PUBLIC HEALTH ASSESSMENT
MCCHORD AIR FORCE BASE
PIERCE COUNTY, TACOMA, WASHINGTON
Sites 10, 49, 50, 51, and 56
Area E encompasses the southern third of industrial and operational activities at McCAFB. Theenvironmental contamination at Area E is largely associated with aircraft maintenance and flightoperations. Most of Area E has a cement cover; grassy areas also exist. Currently, storm runoffdrains into Clover Creek after passing through industrial separating units (Wastewater C Study). Environmental stress (dead grass resulting from spills near one of the buildings) was reported(CH2M 1982) in the IRP Records Search (1982). Drainage of industrial waste runoff into CloverCreek was untreated until 1948. Figure 3, Appendix A, shows the site locations; Table B-19 lists information about the types of wastes disposed or spilled at Area E.
|10||Landfill north of Bldg. 304||Industrial, domestic, and construction wastes||1950s-1966|
|49||Liquid spill area south ofBldg. 392||Waste fuels, POLs, and solvents||1978|
|50||Liquid spill area west of 6thStreet||Waste fuels, including large quantities of JP-4, POL, and solvents; 2,000-gallon spill in 1981, not known if contained||1962-1980|
|51||Liquid spill area, drainageditch west of 6th Street||Waste fuels, POL, paints, and solvents||Unknown|
|56||Septic tank system||Possible herbicide and pesticide residues||Pre-1948|
Because groundwater flows northwest, and Area E lies in the southeastern part of the base, Area E is therefore upgradient of most of the identified contaminant sources on McCAFB. Only Area I, Sites 13 and 22, are upgradient of Area E.
Groundwater contamination at Area E has been investigated during three different studies. Analytical data for the most recent study are summarized in Table B-20.
During the IRP Phase II, Stage 1 investigation, five monitoring wells were installed that werecompleted in the surficial aquifer (maximum depth 78 feet). The main text of this public health assessment contains additional information about the Phase II, Stage I Study.
During Stage 2 of the Phase II investigations, no additional monitoring wells were built in AreaE. Water samples from the wells installed during the Stage 1 investigations were analyzed forcontaminants. The main text of this public health assessment contains additional informationabout the Phase II, Stage 2 Study.
The Phase II groundwater data are not included in Table B-20, because the reports indicate the data may be compromised due to improperly constructed wells and laboratory contamination.
Eight new monitoring wells were installed during the site investigation of Area E in 1990 and 1991. Four monitoring wells were installed upgradient of the suspected sources ofcontamination, and four wells were installed downgradient. Groundwater samples were takenfrom eight of the new wells and from three of the five existing wells.
Forty-four groundwater samples were collected during sampling rounds conducted quarterly fromJune 1990 to May 1991. All groundwater samples collected were analyzed for VOCs and metals. Both filtered and unfiltered groundwater samples were collected and analyzed for inorganiccompounds. Only unfiltered results are included in the data tables.
Analytical data for the most recent investigation at Area E are summarized in Table B-20.
Sites in Areas F and H and Other Sites of Current or Former
Fire Training Areas on Eastern Boundary of Base
Sites 30 and 31 in Area F
Site 27 in Area H
Other Sites 28, 29, and 32
Six fire training areas are included in this group of sites (Sites 27, 28, 29, 30, 31, 32). None ofthese areas are currently in use. The most recently used site (Site 32) has not been used sinceJuly 1990. Site 32 has a clay liner, but, under current EPA standards, an impermeable liner isrequired. All except one of the fire training areas are on the eastern boundary of McCAFB. Oneformer fire training area is included in Area C (Site 33) because of geographic location. Figure 3,Appendix A, shows the locations of the sites; Table B-21 lists information about the types ofwastes disposed or spilled at the areas.
|27||Former Fire Training Area||Waste fuels, JP-4, and AVGAS; 24 exercises per year using about 300gallons of fuel for each exercise; no soil liner||1960-1977|
|28||Former Fire Training Area||Waste fuels, such as JP-4; used for helicopter fire training; 50 trainingexercises per year using about 100 gallons of fuel per exercise||1962|
|29||Former Crash Fire TrainingArea (Shown on base maps,but no other information)||Unknown; base maps list area as a fire training area but no reports of suchactivity at this location were made during the IRP Phase I Record Search;no visible signs of a fire training area at this location||Never Active|
|30||Former Fire Fighter TrainingArea||Solvents, alcohol, AVGAS, and oils were burned during training exercises;35 exercises per year using about 300 gallons of fuel per exercise; no soilliner||1955-1960|
|31||Former Fire Fighter TrainingArea||Solvents, alcohol, AVGAS, and oils were burned during training exercises;35 exercises per year using about 300 gallons of fuel each; no soil liner||1950-1955|
|32||Most Recent Fire FighterTraining Area||Waste fuel (JP-4); 10 exercises per year using 300 to 400 gallons of fuel perexercise; clay liner in place; exercises will not be conducted again untilimpermeable liner is installed.||1976-1990|
Groundwater contamination at the eastern boundary of the base was investigated during bothstages of the IRP Phase II Study. During the IRP Phase II, Stage 1 investigations, one monitoringwell was installed at Area F that was completed in the surficial aquifer. The main text of this public health assessment contains additional information about the Phase II, Stage 1 Study.
During Stage 2 of Phase II, one additional monitoring well was built at the northeastern corner ofMcCAFB at Area H (Site 27). The main text of this public health assessment contains additionalinformation about the Phase II, Stage 2 Study. Because the Phase II data was reported to becompromised due to improper well construction and laboratory contamination, concentrations ofgroundwater contaminants exceeding comparison values are not included here. VOCs andmetals were detected during both Phase II studies at levels exceeding the comparison values.
During site hazard assessment, one well was installed downgradient at Site 27. The groundwaterwas sampled and analyzed for total petroleum hydrocarbons and for benzene, toluene, ethylbenzene, and xylene (BTEX). No contaminants were detected.
As part of the long-term monitoring program, confirmation subsurface soil sampling wasconducted at Sites 30 and 31 in March 1993. One sample was collected from Site 30 andduplicates at Site 31 at a depth of about 10 feet. The samples were analyzed for VOCs,semi-volatile organic compounds, diesel, and priority pollutant metals. No contaminants at Site30 exceeded comparison values. Refer to Table B-22 for a summary of organic contaminants atSite 31 either exceeding comparison values or else for which comparison values are notavailable. The concentration of arsenic in all the samples (2.5-4.8 ppm) exceeded thecomparison value (0.4 ppm, CREG). The maximum concentration for lead was 34 ppm; nocomparison value is available for lead.
|Benzo(a)pyrene||2.3||1993||Ebasco, Long-TermMonitoring Program||0.1||CREG|
|Total Carcinogenic PAHs||12.2||1993||Ebasco, Long-TermMonitoring Program||None||Carcinogen|
Subsurface soil was analyzed for contaminants at three of the former Fire Training Areas duringsite hazard assessment in 1993. At Sites 27 and 32, fuel-contaminated soil was identified duringthe initial test pit investigations. Approximately 6,000 yards of soil were removed at eachlocation; the dimensions of the excavation at Site 27 were approximately 160 by 220 ft with adepth of 6.5 ft, the dimensions of the excavation at Site 32 were approximately 200 by 200 ftwith a depth of 7 ft. Four samples before and after the remediation were collected analyzed fortotal petroleum hydrocarbon compounds and for BTEX at Site 27; three samples before and nineafter the remediation at Site 32 were collected and analyzed for total petroleum hydrocarboncompounds. No detections exceeded the comparison values.
A release from an underground storage tank discovered during the excavation of Site 32occurred. The tank was also removed and the area beneath the tank was excavated to a depth ofabout 29 ft below ground surface to remove the contaminated soils. A confirmation sample wascollected from the bottom of the excavation area directly beneath the tank.
At Site 28, three test pits were excavated to a depth of 5 ft. One soil sample was collected from the base of each test pit and analyzed for total petroleum hydrocarbon compounds. No detections exceeded comparison values.
Area G includes only one site (Site 44), which is the motor pool leach pits in the vehiclemaintenance area. Reports during the IRP Phase I Records Search indicated that large quantitiesof oil were spilled around the diesel tanks. Floor drains in Building 779 discharged into two drywells. No environmental sampling had been conducted in Area G, until site hazard assessmentbegan in January 1993. Figure 3, Appendix A, shows the location of the site; Table B-23 listsinformation about the types of wastes disposed or spilled at Area G.
|44||Motor pool leach pits,disposal/spill site||Waste fuels, POL, and solvents||Unknown|
During site hazard assessment, three groundwater monitoring wells (depths: 25-29 ft) wereinstalled at Site 44, one downgradient, one upgradient, and one within the source area. Twomonths later two additional monitoring wells (depths: 35-45 ft) were installed near the SouthBase Well and one (depth: 27 ft) near the North Base Well. Groundwater samples werecollected in March 1993 from the first set of wells installed; and in May 1993 from the secondset of wells installed. All samples were analyzed for total petroleum hydrocarbon compoundsand volatile and semivolatile organic compounds. The concentrations of groundwatercontaminants exceeding comparison values during the two 1993 sampling events are summarizedin Table B-24.
|Groundwater Contaminants||Range of Levels|
1.4-2 (Near South Base Well)
ND (Near North Base Well)
|Lead (total)||5.6-38.1||March 1993||EBASCO||None||Carcinogen|
|Lead (filtered)||16.8-17.4||March 1993||EBASCO||None||Carcinogen|
Sites 13 and 22
Area I includes Site 13, an inactive general landfill, and Site 22, a burial site; both are on theeastern margin of McCAFB. Interviews with base personnel about Site 13 have indicated thatapproximately 50 drums of liquid waste were disposed in a trench that was dug to a depth ofapproximately 40 feet below the present grade. Subsequent landfill activities have depositedgeneral construction debris across the entire landfill area. The removal and wastecharacterization of the drums is described in the SI report. Figure 3 shows the locations of the sites; Table B-25 lists information about the types of wastes disposed or spilled at Area I.
|13||General landfill||Domestic and construction waste; 50 drums of liquid waste, includingpaints and solvents; open burning took place in 1950s||1950-1979|
|22||Burial site||Cars and heavy equipment; waste POL||1939-1951|
The Area I landfill site is on a flat to gently rolling part of the Tacoma upland. The site has beengraded to a level, sparsely vegetated, surface. Land use in the immediate vicinity of the siteincludes a runway more than 1,000 feet to the west, runway support facilities 600 feet to thenorth, and a family camping area about 1500 feet to the south. There are no continuouslyflowing drainage channels in Area I, largely because of the high infiltration rates in the soil andthe flat topography. The closest stream is Morey Creek, which is about 2000 feet north of thelandfill. Some low-lying marshland is about 400 feet southeast of the site. A large lake(Spanaway Lake) is about 1.5 miles southeast of the site. An off-base residential area isimmediately adjacent to the base, about 1500 feet east of the landfill. The closest downgradient potable water wells are more than a mile away.
From historic records and visual observations, contaminants detected at the site are believed tohave originated from waste disposal in the unlined landfill. A coarse, permeable gravel underliesthe landfill, and there are no significant barriers to groundwater or contaminant movementbetween the landfill and the underlying unconfined aquifer. The approximate limits of thelandfill trench were defined, and the suspected location of the buried drums within the trench was identified during the site investigation (EBASCO Environmental 1991d).
Sampling and analysis of media in Area I were not performed during either the Stage 1 or Stage 2Phase II investigations. During the site investigation, 10 groundwater wells and two double soilgas migration probes were installed on the boundaries of the landfill. A soil gas survey,geophysical surveys, and three source area borings also were conducted at the landfill.
Groundwater flows northeast below McCAFB; Site 13 lies on the eastern boundary of the base. Site 13 is thus upgradient of all other suspected sources of contamination on the base, includingArea I, Site 22, and Area E. Three of the monitoring wells were installed in a cluster upgradientof the area; seven were installed in three clusters downgradient. The downgradient wells consistof three well pairs drilled to between 40 and 60 feet and one deeper well about 100 feet deepcompleted in the first aquifer. The upgradient wells consist of one well pair and a deep well; the three wells are drilled to depths similar to those of the downgradient wells.
Between June 1990 and May 1991, groundwater samples were collected quarterly from the 10monitoring wells. The downgradient wells were sampled twice; the upgradient wells weresampled four times. Each sample was analyzed for metals and VOCs. Contaminantconcentrations are listed in Table B-26.
|Contaminant||Range of Levels|
|Cadmium||6 - 8||6/90-|
Soil Gas Investigations
Ninety-five soil gas samples were analyzed during the soil gas survey. Each sample wasanalyzed with an explosimeter and an organic vapor analyzer while it was being collected. Thesamples were then analyzed with a portable gas chromatograph for VOCs. Most of the samplesexceeded the lower explosive limit. Most of the sample locations also contained more than 1000ppm organic vapor.
During this study, two sets of double soil gas migration probes were installed at depths of about15 and 25 feet to monitor levels of methane and other volatile organic compounds. Gasmigration probe sampling took place in March 1991 and August 1991. Methane concentrationsdid not exceed the state landfilling standards (50,000 ppm) for migrating gas at the site boundary.
The soil gas survey indicates that some organic vapors underlie most of the cleared area of the site, with rapidly diminishing values observed near or just inside the surrounding woods. Mostof the organic vapor was reported to be methane, but other VOCs were detected at the centralpart of the site, as well as near the base boundary. Airborne contaminants are greatly diluted and are below detection limits.
Three soil borings were drilled through the suspected landfill location at Area I. Three soilsamples were collected from each boring, including one sample at the surface to a depth of sixinches and other samples at a depth of up to 24.5 feet. The soil analyses indicated that the soilsand waste in the landfill are not generally regulated hazardous wastes according to RCRA andWashington State Dangerous Waste regulations (EBASCO Environmental 1991d).
Low levels of volatile organic contamination were detected in all of the source area soil samples. No VOCs or heavy metal contamination, except arsenic, exceeded corresponding comparisonvalues.
The concentrations of lead at McCAFB are included in Table B-27 because comparison valuesare not currently available. The concentration of lead in the soil at McCAFB is similar tobackground concentrations found in other soil in the western United States (ATSDR 1992f).
|Arsenic||2.8 - 5.7||6 inches to |
|Lead||2.6 - 43|| 6 inches to |
Sites 36 and 48
Area J consists of Sites 36 and 48; both are in the base civil engineering yard. Site 36 consists ofa storm drain ditch originating near Building 540 and extending east beyond the fence line of thecivil engineering yard. Site 48 includes an aboveground pentachlorophenol (PCP) woodpreservative tank and the soil around it that has become contaminated with spilled PCP. Figure3, Appendix A, shows the site locations; Table B-28 lists the information about the types ofwastes disposed or spilled at Area J.
|36||Storm drain ditch||Waste paint, oil, and fuel||Unknown|
|48||Pentachlorophenol woodpreservative tank||Pentachlorophenol overflow and spills||1950s-?|
Surface runoff from the civil engineering yard and the shop areas, including the entomologyshop, drains into the storm water ditch (Site 36). Unidentified quantities of waste materials havedrained into the ditch. Migration of the wastes into the groundwater is possible. Noenvironmental sampling had been conducted at Site 36 until 1993.
Unknown quantities of PCP have been spilled at Site 48 since the 1950s. Migration of the PCPinto the groundwater by infiltration is possible. Contamination at Area J was not investigateduntil 1993; however, the IRP Phase I Records Search reported that the PCP content of the soilbeneath the tank was less than 69 ppm.
As part of the long-term monitoring program, confirmation subsurface soil sampling wasconducted at the two sites in March 1993. Duplicate samples were collected from Site 36 at adepth of 10 feet and five samples plus one duplicate at Site 48 at a depth of about two feet. Thesamples from Site 36 were analyzed for VOCs, semi-volatile organic compounds,pesticides/PCBs, total petroleum hydrocarbons, gasoline, diesel, and priority pollutant metals. The samples from Site 48 were analyzed for semi-volatile organic compounds, and prioritypollutant metals. Refer to Table B-29 for a summary of organic contaminants at the two siteseither exceeding comparison values or else for which comparison values are not available. Theconcentration of arsenic in all the samples (1.9-4.4 ppm) exceeded the comparison value (0.4ppm, CREG). The maximum concentration for lead was 105 ppm; no comparison value isavailable for lead.
|Site 36-Benzo(a)pyrene||0.4||1993||Ebasco, Long-TermMonitoring Program||0.1||CREG|
|Site 36-Total Carcinogenic PAHs||2.4||1993||Ebasco, Long-TermMonitoring Program||None||Carcinogen|
|Site 48-2-Methylnaphthalene||12.0||1993||Ebasco, Long-TermMonitoring Program||None||Non-carcinogen|
|Site 48-Pentachlorophenol||6.2||1993||Ebasco, Long-TermMonitoring Program||2||Pica-child EMEG|
|Site 48-Total Carcinogenic PAHs||0.03||1993||Ebasco, Long-TermMonitoring Program||None||Carcinogen|
Sites 3, 8, 9, 11, 14-21, 23-25, 43, 59, 63, 64, and 65
All of the sites listed in this section, except Sites 64 and 65, have been recommended byMcChord AFB for "no further action" in accordance with the 1989 "Air Force IRP ManagementGuidance." Table B-30 lists the waste history of those sites. Hazardous materials were not disposed or spilled at Sites 8, 9, 11, 14, 15, 19, 20, 21, 23, and 24.
|3||Burial site||Low-level radioactive waste||1950s|
|8||Burial site||Coal ash||1950s|
|9||Burial site||Fire brick and hardwood flooring||Unknown|
|11||Landfill||Demolition and construction debris||Until 1970|
|14||Burial site||Demolition and construction debris||1972-1973|
|15||Unauthorized surface dump||Domestic wastes||1960-1972|
|16||Burial site||Miscellaneous automotive and aircraft equipment||1940s-?|
|17||Burial site||Demolition debris; small amount industrial wastes||1950s|
|18||Burial site (dry well)||Caustic soda||Until 1970s|
|19||Burial site||Domestic and demolition debris||1952-1965|
|20||Burial site||Domestic and demolition debris||?|
|21||Burial site||Demolition and construction debris||?|
|23||Landfill||Demolition and construction debris||Unknown|
|24||Dump||Flight line sweepings (loose, natural objects, such as rocks and vegetation)||1957-1960|
|25||Surface Dump||Flight line sweepings, chemicals to remove runway rubber deposits,including cresylic acid, benzene, and phenolic compounds||1950s-1970|
|43||Liquid waste disposal site||POL for weed control||Until 1960s|
|59||Fuel oil spill||Fuel oil (1000 gallons)||1960s|
|63||Remediated POL soilcontamination in two areas||POL; contaminated soils removed in 1988||1984|
|64||Entomology shop dry well||Small quantities of entomology wastes: rinsates of pesticides||?|
|65||Underground storage tanks -22 at 7 different locations||Includes tanks eligible for the Defense Environmental Restoration Program;removal of tanks is planned; information about any leakage/ environmentalcontamination will not be available until 1994.||Unknown|
Figure 3, Appendix A, shows the site locations. Environmental sampling has been conductedonly at Sites 63 and 64. Additional information is included for those sites at which hazardousmaterials were either spilled or disposed because they have been proposed for no further action.
Site 3: Low-Level Radioactive Burial Site
Site 3 is within a 15-square-foot fenced and posted enclosure in the center of the 97-acre fenced,secured, and guarded munitions storage area north of the golf course. During the 1950s, smallquantities of discarded, low-level radioactive radar instrument components (e.g., krypton tubes,fluorescent dials and signs painted with radium, and strontium-containing materials) were storedin a 5-foot-cube, pre-cast concrete utility vault. Sometime before 1959, the vault was filled with concrete and buried under 4 feet of soil at its present location.
In 1978, the site was partially excavated by Disaster Preparedness to confirm the existence andcondition of the buried vault. The vault was found to have no discoloration or defects in itssurfaces; detectors monitored no emissions above background levels. The vault wassubsequently reburied.
Site 16: Automotive Equipment and Aircraft Parts Burial
Site 16 is believed to be beneath the baseball field north of the 1100 dormitories and east of therailroad on a large open lawn. Structural components of aircraft and automobiles are reported tobe buried there. This salvage yard was used from the early to mid-1940s, when the area wascovered with clean soil and planted with grass. The baseball field was built in 1967.
Site 17: Motor Pool Building Demolition and Burial
Site 17, which is believed to be in a large, open lawn 400 feet south of Clover Creek betweenBuildings 1110 and 1120, was the location of a small-operation motor pool. In the early 1950s,the building was cleaned out, demolished, and buried where it stood. The area is currently acultivated grass field.
Site 18: Caustic Soda Pit
Site 18 is believed to be on the flight line infield 100-200 feet east of "J" Ramp. The area isadjacent to buildings, the runup pad, and aircraft parking. Only one report during the IRP Phase IRecords Search referred to this area, which may have been a dry well disposal site for spent, "hottank" cleaning solutions. It was reported to have been closed in the mid-1970s and allowed torevegetate naturally.
Site 25: Flight Line Sweepings Surface Dump
Site 25 is believed to be between Buildings 328 and 348 south of Lincoln Boulevard at thesouthwestern end of a taxiway in a slight depression. Flight line sweepings and runway rubberdeposits were disposed of on the surface of the depression between the 1950s and 1970. In 1964,the Air Force began regular maintenance (rubber removal) on runways. Chemicals with a base ofcresylic acid and a blend of benzene and synthetic surfactants were used to remove rubberbuildup on concrete pavements. Alkaline phenolic chemicals were used on asphalt pavements. In the late 1960s, environmental regulations required that runways be bermed to prevent runoffand that the sweepings be drained to collect the solvents for disposal. The use of chemicalsstopped after the mid- 1960s. The annual cleaning of touchdown areas was performed three orfour times after 1964. This site is adjacent to two areas of potentially hazardous waste fuel,petroleum, oil, lubricants, and solvent releases (Sites 49 and 50).
Site 43: Petroleum, Oil, Lubricants Disposal
Site 43 is believed to be 800 feet north of the Perimeter Road, east of Fort Lewis, and adjacent tothe 350 ammunitions area compound. Only one interview source during the Phase I RecordsSearch referred to this disposal site. Waste petroleum, oil, and lubricants occasionally may havebeen spread on the ground for weed control. In the 1960s, mowing replaced the use wastes forweed control adjacent to ammunition areas.
Site 59: 1000 Gallon Fuel Oil Spill
This site is believed to be under the parking lot the west of Building 675, 300 feet east of therailroad. Only one interview source during the Phase I Records Search referred to this fuel oilspill, which took place over a 48-hour period sometime during the 1960s. In the late 1960s,Building 675 was remodeled, and the paved parking lot expanded.
Site 63: Remediated Soil Areas
This site consists of one area adjacent to Building 792 and another area northeast of Building1173. The Washington Department of Ecology noted surface staining in the two areas during aroutine inspection of McChord AFB in 1984. The results of an investigation that included soilborings and laboratory analysis of soil samples in the two areas was published in May 1986(Report of Geotechnical/Environmental Investigation, Hydrocarbon Contamination of Buildings792 and 1173, McChord AFB). The results of another investigation were published in January1987 (Results of Supplemental Sampling and Analysis, Soil Samples Near Buildings No. 792and 1173). That investigation described the finding of TPHs, VOCs, PAHs, halogenatedhydrocarbons, total metals, and tricresyl phosphate in soil samples collected from excavated test pits. Remediation of the relatively small areas of contaminated soils was completed in 1988. The remediation process is described in the Site Description and History section of the main text of this public health assessment.
Site 64: Entomology Shop Drywell
During site hazard assessment at Site 64, the Entomology Shop Drywell, all soil was removed fordisposal within the drywell and to a depth of about 6 to 7 feet. One soil sample was collectedfrom the base of the excavation and analyzed for pesticides and polychlorinated biphenyls(PCBs). Contaminants that were detected at concentrations exceeding comparison values aresummarized in Table B-31.
|alpha-Chlordane||90*||about 7 feet||1993||EBASCO||0.5||CREG|
|gamma-Chlordane||94*||about 7 feet||1993||EBASCO||0.5||CREG|
- * Indicates that a dual column GC technique was employed and that the test results from the two columns differ by more than 25%.
The one groundwater monitor well (depth: 25 feet) that was installed downgradient during sitehazard assessment had no measurable water during the May 1993 sampling event; therefore nogroundwater samples were collected.
Site 65: Underground Storage Tanks
This site includes tanks eligible for the Defense Environmental Restoration Program. Removalof all underground storage tanks is planned. Confirmational soil samples are being collected astanks are removed to determine if there has been any leakage or environmental contamination. Areport about this removal program will be available in 1994.
Toxicologic Summary for
Trichloroethylene (TCE) is a clear, colorless, nonflammable liquid that has a sweet odor. Theagent can be smelled at concentrations of approximately 20 to 80 ppm. Some workers may notbe able to smell TCE at concentrations near the permissible workplace exposure limit of 50 ppm;therefore, relying on employees' sense of smell may not provide adequate warning of its presence (ATSDR 1992a).
Trichloroethylene is a volatile organic compound (VOC) also known as trichloroethene. TCEdoes not occur naturally in the environment; therefore, its presence indicates manufacture, use, orstorage of the chemical. TCE is used extensively for vapor degreasing of fabricated metal parts. Consumer products containing TCE include typewriter correction fluids, paint removers andstrippers, cosmetics, adhesives, spot removers, and rug-cleaning fluids. In the workplace, TCE isseldom used in pure form. Industrial-grade TCE contains small amounts of stabilizers in theform of antioxidants or acid receptors. Total chemical impurities usually do not exceed 0.1% by weight (ATSDR 1992a).
Because of its widespread use, TCE has become a common environmental contaminant. Contamination results from evaporative losses during use; discharge to surface waters andgroundwater by industry, commerce, and individual consumers; and leaching from hazardouswaste landfills into groundwater. In the atmosphere, TCE is destroyed by photooxidation; it hasa half-life of less than seven days. That relatively short half-life significantly limits the transportof TCE in air. On the other hand, the continual volatilization of TCE from emission sources orcontaminated surface waters ensures its persistence in air. TCE in drinking water is a result of itsrapid leaching from landfills and its discharge from industrial wastewaters. TCE volatilizesquickly from water depending on temperature, water movement, and aeration. Thebiodegradation of TCE under anaerobic conditions is slow; therefore, TCE is relatively persistent in subsurface waters (ATSDR 1992a).
TCE is one of the VOCs most frequently found in groundwater. Because TCE is volatile,household activities such as bathing, laundering, and cooking with TCE-contaminated water mayproduce air concentrations above ambient levels. Questions about an association betweeningested TCE and long-term health effects, including malignancies, have been raised, butscientific evidence that the effects are caused by TCE exposure is lacking (ATSDR 1992b).
Compared with dermal absorption, pulmonary and gastrointestinal absorption of TCE is rapid. Absorption of TCE vapor through the skin is negligible (ATSDR 1992a). Once absorbed, TCEis rapidly cleared from the blood. Because of its lipid solubility, TCE accumulates in organscontaining high levels of adipose (fat) tissue. Data from animal studies indicate that body fat,adrenal glands, ovaries, and cellular components of the blood accumulate the greatest portion ofabsorbed TCE. TCE rapidly crosses the placenta in both people and animals and can accumulatein the fetus (ATSDR 1992a).
In people, TCE is metabolized primarily in the liver by the mixed function oxidase system, whichprobably converts TCE to an oxide (epoxide). Subsequently, this reactive intermediate mayrearrange to form trichloroacetaldehyde and then chloral hydrate. The latter forms thetrichloroethanol and trichloroacetic acid metabolites excreted in the urine after TCE exposure(ATSDR 1992b).
A relatively small amount of absorbed TCE is exhaled unchanged; most of an absorbed dose ismetabolized and excreted in the urine. After exposure to air concentrations between 100 and 200ppm, approximately 30% to 50% of an absorbed dose appears in urine as trichloroethanol, andabout 10% to 30% appears as trichloroacetic acid. The time between TCE inhalation and urinaryexcretion of trichloroethanol is relatively short (approximately 10 hours). Urinary excretion oftrichloroacetic acid takes longer (approximately 52 hours). Trichloroacetic acid is theoreticallydetectable in urine for at least a week after TCE exposure (ATSDR (1992a).
TCE-induced central nervous system symptoms depend on both concentration and exposureduration. In one study of human volunteers, exposure to TCE air levels of 27 ppm for four hourscaused drowsiness and mucous membrane irritation; exposure to TCE at 81 ppm causedheadaches. In another study, volunteers reported drowsiness, lethargy, and nausea within fiveminutes of exposures to anesthetic concentrations of 2,000 ppm. TCE presumably anesthetizesby affecting cell membranes and altering neuronal transmission. Symptoms resulting fromshort-term exposures (a few hours) typically resolve within a few hours. Workers exposed toTCE during industrial cleaning and degreasing operations complained of decreased appetite,sleep disturbances, ataxia, vertigo, headache, and short-term memory loss (ATSDR 1992a).
Mortality studies of TCE-exposed workers do not indicate an increased risk of cardiovasculardeath. A few susceptible people exposed to near anesthetic levels (200 ppm) during vigorousactivity, may have an increased risk of cardiac dysrhythmia. However, ventricular ectopy wouldnot be expected from TCE exposure at background environmental levels, or at those currentlyallowed in the workplace (ATSDR 1992a).
When swallowed, TCE causes gastrointestinal irritation and possible inflammation of thegastrointestinal tract manifested as nausea, vomiting, diarrhea, and abdominal pain (ATSDR 1992a).
No increased incidence of congenital malformation has been observed in babies born to mothersoccupationally exposed to TCE. A small cross-sectional study of TCE-exposed degreasingworkers showed no effect on male germ cells. Data from animal studies reveal no adverseeffects on reproductive system histology, fertility, or other reproductive performance parameters (ATSDR 1992a).
Inhalation or oral exposure to high doses of TCE results in liver and lung tumors in mice, andresults in renal adenocarcinomas, testicular tumors, and, possibly, leukemia in rats. The livertumor data obtained from the mice studies is controversial because the mouse species studiedtends to spontaneously form liver tumors. The presence of TCE stabilizers, such asepichlorohydrin, also may confound some of the results. Studies to date indicate that mice aremore susceptible than rats to TCE carcinogenicity (ATSDR 1992a).
Most early epidemiologic studies of workplace exposures to TCE did not demonstrate asignificant increase in the incidence of cancer. A recent follow-up study of workers, however,found excesses of bladder cancer and lymphomas. The significance of the study has yet to beconfirmed. Some inconsistencies between results of animal and human studies may be caused bymetabolic saturation and formation of reactive intermediates in animals exposed to high TCElevels; the same results have not been seen in people with low-level exposure (ATSDR 1992a).
EPA considers the weight of evidence sufficient to conclude that TCE is carcinogenic in animalsand is probably carcinogenic in people. However, findings of animal studies to date do not meetthe National Toxicology Program (NTP) criteria on carcinogenicity in both sexes of multiplespecies. Therefore, NTP does not consider TCE a carcinogen (ATSDR 1992a).
TCE produces minimal irritation of the respiratory tract, except at concentrations exceedingcurrent workplace standards. TCE and other solvents may produce contact dermatitis, rashes,and burns. The defatting dermatitis that may result from prolonged contact can reduce resistanceto skin infections. No deleterious effects on the immune system have been noted in peopleexposed to TCE from environmental sources. Immunologic studies in animals are inconclusive(ATSDR 1992a).
Agency for Toxic Substances and Disease Registry. 1992. Toxicological Profile forTrichloroethylene.
Agency for Toxic Substances and Disease Registry. 1992. Case Study in EnvironmentalMedicine for Trichloroethylene.
Toxicologic Summary for
1,2-dichloroethylene (DCE), also known as 1,2-dichloroethene, is a highly flammable, colorlessliquid with a sharp, harsh odor. People can smell DCE at air concentrations of approximately 17ppm. 1,2-DCE exists in two forms: cis-1,2-DCE and trans-1,2-DCE. Both forms may be presentin a mixture. DCE is used primarily as a chemical intermediate in the synthesis of chlorinatedsolvents and compounds. It also has been used as a lot-temperature extraction solvent fororganic materials such as dyes, perfumes, and lacquers.
DCE's presence in the environment is caused entirely by human activity. DCE is released intothe environment from factories that make or use the chemical; from landfills and hazardouswaste sites; from chemical spills; and from burning of vinyl-containing objects.
DCE is removed from the atmosphere chiefly by reaction with photochemically generatedhydroxyl radicals. The estimated half-lives for cis- and trans- isomers are 8.3 and 3.6 days,respectively. Precipitation also may remove DCE from the atmosphere; however, most DCE thatdissipates in that way probably reenters the atmosphere by volatilization. When released tosurface water, most DCE volatilizes; in a model river, its half-life is estimated to beapproximately three to six hours. When released to soil, DCE volatilizes rapidly from moist soilsurfaces and leaches through subsurface soil, potentially becoming a groundwater contaminant.In groundwater, DCE is susceptible to anaerobic biodegradation. Experimental data indicate thatthe anaerobic biodegradation half-life of DCE in groundwater is approximately 13-48 weeks.
The hepatic microsomal cytochrome P-450 enzyme system catalyzes the first step of metabolismof DCE. The ethylene double bonds undergo epoxidation to form dichlorinated epoxides. Thedichlorinated epoxides in turn can undergo a nonenzymatic rearrangement to formdichloroacetaldehyde, the predominant metabolite of microsomal cytochrome P-450 activity. The dichloroacetaldehyde is extensively converted to dichloroethanol and dichloroacetate bycytosolic or mitochondrial aldehyde and alcohol dehydrogenases present in hepatocytes. Excretion of DCE has not been studied.
Clinical symptoms associated with exposure to DCE in air include nausea, drowsiness, fatigue,intracranial pressure, and ocular irritation. No information is available on its toxic effects inpeople who ingest it or have dermal contact. Pathologic lesions of the heart, liver, and lung havebeen reported in rats exposed to trans-1,2-DCE in air. Rats in those studies experienced ataxiaand respiratory depression before dying. Those effects have not been seen in people.
People who have inhaled DCE have had central nervous system effects such as dizziness,drowsiness, vertigo, and intracranial pressure. Those symptoms disappeared quickly afterexposure stopped. The pharmacologic basis for DCE-mediated narcosis has not been studied.
To date, the association between exposure to the cis- and trans- isomers of DCE anddevelopment of cancer in people and in animals has not been studied.
Agency for Toxic Substances and Disease Registry. 1992. Toxicological Profile for1,2-dichloroethylene.
Comments from Public Comment Period
Comments on McChord Air Force Base Public Health Assessment
The following comments (bold print) were received by ATSDR in response to the publiccomment period for the McChord Air Force Base Public Health Assessment. This list does notinclude comments on the accuracy of stated facts. If the accuracy of a statement was questioned,the statement was verified or corrected. If the same comments were received from more than onesource, only one comment and response is listed. ATSDR's response follows each comment.
1) References to the 1983 AFOEHL study should be removed because the original data ismissing. It is not possible to review the results or the sampling and analytical proceduresto check if proper quality control measures were performed. The data is very suspectbecause the results were not duplicated during the RI in which proper QA/QC procedureswere performed.
- Response: ATSDR's reference to the AFOEHL study was included, but concentrations of theelevated metals were deleted for the reasons listed above in the comment.
2) Since metals are not contaminants of concern at the ALGT, there is no reason to waste limited resources sampling for metals.
- Response: Refer to Appendix B, Table B-17 - Contaminant Concentrations in On-BaseGroundwater Monitoring Wells, Area D. Three metals (arsenic, barium, and cadmium) weredetected in the groundwater at Area D during the Remedial Investigation at levels exceedingATSDR comparison values. Chromium and lead were also detected, but no comparison valuesare available for those metals. Since VOC contamination emanated from Area D into thegroundwater at ALGT, it is possible that the metal contamination in the groundwater at Area Dcould also emanate to the private wells still being used in ALGT.
3) One letter received during the public comment period contained comments, concerns,and questions about the exposure of residents in the American Lake Garden Tract (ALGT)to drinking water from private wells contaminated with chemical wastes disposed of atMcCAFB. The following questions/comments related to the environmental contaminationfrom McCAFB in the ALGT and subsequent health concerns are extracted from the letter:
a) Why was the entire ALGT area included in the cancer rate calculations, when only afew people in the northwest corner were exposed to the contamination? (If only the peopleactually exposed to the contaminated water were included in the computation of the diseaserate, the writer believes that a greater rate of cancer would be seen that would be abovenormal levels.)
- Response: The questioner is concerned that increased cancer rates for a very small part of thepopulation would be overlooked. It is true that data aggregated at the county level (as is the casewith the Washington Cancer Registry) would probably not detect elevations in a very smallgeographic area. However, the important point to make here is that elevated rates themselveswould not provide any evidence of environmental exposure. In this instance, we do not believethat exposure to VOCs from the private wells was at a level that would be expected to cause anincreased incidence of disease.
b) The ALGT area has a highly transient population (military). The government(ATSDR) cannot show accurate numbers concerning cancer, heart disease, etc., becausethey have never followed people living here, then moving on to other areas of the UnitedStates. Has the government followed the personnel stationed at McCAFB in the earlydays?
- Response: Again, the questioner is concerned that disease will be missed. However, thetransience of the population means that they are less likely to be affected because the duration oftheir exposure was relatively brief (the average tour of duty is 3 years). Our estimates ofexposure dose conservatively used the highest levels of TCE detected (15 ppb) and 1,2-DCE(193 ppb) detected and assumed an exposure period of 30 years. That evaluation showed that theexposure did not exceed our health guidelines for non-cancerous health effects and only posed aslight increased risk of developing cancer over a lifetime, therefore, an exposure for only 3 years to the same levels would pose even less of a health concern.
c) In the 1940s - 1960s, the time of highest contamination, the number of people living in the area was much smaller than it is today.
- Response: Again, the questioner is concerned that disease will be overlooked by analyzing by alarger population. The important point is that even for the small group of people who lived in thearea consistently from the 1940s to the 1960s, we do not think that exposure to VOCs was atlevels that would be expected to cause an increased incidence of disease.
d) Concern was expressed that children and grandchildren of those exposed may haveadverse health effects.
- Response: No genetic damage has been linked with trichloroethylene (TCE) exposure at theconcentrations detected in drinking water at ALGT. However, a potentially sensitive populationmay include unborn children in utero during the time the mother was exposed to TCE and/orDCE. Women who drank the contaminated water at concentrations close to those detected in1983 (TCE @ 15 ppb, DCE @ 193 ppb) during the first three months of their pregnancy, mayhave had an increased risk of delivering a child with a congenital heart defect. However, theepidemiologic studies that show this association have significant limitations, including questionsabout whether all of the study population was exposed, how long exposure took place and theexact concentrations of VOCs to which these mothers were exposed. Other than this smallpopulation (children in utero during the time the mother was exposed), children andgrandchildren of the exposed population would not be expected to develop adverse health effects.