Because of the potential presence of interfering chloride salts, the subcommittee believes that some discussion of analytic interference of chloride ion with hydrogen chloride is required; and the assumption that the hydrogen chloride measured with conventional means was from aerosols and particles should be reconsidered.
The subcommittee also recommends quantification of “numerous visual observations” (p. 4) and a discussion of the uncertainty relevance of the statement that “the eggs and produce may represent a possible source of variation from U.S. background” (p. 45) (NEHC 2000).
On p. 64, NEHC (2000) states that “there were few days in which these conditions were actually met; therefore, the analysis itself has low power.” The subcommittee recommends including a discussion of the uncertainty caused by that fact and of how that uncertainty was factored into the analysis.
APPENDIX D
Soil-Trend Analysis
Although sufficient information on the soil-trend analysis was provided in a Radian report (Radian 1998b), the NEHC risk-assessment draft summary report does not provide sufficient information. The subcommittee recommends including more of the details and description provided in the Radian report (1998b), including the following:
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In the first paragraph on p. 29 of the NEHC draft summary report, the second and third sentences should be replaced with the following, based on the Radian report (1998b; p. 1-15):
To determine the deposition trends across NAF Atsugi, the base was divided into areas defined by seven radii starting at the Jinkanpo Incineration Complex and extending to the north, with transects at arbitrary distances of less than 300 m, 300-800 m, 800-1,500 m, and greater than 1,500 m from the complex. For trend-analysis purposes, samples were collected from locations where the soil had not been recently disturbed (such as by construction activities). Also, samples were collected, where possible, from areas of potential sediment accumulation, areas of observed vegetation stress, and areas lacking evidence of erosion or ground cover.
The narrative in the Radian report (1998b) is more factual and demonstrates that the soil-trend samples were taken in a logical manner.
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The second sentence in the second paragraph on p. 29 of the NEHC draft summary report should be replaced with the following based on the Radian report (1998b, p. 4-43):
It is evident that subsurface soils from the soil trend data set are less contaminated than the surface soils.
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In the second paragraph on p. 29 of the NEHC draft summary report, “A definite footprint TEQ's exceeded RBCs” (NEHC uses “RBC” for “risk-based concentrations”) should be deleted. The following, based on the Pioneer draft report (2000; p. 92), should be inserted in its place as a new paragraph:
The soil trend analysis indicates a spatial correlation between concentration and distance from the SIC for total 2,3,7,8-TCDD TEQs (see Figure 7-1). Consequently, concentrations of total 2,3,7,8-
