprovided evidence for the presence/absence of foreign substances inrodent bodies.

SAMPLING RESULTSSampling results for APG and YPG are shown in Exhibit 5.We found no detectable explosives in the groundwater at YPG, and

concentrations of metals were similar to background. For the shallowgroundwater underneath the active impact area at APG, two explosivecompounds, HMX and RDX, were detected in the low part-per-billion

We found no detectableexplosives in thegroundwater at YPG . . .



(ppb) range in 2 of 20 wells. All other wells from the active impact areahad no detectable explosives. For all wells within the active impact areaat APG, the metals were within the background range.

At APG, no detectable explosives were found in surface water (whichincluded creeks draining the range area, and the water ranges). How-ever, some metals were found elevated above background and the healthstandard. Barium, chromium, copper, and zinc were elevated abovebackground and the AWQC in surface water. The same situation oc-curred in sediment at APG. Sediment had no detectable explosives, butsome elevated metals. Arsenic, chromium, copper, and zinc were el-evated above the SQB.

At YPG, the desert pavement soil at the gun positions and impactareas and the sediment in the washes draining the range areas weresampled. Out of 239 soil and sediment samples collected at YPG, explo-sives were found in only 5 samples. RDX was found in the high ppb rangein 5 samples from one impact area. All other soil and sediment samplesboth at the gun positions and in other impact areas at YPG had nodetectable levels of explosives and explosive degradates. Metals in the239 soil and sediment samples were consistent with background levels.

At APG, explosives were found in 13 out of 90 soil samples. HMX,RDX, 2,4-DNT, and nitroglycerin were detected in the ppm range at afew gun positions. There were no detectable explosives in the impactarea. In addition, arsenic, barium, cadmium, chromium, copper, lead,manganese, nickel, tungsten, and zinc were elevated above background

Exhibit 5. Sampling Results for APG and YPG

MEDIA YPG (AZ) APG (MD)Explosives Metals Explosives Metals

Groundwater ND Bkgrnd HMX, RDX (ppb) (2/20) BkgrndSurface water NS NS ND ElevatedSediment NS NS ND ElevatedSoil RDX (ppb) Bkgrnd HMX, RDX, 2,4-DNT, Elevated (46/90)

(5/239) NG (ppm) (13/90)Air ND Bkgrnd NS NSRodents ND Bkgrnd NS NSVegetation ND Bkgrnd NS NSInsects ND Bkgrnd NS NSClams NS NS ND BkgrndDeer NS NS ND BkgrndInvertebrates NS NS Metrics similar to Bkgrnd

ND—not detected.Bkgrnd—detected at levels consistent with background concentrations.NS—media was not sampled.



in 46 out of 90 soil samples at most gun positions sampled. Metals in soilfrom the impact area were consistent with background levels.

Air was sampled at YPG at the gun position during artillery firing. Noexplosives were found in the air samples. Some metals, PAHs, and VOCswere detected, but their concentrations were similar to background.

Rodent, vegetation, and insect tissue were sampled at YPG for metalsand explosives. Again, no explosives were found in any of the tissue. Themetals found were all within the background range for each respectivebiological organism. We found a similar situation at APG for the biologicalorganisms. Both clam and deer tissue were sampled. No explosives werefound. Metals were within the background range for each respectiveorganism. Benthic macroinvertebrates were sampled at APG and variousmetrics were measured (species diversity and richness, dominant taxa,community similarity index). All metrics were similar to background.

In comparing the data from YPG and APG, it is apparent that there aremore positive detections at APG than at YPG. To interpret these positivedetections, health risk procedures and screening tools were employed.Only then could the health significance of sampling results be evaluated.

RISK ASSESSMENT RESULTSResults of the risk assessment for APG and YPG are shown in Exhibit

6. Both human health and ecological risk were evaluated. For people, theexposure route evaluated was ingestion. Dermal exposure at APG wasfound to be insignificant, so we did not quantitatively evaluate it. Forecological risk, we evaluated exposure to range-related compoundsthrough ingestion or eating in the range and impact area.

At APG, two explosive compounds (HMX and RDX) were detected ingroundwater underneath the active range area. This particular situationdid not present an unacceptable health risk to people because the shallowgroundwater that was sampled is not used for a drinking water supply.The shallow groundwater underneath the active range area flows towardsurface water, where no explosives were detected. In addition, the de-tected compounds in the groundwater occurred in safe concentrations(below EPA MCLs and RBCs). Furthermore, at least six potential sourcesfor the explosives in groundwater were identified. They included anabandoned building, three explosives industrial sites that were aban-doned, the site of a World War II train explosion carrying explosives, andthe range itself. It was not clear from the available evidence which of thesix possible sources (or which combination) were responsible for theexplosives in the groundwater. Therefore, in this case, confoundinginfluences prevented a definitive source from being identified.

No explosives were found in surface water or sediment. For waterspecies such as fish and shellfish at APG, we found barium, chromium,copper, and zinc in surface water above the chronic AWQC. No acuteAWQC exceedances were found. In addition, arsenic, chromium, cop-per, and zinc in sediment were above the SQB. These metals’ exceedancesindicated a potential for aquatic risk. However, these exceedances werecounterbalanced by the benthic macroinvertebrate data. The

. . . there are morepositive detections atAPG than at YPG.



macroinvertebrate data suggested a healthy ecosystem. In addition, theobservations of the field biologists at the time of sampling indicated noovert signs of health effects.

The cancer and noncancer risks were within the acceptable limits forunintentionally eating soil (or dust) in the APG range area. Shellfishtissue was analyzed for explosives and metals. No explosives werefound. Cancer and noncancer risks from detected metals were within theacceptable range. Deer tissue was analyzed for metals and explosives.No explosives were found in the deer tissue. Concentrations of metals inthe site and reference deer groups were similar. No unacceptable riskwas found for people eating venison from the range area. The mouse andthe owl living in the range/impact area were evaluated using chemicalexposure modeling. Mouse and owl risk estimates, based on dietaryintake, were within acceptable limits. There does not appear to be any

Exhibit 6. Risk Assessment Results for APG and YPG

Media Result

APGGroundwater Low levels of explosives found in 2 of 20 monitoring wells in active range area.

Shallow aquifer not a drinking water source. Detected compounds in safeconcentrations.

Surface water/ Ba, Cr, Cu, and Zn in surface water found above AWQC. As, Cr, Cu, and Zn inSediment sediment found above SQB. Potential for aquatic risk indicated.

Soil Cancer and noncancer risk from detected metals and explosives estimated to bewithin acceptable range.

Shellfish/ Cancer and noncancer risk from detected metals estimated to be within acceptClams able range.

Deer tissue Levels of detected metals (As, Cd, Cr, Hg, Pb) similar for site and referencegroup. Risk from detected metals estimated to be within acceptable range.

Benthic Species richness, diversity, and taxa abundance consistent with background.Organisms

YPGGroundwater Munition residue is not reaching groundwater. All risk estimates within accept

able range. Detected metals are consistent with background.

Soil Cancer and noncancer risk from detected metals and explosives estimated to bewithin acceptable range.

Air All detected concentrations were below RBCs. Therefore, no unacceptable risks.

Biota Hazard quotients are estimated to be within acceptable range (< 1) for ecosystemspecies. Rodent histopathology tests indicate no exposure to chemicals or otherforeign substances.



additional dietary health risk to these animals by living in the range andimpact area.

At YPG, no explosives were found in the groundwater and concentra-tions of metals were consistent with background levels. Based uponsampling of supply wells for drinking water, munition residue is notmigrating to groundwater and is not affecting water quality. Risks fromdrinking groundwater at YPG were within the acceptable range. Forhuman exposures to soil, all detected concentrations were below theRBCs and therefore were at safe levels. Explosives were not detected inair samples collected at a gun position during artillery firing. Detectedmetals, PAHs, and VOCs were within the background range. All riskestimates for detected concentrations in air during artillery firing werefound to be at safe levels. For ecological species within the range/impactareas at YPG, hazard quotients are estimated to be below one, meaningthe risks to these species are within the acceptable range.

CONCLUSIONSConclusions for the risk assessment are shown in Exhibit 7.For humans, working in the range area and eating both shellfish and

deer from APG are safe activities. The uncertainty about these conclu-sions is low. We are confident they are correct. For ecological risk, theaquatic organisms have a healthy community. Also, terrestrial speciesshould have no predicted health effects living in the range and impactarea. However, the uncertainty associated with the aquatic ecologicalconclusions is moderate to high. We are not as confident about theseconclusions as we are with the human health conclusions. Essentially,conflicting pieces of evidence lowered the confidence of the conclusionsof aquatic ecological risk. The surface water and the sediment chemistrydata indicated the potential for impact, but actual animal data indicateda healthy ecosystem. The conclusion of a healthy aquatic ecosystem wasmade because the benthic data, along with the observations of the fieldbiologists, overshadowed the predicted biological effects that the sur-

Exhibit 7. Human Health and Ecological Risk Conclusions at APG and YPG

APG

Activity Health conclusion UncertaintyHumans working in range areas Safe LowHumans eating shellfish, deer Safe LowFish and Aquatic organism life Healthy community Moderate to high

YPG

Activity Health conclusion UncertaintyHumans working in range areas Safe LowHumans drinking ground water Safe LowAnimals eating typical diet items Safe Low



face water and sediment chemistry data alone would suggest. Moreweight was placed on animal and human observation data.

At YPG, humans working in the range area and drinking on-postgroundwater are safe. Uncertainty regarding these conclusions is low.For ecological risk, species living and eating their typical diet items in therange area are also safe. Explosive residues and by-products are notaccumulating in the food chain. Collateral data (rodent histopathologyresults) were consistent with a “safe health” conclusion. Uncertaintyregarding the ecological conclusion is also low. We essentially used theweight-of-evidence approach to reach an overall conclusion about risk.The overall data suggest munition testing is having a negligible effect onhealth risk at YPG.

The data suggest that munition residue (a major component of theconceptual model from Exhibit 2) has not accumulated in high enoughconcentrations to have health significance. Therefore, munitions fired atthe APG and YPG ranges over many decades have had a negligible tominimal effect on human health and the natural environment. In addi-tion, the data from training range studies support this conclusion. Cookand Spillman (2000) summarized the results of two investigations oftraining ranges, the Marine Corps Range Residual Study and the artilleryimpact study at Camp Grayling, Michigan, conducted by Hunt andHuntington (1998). Cook and Spillman state that “none of the evidencecollected indicates that routine training operations result in environ-mental contamination in quantities that could cause health concerns.”

MUNITION LOADING AND FUTURE RISKA major question that was asked during the early stages of this project

was: “how many total munitions can be fired into a range/impact areabefore a human health or ecological threshold is exceeded”? In otherwords, what is the munition carrying capacity of the range/impact area?

The results of the risk assessments at APG and YPG provide evidencethat a human and ecological risk threshold has not been exceeded. Firingabout 30,000 munitions/year into impact areas for many decades doesnot appear to present an unacceptable risk to people or ecosystems atAPG or YPG. However, the evidence indicates more uncertainty aboutmunition range risks at APG (in a humid climate). This is mainly due tothe presence of abundant water found in the humid, temperate environ-mental setting (precipitation, perennial surface water, wetlands, andshallow groundwater). This conclusion is consistent with the conclusionof other workers. Houston et al. (2001) found that high-resilience impactareas achieve their relative high score because they occur in drierclimates, which limit dissolution. Resilience is defined as “ the inherentcapability of the land to support intensive military testing activity whilesustaining the existing ecological system.” Water provides a mechanism(a hydrologic driver) that can transport and dissolve munition residue.Water can also concentrate residue from a large impact area into narrowstream channels. Understanding that a sufficient munition loading to therange (> 30,000 munitions/year for many decades) and a sufficient

. . . munitions fired at theAPG and YPG rangesover many decades havehad a negligible tominimal effect on humanhealth and the naturalenvironment.



amount of water (a primary environmental setting characteristic) areneeded for a risk situation to develop became the third lesson learned.

Each risk assessment actually represents one data point on a graph ofrisk versus time. Exhibit 8 shows one data point for the APG riskassessment and one for the YPG risk assessment. Error bars indicate theamount of uncertainty associated with the data point. Note that the APGerror bar is larger than the one for YPG. Sampling, for the most part, wasa one-time-only event. Therefore, the risk estimates represent a “snap-shot in time.”

With an ongoing mission at APG and YPG, munition residue mayaccumulate in environmental media to a point where a risk threshold isexceeded. Future accumulations would represent the net effect of theadditional loadings to the media, minus the losses that occur due todegradation. Plants and animals, because of their high degree of directcontact with environmental media, would have a greater potential to incurunacceptable risk in the future. Because of this, conducting additional riskassessments every 10–20 years at APG and YPG was recommended. Atthis time, projections of future munition residue accumulations andassociated risk levels at APG and YPG ranges are not possible. We do notknow whether the risk trends for the ranges at APG and YPG in the futurewill decrease, stay about the same, or increase (see Exhibit 8). Future riskassessments will be able to identify trends of loading of munition residueand associated environmental risk. For long-term environmental manage-ment of active munition ranges, risk trends need to be known.

Exhibit 8. Relationship of APG and YPG Risk Assessments to Time



Conducting future risk assessments at APG and YPG is consistentwith the objectives of the Munitions Action Plan (MAP) developed bythe Operational and Environmental Executive Steering Committeefor Munitions (OEESCM). One of the objectives of the MAP is todevelop a plan to obtain data and assess the impact of munitions andtheir residues on the environment (Cornelius et al., 2001). Environ-mental risk assessment is an appropriate technical approach to meetthis objective.

LESSONS LEARNEDThree lessons were learned from this experience. First, we needed to

know the health risks to people, plants, and animals from testing andfiring munitions at these ranges. Chemical characterization alone isinsufficient to answer the many questions that were asked when thesample results came back from the lab. We investigated the range andimpact areas and generated a lot of sampling results. But we had no wayof evaluating the significance of the positive detections until we placedour sampling results within the framework of health risk assessment.This risk assessment framework allowed us to make wise and defensiblerisk management decisions.

Second, early on in these studies we realized that there are manyconfounding influences when conducting investigations of firing ranges.Additional sources of contamination were known to exist in and aroundthe range areas. So an attempt was made to focus the sampling and riskassessment on health risks from firing conventional munitions, whichincluded potential exposures associated with firing munitions at the gunposition and potential exposures from the residue of detonating orimpacting munitions downrange in the impact area. All other forms ofpotential or known contamination on the range were considered con-founding influences and were avoided. We tried to exclude from consid-eration all confounding influences and evaluate the risk contributionfrom munition firing only.

Third, based on our experience, both a sufficient munition loadingand a hydrologic driver are needed for significant surface/subsurfaceenvironmental contamination and health risk to develop. There has to bea buildup of residue from a substantial number of munitions fired plusa hydrologic driver (precipitation, abundant water) to dissolve, trans-port, and/or concentrate residue for a risk situation to develop. Implica-tions are that heavily used ranges and impact areas in the humid easternUnited States will present more risk challenges than ranges in the semi-arid western United States.

In summary, this effort is a proactive approach to environmentalstewardship. We believe that these studies present scientific data tosupport the argument that firing high-explosive munitions in both adry desert and a humid temperate climate (as a form of military landuse) is a relatively clean industry. Risks to human health and thenatural environment from 80+ years of munition testing appear to benegligible to minimal.

There has to be a buildupof residue from asubstantial number ofmunitions fired plus ahydrologic driver(precipitation, abundantwater) to dissolve,transport, and/orconcentrate residue for arisk situation to develop.



ACKNOWLEDGEMENTSThe authors would like to thank Steve Wampler, of the U.S. Army

Garrison, APG, plus Jenny Roe and Barrett Borry, of CHPPM, for theircritical review of this work. In addition, this study was a team effort. Theauthors would also like to acknowledge numerous workers withinCHPPM, DTC, YPG, Aberdeen Test Center (ATC), APG, and ArgonneNational Laboratory who made this project possible. ❖

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