Moreover, the indoor and outdoor PM10 samples were from the GEMB, not from residential buildings, where indoor-dust analysis might be more informative if residents at NAF Atsugi are NEHC's primary concern.
The dust samples were analyzed for dioxins and furans, but background apartment concentrations of dioxins and furans are not provided, so the measurements are difficult to interpret.
The dust samples should have been analyzed for heavy metals because dust and wipe samples typically are good indicators of air and soil pathways for heavy metals (such as, lead, cadmium, and arsenic). Metals are common constituents of incinerator emissions, and metals can be cheaply and reliably analyzed. Furthermore, the average concentrations of all metals except selenium measured in the soil samples seemed to be higher at the residential towers than at the elementary school or the Child Development Center (see Table 2-6, NEHC 2000); that indicates that the soil might be contaminated by metals. Soil is a poor surrogate for indoor dust, however, and it is important to determine whether the dust is contaminated by metals.
In particular, dust samples should have been monitored for lead. Although relatively low lead concentrations were found in the soil, indoor sampling for lead is needed because of the presence of a potential emission source nearby, because lead- contaminated dust is difficult to remove, and because dust is a main source of indoor lead exposure in children up to 4 years old (Manton et al. 2000). Experience at other sites has demonstrated that indoor-dust lead will slowly accumulate if there is a continuous emission source. Table 2-6 (NEHC 2000), which reports data on soil up to 3 in. deep (7.6 cm deep), suggests that lead and other metals might be slowly accumulating around the residential apartment buildings or towers. The average and the RME lead concentrations in soil of that depth are apparently higher at the residential buildings than at the elementary school. Therefore, lead concentrations in dust in the residential buildings could be high.
Other Data Gaps
NEHC states (pp. 4-5) that it could not conduct monitoring off NAF Atsugi, and the Pioneer draft report (Pioneer 2000; p. 15) states that site-specific background concentrations could not be evaluated, even in ambient air, because all sites on NAF Atsugi were affected by the incinerator complex. No other reason is stated for the failure to evaluate background concentrations. The NEHC report should clearly and specifically describe why off-site monitoring was not possible, even if the reasons are legal or political.
The NEHC draft summary report compares NAF Atsugi air-contaminant concentrations with US standards and guidelines, but there is no comparison with or mention of Japanese standards or guidelines. In addition to US guidelines, NEHC should state what, if any, Japanese standards apply and should provide adequate comparisons with them.
The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity equivalence factors for polychlorinated dibenzodioxins and furans are values agreed on by the scientific community through consensus reports. The latest such consensus report (Van den Berg et al. 1998) updated those values, and NEHC should use the latest values in its risk assessment.
SUGGESTED IMPROVEMENTS IN THE PRESENTATION AND ORGANIZATION OF THE NEHC DRAFT SUMMARY REPORT
The NEHC draft summary report lacks a framework that would allow readers to examine what was done, why it was done, and what the results were. The report should begin with a clear statement of the purpose and objectives of the risk assessment. The methods, assumptions, and limitations of the project and its results should be described more thoroughly. The rationales for using or not using particular monitoring techniques and methods and particular analyses are also essential.