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Review of the US Navy's Human Health Risk Assessment of the Naval Air Facility at Atsugi, Japan The NEHC draft summary report seems to be a summary of the project, but the audience for the report is not clear. The draft summary report is too technical for lay readers but does not provide adequate details for a risk assessor to understand and evaluate the project—planning, sampling, measurement results, or the risk assessment itself. The expected audience of the report should be indicated, and the report should be geared toward that audience. The NEHC draft summary report does not include enough details of the incinerator facility and NAF Atsugi. A paragraph explaining the Enviro-Tech incinerator complex should be added, including information on the number of bypass stacks present and the potential for fugitive emissions from waste and ash handling. The draft summary report lacks adequate citations, and it is difficult to evaluate some statements without them. References to specific sections or pages in the extensive supporting documents should be included. Furthermore, the NEHC risk assessment is based on EPA methods, but the NEHC draft summary report and the draft report by Pioneer Technologies Corporation (Pioneer 2000) do not reference current EPA methods for assessing risks associated with indirect exposure to emissions from combustion (EPA 1998a). Similarly, the EPA Region VI incinerator risk-assessment protocol (EPA 1998b) is not cited or referenced. The subcommittee recommends that the NEHC report be professionally edited. Abbreviations should be spelled out the first time they are used, and there should be a list of them. The subcommittee noted some instances of inadequate paraphrasing in the NEHC draft summary report of technical discussions and conclusions in the supporting documents. Direct quotation of the wording of contractor reports would be preferable, particularly for technically precise statements. Appendix D presents specific sections of the soil-trend analysis discussion that the subcommittee recommends be quoted directly. Outdoor air samples appear to have been collected mainly for a period of 24 h, although it is difficult to be sure, because Table 4-5 of the Final Monitoring Summary (Radian 2000a) contains an incomplete summary of the sample periods. It is not clear why some samples were collected for more or less than 24 h or why there was a deviation in some cases in measuring from midnight to midnight. The Final Monitoring Summary (Radian 2000a) indicates that the incinerator was generally shut down from Sunday at 1600 hours until Monday at 1600 hours, and Table 4-5 indicates that the sample-collection times took those hours into account. That report also indicates that occasionally the incinerator was shut down for those same times a day later, but what happened to monitoring when the incinerator was shut down on Tuesday rather than Monday is not stated. Depending upon what was done under those circumstances biases could have been introduced in the data. Sampling protocols should be clearly stated in the report. Some essential information (such as sample times and comparison of contaminant concentrations when the incinerator was operating with and without bypass stacks) was not included in the available reports. NEHC should ensure that such information is included in the risk-assessment documents. If readers of the report are expected to be varied, it would be helpful to explain the “wind rose” better, that is, that it shows the direction from which the wind is coming, not the direction toward which the wind is going. On page 80, paragraph 1, PM10 effects are mentioned, but not PM2.5. The PM2.5 concentration exceeds the National Ambient Air Quality Standard (NAAQS) and should be discussed. Specific comments on the air-monitoring and health risk-assessment sections of the NEHC draft summary report are presented in Appendix E and Appendix F, respectively. RESPONSIVENESS TO PREVIOUS NATIONAL RESEARCH COUNCIL COMMENTS COT reviewed NEHC's report on the screening-level risk assessment conducted in 1997 at NAF Atsugi (NRC 1998). COT concurred with the overall recommendations of the NEHC (1998) report, including the recommendation to conduct a full-year air-monitoring study. The subcommittee identified a number of concerns and made recommendations to NEHC for improving the 1998 risk assessment. The current NEHC draft summary report appears to have incorporated some—but not all—of the recommendations.
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Review of the US Navy's Human Health Risk Assessment of the Naval Air Facility at Atsugi, Japan NEHC took the following appropriate measures in response to the previous recommendations (NRC 1998): A rigorous QA-QC program was established for sampling in the current risk assessment (IT 1999; UAI 1999; Weston 1999; NEHC 2000). Therefore, the present subcommittee is not seriously concerned about the quality of the data collected. As recommended, risks of acute and chronic toxicity end points and for different target populations were not summed. More-extensive meteorologic data were collected at NAF Atsugi (NEHC 2000; Radian 2000a, b). Appropriate measurements were made for obtaining local estimates of atmospheric stability and used in dispersion-modeling calculations. In addition to the previously monitored air pollutants, ozone, nitrogen dioxide, carbon monoxide, sulfur dioxide, PM10 3, and PM2.5 were monitored. Soil-trend analysis was conducted for NAF Atsugi as a whole and at the sites where exposures might occur (Radian 1998b). NEHC partially responded to the following problems identified in the previous risk assessments but has not fully resolved them: In the previous report (NEHC 1998), NEHC assumed, without appropriate supporting data, that the concentrations measured at the background site were substantially affected by emissions from the incinerator complex. Better use of meteorologic data to define upwind sites (Radian 2000a, b) has addressed that issue in this risk assessment; however, as discussed in the section on attributable risk, the criteria used to determine the background site are still not clear. COT previously recommended that continuous or semicontinuous monitoring methods be used to correlate meteorologic data and emission-dispersion estimates with ambient concentrations of pollutants (NRC 1998). Some FTIR monitoring was done (Radian 2000a). The limitations of that monitoring are discussed in the section on attributable risk. COT previously indicated that the 6 weeks of sampling is not representative of long-term exposure, and a 12-month sampling period was recommended (NRC 1998). For the current risk assessment, NEHC performed a 14-month study. The implications of a 14-month, rather than a 12-month, sampling period are discussed earlier in this report. As recommended previously by COT (NRC 1998), multiple exposure pathways were explored in the current NEHC risk assessment. Appropriate methods have been used except for the use of outdoor-air concentrations as surrogates for indoor concentrations. Other than a brief mention in Appendix B, potential sources of air pollutants near NAF Atsugi, other than the incinerator complex, are not characterized, and their potential contributions to total risk are not evaluated. Such an evaluation would be helpful in differentiating risks attributable to the incinerator from ambient background risks or risks posed by other activities. NEHC did not follow several of the COT's previous recommendations (NRC 1998), including: 3 PM10 refers to particulate mass collected by a sampling device with a size-selective inlet that efficiently collects small particles and rejects large particles. For PM10, the device has a 50% collection efficiency for particles with an aerodynamic diameter of 10 µm, higher efficiency for smaller particles, and lower efficiency for larger particles. PM2.5 is similarly defined except with reference to a 2.5 µm cut size.
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