PUBLIC HEALTH ASSESSMENT
NAVAL AIR WARFARE CENTER
[a/k/a NAVAL AIR DEVELOPMENT CENTER (8 WASTE AREAS)]
WARMINSTER TOWNSHIP, BUCKS COUNTY, PENNSYLVANIA
APPENDIX A: SITE EVALUATION TABLE
Table A-1: Evaluation of Potential Public Health Hazards at NAWC Warminster
| Site | Site Description/ Waste Disposal History |
Investigation Results/ Environmental Monitoring Results |
Corrective Activities and/or Current Status |
Evaluation of Public Health Hazard |
| Areas A and B (OU1, OU6, OU7, OU9, and OU10) | ||||
| Area A | ||||
| Area A, Site 1 | Area A, Site 1 is located in the western portion of the
Naval Air Warfare Center (NAWC), adjacent to the wastewater treatment plant.
This site was used for waste disposal from 1948 to 1950. Paints, oils, asphalt,
roofing material, solvents, scrap metals, wastewater treatment plant sludge,
and other unknown materials may have been disposed of here.
Surface water runoff from Area A flows into Little Neshaminy Creek, which runs through residential areas north of the base. |
Groundwater: Volatile organic compounds
(VOCs) and metals were detected above state and federal drinking water standards
and Agency for Toxic Substances and Disease Registry (ATSDR) comparison
values (CVs). Investigation showed that contaminants have migrated off site
north of Area A. Soil gas: VOCs were detected. Surface soil: Metals were detected above background levels but below CVs. Subsurface soil:. Aldrin, Aroclor-1260 (a polychlorinated biphenyl [PCB]), benzo(a)pyrene, arsenic, antimony, cadmium, chromium, and silver were detected above CVs. Lead was detected above the U.S. Environmental Protection Agency (EPA) soil screening level (SSL). Surface Water/Sediment: VOCs, polyaromatic hydrocarbons (PAHs), pesticides, PCBs, and metals were detected above CVs. |
Groundwater: An Interim Record of Decision
(ROD) is in place for groundwater contamination. The ROD selected installing
extraction wells and a treatment system to limit movement of groundwater
contamination and sampling monitoring wells and residential wells as the
preferred remedial action. The treatment system is in place and extraction
wells in Area A were installed in November and December 1998. Soil: A soil removal action was conducted at Site 1 in November 1998. A ROD was signed in June 2000. Surface Water/Sediment: A ROD requiring regular stream monitoring was signed in June 2000. Site 1 is included in a parcel of land that will likely be transferred to the Warminster Municipal Water Authority (WMWA) for construction of a wastewater treatment plant. |
Groundwater: ATSDR evaluated public
health hazards associated with on-site groundwater use in this table under
Area D. Off-site groundwater was addressed separately in this table. Soil: No public health hazards are associated with soil at this site because contaminants were detected in surface soil at levels below CVs. Contaminated subsurface soil was remediated as part of the 1998 removal action. Construction workers could be exposed to areas of contaminated subsurface soil during future construction. Construction workers dealing with soil at this site should follow Occupational Safety and Health (OSHA) regulations as needed. Surface Water/Sediment: Infrequent exposure during on-site drainage cleaning activities or recreational use by off-site residents is unlikely to pose a public health hazard based on an evaluation of exposure doses. Streams and drainage channels at NAWC and immediately down stream have insufficient flow to support a fish population. |
| Area A, Site 2 | Area A, Site 2 includes two trenches in the western portion of NAWC where wastewater sludge was dumped from 1965 to 1970. The trenches were 12 feet wide, 200 feet long, 8 feet deep, and may have contained 700 cubic yards of waste. Upon closure the pit was covered with 2 feet of fill. This site may also include other disposal areas that received waste from base operations. | Groundwater: See Area A, Site 1. Soil gas: VOCs were detected. Surface soil: Benzo(a)pyrene, antimony, and arsenic were detected above CVs. Lead was detected above its SSL. Subsurface soil: Aldrin, benzo(a)pyrene, PCBs, arsenic, antimony, cadmium, and chromium above CVs. Lead was detected above the SSL. No CV was available for delta-BHC. |
Groundwater: See Area A, Site 1. Soil: A soil removal action was conducted at Site 2 in November 1998. A ROD was signed in June 2000. Site 2 is included in a parcel of land that will likely be transferred to the WMWA for construction of a wastewater treatment plant. |
Groundwater: See Area A, Site 1. Soil: Based on an evaluation of exposure, no public health hazards from use of the site were identified. The site is located in a former industrial portion of NAWC. Exposures were infrequent during use and ceased when the NAWC was closed under the Base Realignment and Closure (BRAC) program. The soil removal action is expected to reduce soil contaminants to levels suitable for industrial use. Construction workers at this site should follow OSHA regulations as needed. |
| Area A, Site 3: Waste Burn Pit No. 3 | From 1955 to 1965, solvents, paints, roofing material, and other unknown materials were burned in a pit located in the western portion of NAWC. The pit is 20 feet wide, 30 feet long, and 10 feet deep. Upon closure, the pit was reportedly backfilled with on-site soil. | Groundwater: See Area A, Site 1. Surface soil: Benzo(a)pyrene was detected above its CV. Subsurface soil: PAHs, aldrin, and arsenic were detected above CVs. Lead was detected above its SSL. |
Groundwater: See Area A, Site 1. Soil: A limited soil removal action was conducted at Site 3 in November 1998. A ROD addressing soil contamination was signed in June 2000 and includes institutional controls to limit property use. Site 3, which will likely be used as a buffer zone or parking lot, is included in land being transferred as part of an economic development conveyance. |
Groundwater: See Area A, Site 1. Soil: No public health hazards were identified. The site is located in a former industrial portion of NAWC. Exposures were infrequent during site use and ceased when NAWC was closed under the BRAC program. Construction workers at this site should follow OSHA regulations as needed. |
| Area A, Imp. Area | The Navy operated eight unlined impoundments for storage of wastewater treatment plant sludge. The sludge was removed and the areas were backfilled in 1973. The excavated sludge was reportedly disposed of at Site 7 (see below). | Groundwater: See Area A, Site 1. Soil gas: VOCs were detected. Subsurface soil: Aroclor-1260, benzo(a)pyrene, chromium were detected above CVs. |
Groundwater: See Area A, Site 1. Soil: A ROD addressing soil contamination was signed in June 2000 and includes institutional controls to limit property use. The Impoundment Area is included in a parcel of land that will likely be transferred to the WMWA for construction of a wastewater treatment plant. |
Groundwater: See Area A, Site 1. Soil: No public health hazards are associated with this site. The site is located in a former industrial portion of NAWC. Exposure to surface soil is expected to be infrequent and sludges were reportedly removed in 1973. Construction workers at this site should follow OSHA regulations as needed. |
| Area B | ||||
| Area B, Site 5: South Runway Landfill and S. Woods housing complex | This landfill consists of six to eight disposal trenches
located south of the main runway and partially under the Shenandoah Woods
housing complex. Units are occupied by Navy personnel and their families.
Paints, solvents, scrap metal, demolition debris, and drums of asphalt were
disposed of in these trenches. The trenches are at least 12 feet wide, 70
feet long, and 8 feet deep. Buried waste extends north, east, and west of
Housing Unit 401. The housing complex has always received public drinking
water. Ground cover around the housing complex includes grass, woodland,
and overgrowth, as well as paved road.
Surface water runoff from Area B drains into tributaries of Southampton Creek. |
Groundwater: Trichloroethylene (TCE)
was detected above EPA's Maximum Contaminant Level (MCL) beneath Area B.
Low levels of other VOCs were also detected. Manganese was detected above
CVs but there was no identifiable plume of metal contaminants. Investigation
showed that contaminants could migrate off-base to the south of Area B. Soil gas: Low levels of VOCs were detected in soil gas near Housing Unit 401 and elsewhere at Site 5. Air samples from inside Unit 401 and soil gas samples adjacent to the foundation did not detect elevated VOCs. Surface soil: Benzo(a)pyrene, Aroclor-1254, and cadmium were detected above CVs. Lead was detected above the SSL. Subsurface soil: Ten inorganics were detected above CVs. Lead was detected above the SSL. Surface Water/Sediment: Thallium was detected above the MCL in surface water. Aroclor-1260 and benzo(a)pyrene were detected above CVs. Benzo(a)anthracene, benzo(b)fluoranthene, and indeno(1,2,3-cd)pyrene were detected in sediment above the residential risk-based concentration (RBC). Benzo(g,h,i)perylene was found above the Pennsylvania media-specific concentration (MSC). No CVs were available for delta-BHC. Lead paint: An investigation found no lead in paint, dust, or soil at the housing units. |
Groundwater: The Navy initiated constructed
of a groundwater extraction in November 1998. A final ROD was signed in
September 2000 and required no further action. Soil: The Navy completed soil investigations in 1999. A ROD was signed in August 2000 and identified no further actions at the site. Surface Water/Sediment: A ROD requiring monitoring was signed in August 2000. The Navy will retain this property for housing Navy personnel on base. The remaining areas of Site 5 will be reused as a parks and recreation area. |
Groundwater: ATSDR evaluated public
health hazards associated with on-site groundwater use in this table under
Area D. Off-site groundwater was addressed separately in this table. Soil: No public health hazards were identified from exposure to surface soil. ATSDR evaluated the potential for adverse health effects to residents based on conservative assumptions believed to overestimate the levels of actual exposure. Estimated doses were below those likely to result in adverse health effects. Surface Water/Sediment: Contaminants were detected at levels that pose no public health hazards. Furthermore, recreational exposure to these streams is likely to be limited. The streams do not support a fish population suitable as a food supply. |
| Area B, Site 6: Disposal Pits and Trenches (Waste Pit No. 3) | An unknown number of disposal pits and trenches are located south of the main runway, covering an area of approximately 70,000 square feet. Paints, solvents, demolition debris, waste oils, wastewater treatment sludge, and grease trap waste were disposed of in this area from 1960 to 1980. | Groundwater: See Area B, Site 5. Surface Soil: The Navy collected surface soil samples at Site 6 as part of RIs completed in 1996 and 1999 and completed a Removal Action Report in 1996. These investigations found four PAHs, Aroclor-1260, arsenic, chromium, and mercury above CVs in surface soil. Surface soil sampling also detected lead above the SSL. |
Groundwater: See Area B, Site 5. Soil: The Navy performed a limited soil removal in 1997. A ROD addressing Sites 6 and 7 was signed in June 2000. Deed restrictions and monitoring of a 2-foot vegetated soil cover were selected as the site remedy. This site is planned for reuse as part of a parks and recreation area. |
Groundwater: See Area B, Site 5. Soil: No public health hazards are associated with this site. The site is located between the runways and a perimeter security fence, which restricts access. Exposure to past workers was expected to be infrequent and of short duration. No current or future public health hazards are associated with soil at this site because remediation is expected to reduce soil contaminants to levels suitable for recreational use. |
| Area B, Site 7: Sludge Disposal Pits | Two disposal trenches were reportedly located east of the Inertial Research Building. These trenches received sludge from the wastewater treatment plant from 1950 to 1955. The trenches were reportedly covered with 2 feet of soil and were 100 feet long, 12 feet wide, and 8 feet deep. The site is now covered with grass. | Groundwater: See Area B, Site 5. Surface Soil: The Navy conducted investigations at Site 7 as part of an RI completed in 1996. No soil contamination was found at that time. The Site 7 trenches were thought to actually be a part of Site 6. Site 7 was evaluated as a part of Site 6 in a RI completed in 1999. |
Groundwater: See Area B, Site 5. Soil: The Navy performed a limited soil removal at Site 6, which may also include Site 7, in 1997. A ROD addressing Sites 6 and 7 was signed in June 2000. This site is planned for reuse as part of a parks and recreation area. |
Groundwater: See Area B, Site 5. Soil: No public health hazards are associated with this site because no contaminants were detected. |
| Groundwater Contamination in Off-site Drinking Water Wells (OU2) | ||||
| Off-site Muni-cipal Wells: WMWA | Two Warminster Municipal Water Authority (WMWA) supply wells are located within Area 1 North (Ivyland/ Kirk Road). Well 13 is located approximately 0.3 miles north of Area C. Well 26 is located approximately 0.3 miles north of Area A. | VOCs have not been detected above MCLs in Well 13. In
1979, TCE (to 67.8 parts per billion [ppb]) and PCE (to 17 ppb) were detected
in water from Well 26.
Well 26 was sampled as part of the Phase II RI in 1992. At that time, TCE (110 ppb), tetrachloroethylene (PCE) (20 ppb), 1,1-dichloroethene (1,1-DCE) (18 ppb), and arsenic (3.7 ppb) were detected in untreated water. Untreated water from Well 26 was tested again in January 1997 and contained TCE (48 ppb), PCE (112 ppb), and 1,1-DCE (49 ppb) above CVs. Regular monitoring of treated water from this well has not detected any VOCs above MCLs. |
Well 26 was closed in 1979 after concentrations of TCE
and PCE were detected above MCLs.
In 1986, WMWA installed an air stripper and groundwater treatment system on Well 26. Treated water from Well 26 is currently used as a water supply. Water from this well and others in the WMWA system are blended in the distribution system. Treated water entering the distribution system is monitored under local and state regulations. |
No public health hazards exist from past exposure. ATSDR
evaluated past potential exposures using the maximum detected concentrations
and very conservative exposure assumptions. This evaluation revealed that
doses of VOCs from Well 26 are lower than those associated with health hazards.
No public health hazards from current or future use of Well 26 were identified. To prevent exposure, WMWA installed a treatment system and monitors Well 26 regularly under local and state regulations. In addition, the Navy has implemented remedial actions to treat contaminated groundwater at NAWC. |
| Off-site Private Wells in Area 1 North: Ivyland/Kirk Road | Area 1 North encompasses portions of Warminster Township and Ivyland Borough. This area is located north of the base and is bound by Bristol Road, Newtown Road, Kirk Road, and Greely Avenue. Area 1 North is shown on Figure 2. | In 1992, the Navy sampled one residential and two commercial
wells in this neighborhood. One of the commercial wells, which was used
for the production process, contained TCE (720 ppb), arsenic (4.4 ppb),
and manganese (52.5 ppb) above ATSDR's CVs. Lead (468 ppb) was above EPA's
MCL action level. The second commercial well, which may have been used for
drinking water, contained only arsenic (4.6 ppb) above ATSDR's CV.
In 1993, the Navy identified 52 residential wells, 3 commercial wells, and 2 municipal wells in this area. The Navy sampled 51 wells in this area, including the 3 commercial and 2 municipal wells. Several wells were not sampled due to property access restrictions. PCE (31 ppb) exceeded EPA's MCL and ATSDR's CV in 14 of the 51 wells sampled. |
By 1995, the Navy and EPA connected public water to homes in the path of groundwater contamination in the Ivyland/Kirk Road area. The Navy conducts annual on- and off-base groundwater monitoring in this area. Source treatment of contaminated groundwater in Areas A and B is addressed under a ROD for OU1 | No public health hazard from past site use was identified.
ATSDR evaluated the potential for adverse health effects to resident adults
and children who drank water from affected wells in the past. ATSDR estimated
exposure doses based on very conservative assumptions believed to overestimate
the levels of actual exposure. Estimated doses for adults and children were
below doses reported in the literature to result in adverse effects.
There are no public health hazards under current and future uses since residences have been connected to the municipal water supply and the Navy continues to monitor contaminant movement from NAWC. |
| Area C (OU3 and OU5) | ||||
| Area C, Site 4: North Runway Landfill | This landfill was the largest waste disposal area at NAWC and consists of eight trenches located at approximately the mid-point of the main runway near the facility boundary. Solid waste, paints, waste oils, waste metals, construction debris, solvents, and sewage sludge were disposed of in the trenches between 1966 and 1970. Approximately 25,000 cubic yards of waste were buried. | Groundwater: As part of the OU2 investigation
at Area 1 North, the Navy sampled the 46 residential, 3 commercial, and
2 municipal wells located north of Area C in the Ivyland/Kirk Road neighborhood.
PCE was detected above MCLs in groundwater flowing north from Area C. The
source of groundwater contamination has not yet been identified, but does
not appear to be Site 4. Surface Soil: The Navy conducted an investigation in preparation for a removal action. Sampling detected elevated concentrations of several PAHs above CVs. Surface Water/Sediment: Sampling detected manganese in surface water and PAHs, arsenic, and iron in sediment above CVs. Lead was also detected in surface water above the MCL action level. |
Groundwater: The Navy installed a pump-and-treat
system and began operation in July 1996. The Navy conducts regular groundwater
monitoring at Area C. Off-base groundwater near Area C is addressed as Area
1 North (see above). Soil: During site closure in 1970, 2 feet of fill was placed over the trenches. The Navy completed a removal action in 1996. The entire waste area was removed and backfilled. Confirmation sampling indicated the contamination was reduced below action levels. A ROD selecting no further action was released in April 2000. Surface Water/Sediment: A ROD selecting no further action was released in April 2000. This site is planned for reuse as part of a parks and recreation area. |
Groundwater: ATSDR evaluated public
health hazards associated with on-site groundwater use in this table under
Area D. Off-site groundwater was addressed separately in this table. Soil: No public health hazards are associated with this site. The site is located between the runways and a perimeter security fence. The site was operated for only 4 years and access was expected to be infrequent and of short duration. No present or future public health hazards are associated with soil at this site because remediation reduced soil contaminants to levels suitable for recreational use. Surface Water/Sediment: Infrequent exposure during drainage cleaning activities or recreational use by off-base residents is unlikely to pose a public health hazard based on an evaluation of exposure doses. Streams and drainage channels at NAWC and immediately down stream have insufficient flow to support a fish population. |
| Area C, Site 8: Fire-Fighting Training Area (FFTA) | The FFTA is located north of the main runway at the northeast end of an abandoned runway. The site was a paved area surrounded by bermed soil and was used to burn aircraft fuel, scrapped cars and aircraft, and other debris. From 1960 to 1988, approximately 3,000 gallons of fuel were burned annually. | Groundwater: See Area C, Site 4 Soil gas: Elevated VOCs (162 parts per million [ppm]) were detected in soil gas next to the airplane mockup used for fire fighting training. Low levels of VOCs were detected in scattered locations. Surface soils: Benzo(a)pyrene, dioxins, and arsenic were detected above CVs. Lead was detected above the SSL. Subsurface soil: Benzo(a)pyrene was detected above CVs. |
Groundwater: See Area C, Site 4. Soil: The Navy removed lead-contaminated soil in 1999. A ROD signed in June 2000 recommend no further action. This site is planned for reuse as part of a business campus. |
Groundwater: See Area C, Site 4. Soil: No public health hazard was identified from past, current, and future site use. Past workers were expected to access the site infrequently and for a short duration. Currently, the site is not used. Construction workers at this site during redevelopment should follow OSHA regulations to prevent exposures. |
| Area C, Maintenance Area | A complex of three buildings in Area C was used for vehicle maintenance storage and also housed a laboratory and testing facilities. | Groundwater: See Area C, Site 4 Soil gas: Low levels of VOCs were detected at scattered locations in surface soil but not in deeper soils. Surface and subsurface soil: No contaminants were detected above CVs and background levels. |
Groundwater: See Area C, Site 4 Soil: No further action recommended. This site is planned for reuse as part a business campus. |
Groundwater: See Area C, Site 4 Soil: No public health hazards are associated with this site because no contaminants were detected. |
| Area C, Tile Field | A tile field consisting of several drain lines is located east of the base commander's residence. | The presence of VOCs in a nearby monitoring well led to investigation of this area (see Area C, Site 4). No contaminants were detected in soil samples from the tile field, however, PCE was found in soil gas samples. | Groundwater: See Area C, Site 4. Soil: No further actions are planned. This site will be reused for residential housing. |
Groundwater: See Area C, Site 4 Soil: No public health hazards are associated with this site because no contaminants were detected. The Navy is conducting ongoing investigations and will conduct remedial actions as needed to prevent future exposures. |
| Area D (OU4 and OU8) | ||||
| Area D, Site 9: Base Supply Wells | Four of the ten water supply wells, Wells 1 through 4, are located in Area D near Buildings 1 and 2 in the western portion of NAWC. Wells 1 and 2 are approximately 250 feet deep, and Wells 3 and 4 are almost 600 feet deep. No waste disposal has been reported in this area, but hazardous materials have contaminated groundwater under Area D. The source of this contamination is unknown. | NAWC first sampled the on-base water supply system in 1979 when regional groundwater contamination was discovered. As a result of VOC contamination detected at this time, the Navy closed Wells 1, 2, and 5. Ongoing sampling between 1979 and 1981, detected TCE (293 ppb) and PCE (36 ppb) in these wells above their MCLs. No other wells at NAWC were found to contain VOCs above MCLs. | In 1979, the Navy removed Wells 1, 2, and 5 from service as drinking water wells. Well 5 was permanently closed. Wells 1 and 2 are only used for additional fire protection. The Navy regularly monitors tap water quality at the base. An interim ROD is in place and includes installation of a treatment system and extraction wells. Installation was expected to be complete in winter 1999. The final ROD will likely include ongoing groundwater treatment and monitoring. | No public health hazards exist from past exposure. ATSDR
evaluated potential past exposures using maximum detected concentrations
and conservative exposure assumptions. This evaluation revealed that base
residents and workers were exposed to doses of VOCs below those associated
with health hazards. In addition, the water supply was blended such that
it is likely residents and workers were exposed to concentrations much lower
than the maximum detected concentration.
Use of the NAWC water supply wells poses no current or potential future public health hazards. The contaminated wells are no longer contributing to the water supply system. Supply wells at the base are monitored regularly. The Navy monitors on-base groundwater to track contaminant movement and operates groundwater treatment systems to remove contaminants from groundwater. In addition, the ROD for OU4 includes institutional controls for Area D to prevent supply well use and installation without proper treatment systems and approval by regulatory authorities. |
Sources: Ambler Laboratories 1979; Ames 1998, 1999, 2000; Analytical Laboratories, Inc. 1997; Brown & Root 1996, 1996b; Department of the Navy 1993, 1994, 1995, 1996, 1997a, 1997b, 1997, 1999, 2000a-e; EA Engineering 1995; Fischer & Porter no date; Foster Wheeler 1998; Halliburton NUS 1992, 1993, 1993b, 1994a, 1994b; Hunter 1998; Ostrauskas 1999; Pursel 1998; Smith 1998; Tetra Tech NUS, Inc. 1999a, 2000b, 2000c; USGS 1998; Warminster Township 1999.
Table A-2: Evaluation of Potential Public Health Hazards
for Water Supplies Affected by Off-Base Sources
|
Site |
Site Description/ |
Investigation Results/ |
Corrective Activities |
Evaluation of Public Health Hazard |
| Off-site Muni-cipal Wells: SMWA | In September 1979, the Upper Southampton Municipal Water Authority (SMWA) shut down three supply wells due to volatile organic compound (VOC) contamination. | The source of VOC contamination, primarily trichloroethylene (TCE) (to 44 parts per billion [ppb]), is not known. An independent review of data from the Naval Air Warfare Center (NAWC) and Fischer & Porter concluded that NAWC was not the source of VOC contamination. Fischer & Porter may be a potential contributor to the VOC contamination. | SMWA stopped pumping water from the contaminated well in 1979 and permanently closed two of the three wells in the early 1990s. The third well is still inactive, but sampled periodically. VOCs are detected above MCLs when this well is pumped. | The Agency for Toxic Substances and Disease Registry
(ATSDR) evaluated the potential for adverse health effects to residents
using the SWMA water supply. ATSDR calculated an exposure dose based on
very conservative assumptions believed to overestimate the levels of actual
exposure. Calculated doses for adults and children were well below doses
reported in the literature that result in adverse effects. No public health
hazard from past use was found.
Current exposures are not occurring because SWMA closed contaminated wells and monitors active wells. |
| Off-site Muni-cipal Wells: HWA | Within the Hatboro Water Authority HWA water supply system, one well is located southwest of NAWC and near the Fischer & Porter manufacturing plant. | In 1979, VOC contamination was detected in the HWA well proximate to the NAWC. The levels of contamination detected at this time are unavailable. Manufacturing processes and a TCE spill at the Fischer & Porter manufacturing plant was originally thought to be the source of the VOC contamination in the HWA well. Later investigations concluded that Fischer & Porter was not likely the contamination source. The actual source is unknown. | HWA stopped pumping water from the contaminated well in 1979. Fisher & Porter funded installation of a treatment system for the contaminated well. In addition, Fischer & Porter has been operating a groundwater treatment system at the manufacturing plant since 1986. | ATSDR was unable to evaluate exposures prior to 1979 because necessary information was unavailable. To prevent past (after 1979), current, and future exposures, HWA closed the contaminated wells and regularly samples active water supply wells under state and local regulations to ensure the safety of the water supply. |
| Off-site Muni-cipal Wells: WHDC | Two municipal wells are located in Warminster Heights south of Street Road, approximately 2,500 feet from Area D. VOC contamination in this well is attributed to the Fischer & Porter site to the south. | VOCs were detected in a Warminster Heights Development Corporation (WHDC) well in 1979. The levels of contamination detected at that time are unavailable. Sampling from 1986, found TCE at approximately 150 ppb and tetrachloroethylene (PCE) at highs of 70 ppb. Manufacturing processes and a TCE spill at the Fischer & Porter manufacturing plant are the source of the VOC contamination in the WHDC well. | WHDC stopped pumping water from the contaminated well in 1979. In 1984, Fisher & Porter funded installation of a treatment system for the contaminated well. In addition, Fischer & Porter has been operating a groundwater treatment system at the manufacturing plant since 1986. | In March 1999, the Pennsylvania Department of Health (PADOH), completed a Health Consultation addressing community concerns about past exposure to VOCs in WHDC supply wells, specifically increased cancer risk. PADOH concluded that while there were past exposures to contaminants in groundwater, the wells no longer present a public health hazard because WHDC wells are treated and monitored under state and local regulations. In addition, PADOH concluded that no increase in risk for cancer exists due to exposure to VOCs in the contaminated water supply. |
| Off-site Private Wells in Area 1 South: Speed-way | Area 1 South includes a portion of Speedway within the Warminster Township. The area extends from Area D west to Meams Road and the west side of Sunnemeade Avenue, south to Kalmia Road, and east to Steamboat Drive. Area 1 South is shown on Figure 2. | In 1993, the Navy identified 43 residential wells in this area, and sampled 37 wells. Several wells were not sampled due to property access restrictions. TCE (46 ppb) and PCE (6 ppb), were detected above the ATSDR comparison values (CVs) in three wells. However, only one well contained these contaminants above CVs and the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Levels (MCLs). Subsequent investigations found no contaminants above CVs and concluded that no extensive groundwater contamination is present in this neighborhood. | Based on the 1993 sampling data, the Navy provided the home with contaminants above EPA's MCLs with a water treatment system. Additional data later collected by the Navy were reviewed by EPA and the United States Geological Survey (USGS) and showed that groundwater contaminants in Area 1 South probably originated from off-base sources. Therefore, the Navy conducted final maintenance on the water treatment system in November 1998 and transferred responsibility for operation and maintenance to the homeowner. | ATSDR evaluated the potential for adverse health effects
to resident adults and children who drank water from affected wells in the
past. ATSDR calculated an exposure dose based on very conservative assumptions
believed to overestimate the levels of actual exposure. Calculated doses
for adults and children were well below doses reported in the literature
that result in adverse effects. No public health hazard from past site use
was identified.
Current exposures are not occurring because the Navy provided the one home with contaminants above CVs with a water treatment system. Potential future exposures are expected to be minimized through ongoing treatment and monitoring programs. |
| Off-site Private Wells in Area 2 West: Flying Heels | Area 2 West encompasses portions of Warminster and Upper Southampton townships and includes Flying Heels. This neighborhood is south of the base and is bounded by Reeves Lane, E Street Road, Davisville Road, and Parmentier Road. Area 2 West is shown in Figure 2. | In 1993, the Navy identified 79 residential wells in this area and sampled 73 of these wells. Several wells were not sampled due to property access restrictions. TCE (6 ppb) slightly exceeded the MCL and CV in one well. Subsequent sampling by the Navy was unable to replicate this result. | The Navy installed a water treatment system at the home where TCE exceeded its MCL. Review of additional data collected by the Navy indicated that it is unlikely that the TCE found in this neighborhood was the result of NAWC sources. Other neighborhood residents still use private wells as a drinking water supply. The Navy currently conducts annual on-base groundwater monitoring in this area. Source treatment of contaminated groundwater in Area B is addressed under the ROD for OU1. | No public health hazard from past site use was identified.
ATSDR evaluated the potential for adverse health effects to resident adults
and children who drank water from the affected well in the past. ATSDR estimated
exposure doses based on very conservative assumptions believed to overestimate
the levels of actual exposure. Estimated doses for adults and children were
well below doses reported in the literature to result in adverse effects.
There are no public health hazards under current and future uses. The Navy installed a treatment system at the home with TCE above its MCL. In addition, the Navy monitors on-base wells to track contaminant movement from NAWC, and has implemented remedial actions to treat contaminated groundwater at NAWC. |
| Off-site Private Wells in Area 2 East: Casey Village | Area 2 East encompasses portions of Warminster and Upper Southampton townships and includes Casey Village. The area extends northeast from Area B and is bounded by W. Bristol Road, Davisville Road, and Deerfield Road. Area 2 East is shown in Figure 2. | In 1993, the Navy identified and sampled 71 residential
wells in this area. The following contaminants were detected above CVs and
MCLs in 34 of the wells sampled: TCE (1,200 ppb), PCE (480 ppb), carbon
tetrachloride (8.7 ppb), 1,1-dichloroethene (19 ppb), and 1,2-dichloroethene
(530 ppb).
The Navy installed seven monitoring wells proximate to the Shenandoah Woods housing complex to evaluate whether NAWC was a potential source of groundwater contamination under Casey Village, specifically carbon tetrachloride. Carbon tetrachloride was not detected in these wells. |
By 1995, the Navy had connected homes in Casey Village
to the municipal water supply.
USGS determined that releases within Casey Village are the likely source of groundwater contamination. In a 1998 report by USGS, the PCE plume was identified as originating from an unknown source within Casey Village and the TCE plume was identified as originating at a former septic system and drain field within the neighborhood. EPA and the Pennsylvania Department of Environmental Protection (PADEP) are conducting ongoing investigations within Casey Village and may be contacted for additional information. |
No public health hazard from past site use was identified.
ATSDR evaluated past potential health hazards for adults and children who
drank water from affected wells. ATSDR estimated exposure doses based on
very conservative assumptions believed to overestimate the levels of actual
exposure. Estimated doses for adults and children were below doses reported
in the literature that result in adverse effects.
No public health hazards exist under current and potential future uses as residences have been connected to the municipal water supply. EPA and PADEP are continuing to investigate the area to prevent harmful exposures. |
Sources: Ames 1998; Feeney 2000; Fischer & Porter no date; Halliburton NUS 1993b; Hunter 1998; Ostrauskas 1999; PADOH 1999; Pursel 1998; EPA 1999; USGS 1998; Warminster Township 1999.
The conclusion that a contaminant exceeds the comparison value does not mean that it will cause adverse health effects. Comparison values represent media-specific contaminant concentrations that are used to select contaminants for further evaluation to determine the possibility of adverse public health effects. The following presents a description of the comparison values (CVs). CVs are presented in the order that was used by ATSDR to select the most appropriate CV for an individual contaminant.
Cancer Risk Evaluation Guides (CREGs)
Estimated contaminant concentrations that would be expected to cause
no more than one excess cancer in a million (10-6) persons exposed
over a 70-year life span. ATSDR's CREGs are calculated from EPA's cancer potency
factors (CPFs).
Environmental Media Evaluation Guides (EMEGs)
EMEGs are based on ATSDR minimal risk levels (MRLs) and factors in
body weight and ingestion rates. A MRL is an estimate of daily human exposure
to a chemical (in milligrams of contaminant per kilogram of body weight per
day [mg/kg/day]) that is likely to be without noncarcinogenic health effects
over a specified duration of exposure.
Reference Media Evaluation Guides (RMEGs)
ATSDR derives RMEGs from EPA's oral reference doses (RfDs). The RMEG
represents the concentration in water or soil at which daily human exposure
is not expected to result in adverse noncarcinogenic effects.
Risk-Based Concentration (RBC)
The RBCs were developed by EPA Region III, which includes Pennsylvania. RBCs
for tap water, air, and soil were derived using EPA RfDs and CPFs combined with
standard exposure scenarios, such as ingestion of 2 liters of water per day,
over a 70-year life span. RBCs are contaminant concentrations that are not expected
to cause adverse health effects over long-term exposures.
Soil Screening Level (SSL)
Generic SSLs were derived by EPA for nation-wide application to sites
used for residential areas. SSLs are estimates of contaminant concentrations
that would be expected to be without noncancer health effects over a specified
duration of exposure or to cause no more than one excess cancer in a million
(10-6) persons exposed over a 70-year life span.
Maximum Contaminant Level (MCL)
The MCL is the drinking water standard established by EPA. It is the
maximum permissible level of a contaminant in water that is delivered to the
free-flowing outlet. MCLs are considered protective of public health over a
lifetime (70 years) for people consuming 2 liters of water per day.
Media-Specific Concentrations (MSC)
MSCs for soil were derived by PADEP. These standards are based on direct
ingestion of soil under residential use of a site. MSCs are estimates of contaminant
concentrations that would be expected to be without noncancer health effects
over a specified duration of exposure or to cause no more than one excess cancer
in 100,000 (10-5) persons exposed over a 70-year life span.
APPENDIX C: ESTIMATED EXPOSURES AND HEALTH EFFECTS
Estimates of Human Exposure Doses and Determination of Health Effects
Deriving Exposure Doses
The Agency for Toxic Substances and Disease Registry (ATSDR) estimated the human exposure doses from ingestion of drinking water from groundwater supplies, incidental ingestion of surface soil, and incidental ingestion of surface water and sediment. Deriving exposure doses requires evaluating the concentrations of the contaminants to which people may have been exposed and how often and how long exposures to those contaminants occurred. Together, these factors help influence the individual's physiological response to chemical contaminant exposure and the potential for noncancer or cancer outcomes. In the absence of exposure specific information, ATSDR applied several conservative assumptions to define site-specific exposures as accurately as possible for people contacting contaminated media.
Evaluating Potential Health Hazards
The estimated exposure doses are used to evaluate potential noncancer and cancer effects associated with contaminants detected in site media. When evaluating noncancer effects, ATSDR first compares the estimated exposure doses to standard toxicity values, including ATSDR's minimal risk levels (MRLs) and the U.S. Environmental Protection Agency's (EPA) reference doses (RfDs), to evaluate whether adverse effects may occur. The chronic MRLs and RfDs are estimates of daily human exposure to a substance that is likely to be without appreciable risk of adverse noncancer effects over a specified duration. The chronic MRLs and RfDs are conservative values, based on the levels of exposure reported in the literature that represent no-observed-adverse-effects-levels (NOAEL) or lowest-observed-adverse-effects-levels (LOAEL) for the most sensitive outcome for a given route of exposure (e.g., dermal contact, ingestion). In addition, uncertainty (safety) factors are applied to NOAELs or LOAELs to account for variation in the human population and uncertainty involved in extrapolating human health effects from animal studies. If estimated exposure doses are greater than the MRL or RfD, ATSDR reviews the toxicological literature to determine the likelihood of adverse effects.
When evaluating the potential for cancer to occur, ATSDR uses cancer potency factors (CPF) that define the relationship between exposure doses and the likelihood of an increased risk of developing cancer over a lifetime. The CPFs are developed using data from animal or human studies and often require extrapolation from high exposure doses administered in animal studies to lower exposure levels typical of human exposure to environmental contaminants. The CPF represents the upper-bound estimate of the probability of developing cancer at a defined level of exposure; therefore, they tend to be very conservative (i.e., overestimate the actual risk) in order to account for a number of uncertainties in the data used in extrapolation.
ATSDR estimated the potential for cancer to occur using the following equation. The estimated exposure doses and CPF values for the contaminants of concern are incorporated into the equation:
| Lifetime Cancer Risk = | Estimated exposure dose (milligrams contaminant per kilogram body weight per day [mg/kg/day]) x CPF (mg/kg/day)-1 |
Although no risk of cancer is considered acceptable, because a zero cancer risk is not possible to achieve, ATSDR often uses a range of 10-4 to 10-6 estimated lifetime cancer risk (or 1 new case in 10,000 to 1,000,000 exposed persons), based on conservative assumptions about exposure, to determine whether there is a concern for cancer effects. This information is then evaluated with respect to the toxicological literature regarding a specific type of cancer.
Estimated Exposure Doses for Groundwater Use
Investigations of the Naval Air Warfare Center (NAWC) wells detected concentrations of tetrachloroethylene (PCE) and trichloroethylene (TCE) above comparison values (CVs). Investigations of Well 26 of the Warminster Municipal Water Authority (WMWA) supply system and private wells in three neighborhoods surrounding NAWC found PCE, TCE, and arsenic above CVs. Because volatile organic compounds (VOCs), including PCE and TCE, were found in Casey Village at concentrations an order of magnitude higher than concentrations found in other neighborhoods and water supplies, ATSDR evaluated exposures in Casey Village separately, as detailed in Appendix D. To determine whether exposures to contaminants in drinking water supplies may be related to adverse health effects, if any, ATSDR estimated exposure doses for people using contaminated well water. In estimating to what extent people might be exposed to contaminants, ATSDR used "conservative" assumptions about contaminant concentrations in well water, as well as how much and how often people drink well water. These assumptions allow ATSDR to estimate the highest possible exposure dose and determine the corresponding health effects. Although ATSDR expects that few residents were exposed to the highest contaminant concentrations, the "conservative" estimates are used to protect public health.
ATSDR used to following equation and exposure assumptions to estimate an exposure dose for water:
where:
C Maximum concentration (parts per million [ppm]) IR Intake rate (accounts for ingestion, inhalation, and dermal contact): adult=4 liters per day; child=3 liters per day EF Exposure frequency: on-base worker=250 days/year; on- and off-base residents=365 days/year ED Exposure duration or the duration over which exposure occurs: on-base workers= 30 years; on-base residents (adults and children)=6 years; on-base workers (adults)=30 years, off-base residents (adults)=43 years, (children)=6 years (Exposure durations represent the maximum period people are expected to live in on-base housing [6 years], the time from when on-base disposal commenced in 1950 until base well closure in 1979 [30 years], or the time from when on-base disposal commenced in 1950 until private well users were provided with alternate water supplies in 1993 [43 years].) BW Body weight: adult=70 kg (154 pounds); child=10 kg (22 pounds) AT Averaging time or the period over which cumulative exposures are averaged (6, 30,or 43 years x 365 days/year for noncancer effects and 70 year [considered a lifetime] x 365 days/year for cancer effects)
NAWC Wells
Sampling of NAWC wells in 1979 detected PCE (36 part per billion [ppb]) and TCE (293 ppb) in three of the ten water supply wells. As a result, the Navy closed these wells and they no longer contribute to the water supply system. On-base workers and residents in on-base housing may have been exposed to PCE and TCE in drinking water in the past. Exposures are no longer occurring or are expected to occur in the future as contaminated wells were closed and the Navy monitors active water supply wells. In addition, the Navy monitors wells throughout the base and installed groundwater treatment systems to ensure the ongoing safety of the water supply. Evaluation of estimated exposure doses found that use of the NAWC drinking water supply is not expected to result in noncancer or cancer health effects.
Noncancer
Most health effects information on PCE is from experimental animal studies or epidemiologic studies looking at worker exposures. Available human health studies are largely inconclusive about the effects of low-level exposures to PCE (ATSDR 1997b). An acute MRL for PCE was used to evaluate potential noncancer effects associated with drinking water exposures. The resulting estimated exposure doses of 0.002 mg/kg/day for workers and resident adults and 0.01 mg/kg/day for resident children do not exceed ATSDR's MRL of 0.05 mg/kg/day for acute oral exposure. In addition to using extremely conservative assumptions about the intake rates, exposure frequency, and exposure duration, the MRL is derived using uncertainty factors designed to be overly protective of human health. For PCE, the acute MRL was based on a study of rats that found a LOAEL of 5 mg/kg/day for ingestion of oil containing PCE. Hyperactivity was the observed effect. The lowest dose that has been shown to cause adverse health effects in animals drinking contaminated water was approximately 400 mg/kg/day, which is 10,000 times higher than the estimated doses for residents. A chronic oral exposure MRL is not available for TCE. ATSDR reviewed the available toxicologic studies using intermediate and chronic exposures for animals and found that the conservative exposure dose estimates for NAWC were less than the lowest LOAEL in the literature (ATSDR 1997b).
In ATSDR Toxicological Profiles, MRLs are developed for acute, intermediate, and chronic exposure intervals. A MRL for TCE is only available for acute (14 days or less) exposures and was, thus, used to evaluate potential noncancer effects associated with drinking water exposures. The resulting estimated exposure doses of 0.02 mg/kg/day for workers and resident adults and 0.09 mg/kg/day for resident children do not exceed ATSDR's MRL of 0.2 mg/kg/day for acute oral exposure. The MRL is based on a study of mice at an exposure dose of 50 mg/kg/day modified with an uncertainty or safety factor of 300. A chronic oral exposure MRL is not available for TCE. ATSDR reviewed the available toxicologic studies using intermediate and chronic exposures for animals and found that the conservative exposure dose estimates for NAWC were less than the lowest LOAEL in the literature (ATSDR 1997c).
Cancer
The link between PCE exposure and cancer in humans is also uncertain. Studies looking at occupational and drinking water exposures have been largely inconclusive, but PCE has been shown to cause cancer in laboratory animals (rodents) at high doses (ATSDR 1997b). EPA, in an effort to determine a cancer classification for PCE, is currently reviewing the scientific literature on the carcinogenicity of PCE. For screening purposes, ATSDR used a previously derived CPF for PCE of 0.05 (mg/kg/day)-1. This approach provides a conservative evaluation of the likely effects from exposures to PCE in drinking water supplies. ATSDR derived a lifetime cancer estimate for on-base workers and residents from drinking water below 5 x 10-5 (or an increased likelihood of 5 in 100,000 of developing cancer). This estimate is in the middle of the regulatory range of 10-4 to 10-6. Nonetheless, no adverse cancer health effects are expected from exposure to PCE in NAWC wells. In addition to using extremely conservative assumptions about the intake rates, exposure frequency, and exposure duration, the cancer effect level (386 mg/kg/day) is nearly 600,000 times higher than the cancer dose (0.0006 mg/kg/day) estimated by ATSDR. The cancer effect level is the lowest level associated with the onset of cancer, as seen in experimental studies (ATSDR 1997b).
Although TCE has been shown to produce cancer in experimental animals when administered in large doses, the link between TCE in drinking water and human cancer cases is not well established (ATSDR 1997c). EPA, in an effort to determine a cancer classification for TCE, is currently reviewing the scientific literature on the carcinogenicity of TCE. For screening purposes, ATSDR used a previously derived CPF for TCE of 0.011 (mg/kg/day)-1. This approach provides a conservative evaluation of the likely effects from exposures to TCE in drinking water supplies. ATSDR derived a lifetime cancer estimate for on-base workers and residents from drinking water below 9 x 10-5 (or an increased likelihood of 9 in 100,000 of developing cancer). This estimate is in the middle of the regulatory range of 10-4 to 10-6. This estimate overestimates the actual risk. In addition to using extremely conservative assumptions about the intake rates, exposure frequency, and exposure duration, the cancer effect level (1,000 mg/kg/day) is about 200,000 times higher than the cancer dose (0.005 mg/kg/day) estimated by ATSDR (ATSDR 1997c).
WMWA Well 26, Ivyland/Kirk Road, Speedway, Flying Heels
Sampling of WMWA Well 26, and private wells within the Ivyland/Kirk Road, Speedway, and Flying Heels neighborhoods detected similar contaminants at similar concentrations. To evaluate potential exposures, ATSDR selected the maximum detected concentration for each contaminant to represent the concentration to which off-base residents may be exposed. As the exposure duration, ATSDR assumed that people could have been exposed between 1950, when on-base disposal commenced, until 1993, when private wells were tested and alternate water supplies were provided. This overestimates exposures from the WMWA Well 26, which was opened in 1974. The maximum PCE concentration (31 ppb) was detected in a private well in the Ivyland/Kirk Road Neighborhood. The maximum TCE concentration (67.8 ppb) was in WMWA Well 26. The maximum arsenic concentration (4.6 ppb) was detected in a commercial well in the Ivyland/Kirk Road neighborhood. Exposures are no longer occurring or are expected to occur in the future as WMWA treats and monitors its water supply and homes have been connected to municipal water supplies or provided treatment systems. The Navy continues to monitor perimeter wells and residential wells to insure the ongoing safety of the water supply. Evaluation of exposure doses found that use of drinking water supplies is not expected to result in noncancer or cancer health effects.
Noncancer
MRLs for PCE and TCE are only available for acute (14 days or less) exposures and were used to evaluate potential noncancer effects associated with drinking water exposures. For PCE, the estimated exposure doses for off-base residents (adults=0.002 mg/kg/day and children=0.02 mg/kg/day) did not exceed ATSDR's MRL of 0.05 mg/kg/day for acute oral exposure. For TCE, the estimated exposure doses of 0.004 mg/kg/day for adults and 0.01 mg/kg/day for children do not exceed ATSDR's MRL of 0.2 mg/kg/day for acute oral exposure. Because chronic oral MRLs were not available, ATSDR reviewed the available toxicologic studies using intermediate and chronic exposures for animals and found that the conservative exposure dose estimates for NAWC were less than the lowest LOAELs reported in the literature (ATSDR 1997b, 1997c).
The estimated dose for adults (0.0001 mg/kg/day) exposed to arsenic in drinking water was below the arsenic MRL of 0.0003 mg/kg/day, whereas the dose for children (0.0005 mg/kg/day) slightly exceeded the arsenic MRL. Epidemiologic investigations suggest that noncancer effects from chronic arsenic exposure may lead to skin problems, neurological effects, and gastrointestinal irritations. The lowest observed levels at which these adverse health effects have been reported range from 0.014 to 0.05 mg/kg/day (ATSDR 1998a). The estimated doses for adults and children exposed to arsenic in drinking water from wells near NAWC are at least 100 times lower than the lowest arsenic dose reported to cause health effects. In addition, ATSDR calculated doses using conservative assumptions about exposure concentration and frequency and duration of groundwater consumption. An actual resident is very unlikely to be in contact with the highest level of contamination over the entire exposure period. Actual doses are expected to be much lower than assumed by ATSDR.
Cancer
ATSDR derived a lifetime cancer risk for residents exposed to PCE in drinking water of 6 x 10-5 (or an increased likelihood of 6 in 100,000 of developing cancer). ATSDR derived a lifetime cancer risk for residents exposed to TCE in drinking water of 3 x 10-5 (or an increased likelihood of 3 in 100,000 of developing cancer). These estimates are in the middle of the regulatory range of 10-4 to 10-6. However, these are overestimates of the actual risk. In addition to using extremely conservative assumptions about the intake rates, exposure frequency, and exposure duration, the cancer effect level for PCE (386 mg/kg/day) is about 300,000 times higher than the cancer dose (0.001 mg/kg/day) estimated by ATSDR and the cancer effect level for TCE (1,000 mg/kg/day) is about 400,000 times higher than the cancer dose (0.003 mg/kg/day) estimated by ATSDR (ATSDR 1997b, 1997c). The cancer effect level is the lowest level associated with the onset if cancer, as seen in experimental studies.
ATSDR derived a lifetime cancer risk for residents exposed to arsenic in drinking water of 1 x 10-4 (or an increased likelihood of 1 in 10,000 of developing cancer). This estimate at the upper end of the regulatory range of 10-4 to 10-6. EPA classified arsenic as a carcinogen based on epidemiological studies. However, unlike other carcinogens, arsenic does not cause cancer in laboratory animals when administered orally. The basis for classifying arsenic as a human carcinogen are results of a Taiwanese study in which the lowest exposure levels associated with the onset of cancer (skin) were observed in people drinking 170 to 800 ppb arsenic for a 45-year exposure period (ATSDR 1998a). Residents using private wells were exposed to a maximum detected concentration of 4.6 ppb arsenic. It is not expected that the level of exposure to off-site residents would lead to cancer.
Estimated Exposure Doses for Contact with Surface Soil
At six sites throughout NAWC (Sites 2, 3, 4, 5, 6, and 8), contaminants were detected in surface soil samples at concentrations above CVs. Contaminants detected above CVs at various sites included benzo(a)pyrene (a polyaromatic hydrocarbon [PAH]), Aroclor-1254 (a polychlorinated biphenyl [PCB]), antimony, arsenic, beryllium, cadmium, and lead. Access to five of the six sites (Sites 2, 3, 4, 6, and 8) was limited to past and current site workers. Workers are expected to have worn protective equipment, such as long pants, work gloves, and work boots, that would prevent exposure to contaminants in surface soil. In addition, the Navy has completed removal actions to prevent current and future exposures.
Site 5 consists of a former landfill that was used to dispose of wastes produced by NAWC. The Navy capped the landfill with 2 feet of soil and seeded the area when they closed the landfill. The Navy constructed two buildings (Units 401 and 402) of the Shenandoah Woods housing complex, an on-base housing area for enlisted personnel and their families, on part of this former landfill. Access to Site 5 is unrestricted, therefore, residents (adults and children) may be exposed to contaminants in surface soil. Redevelopment plans propose ongoing use of this area as military housing. To determine the potential for adverse health effects from contact with contaminants in surface soil at Site 5, ATSDR estimated exposure doses using conservative assumptions. ATSDR used the following equation and exposure assumptions to estimate an exposure dose for incidental ingestion and dermal contact with soil:
where:
C Maximum concentration (ppm) IR Intake rate:
ingestion: adult=100 milligrams per day; child=200 milligrams per day
dermal contact: adult=1,380 milligrams per day; child=426 milligrams per day (Dermal contact intake rates are multiplied by chemical-specific absorptions factors which account for the skin's protective ability. The absorption factors are 0.1 for PAHs, 0.06 for PCBs, and 0.01 for metals.)EF Exposure frequency: resident=365 days/year ED Exposure duration or the duration over which exposure occurs: adult and child=6 years BW Body weight: adult=70 kg (154 pounds); child=10 kg (22 pounds) AT Averaging time or the period over which cumulative exposures are averaged (6 years [conservative estimate of average stay in military housing] x 365 days/year for noncancer effects and 70 years [considered a lifetime] x 365 days/year for cancer effects)
Site 5
The Navy is conducting ongoing investigations to evaluate potential remedial actions for Site 5. Previous investigations at Site 5 detected benzo(a)pyrene (to 0.27 ppm), Aroclor-1254 (to 24 ppm), cadmium (to 10.5 ppm), and lead (to 1,020 ppm) in surface soil.
Noncancer
Exposures to the maximum detected concentration of cadmium using conservative exposure assumptions resulted in a dose less than its MRL. A MRL has not been developed for benzo(a)pyrene. The estimated exposure doses for Aroclor-1254 were 0.00003 mg/kg/day for adults and 0.0005 mg/kg/day for children exceed ATSDR's MRL of 0.00002 mg/kg/day for acute oral exposure. ATSDR reviewed the available toxicologic study used as a basis for this MRL. This study identified a LOAEL of 0.005 mg/kg/day for monkeys (ATSDR 1997a). The conservative exposure dose estimates for NAWC were at least 10 times less than this LOAEL. In addition, Aroclor-1254 doses at NAWC were calculated using conservative assumptions about frequency and duration of site use. A resident is very unlikely to be in contact with the highest level of contamination daily over a period of 6 years, military personnel reside in on-base housing for an average of 2 to 3 years.
Cancer
ATSDR evaluated exposures to benzo(a)pyrene, Aroclor-1254, and cadmium, known or suspected human carcinogens. The derived lifetime cancer risk for exposure to each of these contaminants was below 8 x 10-6 (or an increased likelihood of 8 in 1,000,000 of developing cancer). This estimate is within the regulatory range of 10-4 to 10-6. In addition, cancer estimates were calculated using conservative assumptions about frequency and duration of site use. An actual resident is very unlikely to be in contact with the highest level of contamination daily over a period of 6 years.
Lead
Lead was detected above the 400 ppm EPA's soil screening level (SSL) in three (1,020 ppm) of the 36 surface soil samples collected. These samples were collected from near a roadway in the housing area. For comparison, national estimated lead levels in the upper layer of soil near roadways are typically 30 to 2,000 ppm higher than natural levels. These levels typically decrease further from the roadway (ATSDR 1999b).
Although lead is a concern for adults, children are particularly susceptible to adverse effects from lead exposures. Scientific evidence indicates that blood lead levels of 10 to 25 microgram per deciliter (ug/dL) may be related to delayed mental development, reduced intelligence quotient (IQ) scores, poor attention span, speech and language delays, and impaired hearing. Although site-specific data regarding child blood lead levels at Shenandoah Woods are not available, numerous investigations have been conducted to correlate soil concentrations with blood lead levels. In general, blood lead levels increase approximately 1 to 7 ug/dL for every 1,000 ppm increase in soil concentrations (ATSDR 1999b).
Exposure to lead in surface soil in the Shenandoah Woods housing complex is not expected to result in adverse health effects. Lead was found above its CV in only a few samples. In addition, exposure is expected to be infrequent and of short duration since the maximum detected concentration was found in a sample collected adjacent to a roadway, where children are not expected to play frequently. The soil surrounding the housing complex is also covered with grass, which generally reduces likely exposures to contaminants in soil.
Estimated Exposure Doses for Contact with Surface Water and Sediment
Tributaries to Little Neshaminy Creek are located along the NAWC boundary near Areas A and C. Streams and drainage channels comprising the headwaters to Southampton Creek are located along the NAWC boundary near Area B. Investigations at NAWC detected chloromethane, PAHs, and metals above drinking water CVs in surface water and PAHs, aldrin, PCBs, and metals above soil CVs in sediment from these streams and drainage channels. To determine the potential for adverse health effects from exposure to contaminants in surface water and sediment, ATSDR estimated oral (incidental ingestion) and dermal (skin) contact exposure doses using conservative assumptions based on past, current, and proposed future land uses. These streams may be used for recreational purposes by on- and off-base residents, including past, current, and potential future residents. Because these streams are intermittent, surface water is present only part of the year, the streams do not support a fish population that could serve as a food source nor a stream flow that would allow boating or swimming. ATSDR considered wading as the most likely recreational use, therefore, exposure may occur through incidental ingestion or dermal contact with surface water and sediment. Adult and child exposures were considered.
ATSDR used to following equation and exposure assumptions to estimate exposure doses for contact with surface water and sediment:
where:
C Maximum concentration (ppm) IR Intake rate:
incidental ingestion: surface water (adult and child)=0.15 liters/day; sediment (adult)=100 milligrams per day, (child)=200 milligrams per day
dermal contact: adult=1,380 milligrams per day; child=426 milligrams per day (Dermal contact intake rates are multiplied by chemical-specific absorptions factors which account for the skin's protective ability. The absorption factors are 0.1 for PAHs and pesticides, 0.06 for PCBs, 0.01 for metals.)EF Exposure frequency: recreational user=130 days/year ED Exposure duration or the duration over which exposure occurs: adult=50 years; child=6 years BW Body weight: adult=70 kg (154 pounds); child=10 kg (22 pounds) AT Averaging time or the period over which cumulative exposures are averaged (6 or 30 years x 365 days/year for noncancer effects and 70 year [considered a lifetime] x 365 days/year for cancer effects)
Each of the three drainage ditch and stream systems flows from the base through residential neighborhoods. Flow within each stream is intermittent and off-base access is unrestricted. As a result, ATSDR assumed that recreational uses and likely exposures would be similar for each of the drainage ditch and stream systems. Therefore, ATSDR evaluated doses for these three areas together using the maximum detected contaminant concentration detected in any of the streams. Surface water samples collected from Area A contained the maximum detected concentrations of chloromethane (to 4 ppb), PCE (to 1 ppb), the PAHs benzo(a)pyrene (to 0.1 ppb) and benzo(b)fluoranthene (to 0.2 ppb), cadmium (to 2.5 ppb), lead (to 28.5 ppb), and manganese (to 486 ppb). A surface water sample from Area B contained the maximum detected concentration of thallium (to 4.9 ppb). Sediment samples from Area A contained the maximum concentrations of all PAHs, including benzo(a)anthracene (to 20 ppm), benzo(a)pyrene (to 17 ppm), benzo(b)fluoranthene (to 25 ppm), benzo(g,h,i)perylene (to 13 ppm), benzo(k)fluoranthene (to 20 ppm), dibenz(a,h)anthracene (to 5.3 ppm), and indeno(1,2,3-c,d)pyrene (to 14 ppm). Maximum concentrations of aldrin (to 0.0785 ppm), Aroclor-1248 (to 1.5 ppm), arsenic (to 14.05 ppm), chromium (to 224 ppm), iron (to 115,500 ppm), lead (to 404 ppm), and manganese (to 11,400 ppm) were also found in sediment samples from Area A. A sediment sample from Area B contained the maximum detected concentration of Aroclor-1260 (to 1.9 ppm).
Noncancer
Exposure doses to the maximum detected concentrations of cadmium, manganese, and thallium in surface water were below their associated MRLs for both adults and children. MRLs are not available for the PAHs: potential cancer effects are considered a greater threat to human health than noncancer effects. In sediment, exposure doses to the maximum detected concentrations of aldrin, arsenic, beryllium, chromium, and manganese were below their MRLs. The calculated dose for a child exposed to iron in sediment (0.8 mg/kg/day) is slightly above the RfD of 0.3 mg/kg/day. RfDs are developed with uncertainty (safety) factors. These uncertainty factors may result in a derived RfD hundreds of times less than the LOAEL observed in laboratory studies. In addition, the dose was calculated using conservative assumptions about frequency and duration of site use. An actual child using the stream for recreation is very unlikely to be in contact with the highest level of contamination 5 days per week, 26 weeks per year, over a period of 6 years. Iron is also considered an essential nutrient and necessary for proper health.
Cancer
For surface water contact, ATSDR evaluated exposures to the potential carcinogens chloromethane, the PAHs, and chromium. The derived lifetime cancer risk for exposure to each of these contaminants was below 5 x 10-6 (or an increased likelihood of 5 in 1,000,000 of developing cancer). For sediment contact, ATSDR evaluated exposures to PAHs, aldrin, Aroclor-1248, Aroclor-1260, arsenic, beryllium, and chromium, known or suspected human carcinogens. The derived lifetime cancer risk for exposure to each of these contaminants, except chromium, was below 3 x 10-5 (or an increased likelihood of 3 in 100,000 of developing cancer). These lifetime cancer risk estimates are in the middle of the regulatory range of 10-4 to 10-6. The derived lifetime cancer risk for exposure to chromium in sediment was below 2 x 10-3 (or an increased likelihood of 2 in 1,000 of developing cancer). This estimate is above the acceptable range, therefore, ATSDR reviewed the available toxicological literature to evaluate potential exposures at NAWC. Studies of workers in chromate production plants found that chromium is carcinogenic if inhaled. No evidence of carcinogenicity has been found in studies of ingestion and dermal exposures (ATSDR 1998b). Recreational users of the streams near NAWC are not expected to come into contact with chromium through inhalation. In addition, cancer estimates were calculated using conservative assumptions about frequency and duration of site use. An actual resident is very unlikely to be in contact with the highest level of contamination 5 days a week for 26 weeks a year over a period of 30 years.
Lead
Lead (to 28.5 ppb) was detected in surface water above the 15 ppb MCL action level, which was established by EPA based on available treatment technologies. In sediment, lead (to 404 ppm) was detected only slightly above the SSL of 400 ppm. The MCL and SSL are drinking water and soil exposure CVs used to screen surface water and sediment, respectively, because media-specific CVs have not been developed. The MCL is derived assuming daily ingestion of 2 liters of water and the SSL is derived assuming daily ingestion of contaminants in soil. Recreational exposure to surface water and sediment are expected to be less frequent and of shorter duration than assumed by the MCL and SSL. Recreational exposure is only likely for short periods a day and for only portions of the year, based on weather constraints.
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