Figure 5. ATSDR's Exposure Evaluation Process
PUBLIC HEALTH ASSESSMENT
AIR FORCE PLANT 85
COLUMBUS, FRANKLIN COUNTY, OHIO
3.0 EVALUATION OF ENVIRONMENTAL CONTAMINATION AND EXPOSURE PATHWAYS
In this section, environmental pathways (i.e., soil, groundwater, surface water/sediment, air, food sources, and physical hazards) are evaluated to determine whether people accessing or living near AFP 85 could be exposed to site-related contamination. In evaluating exposure pathways, ATSDR identifies whether exposure occurs through ingestion, dermal contact with the contaminated media, or inhalation of vapors or fugitive dust. The potential for adverse health effects from an exposure is related to contaminant concentration, exposure variables (e.g., duration and frequency), and the toxicology of the contaminant. ATSDR considers these factors together to determine whether the site poses any health hazards. This exposure evaluation process is further explained in Figure 5. Each potential exposure pathway is systematically evaluated below to determine likely health hazards.
Investigations conducted through the IRP attempted to characterize soil contamination in several waste areas throughout the plant (i.e., Sites 2, 3, 4, 8, 11, 12, the Waste Water Treatment Plant, and the UST Removal Areas). Soil monitoring activities suggested that subsurface soils (those more than three inches below the ground's surface) contained higher levels of contamination than the top soil layer. Contaminants detected in the subsurface soils include volatile organic compounds (VOCs), metals, and PCBs. PCBs were the only soil contaminant detected (maximum concentration 700 ppm) in excess of ATSDR health comparison values (ATSDR, 1995a). The health comparison values are media-specific (water, soil, or air) concentrations calculated from various health guidelines designed to protect public health. These values are not legally enforceable but they are used to make decisions to include the contaminants for further public health evaluation. The industrial areas containing subsurface soil contamination have been fenced and guarded to limit public access. Therefore, no exposures to contaminated soil (and no adverse health effects) are expected for the general population.
Contact with contaminated subsurface soils could occur during soil disturbance activities such as the construction of the third runway. Construction workers and utility installers would have an opportunity for exposure to PCB-contaminated subsurface soils during activities directly involved with disruption of subsurface soil. The PCB Spill Site 11, the WasteWater Treatment Plant, and the Coal Leachate Pile have been remediated or contained low levels of contamination and are not expected to pose a health hazard to future runway workers accessing the site. Current and future remediation efforts in the PCB Spill Site 3, the Fire Department Training Area, and the James Road Hazardous Waste Storage Pad are expected to further reduce opportunities for exposures and any subsequent health concerns. Personal protective equipment should protect construction and utility workers from any unavoidably unacceptable levels of PCBs remaining in the soil. Exposures to PCB-contaminated subsurface soils, therefore, are not likely to occur, either now or in the future.
Figure 5. ATSDR's Exposure Evaluation Process
Groundwater at the site is not used by anyone. All area residents use municipal water which has a surface water source. Hydrogeology investigations suggest that the site lies above a low yielding aquifer of compacted glacial till and tightly bound clay fragments. The restricted flow in the aquifer precludes significant lateral (or vertical) movement of site-related contaminants. Off-site migration is unlikely to have occurred because no contaminant plumes radiating from source areas have been identified beneath the site. Furthermore, no private wells lie in the area of the AFP 85 site. Groundwater under AFP 85 should not impact drinking water sources.
No significant pathway currently exists for exposure to contamination found in the surface water and sediment. The creeks are not used as a source of drinking water and, because of heavy vegetation and low stream flow, are probably not used for swimming or fishing. Although children playing along the creek beds may ingest sediments through hand-to-mouth activity, significant exposure through this pathway is remote. Young children prone to this behavior (typically children between the ages of 1 and 6 years) are not likely to be near the creek without supervision. Furthermore, any exposure that may occur to low level contamination is likely to be brief and intermittent. VOCs were detected below levels that pose a health hazard in the surface water of Mason's Run. PAHs and metals were present in the sediment of Mason's Run at levels that do not pose a health hazard. Other upstream sources of hydrocarbon combustion products (e.g., the Port Columbus International Airport) may also have contributed PAHs and other materials to Mason's Run (USAF, 1996b). Turkey Run surface water and sediment samples contained low levels of the metals cadmium, nickel, and lead, but no organic compounds (USAF, 1996a). Large portions of the Mason's Run and Turkey Run have been dredged over time to remove contaminated sediment and an oil skimmer is installed on Mason's Run (Lewis, 1996). These measures most likely prevented surface water and sediment contaminants from migrating to downstream reaches. Sediment monitoring of Mason's Run is scheduled for October 1996.
For the cited reasons, exposure to Mason's and Turkey Runs surface water and sediment is not expected to pose a health hazard. If future sediment monitoring indicates that concentrations are increasing in reaches of Mason's Run downstream from the site and exposures are occurring frequently, then the data should be evaluated to determine if a health hazard exists.
Air exposure involves inhalation of site-related contaminants that have volatilized or adsorbed to airborne particles. The site no longer releases process emissions since the Air Force decommissioned manufacturing activities. Airborne particles could be released from contaminated soils during soil excavation or future construction activities. Workers associated with construction of the third runway will most likely have the highest potential for exposure to airborne particles. Exposure to workers is expected to be minimal as long as PCB subsurface soil contamination continues to be reduced through remedial activities, proper engineering controls are followed during construction to further minimize releases, and proper worker health and safety measures are implemented. The general population is not expected to be impacted through air exposures.
Food chain pathways refers to exposure that can occur through consumption of contaminated foods. Fruits or vegetables grown in contaminated soils, fish that accumulated contaminants from surface water or sediment, or game that foraged in contaminated feeding areas are examples of potentially contaminated foods that may be consumed by humans. Since AFP 85 was used for industrial processes, and hunting and gardening are not known to have occurred on site, exposure through ingestion of contaminated vegetables or game is unlikely to have occurred or to occur in the future.
Fish have the ability to bioaccumulate contaminants (e.g., lead, chromium, and cadmium) to levels many magnitudes greater than those present in surface water or sediment. Fish monitoring data are typically evaluated to determine whether consumption of the fish may pose a public health hazard. Fish monitoring data for Mason's Run or Turkey Run are not available to determine whether fish present in these creeks are accumulating contaminants at levels of public health concern. Consumption of fish, however, does not appear to be a viable exposure pathway. Because of low flow conditions and dense vegetation restricting access, the creeks do not support an abundant fish population nor attract anglers (Lewis, 1996). For these reasons, consumption of fish caught from Mason's Run or Turkey Run is not expected to be a viable exposure pathway of concern.
The nearest notable recreational fishing spot lies approximately 5 miles downstream of the site along the Big Walnut Creek. Contamination from AFP 85 is not expected to impact Big Walnut Creek because low contaminant concentrations have been detected in Mason's and Turkey Runs surface water and sediment and remediation measures (i.e., sediment dredging and oil skimming) have or continue to reduce contaminant migration to downstream reaches.
Several AFP 85 buildings contain both friable (easily crumbled) and nonfriable asbestos. The Air Force plans to leave the buildings that contain asbestos intact. ATSDR does not expect the nonfriable (intact) asbestos to pose human hazards; however, friable (easily crumbled) asbestos fibers from deteriorating insulating material or siding may pose a human health hazard to on site workers who do not wear protection. Information on buildings that contain asbestos will be provided to future occupants. The property will not be used for residential purposes, thus children will not be exposed to the asbestos.
On-site buildings are suspected to contain lead-based paint. Ingestion of lead-based paint chips is a significant exposure pathway for young children because of their propensity for hand-to-mouth activity. Because the site is zoned for nonresidential uses, the buildings will not be used for child care centers or residential housing where susceptible children may ingest the paint chips.
AFP 85 found radioactive residues and caustic acids in on-site buildings. The radioactive materials were associated with X-ray equipment that was formerly used in Buildings 3, 4, and 6. AFP 85 also discovered a small quantity of thorium in the basement of Building 6. The radioactive materials/equipment and thorium have been removed and disposed off site to reduce potential human health hazards. Radon testing determined that radon levels were below the Ohio Environmental Protection Agency mitigation levels of 4 picocuries/liter.
ATSDR sought information on the health concerns of the community by conducting meetings with public health officials, corresponding with the Columbus Port Authority, and reviewing information available in EPA, state, and local agency files. The following are health concerns regarding AFP 85:
Elevated levels of PCBs were detected in subsurface soils collected from one area, however, significant exposure of runway workers to PCB-contaminated subsurface soils is not likely to occur, either now or in the future.
PCBs were the only soil contaminant detected in areas investigated at concentrations in excess of ATSDR health comparison values. Currently, exposure to contaminated subsurface soils is not occurring. Contact with contaminated subsurface soils could only occur during soil disturbance activities (e.g., construction and installation of utilities) associated with the construction of the third runway. Construction workers and utility installers directly involved with disruptive subsurface soil activities would have the only opportunity for exposure to PCB-contaminated subsurface soils. Potential exposure routes include dermal contact with contaminated soils and inhalation of fugitive dust released during soil disturbances.
Remedial activities proposed through the IRP continue to reduce PCB subsurface soil concentrations to levels within acceptable cleanup standards. If acceptable cleanup goals are not met, ATSDR recommends use of appropriate protective equipment and clothing to further reduce the opportunity for potential exposure of future runway workers to contaminated soils.
2. Exposure to asbestos and other building and equipment-related hazards on AFP 85.
Friable asbestos has been detected in on-site buildings. However, information on the location of friable asbestos at AFP 85 is available to prospective site owners through the Invitation to Bid process. Asbestos is the name applied to a group of six different minerals that occur naturally in the environment. Asbestos minerals are comprised of strong, long, thin fibers that are resistant to heat and chemicals. People may be exposed to asbestos by breathing in tiny asbestos fibers that may have been released during the degradation of man-made products such as insulation and ceiling and floor tiles. Adverse health effects can develop when asbestos fibers lodge in the smallest parts of the lungs and remain for an extended period of time (ATSDR, 1990a).
Most of the health effects information comes from occupational studies in which workers were exposed to high levels of asbestos. Workers were found to have increased rates of lung cancer, mesothelioma, and the development of scar-like tissue in the lung (ATSDR, 1990a). Factors influencing the development of adverse health effects include smoking status and length of exposure to asbestos. Other factors that determine the extent of disease may include the type and size (fibers greater than 1/5,000th inch long may cause more injury) of asbestos material. Amphiboles asbestos fibers--naturally occurring minerals characterized by a double chain silicate ions--may be more potent than chrysotile asbestos fibers--or white asbestos--and fibers greater than 1/5,000th inch long may cause more injury than smaller fibers. Intact asbestos is not expected to present a health hazard for future nonresidential building occupants. Friable asbestos, however, may increase the likelihood of chronic health effects among workers or future building occupants. Because information on the location of friable asbestos at AFP 85 is available to prospective site owners through the Invitation to Bid process, the potential health threat is greatly diminished.
Lead-based paint is suspected to be present in on-site buildings. Children are especially sensitive to the toxic properties of lead. Because the site is zoned for nonresidential uses, the buildings will not be used for child care centers or residential housing where susceptible children may ingest the paint chips. If the zoning status changes to allow residential use, additional measures may be warranted to reduce a suspectable individual's opportunity for exposure to lead-based paint. No radioactive hazards exist at the site because radioactive materials have been removed and radon levels are below Ohio EPA acceptable guidance levels.