PUBLIC HEALTH ASSESSMENT
NAVAL AMPHIBIOUS BASE LITTLE CREEK
VIRGINIA BEACH, VIRGINIA
Table 1. Evaluation of Sites at Naval Amphibious Base, Little Creek
| Site | Site Description and History | Investigation Results/Environmental Monitoring Results1 | Corrective Action and/or Current Status | Evaluation of Public Health Hazard |
| Installation Restoration Program (IRP) and Miscellaneous Sites | ||||
| Site 4 - Reserve Center Oil Disposal Area | Site 4 is the location of an outdoor vehicle maintenance pad, where about 2,000 gallons of waste oils and antifreeze a year were disposed of into a storm sewer between 1967 and 1981. Oil in the ground around the pad would be expected to migrate to the groundwater and then to Piers 9 and 10, about 300 feet to the northeast. | Mitigation measures were recommended for this site to prevent migration of contaminants from oil soaked soils to nearby surface waters. The site is closed with no further action required under CERCLA. | No information provided for evaluation. | |
| Site 5 - Building T-9 and T-11 Motor Oil Disposal Area |
Site 5 consist of Building T-9 and Building T-11. Reportedly, 50,000 gallons of oil and antifreeze were dumped on the ground between the two buildings. But Marsden matting (solid steel plates under steel braces) in the disposal area would have made it virtually impossible for disposal of this magnitude to have occurred. Also, 43,000 gallons of oil and antifreeze were reportedly dumped in cable tanks in Building T-11. No physical/visual evidence was ever found, however, to substantiate improper disposal either between the building or in Buildings T-11. | Groundwater: Volatile organic compounds
(VOCs) and lead were detected in groundwater but at levels below the EPA's
risk-based concentrations (RBC) for tap water.
Soil: Low levels of total petroleum hydrocarbons were detected. |
No further action is planned. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential or public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. |
| Site 7 - Naval Amphibious Base (NAB) Landfill | The 30-acre landfill located in the south-central portion of the facility operated from 1962 to 1979, initially as a trench-style landfill then as an area landfill. The area was once an arm of Little Creek Cove, but was filled with dredged soil before it was used as a landfill. The majority of the waste at the landfill likely consisted of municipal refuse. Potentially hazardous materials disposed of at the landfill include paints, acids, polychlorinated biphenyls (PCBs), and pesticides. After closure in 1979, the area was used as a metal collection and transfer station. No waste storage or burning activities have occurred since the 1980s. Runoff/drainage drains the site via a drainage ditch toward Little Creek Cove. | Groundwater: Metals were detected.
Surface Soil: Semivolatile organic compounds (SVOCs), metals, and PCBs, as Aroclor 1260, were detected in the soil. |
Buildings and traveled roads are prohibited at the site. At the time of closure the landfill was covered with 24 inches of soil. In October 1994 two to three additional layers of topsoil were spread over the area and then revegetated. As part of the remedial investigation in 1998, 610 cubic yards of soil were removed, 20,000 cubic yards of soil were then added and vegetated, and the fence around the landfill was replaced. Also in 1998, groundwater sampling for long-term monitoring began at the site. Today, because of the additional soil cover, the landfill waste lies below ground surface. | No identified public health hazards are associated with
this IRP site under past or present use. There is limited potential or public
contact with contaminated soil from the contents of the landfill and no
one uses the groundwater at the site as a drinking water source. Some contamination
could have reached Little Creek Harbor via a drainage canal, possibly contaminating
harbor sediment and fish. Recreational swimmers should not come in contact
with harmful levels of contaminants in sediment and restrictions against
taking fish or shellfish has been issued for the harbor.
ATSDR recommends that the Navy consider potential movement of landfill gases before constructing any future buildings near the former |
| Site 8 - Demolition Debris Landfill | The 2-acre Demolition Debris Landfill was operated from 1971 to 1979 for the disposal of demolition debris. Material disposed of at the landfill potentially contained mercury-contaminated carpet, building debris, and concrete piping. | Groundwater: Metals, including arsenic,
were detected.
Soil: During 1998 site investigation activities, metals and pesticides (dieldrin) were detected. Sediment: Polycyclic aromatic hydrocarbons (PAHs) and metals were detected in sediment. |
The Navy will conduct another round of groundwater sampling to support a quantitative baseline human health and ecological risk assessment. The Navy is also in the process of preparing a remedial investigation RI/ feasibility study (FS) report for Site 8. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil or the contents of the landfill and no one uses the groundwater at the site as a drinking water source. ATSDR recommends that the Navy consider potential movement of landfill gases before constructing any buildings in the future near the former landfills. |
| Site 9 - Driving Range Landfill | Site 9 is the 6-acre Driving Range Landfill that served as the base's primary disposal area for solid waste between 1952 and the 1960s. This unlined landfill was situated in the northeastern section of the base, about 500 feet south of the shoreline of the Chesapeake Bay. Solid waste could have included pesticides refuse, solvents, heavy metals, PCBs, and incinerator ash. Before landfilling operations were started, the area was a marshy lowland. After closure, sludge from the Hampton Roads Sanitation Treatment Plant was added to encourage growth of grass. The area has since been used as a driving range. Runoff from the area moves towards a golf course lake and the Chesapeake Bay. | Groundwater: Metals, including arsenic,
barium, beryllium, lead, nickel, and zinc, have been detected.
Surface Soil: VOCs (toluene) and pesticides (DDD, DDE, dieldrin, endrin) were detected. |
Long-term groundwater monitoring is underway at the site.
The site contains cover. |
No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil or the contents of the landfill and no one uses the groundwater at the site as a drinking water source. Contamination in surface runoff is not directed toward Little Creek Harbor, possibly Therefore, recreational swimmers at the harbor should not come in contact with harmful levels of contaminants in sediment. |
| Site 10 - Sewage Treatment Plant Landfill | Site 10, the 7-acre Sewage Treatment Plant Landfill, is located in the northeast portion of the base, about 500 feet south of the Chesapeake Bay. Between 1941 and 1952, solid waste generated from base activities was deposited at the landfill. Waste was mostly non-hazardous, but could have included pesticides, paints, solvents, PCBs, and heavy metals. Early on, waste was deposited directly into the water at Desert Cove, eventually filling in 5 acres of land. Runoff from the landfill is believed to enter Desert Cove. | Groundwater: Metals, including arsenic,
barium, beryllium, lead, nickel, and zinc, have been detected.
Surface Soil: VOCs (toluene) and pesticides (DDD, DDE, dieldrin, endrin, and chlordane) were detected. |
Today, the landfill is covered with soil and grass and a portion of the site has been used for baseball diamonds. Corrective actions were completed for underground storage tanks and long-term groundwater monitoring is underway at the site. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil or the contents of the landfill and no one uses the groundwater at the site as a drinking water source. Contaminants may enter Desert Cove with runoff from Site 10, possibly contaminating harbor sediment and fish. Recreational swimmers should not come in contact with harmful levels of contaminants in sediment and restrictions against taking fish or shellfish has been issued for the harbor. ATSDR recommends that the Navy consider potential movement of landfill gases before constructing any buildings in the future near the former landfills. |
| Site 11 - School of Music Plating Shop, including the Neutralizing Tank, Contaminated Soil, and Groundwater | Site 11 is the tank, contaminated soil and groundwater associated with the School of Music Plating Shop, located in Building 3651 along the eastern portion of the base. Between 1964 and 1974, musical instruments were electroplated at the shop. Plating bath solutions containing silver cyanide, copper cyanide, chromic acid, nickel, acids, and lacquers were disposed of down a drain inside the shop. The material was then carried by an acid-resistant pipe to a concrete neutralization pit about 10 feet from the shop, before emptying into a storm sewer. Runoff from the area moves toward Desert Cove and Little Creek Cove. | Groundwater: VOCs and metals were detected.
Recent investigations indicated that only the lower portion (17-21 feet
below ground surface) of the surficial aquifer was contaminated with VOCs,
where trichloroethylene (TCE) and dichloroethylene (DCE) were measured.
Concentrations in the shallow portion (8-12 feet below ground surface) of
the surficial aquifer are being investigated.
Soil: Metals were detected. |
During 1995 and 1996, the tank and its contents and inlet and outlet piping were removed. About 190 gallons of hazardous liquids and about 11 tons of debris were removed. Contaminated materials along the pipeline and below the tank also were removed, including 94 tons of contaminated soil and almost 11 tons of debris (tank, concrete floor, piping). Following the removal, the excavated area was backfilled, the floor and cooling towers were replaced, and the area was spread with topsoil. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. Contaminants may reach Desert Cove and Little Creek Cove in runoff from Site 11, possibly contaminating harbor sediment and fish. Recreational swimmers should not come in contact with harmful levels of contaminants in sediment and restrictions against taking fish, crabs, and shellfish have been issued for the harbor. |
| Site 11A - Area of Elevated TCE Contamination | Site 11A is a separate area discovered during the investigation of Site 11. The TCE contamination is unrelated to Site 11 and the source of contamination at Site 11A has not yet been determined. The TCE contamination is believed to be as a result of an isolated dumping of a small volume of TCE. | Groundwater: TCE concentrations were detected at levels slightly above EPA's MCL and ATSDR's CV of 5 ppb. | This site is being worked on along with Site 11. | No identified public health hazards are associated with Site 11A because no one uses the groundwater at the site as a drinking water or industrial water source. |
| Site 12 - Exchange Laundry Waste Disposal Area | Site 12, the Exchange Laundry Waste Disposal Area, consists of Building 3323 the site of base dry cleaning operations from 1973 until 1978. Waste containing tetrachloroethylene (PCE), soap, and dyes were dumped into a catch basin which emptied into a storm sewer. The sewer flows north into a 9-foot-deep drainage canal that connects with Lake Bradford and Little Creek Cove. A Base Exchange/ Commissary was built on the property in 1993. Runoff /drainage via a drainage canal moves from the area toward Little Creek Cove. | Groundwater: VOCs (primarily PCE) were
detected.
Surface Soil: VOCs, SVOCs, and lead were detected in soil. Surface Water/Sediment: In 1993, VOCs (TCE and PCE) were detected in the canals, but in 1991 and 1997 sampling VOCs were not detected. |
In 1987 Building 3323 was demolished and the catch basin and a portion of the storm sewer were removed. Eventually the rest of the storm sewer was removed and the area regraded to prepare for the construction of the Base Exchange/Commissary. The Navy has equipped the new building with a passive gas removal system to remove vapors in the event they should seep into the building from nearby groundwater contamination. The Navy is evaluating multiple options for groundwater remediation in the Feasibility Study. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. Some contamination could have reached Little Creek Cove via a drainage canal, possibly contaminating harbor sediment and fish. Recreational swimmers should not come in contact with harmful levels of contaminants in sediment and restrictions against taking fish or shellfish has been issued for the harbor. Groundwater contamination in the area is not expected to affect indoor air quality of the new Base Exchange/ Commissary. |
| Site 13 - Pentachlorophenol (PCP) Dip Tank and Wash Rack Area | Between 1960 and 1975 a PCP Dip Tank and a Wash Rack were used to treat wood with PCP. Wash racks near the dip tank were used for cleaning vehicles and equipment with steam or solvents and the drying rack was used for treated wood. Solutions on the treated materials could have dripped onto the ground. Runoff from the area is directed toward Little Creek Cove. | Groundwater: VOCs (TCE and PCE) were
detected.
Surface Soil: SVOCs were detected. |
All PCP contaminated soil was removed in 1999. In 2000, a pilot study was conducted using Oxygen Release Compound to remediate groundwater at the site. Several remedial alternatives are being evaluated for groundwater remediation. | No identified public health hazards are associated with this IRP site under past or present use. There is limited potential for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. Runoff from Site 13 enters Little Creek Cove, possibly transporting contaminants that could be taken up by harbor sediment or fish. Recreational swimmers should not come in contact with harmful levels of contaminants in sediment restrictions against taking fish or shellfish has been issued for the harbor. |
| Site 15 - PCB Capacitor Spill - Fire Station No. 1 | Site 15 is the soil beneath the capacitor pole behind Fire Station No. 1, where a capacitor was damaged by lightening in the early 1980s. Reportedly, less than 5 gallons of dielectric fluid leaked onto the ground in the immediate area of the spill. Migration of the contaminants is unlikely. | Groundwater: No data were available.
Soil: PCBs (up to 170,061 milligrams per kilogram [mg/kg]) were detected. |
PCB contaminated soils were removed in 2002. No further action for this site. | Under past or present use no identified public health hazards are associated with this IRP site. There is only limited potential for public contact with contaminated soil, and no one uses the groundwater at the site as a drinking water source. |
| Site 16 - Pole # 425 PCB Capacitor Spill | Site 16 is the location of a PCB-containing dielectric fluid leak. The spill of less than 5 gallons resulted when lightening struck the capacitor on pole #425 pole. | Soil: PCBs, as Aroclor 1260, were detected in soil. | The PCB-contaminated soil, the pole, and the surrounding vegetation were removed in 1995, as approved by the state and EPA. PCB contaminated soils were removed in 2002. No further action for this site. | Under past or present use, no identified public health hazards are associated with this IRP site. There is only limited potential for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. |
| SWMUs | ||||
| SWMU 1 - Small Transformer Storage Area | Beginning in 1975, the Navy used this area for storage of small, non-PCB transformers and repairs of PCB transformers. , Whether releases of PCBs have occurred is, however, unknown. | Groundwater: None tested.
Soil: PCBs were detected but at levels below risk-acceptable, industrial risk-based concentrations (RBCs). SVOCs and pesticides were also detected. |
This site is proposed for no further action. | No identified public health hazards are associated with this SWMU under past or present use. There is only limited potential for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. |
| SWMU 3 - Pier 10 Sandblast Yard | From 1962 to 1984 this area was used for sandblasting activities for boats, and from 1980 to 1995 for anchors and anchor chains. Items were sandblasted on a concrete pad. Periodically, the residue was removed from the area. No hazardous materials were found on the site, but some residue was found along the unpaved ground extending from the concrete pad to the shore of Little Creek Harbor. In 1982 a fence was constructed to limit windblown residue migration, and, in 1993 an asphalt cover and catch basin were added. | Groundwater: VOCs and metals detected
in groundwater.
Soil: Metals and PAHs were detected in soil. Sediment: Metals and PAHs were detected in sediment. |
Additional groundwater monitoring and completion of a quantitative risk assessment are proposed for this SWMU. This SWMU will also be followed as part of a multi-site ecological risk assessment. | No identified public health hazards are associated with this SWMU. A fence limits any possibility of public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. |
| SWMU 4 - Special Boat Squadron 2 Battery Storage Yard | This 300 to 400-square foot area was used from 1943 to 1980 for storage of lead-acid batteries, paint waste, and scrap metals. The site is surrounded by a fence and a controlled security gate. Pavement covers the area, except in the grassy area along the fence and near a building. | Groundwater: Metals were detected in
groundwater.
Soil: Metals were detected in soil. |
This SWMU could be recommended for further investigations. | No identified public health hazards are associated with this SWMU under past or present use. A fence limits the possibility for public contact with contaminated soil and no one uses the groundwater at the site as a drinking water source. |
| SWMU 6 - SeaBee Area | The General Services Administration used the area to stockpile mineral ores. Most of the ores have been removed. Currently, the ore storage area consists of three grass-covered piles ranging from 40 to 70 feet high. | Groundwater: VOCs were detected, but
generally at low levels. Antimony, arsenic, beryllium, cadmium, chromium,
and lead were also detected.
Surface Soil: No data were available. Sediment: Sediment contained PAHs and PCBs, but generally at low concentrations. |
The area has been paved. | No identified public health hazards are associated with this SWMU under past or present use. Pavement covering the area prevents public exposure with exposed soil and no one uses the groundwater at the site as a drinking water source. |
| SWMU 8 - West Annex Sandblasting Areas | This SWMU consists of a vacant lot which 1949 to 1971 was used for sandblasting of boats. Sandblasting residue accumulated on the ground to an average thickness of 4 inches. Periodically, the residue was removed and disposed of off base. | Groundwater: VOCs and metals were detected
in groundwater.
Soil: Metals, primarily lead, and PAHs were detected in surface soil. Sediment: Metals and PAHs were detected in soil. |
The Navy delineated the boundaries of grit at SWMU 8 and a nearby water tower. the Navy also removed lead contaminated soil within those areas to levels for residential settings. | No identified public health hazards are associated with this SWMU IRP site under past or present use. Contaminated soil has been removed from this SWMU and no one uses the groundwater at the site as a drinking water source. Residential property lies about 100 feet from the water tower. ATSDR is concerned that in the past lead-contaminated soil could have migrated to the off-base property where children might live or play. No sampling or comprehensive exposure (blood lead levels) data are available to state definitely whether lead exposure could have or has occurred. ATSDR recommends blood lead level screening for all children age 6 or under. |
Sources: NEESA 1984, OHM/IT 2001.
Key
| ATSDR DCE EE/CA µg/L µg/kg mg/kg PAH |
Agency for Toxic Substances and Disease Registry dichloroethylene engineering evaluation/cost analysis micrograms per liter = ppb micrograms per kilogram = ppb milligrams per kilogram = ppm polycyclic aromatic hydrocarbons |
PCBs PCE RBC ROD SVOCs SWMU TCE VOCs |
polychlorinated biphenyls tetrachloroethylene EPA's risk based concentration record of decision semivolatile organic compounds solid waste management unit trichloroethylene volatile organic compounds |
Table 2. Exposure Pathways Evaluation Table
| Pathway Name | Exposure Pathway Elements | Comments | ||||
| Source of Contamination | Environmental Medium | Point of Exposure | Route of Exposure | Potentially Exposed Population | ||
| Completed Exposure Pathway | ||||||
| Consumption of Local Fish and Shellfish from Little Creek Harbor |
Mercury, tributyltin, and PCBs from the NAB Little Creek operations and numerous other sources associated with routine harbor activity | Local fish and shellfish populations | Consumption of locally caught fish and shellfish | Ingestion | Local anglers and harvesters of crab (who disregard the no fishing /shellfishing advisory) | Past: Fish and crab in Little Creek Harbor have been
impacted by mercury and tributyltin. Contaminant levels in local fish/shellfish/crab
could have posed a public health hazard if consumed in sufficient quantities.
Current and Future: To best protect themselves against exposure to biologic and chemical contaminants, people should adhere to the Little Creek Harbor restrictions and advisory. |
|
Potential Exposure Pathways |
||||||
| Surface Soil - On base | Several areas of soil contamination associated with former site activities exist throughout NAB Little Creek. | Surface soil | Surface soil at nearby residential property | Dermal contact and incidental ingestion | Nearby off-base residents | Past: Exposure to contaminated surface soil at NAB Little
Creek sites is largely prevented because the majority of the land's surface
is paved, covered by buildings, fenced, or is in restricted land use locations.
Any sporadic contact with or incidental ingestion of the contaminants detected
in the base surface soil is not expected to have harmful effects.
Current and Future: No public health hazards are occurring or are expected to occur. |
| Surface Soil - Off base | NAB Little Creek SWMU 8 and Water Tower 1553. Lead is the primary contaminant of concern. Exposure to contaminated surface soil at other NAB Little Creek sites is largely prevented because the majority of the land's surface is paved, covered by buildings, fenced, or is in restricted land use locations. | Surface soil | Surface soil at nearby off-base residential property | Dermal contact and incidental ingestion | Nearby off-base residents | Past: Children at certain homes in the Turner Road area could have been exposed to site-related lead in soil if lead migrated from the base. Data are not available to confirm whether or to what extent migration occurred.
Current and Future: No exposures are expected to occur; the grit has been removed from SWMU 8/ water tower. Furthermore, soil cover at the residential properties greatly reduces contact with possible residual lead in soil. Cumulative exposure to all possible sources of lead in the neighborhood could pose a risk for some children. |
Table 3. Contaminant Concentrations in Fish and Crab From
Little Creek Harbor
| Study | Sample Location | Species | Number of Individual Samples | Total Mercury (mg/kg) | Tributyltin (mg/kg) |
PCBs (mg/kg) |
| Base Study 1994 | Little Creek Harbor | Fish (Spot) | 3 | 0.132 | nd | na |
| Fish (Croaker) | 1 | 0.134 | nd | na | ||
| Crab | 8 | 0.225 | nd | na | ||
| Crab | 7 | 0.193 | nd | na | ||
| Base Study 1995 | Little Creek Canal | Crab | composite samples | 0.097 | 0.028 | na |
| Pier 58 | Fish (Croakers) | composite samples | 0.148 | 0.006 | na | |
| VDEQ 1998 |
Little Creek Channel | Fish (Mummichog) | 1 | na | na | 0.127 |
| Fish (Spot) | 1 | na | na | 0.062 |
Source: Baker Environmental Inc. 1996.
Key: mg/kg = milligrams per kilogram; na = not analyzed; nd = not detected.
Note: EPA risk-based concentrations (RBCs) for contaminants detected in Little Creek Harbor fish/crab are: mercury, 0.14 mg/kg; tributyltin, 0.41 mg/kg; and PCBs, 0.0016 mg/kg. Concentrations of mercury and PCBs in fish and crab exceeded EPA's RBCs. Nevertheless, ATSDR's evaluation determined that exposure to the detected levels of these contaminants in fish/shellfish should not pose a health threat to those who ate fish or crab from the harbor in the past. The Navy currently maintains a no fishing advisory for the harbor based on bacteriological contamination. People can best protect themselves from exposure to all contaminants in fish and shellfish by adhering to the existing advisory.
Figure 8. SWMU 8 and Water Tower 1553
ATSDR defines an exposure pathway as having 5 parts:
When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.
APPENDIX B: ATSDR'S EXPOSURE EVALUATION PROCESS
INFORMATION ON HOW ATSDR ASSESSES EXPOSURE
What is meant by exposure?
ATSDR's public health assessments are driven by exposure or contact. Chemicals released into the environment have the potential to cause harmful health effects. Nevertheless, a release does not always result in exposure. People can only be exposed to a chemical if they come in contact with that chemical. If no one comes into contact with a chemical, then no exposure occurs, thus no health effects could occur. Often the general public does not have access to the source area of the environmental release; this lack of access becomes important in determining whether the chemicals are moving through the environment to locations where people could come into contact with them.
The route of a chemical's movement is the
pathway. ATSDR identifies and evaluates
exposure pathways by considering how people
might come into contact with a chemical. An
exposure pathway could involve air, surface water,
groundwater, soil, dust, or even plants and
animals. Exposure can occur by breathing, eating,
drinking, or by skin contact with a substance
containing the chemical.
How does ATSDR determine which exposure situations to evaluate?
ATSDR scientists evaluate site-specific conditions to determine whether people are being exposed to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure to contaminated media (soil, water, air, waste, or biota) is occurring through ingestion, dermal (skin) contact, or inhalation.
If exposure is possible, ATSDR scientists then consider whether contamination is present at levels that might affect public health. ATSDR selects chemicals for further evaluation by comparing them against health-based comparison values. Comparison values are developed by ATSDR from available scientific literature concerning exposure and health effects. Comparison values are derived for each of the media and reflect an estimated chemical concentration that is not expected to cause harmful health effects for a given chemical, assuming a standard daily contact rate (e.g., amount of water or soil consumed or amount of air breathed) and standard body weight.
Comparison values are not thresholds for harmful health effects. ATSDR comparison values represent chemical concentrations many times lower than levels at which no effects were observed in experimental animal or human epidemiologic studies. If chemical concentrations are above comparison values, ATSDR further analyzes exposure variables (e.g., duration and frequency) for health effects, including the toxicology of the chemical, other epidemiology studies, and the weight of evidence.
Some comparison values used by ATSDR scientists include ATSDR's environmental media evaluation guides (EMEG), reference dose media evaluation guides (RMEG), and cancer risk evaluation guides (CREG). EMEGs, RMEGs, and CREGs are non-enforceable, health-based comparison values developed by ATSDR for screening environmental contamination for further evaluation. Risk-based concentrations (RBCs) and soil screening levels (SSLs) are health-based comparison values developed by EPA Region III to screen sites not yet on the National Priorities List (NPL), respond rapidly to citizens inquiries, and spot-check formal baseline risk assessments.
More information about the ATSDR evaluation process can be found in ATSDR's Public Health Assessment Guidance Manual at http://www.atsdr.cdc.gov/HAC/HAGM/ or by contacting ATSDR at 1-888-42-ATSDR. For reference, Appendix A defines some of the technical terms used in this public health assessment and a List of Acronyms is available after the Table of Contents.
If someone is exposed, will they get sick?
Exposure does not always result in harmful health effects. The type and severity of health effects that occur in an individual as the result of contact with a chemical depend on the exposure concentration (how much), the frequency and duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of chemicals). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, lifestyle, and health status of the exposed individual influence how that individual absorbs, distributes, metabolizes, and excretes the chemical. Taken together, these factors and characteristics determine the health effects that can occur as a result of exposure to a chemical in the environment.
Considerable uncertainty exists regarding the true level of exposure to environmental contamination. To account for that uncertainty and to protect public health, ATSDR scientists typically use high-end, worst-case exposure level estimates to determine whether harmful health effects are possible. These estimated exposure levels are usually much higher than the levels to which people are really exposed. If the exposure levels indicate harmful health effects are possible, a more detailed review of exposure, combined with scientific information from the medical, toxicologic, and epidemiologic literature about the health effects from exposure to harmful substances, is performed.
Overview of ATSDR's Methodology for Evaluating Potential Public Health Hazards
To evaluate exposures at NAB Little Creek, ATSDR evaluated available data to determine
whether contaminants were above ATSDR's comparison values. For those that were, ATSDR
derived exposure doses (see text box for definition) and compared
them against health-based guidelines. ATSDR also reviewed
relevant toxicologic and epidemiologic data to obtain information
about the toxicity of contaminants of interest. Exposure to a certain
chemical does not always result in harmful health effects. The type
and severity of health effects expected to occur depend on the
exposure concentration, the toxicity of the chemical, the frequency and duration of exposure, and
the multiplicity of exposures.
Comparing Data to ATSDR's Comparison Values
Comparison values are derived using conservative exposure assumptions. Comparison values reflect concentrations that are much lower than those that have been observed to cause adverse health effects. Thus, comparison values are protective of public health in essentially all exposure situations. As a result, concentrations detected at or below ATSDR's comparison values are not considered to warrant health concern. While concentrations at or below the relevant comparison value may reasonably be considered safe, it does not automatically follow that any environmental concentration that exceeds a comparison value would be expected to produce adverse health effects. It cannot be emphasized strongly enough that comparison values are not thresholds of toxicity. The likelihood that adverse health outcomes will actually occur depends on site-specific conditions and individual lifestyle and genetic factors that affect the route, magnitude, and duration of actual exposure, and not an environmental concentration alone.
For this public health assessment ATSDR reviewed soil data that were collected from SWMU 8 and water tower 1553 because these areas are located near off-base residential property. We also reviewed fish and crab tissue data collected from Little Creek Harbor to determine whether people were exposed to contaminant concentrations that exceeded ATSDR's comparison values. The majority of detected contaminants fell at or below comparison values and were not evaluated further. Contaminants that were above comparison values were evaluated further, prompting ATSDR to estimate exposure doses using assumption specific to this site.
Deriving exposure doses
ATSDR derived exposure doses for those contaminants that were detected above ATSDR's comparison values or did not have comparison values. Exposure doses are expressed in milligrams per kilogram per day (mg/kg/day). When estimating exposure doses, health assessors evaluate chemical concentrations to which people could be exposed, together with the length of time and the frequency of exposure. Collectively, these factors influence an individual's physiological response to chemical exposure and potential outcomes. Where possible, ATSDR used site-specific information about the frequency and duration of exposures. In cases where site-specific information was not available, ATSDR applied several conservative exposure assumptions to estimate exposures for on-base and off-base residents and recreational users.
Using exposure doses to evaluate potential health hazards
ATSDR analyzes the weight of evidence of available toxicologic, medical, and epidemiologic data to determine whether exposures might be associated with harmful health effects (noncancer and cancer). As part of this process, ATSDR examines relevant health effects data to determine whether estimated doses are likely to result in harmful health effects. As a first step in evaluating noncancer effects, ATSDR compares estimated exposure doses to conservative health guideline values, including ATSDR's minimal risk levels (MRLs) and EPA's reference doses (RfDs). The MRLs and RfDs are estimates of daily human exposure to a substance that are unlikely to result in noncancer effects over a specified duration. Estimated exposure doses that are less than these values are not considered to be of health concern. To maximize human health protection, MRLs and RfDs have built in uncertainty or safety factors, making these values considerably lower than levels at which health effects have been observed. The result is that even if an exposure dose is higher than the MRL or RfD, it does not necessarily follow that harmful health effects will occur.
For carcinogens, ATSDR also calculates a theoretical increase of cancer cases in a population (for example, 1 in 1,000,000 or 10-6) using EPA's cancer slope factors (CSFs), which represent the relative potency of carcinogens. This is accomplished by multiplying the calculated exposure dose by a chemical-specific CSF. Because they are derived using mathematical models which apply a number of uncertainties and conservative assumptions, risk estimates generated by using CSFs tend to be overestimated.
If health guideline values are exceeded, ATSDR examines the health effect levels discussed in the scientific literature and more fully reviews exposure potential. ATSDR reviews available human studies as well as experimental animal studies. This information is used to describe the disease-causing potential of a particular chemical and to compare site-specific dose estimates with doses shown in applicable studies to result in illness. For cancer effects, ATSDR compares an estimated lifetime exposure dose to available cancer effects levels (CELs), which are doses that produce statistically significant increases in the incidence of cancer or tumors, and reviews genotoxicity studies to understand further the extent to which a chemical might be associated with cancer outcomes. This process enables ATSDR to weigh the available evidence in light of uncertainties and offer perspective on the plausibility of harmful health outcomes under site-specific conditions.
Using other methods to evaluate potential health hazards
When dealing with exposure to lead, ATSDR uses an additional approach to the traditional methodologies described above. A substantial part of human health effects data for lead are expressed in terms of blood lead level rather than exposure dose. Thus, ATSDR developed a secondary approach to utilize regression analysis with media-specific uptake parameters to estimate what cumulative blood lead level might result from exposure to a given level of contamination. This is accomplished by multiplying the detected concentration by a media-specific slope factor, which is 0.0068 micrograms per deciliter (µg/dL) per mg/kg of lead ingested in soil (ATSDR 1999c). The Centers for Disease Control and Prevention (CDC) has determined that health effects are more likely to be observed if blood lead levels are at or above 10 µg/dL.
Essential nutrients (e.g., calcium, magnesium, potassium, and sodium) are important minerals that maintain basic life functions; therefore, certain doses are recommended on a daily basis. Because these chemicals are necessary for life, MRLs and RfDs do not exist for them. They are found in many foods, such as milk, bananas, and table salt. Ingestion of these essential nutrients at the concentrations found at NAB Little Creek will not result in harmful health effects.
Sources for health-based guidelines
By Congressional mandate, ATSDR prepares toxicological profiles for hazardous
substances found at contaminated sites. These toxicological profiles were used
to evaluate potential health effects from contamination at NAB Little Creek.
ATSDR's toxicological profiles are available on the Internet at http://www.atsdr.cdc.gov/toxpro2.html
or by contacting the National Technical Information Service at 1-800-553-6847.
EPA also develops health effects guidelines, and in some cases, ATSDR relied
on EPA's guidelines to evaluate potential health effects. These guidelines are
found in EPA's Integrated Risk Information System (IRIS)–a database of
human health effects that could result from exposure to various substances found
in the environment. IRIS is available on the Internet at http://www.epa.gov/iris
. For more information about
IRIS, please call EPA's IRIS hotline at1-301-345-2870 or e-mail at Hotline.IRIS@epamail.epa.gov.
Evaluation of Health Hazards Associated with Contamination at NAB Little Creek
Surface Soil at SWMU 8 and Water Tower 1553
The majority of the chemicals in the surface soil at SWMU 8 and water tower 1553 were detected below comparison values. Table B-1 lists the chemicals that were detected above comparison values, including benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, arsenic, and lead.
ATSDR estimated exposure doses from incidental ingestion of surface soil for each chemical listed in Table B-1 using the formulas and assumptions described previously. Exposure doses for all chemicals except lead are compared to ATSDR's MRLs or EPA's RfDs. As indicated in Table B-1, the exposure doses are below their respective MRL or RfD and, therefore, are not at levels of health concern. Given this finding, those exposed via incidental ingestion even to the highest detected level of contaminants in surface soil at NAB Little Creek (specifically SWMU 8 and the water tower) are not expected to develop adverse health effects.
To conservatively assess potential increase in blood lead levels for a child eating soil, ATSDR multiplied the maximum concentration of lead in soil (1,820 ppm) by the media-specific slope factor for soil of 0.0068 micrograms per deciliter (µg/dL) per mg/kg of lead ingested in soil. As mentioned, the CDC has determined that health effects are more likely to be observed if blood lead levels are at or above 10 µg/dL. ATSDR estimated contribution to blood lead levels for a child eating soil containing the maximum contaminant concentration detected on base is 12 µg/dL. While this level is slightly higher than CDC's recommended action level of 10 µg/dL, ATSDR believes that children in the Turner Road neighbor probably incurred much lower lead exposures, if any, and are not at risk of developing adverse health effects. In effort to be protective, ATSDR had evaluated the maximum detected concentration found on base , recognizing that, in any reasonable exposure situation, it is highly unlikely that a child could have been continuously exposed to the similarly high concentrations in their yards over time.
Consumption of fish, shellfish, crab from Little Creek Harbor
ATSDR estimated exposure doses to the maximum levels of mercury, tributyltin, and PCBs in fish or crab using the formulas and assumptions described previously. All exposure doses were at or below their respective MRLs and RfDs and therefore not at a level of health concern. Given the findings and the conservative assumptions used in deriving the estimates, ATSDR does not expect those who ate fish or crab from the harbor to incur any adverse health effects from the chemicals that were sampled.
Table B-1: Exposure Doses for Chemicals Above Comparison Values at NAB Little Creek
| Chemical | Maximum Detected Concentration (mg/kg) |
Estimated Exposure Dose (mg/kg/day) | Oral Health Guideline (mg/kg/day) |
Basis for Health Guideline | |
| Adult | Child | ||||
|
Surface Soil at SWMU 8 and Water Tower 1553 |
|||||
| Benzo(a)anthracene | 2.7 | 0.000003 | 0.00003 | 0.03 (for pyrene) | chronic RfD |
| Benzo(a)pyrene | 1.7 | 0.000002 | 0.00002 | 0.03 (for pyrene) | chronic RfD |
| Benzo(b)fluoranthene | 2.7 | 0.000003 | 0.00003 | 0.03 (for pyrene) | chronic RfD |
| Dibenz(a,h)anthracene | 0.51 | 0.0000007 | 0.000006 | 0.03 (for pyrene) | chronic RfD |
| Ideno(1,2,3-cd)pyrene | 1.3 | 0.000001 | 0.00001 | 0.03 (for pyrene) | chronic RfD |
| Arsenic | 16 | 0.00002 | 0.0002 | 0.0003 | chronic MRL |
| Lead | 1,820 | 0.002 | 0.02 | no value | |
|
Fish and Crab from Little Creek Harbor |
|||||
| Mercury | 0.225 | 0.0001 | 0.0003 | 0.0003 | chronic MRL for |
| Tributylin | 0.028 | 0.00002 | 0.00004 | 0.0003 | chronic RfD |
| PCBs | 0.0016 | 0.000001 | 0.000002 | 0.00002 | chronic MRL |
APPENDIX C: ATSDR'S RESPONSE TO PUBLIC COMMENTS
The Agency for Toxic Substances and Disease Registry released the Naval Amphibious Base (NAB) Little Creek Public Health Assessment (PHA) for public review and comment on May 27, 2003. The public comment period was announced in a press release on June 10, 2003. Copies of the PHA were made available for review at the Bayside Area and Central Libraries in Virginia Beach and the Little Creek and the NAB Little Creek Libraries in Norfolk, Virginia. The PHA was also sent to state and federal agencies and interested members of the general public.
ATSDR received the following comments during the public comment period (May 27 to July 11, 2003).
Response: ATSDR has modified the text in the Summary section of the PHA to reflect the correct date of May 10, 1999, that the U.S. Environmental Protection Agency added NAB Little Creek to the NPL.
Response: ATSDR has stated in several places in the PHA that sources other than NAB Little Creek operations have contributed to the pollutant load in the harbor. As suggested, ATSDR has also added this information to page 9 of the PHA.
Response: ATSDR agrees that the public should be notified about bacterial contamination of fish and shellfish at NAB Little Creek Harbor. Due to this contamination, shellfish taking from the harbor is prohibited. In 1938, the Virginia Department of Health (VDH), Division of Shellfish Sanitation, restricted shellfish taking in Little Creek Harbor because of bacteriological contamination. The "restricted" status allowed shellfish taking during warm weather months, as long as the fisher had a permit (issued by marine police and VDH) and transferred the shellfish to another water body, where they would undergo a cleaning-out period. In 1990, the status was changed from "restricted" to "prohibited" to comply with the National Shellfish Sanitation Program. "Prohibited" means no shellfish taking is allowed. Signs are currently in place along the harbor at NAB Little Creek warning people against fish and crabbing due to security reasons. Through the PHA assessment process, ATSDR has coordinated discussion with Virginia Marine Resources Commission (VMRC), Navy Environmental Health Center (NEHC) and NAB Little Creek on the signage at the base that warns about the shellfish prohibition along Little Creek Harbor. VMRC has offered to provide or post signs along the harbor if the Navy judges it necessary to do so.
Response: The reference to contaminants of concern in the Summary section of the PHA is not meant to describe which contaminants placed NAB Little Creek on the NPL. Rather, this sentence is intended to note those contaminants that are of concern to ATSDR from a public health perspective. ATSDR has modified the sentence to clarify this distinction.
Response: ATSDR has modified the statement in the Summary of the PHA to reflect that localized contamination appears in groundwater in certain portions of the base.
Response: ATSDR has modified the sentence in the Summary to indicate that the Navy removed surface soil with levels above residential guidance in the area of the water tower.
Response: ATSDR emphasizes that the goal of its PHA is to help put environmental data into meaningful public health perspective for the community. That is, ATSDR tries to answer the question of whether environmental exposure occurred and whether any such exposure might be harmful. One of the challenges we face is to evaluate potential health hazards given the lack of environmental monitoring data at points of human exposure. As noted, sampling showed that lead was present in soil at the water tower and SWMU 8, and decreased in concentration with distance from the tower. However, the area between the water tower and residential areas are in areas of flood plains and increased drainage of surface water and transport of associated material. Although vegetated along the banks part of the drainage ditch near the fence line is deeply eroded and scouring is ongoing. Information on the different wind direction and wind speeds during each of the paint removal operations is not available. Sampling data to help us understand soil quality off base near the SWMU 8 and water tower, where local residents live, was not available. While the available information about contaminant concentrations helps in our evaluation, without information at the point of exposure, ATSDR cannot state with certainty whether contaminants might have migrated off site.
Response: ATSDR has updated its demographics discussion to reflect the correct demographic statistics for the area around NAB Little Creek as presented in Tables 3A and 3B of the PHA.
Response: The comment refers to drinking water at the base and in the communities of Norfolk, Virginia Beach, and Chesapeake that is drawn from Lake Smith, Lake Wright, Lake Whitehurst, Lake Lawson, Stumpy Lake, Little Creek Reservoir, and three lakes to the west of the city of Suffolk. ATSDR has added the treatment and testing information to the text of the PHA.
Response: ATSDR has added information about the soil cover depth and long-term monitoring groundwater monitoring to its discussion on landfill closure as suggested.
Response: This comment addresses the extent of soil removed from the water tower area located near SWMU 8. ATSDR has modified the text to reflect that the confirmatory sampling conducted at and near SWMU 8 verified that soil contaminated with lead and other contaminants was removed to levels below or at residential cleanup standard for each contaminant.
Response: The comment refers to ATSDR's discussion that mentions that these six sites contribute runoff or were connected to canals or drainage systems that eventually led to Little Creek Harbor. ATSDR's discussion that mentions these sites is intended to describe surface water flow pattern at the base that might discharge water into the harbor. ATSDR is aware of and commends the Navy's efforts on the measures they have taken to reduce or prevent contamination from entering surface water that might reach the harbor. These measures help ensure that contamination now and in the future will not enter the harbor.
Response: The comment refers to ATSDR's conclusions about exposure to lead in soil at and near the on-base SWMU 8 and the water tower. ATSDR acknowledges that the Navy has removed contaminated soil to residential standards on base near SWMU 8 and the water tower. The particular sentence in question, however, refers to soil at the neighboring off-base properties along Turner Road. While ATSDR does not know with certainty, we believe that it is possible that some soil at these off-base properties has been removed over time when homes were constructed or landscaped.
Response: ATSDR has updated information into the Public Health Action Plan and/or Table 1 (Evaluation of Sites at Naval Amphibious Base, Little Creek) portions of the PHA as suggested, including:
Response: This comment notes the description of surface water runoff and groundwater flow from at Site 9 in Table 1 of the document. ATSDR has modified the description in the text to reflect the suggested the change.
