PUBLIC HEALTH ASSESSMENT
|Table 1: Travis AFB - Evaluation of Exposure Situations|
|PATHWAY NAME||CONTAMINANT||POTENTIAL EXPOSURE PATHWAY ELEMENTS||TIME FRAME||CONCLUSION CATEGORY||COMMENTS|
|SOURCE||ENVIRONMENTAL MEDIA||POINT OF EXPOSURE||ROUTE OF EXPOSURE||POTENTIALLY EXPOSED POPULATION|
|B-29 crash||radionuclides||plane crash||surface soil||area of crash, adjacent to present family campground, NW quadrant of base||inhalation, dermal||N/A||crash occurred in 1950||No Public Health Hazard||ATSDR Health Consultation found no evidence of public health hazard. Crash did not contribute radionuclides to environment.|
Table 2 summarizes ATSDR's public health conclusions for the exposure situations identified at Travis AFB. Following sections contain detailed discussions of each situation. Additional information describing ATSDR's conclusion categories is provided in Appendix D.
|Table 2: Summary of ATSDR's Public Health Conclusion for Travis AFB.|
|No Public Health Hazard||- Drinking or Other Exposure to Groundwater at: |
1) Fire training Area 4;
2) Landfill 2; or,
3) Bldg. 1125
- B-29 Crash Site
- Grazing Areas 7,8, Landfill X
On August 5, 1950, a B-29 bomber crashed shortly after takeoff. The impact occurred in the northwestern portion of Travis AFB, as shown in Figure 9. About 20 minutes after the crash, 6,700 pounds of explosives on the plane detonated. The explosive, cyclotrimethylenetrinitramine ("RDX") is an explosive used in nuclear weapons, as well as conventional artillery. Nineteen fatalities and numerous injuries resulted from the explosion.
The B-29 was carrying a small quantity of depleted uranium. According to Air Force documents, depleted uranium, with very low radioactivity levels, has been commonly used as ballast in nuclear weapons. Its high density provided appreciable weight while occupying relatively less space than less dense materials, and therefore allowed for the construction of smaller weapons. Also, small amounts of radium would have been present as the luminous material in aircraft dials and gauges.
According to reported Air Force procedures at the time, while in transit over United States territory, the weapons-grade radioactive material was transported in one airplane while the nuclear weapon (trigger mechanism, etc.) was transported in a second airplane. The crash involved the second instance, that is, the airplane carrying the weapon, but not the radioactive material. In 1994, radionuclides detected in sampling and analysis by the Air Force were found at levels attributable to naturally-occurring materials in the environment (e.g., soil and rocks). Surface soil, subsurface soil and groundwater samples were collected from the vicinity of the crash. Sample sites were chosen by taking into account the prevailing wind directions for soil samples, and the groundwater flow for groundwater samples.
The following table depicts the average radiation levels found in soil in comparison to average background levels for northern California for the same radionuclides.
In the course of the environmental evaluation, three groundwater monitoring wells were sampled, twenty-six subsurface soil samples were collected, and eighty surface soil samples were collected. The groundwater sampling and analysis found no radionuclides above the levels occurring naturally in the area. Based on the results of the environmental sampling, it is not likely that radioactive contamination was released as a result of the crash of the B-29. Therefore, in terms of possible exposure to radionuclides carried onboard the airplane, this crash site does not present a public health hazard.
|Table 3: Radionuclides in Soil at the Site of the B-29 Crash (4)|
|Radionuclide||Level Detected (picoCuries per gram of dry soil- pCi/g dry)||Background Level|
|Plutonium||level too low to measure or not present||0.01|
In preparing this Public Health Assessment (PHA), ATSDR relies on the information provided in the referenced documents. The Agency assumes that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn in this document are determined by the availability and reliability of the referenced information.
The majority of the environmental data presented in this public health assessment are from the Remedial Investigation (RI) preliminary data. Data collection and analysis are conducted in consultation with EPA and California environmental regulatory agencies. Generally, the methodology used in the RI activity is appropriate for characterizing contamination at Travis AFB. Additional information collection is planned during completion of RI activities. If this information suggests previously undetected concerns about potential public health hazards, ATSDR will conduct a re-evaluation of that information. Conclusions and Recommendations of this PHA will be modified if appropriate and necessary.
Public health concerns were investigated by ATSDR through meetings, correspondence, telephone conversations and technical information from Travis AFB, EPA, and state agencies. Extensive outreach programs have been conducted by these agencies. Specific community public health concerns have been identified in regard to groundwater contamination, possible exposure to contaminants from soil gas under the trailer park, the potential for exposure resulting from contamination in Union Creek, the B-29 crash and the occurrence of "horse swelling" incidents that occurred in 1985 - 1987. The evaluations of these situations are presented in the body of this document. As discussed in the environmental evaluations sections of this document, there are no public health problems resulting from these incidents.
HEALTH OUTCOME DATA
We did not evaluate health outcome databases because people were not exposed to site contaminants at levels that would result in public health hazards.
CHILD HEALTH ISSUES
Possible issues related to children's health were evaluated in relation to the trailer park, Union Creek and the B-29 crash. These situations were found NOT to have an adverse impact on children's health. The exposure situation at the Duck Pond is considered unlikely to result in a health hazard, since its use as a frequent, regular and long-term source of fish is not likely, but is indeterminate, due to a need for further information.