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PUBLIC HEALTH ASSESSMENT

LANGLEY AIR FORCE BASE
and
NASA LANGLEY RESEARCH CENTER
HAMPTON, YORK COUNTY, VIRGINIA


EVALUATION OF ENVIRONMENTAL CONTAMINATION AND POTENTIAL
EXPOSURE PATHWAYS

Introduction

In this section, ATSDR evaluates whether people were or continue to be exposed to contaminants originating from Langley AFB and NASA LaRC at levels that might pose a health hazard. A health hazard can only exist if all elements of an exposure pathway exist. These elements include a source of contamination, an environmental medium in which contaminants may be present, a point of human exposure, a route of human exposure (such as ingestion, inhalation, or skin contact), and a receptor population. Figure 4 explains the exposure evaluation process in more detail. Appendix A contains a glossary of environmental and health terms used in this document.

For each environmental medium under consideration (i.e., groundwater, soil, surface water, sediment), ATSDR examines the types and concentrations of contaminants in the medium. ATSDR uses comparison values to screen contaminant concentrations in environmental media and to select contaminants for further evaluation. The comparison values include environmental media evaluation guides, reference dose media evaluation guides, cancer risk evaluation guides, and EPA's maximum contaminant levels. A description of the comparison values used in this public health assessment is provided in Appendix B.

Tables 1 and 2 list contaminants in each medium that are present at levels greater than or equal to health-based comparison values at Langley AFB and NASA LaRC, respectively. Contaminants at or below the comparison values are reasonably regarded as harmless. Because comparison values are designed to be many times lower than levels at which adverse health effects have been observed in experimental animal or human health studies, contaminants that exceed the comparison values would not necessarily be expected to produce adverse health effects.

This section evaluates potential exposure pathways at Langley AFB and NASA LaRC in more detail, considering data gathered and remedial activities conducted, to determine whether they represent, under site-related conditions, a threat to human health. Table 3 summarizes the potential exposure pathways discussed.

As part of the Superfund process, ATSDR made an initial site visit in August 1994 (ATSDR, 1994). During that visit, no potential exposure pathways were identified; however, several potential public health concerns were raised. During a second visit in November 1997, ATSDR identified one additional potential public health concern at a NASA LaRC site, and learned that several of ATSDR's original concerns had been addressed.

Most of the concerns that ATSDR raised in 1994 involve various IRP sites at Langley AFB; one concern raised in 1997 involves an IRP site at NASA LaRC (Figure 5). The potential for contamination to affect fish and shellfish in the adjacent estuary involves both facilities. NASA LaRC is responsible for cleaning up the contamination at Tabbs Creek. Conditions at the Back River are currently being studied and addressed by the Air Force.

The following discussion addresses the concerns that were raised in 1994 and 1997, the current status of the sites involved, and ATSDR's conclusions about the potential for public health hazards at these sites based on review of the environmental data and observations made during the second site visit.

LANGLEY AFB AND NASA LaRC

Concern: Fish and shellfish in the adjoining estuary

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Fish and shellfish in Tabbs Creek are contaminated with herbicides, pesticides, PCBs, PCTs, dioxins, furans, and metals.
  • Fishing is currently prohibited in Tabbs Creek; therefore, no exposures currently exist to contaminants in fish or shellfish.
  • Past occasional ingestion of fish or shellfish from Tabbs Creek is not expected to be associated with adverse health effects.
  • The Back River is still under study and data is not available yet for analysis.

Discussion

People have fished, crabbed, and harvested oysters in Tabbs Creek and the Back River. Surface water and sediment from Tabbs Creek, which empties into the Back River, are contaminated with volatile organic compounds, semivolatile organic compounds, PCBs, PCTs, pesticides, dioxins, furans, and metals. During the 1994 visit, ATSDR raised the concern that, if fish and shellfish in the estuary are also contaminated, eating those fish could pose a public health hazard.

Portions of the Back River near Tabbs Creek are leased for oyster bedding. There was a substantial decline in the oyster catch during the 1980s due to disease caused by a virus and a parasite. The Virginia State Department of Health has condemned Tabbs Creek, the northwestern area of the northwest branch of the Back River, and the southwest area of the southwest branch of the Back River for shellfish harvesting (Foster Wheeler, 1996). Local authorities post signs prohibiting fishing at Tabbs Creek. Because fishing and shellfish harvesting are prohibited, there are no health hazards currently associated with Tabbs Creek.

Since ATSDR's initial visit, a remedial investigation was performed at Tabbs Creek. As a result of the investigation, NASA developed a cleanup plan for Tabbs Creek, which calls for the dredging of sediment throughout the creek. Because contaminants were detected at higher levels in the upper reaches of the creek, the cleanup action will focus on that area (Figure 6). Furthermore, NASA has identified and remediated the possible sources of contamination, including past leakage from transformers and hydraulics systems at Building 1247D, and decontaminated the storm sewer system that drains to Tabbs Creek (see Storm Sewer System, West Area, in Table 2). The remediation of contaminant sources and the removal of contaminated sediment in Tabbs Creek will help to decrease contaminant concentrations in fish and shellfish in the future.

The remedial investigation of Tabbs Creek also included fish and shellfish sampling. The representative species sampled were mummichog (analyzed the whole fish), Atlantic croaker (analyzed the fish fillets only), eastern oyster, blue crab, grass shrimp, ribbed mussel, and snapping turtle. Fish and shellfish caught in Tabbs Creek contain levels of pesticides, PCBs and PCTs, dioxins, furans, and arsenic above comparison values. ATSDR analyzed the sampling data to determine if past ingestion of fish or shellfish from Tabbs Creek could pose a public health hazard. Details of ATSDR's analysis are presented in Appendix C.

ATSDR evaluated possible health effects for adults and children consuming fish or shellfish meals from Tabbs Creek. In the analysis, ATSDR used the highest detected contaminant concentrations. For both adults and children, exposure to PCTs, dioxins, furans, and arsenic in one Tabbs Creek fish meal per month poses a slight potential for adverse health effects. Due to the conservative nature of ATSDR's exposure evaluation process and the use of only the highest detected contaminant level, however, adverse health effects are not expected to occur from the occasional ingestion of fish or shellfish from Tabbs Creek (see Appendix C). Based on these results, ATSDR concludes that the past occasional ingestion of fish from Tabbs Creek is not likely to pose a public health hazard. ATSDR recommends that the creek continue to be posted for no fishing to prevent possible future exposures to contaminants in fish.

A preliminary assessment/site investigation of the Back River, including a sediment study, is being performed by the Air Force. A water quality assessment of the Back River, including fish and shellfish sampling, is also currently underway by the Department of Natural Resources at Langley AFB. ATSDR will review the results of these studies when they are available and change the conclusions of this public health assessment, if necessary.

LANGLEY AFB

Concern: Contaminated soil at the site of the former playground

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Soil at the former playground is contaminated with pesticides, herbicides, polycyclic aromatic hydrocarbons (PAHs), and metals.
  • The playground has been moved, the site is currently unused open space, and there are no plans for alternative future uses of the site; therefore, no public health hazards currently exist or are expected to exist in the future.
  • Past exposure to contaminants in soil at the former playground is not expected to result in adverse health effects.

Discussion

When ATSDR visited the Abandoned Entomology Site/Former Waste Water Treatment Plant site (Langley AFB Site OT-06) in 1994, the site had not been fully characterized. A playground was located at Site OT-06 and the Air Force had plans to build a Child Development Center across the street. Because chlordane was detected in the soil above the Resource Conservation and Recovery Act action level, ATSDR recommended that the site be characterized and, if necessary, remediated before construction of the Child Development Center began.

Soil at Site OT-06 has been characterized since ATSDR's initial visit and found to be contaminated with pesticides, herbicides, PAHs, and metals. Although a risk assessment conducted during the remedial investigation did not indicate elevated risks from exposure to contaminants at the site, the Air Force decided not to build the Child Development Center at this location. Furthermore, the playground has been moved to another location. Currently, the site is manicured, grassed over open space near the main entrance of Langley AFB. There are no plans to change the land use of Site OT-06. Because the site is no longer used as a playground and the Child Development Center will not be built here, there are no current or future health hazards associated with Langley AFB Site OT-06.

ATSDR reviewed soil data to determine if past exposure by incidental ingestion and dermal contact to soil contaminants could potentially result in a health hazard for children playing at the former playground. Pesticides, herbicides, PAHs, and metals were detected in soil above comparison values. Estimated exposure doses for a child exposed to the maximum detected concentration for most of the contaminants at Langley AFB Site OT-06 were below health guidelines and therefore do not pose a public health hazard. For a few contaminants, incidental ingestion estimated exposure doses were only slightly elevated, however, these contaminants were detected above comparison values infrequently (see Appendix C).

Several contaminants also may pose a slight health hazard for children who exhibit pica behavior (an abnormally high soil ingestion rate). In order for past exposure to contaminated soil at Site OT-06 to have the potential to result in adverse health effects for a pica child, the child would have to have visited the site frequently, actively disturbed the soil with the highest contaminant levels, and ingested 5,000 milligrams of contaminated soil on each visit. Due to the conservative nature of ATSDR's exposure evaluation process and the fact that most contaminants were detected infrequently above comparison values, ATSDR concludes that no apparent public health hazards exist from past exposure to contaminants at the former playground at Langley AFB Site OT-06.

Concern: Soil and physical hazards at the abandoned entomology building

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Soil at the site was contaminated with pesticides, herbicides, and fuel products. Physical hazards were associated with a dilapidated, abandoned building.
  • The building has been removed and soil remediated; therefore, no public health hazards currently exist or are expected to exist in the future.
  • Past potential exposure to contaminated soils at the site is not expected to be associated with adverse health effects.

Discussion

During ATSDR's 1994 visit, a dilapidated, abandoned entomology building (Building 965, Langley AFB Site OT-25) was located near an on-base housing area, playground, and tennis courts. Soil at the site was contaminated with pesticides, herbicides, and fuel products. The building was posted "Off Limits," but children reportedly played inside it. ATSDR was concerned that children or youth trespassing at the site could be exposed to physical hazards and soil contaminants.

When ATSDR conducted a second visit in November 1997, the building was demolished, the soil was remediated, and access to the site was restricted by a locked chain link fence. The potential for current and future exposure to physical hazards and soil contaminants has been eliminated.

ATSDR reviewed soil data to determine if past exposure to soil contaminants could potentially result in a public health hazard to trespassers (see Appendix C). Dieldrin and chlordane were detected in some surface soil samples above comparison values. ATSDR calculated exposure dose estimates for incidental ingestion of the highest detected concentrations of dieldrin and chlordane in soil by a trespassing child or youth. Although the site is industrial and posted for no trespassing, ATSDR used conservative assumptions. Potential exposures to on-site soil contamination would not cause adverse health effects. Based on these results, ATSDR concludes that past potential exposure to contaminated soils at OT-25 does not pose a public health hazard.

Concern: Soil and physical hazards at the fire training area

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Soil at the site is contaminated with pesticides and metals. Physical hazards may be associated with fire training structures.
  • A fence has been erected across the access road, partially restricting access to the site.
  • Potential exposure to contaminated soils at the site is not expected to be associated with adverse health effects.

Discussion

The Abandoned Fire Training Area/Firing-in Abutment (Langley AFB Site FT-41) borders the base horse stables and a main road that is adjacent to the flight line. The structures in the fire training area, which include a mock airplane, may be alluring to children and youths, and may pose a physical hazard those who trespass the site. During the 1994 site visit, ATSDR recommended that the Air Force restrict access to this site.

The Air Force installed a chain link fence with a locked gate across the front of the site. The fence restricts access for vehicular traffic. The fence borders only the front of the site, however, and children and youth could still trespass onto the site around the fence or from the stable area. ATSDR recommends that the Air Force install a fence completely surrounding the site that would more fully restrict access to potential trespassers, who may be on foot or on bicycles.

ATSDR reviewed soil data to determine if exposure to soil contaminants could potentially result in a public health hazard to child or youth trespassers (see Appendix C). Dieldrin and several metals were detected in some surface soil samples above comparison values. ATSDR calculated exposure dose estimates for incidental ingestion of the highest detected concentrations of contaminants in soil by a child or youth trespasser. These potential exposures would not cause adverse health effects. Based on these results, ATSDR concludes that potential exposure to contaminated soils at Langley AFB Site FT-41 does not pose a public health hazard.

Concern: Storage of fill material at Landfill 12

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Metals were detected sporadically in surface soil at the site.
  • The landfill is no longer used to store fill material; therefore, no public health hazards currently exist or are expected to exist in the future.

Discussion

When ATSDR visited the base in 1994, the Air Force was storing fill material in an area of Landfill 12 (Langley AFB Site LF-12) before using it elsewhere on base. ATSDR recommended that the area not be used to store fill material until the soil contamination was characterized so that potentially contaminated soil would not be transported from the site to other areas of the base.

During ATSDR's 1997 site visit, the Air Force reported that it no longer uses the site to store fill material. This will ensure that, currently and in the future, no contaminants from Site LF-12 will be transported to other areas of the base in fill material.

LF-12 was evaluated during the 1996 site inspection. Metals were detected slightly and sporadically above comparison values in surface soil. No volatile organic compounds or semivolatile organic compounds were analyzed at that time. While it may have been possible for some of the metals in soil at LF-12 to leach into fill material stored there, metal levels detected at LF-12 were generally very low. Based on available data, ATSDR concludes that Langley AFB Site LF-12 and the fill material that was stored there do not pose a public health hazard. A remedial investigation is being performed at Langley AFB Site LF-12. ATSDR will review the data presented in the report and modify the conclusions of this public health assessment, if necessary.

Concern: Lead-contaminated soil in the housing areas

Conclusions

After detailed review of the available data, ATSDR has drawn the following conclusions:

  • Lead-based paint has peeled and flaked off into residential yards; the extent of contamination is unknown.
  • The Air Force has a lead-based paint management plan in effect that includes screening children for elevated blood lead levels and sampling lead in soil if no other sources for a detected elevated blood lead level can be determined.
  • Surface soil should be characterized for lead contamination and appropriate remedial actions taken, if necessary.

Discussion

Lead-based paint was used to paint the exterior of on-base housing at Langley AFB prior to 1978. This paint has peeled and flaked off into residential yards, potentially contaminating the soils with lead. During the August 1994 site visit, ATSDR recommended that the soil in the housing areas be sampled for lead.

While the Air Force has not instituted basewide sampling of soil in housing areas, they do have a comprehensive lead-based paint management plan (Langley AFB, 1995). The plan includes a survey of lead-based paint throughout the base to identify the areas of highest risk. In areas where lead-based paint is found to be a potential health concern, the Air Force must either relocate families with children or pregnant women, perform in-place management of the hazard, or perform an abatement. Newcomers to the base are informed of potential lead-based paint hazards and the public health staff perform blood lead level screening for all children on base. When investigating a child with an elevated blood lead level, the Air Force may sample soil and water if no other source of the lead poisoning had been identified. At the time of ATSDR's 1997 site visit, the Air Force stated that this practice had never been implemented.

The Air Force has a comprehensive lead-based paint management plan in place. While screening tests can detect elevated blood lead levels in children, however, they cannot prevent them. ATSDR continues to recommend that soil in the on-base residential areas be sampled for lead and that soil be remediated, if indicated.

NASA LaRC

Concern: Soil at the open storage area

Conclusions

ATSDR has drawn the following conclusions:

  • Surface soil at this site has not been characterized.
  • Surface soil at this site should be characterized to ensure that no public health hazards exist.

Discussion

Since 1968, an open storage area (NASA LaRC Site 4) has been used to store aircraft, trailers, trucks, tanks, construction material, and other miscellaneous items. According to the site investigation, rocket fuel was also stored here (Ebasco, 1996). There are no known or suspected instances of release. During ATSDR's site visit in 1997, several barrels were located in the storage areas. This is an industrial area with a chain link fence surrounding it. Although access to the storage area is restricted to NASA personnel depositing or removing materials, the soil at this site has never been characterized. Although there are no known spills or releases, ATSDR recommends that NASA characterize the surface soil because rocket fuel has been stored on site and NASA personnel may access the site on a regular basis.


COMMUNITY HEALTH CONCERNS

In order to identify community concerns regarding Langley AFB and NASA LaRC, ATSDR contacted Restoration Advisory Board (RAB) members during both site visits. No community concerns were identified through the RAB.

Environmental concerns were expressed by community members during the development of the Community Relations Plan (CRP) for Langley AFB. These concerns included water pollution, the resulting economic impacts of water pollution on the seafood industry, and the effects of contamination from fuel spills and leaking underground storage tanks. In general, however, the CRP found the community to be supportive of the presence and activities of the Air Force (Langley AFB, 1997).

The CRP for NASA LaRC states that community concern about the facility has been and continues to be low (NASA LaRC, 1996). Health and environmental concerns identified include Chesapeake Bay water quality, overall water quality, noise from the wind tunnels, and asbestos and hazardous chemicals in the workplace. The CRP also notes that there was and is concern regarding high levels of dioxins reportedly emanating from the Refuse-Fired Steam Generating Facility. While NASA LaRC and Langley AFB were involved in the funding of this facility, the City of Hampton is and always has been the owner and operator of the facility.


ATSDR'S CHILD HEALTH INITIATIVE

ATSDR recognizes that infants and children may be more sensitive to environmental exposure than adults in communities faced with contamination of their water, soil, air, or food. This sensitivity is a result of the following factors: (1) children are more likely to be exposed to certain media (e.g., soil or surface water) because they play outdoors; (2) children are shorter than adults, which means that they can breathe dust, soil, and vapors close to the ground; and (3) children are smaller, therefore childhood exposure results in higher doses of chemicals per body weight. Children can sustain permanent damage if these factors lead to toxic exposure during critical growth stages. ATSDR is committed to evaluating their special interest at sites such as Langley AFB and NASA LaRC, as part of ATSDR's Child Health Initiative.

ATSDR evaluated the likelihood that children living at Langley AFB may have been or may be exposed to contaminants at levels of health concern. ATSDR did not identify any situations where children were likely to be or have been exposed to contaminants at levels that would be associated with adverse health effects. ATSDR based this conclusion on several factors after reviewing the available data, including:

  • No adverse health effects are expected from past occasional ingestion of contaminants in fish or shellfish from Tabbs Creek. Because fishing is currently prohibited, no exposures currently exist.
  • No adverse health effects are expected from past exposure to contaminants in soil at the former playground at Langley AFB Site OT-06.
  • No adverse health effects are expected from occasional exposure to contaminants at detected levels in soil at Langley AFB Sites OT-25 or FT-41, where children or youths might trespass.
  • The Air Force has a program in place to screen children for elevated blood lead levels.


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