Critical Measurements. The critical measurement associated with this project is the measurement of the levels of LA in tree bark as surficial loading structures per centimeter squared (s/cm2) and duff as concentration structures per gram (s/g) from locations within two miles of the NPL boundary and east of Kootenai Falls. The analysis of LA may be achieved using several different types of microscope, but the EPA generally recommends using TEM because this technique has the ability to clearly distinguish asbestos from non-asbestos structures, and to classify different types of asbestos (i.e., LA, chrysotile). In addition, analysis by TEM provides structure-specific dimensions that allow for the estimation of PCM-equivalent2 (PCME) concentrations, which is the concentration metric necessary to estimate exposure and risks. Thus, all analyses for this study will be performed by TEM.
Critical Measurements. The critical measurement associated with this project is the measurement of the concentration of LA in tissue samples from fish, deer, and elk collected from OU3. The analysis of LA may be achieved using several different types of microscope, but the EPA generally recommends using TEM because this technique has the ability to clearly distinguish asbestos from non-asbestos structures, and to classify different types of asbestos (i.e., LA, chrysotile). In addition, the results of the TEM analysis include information on the dimensions and attributes of each asbestos structure observed. This is important for the purposes of comparison to ingestion toxicity values because these values are based on structures longer than 10 micrometers (µm) in length. In addition, data are needed on the moisture content of the tissues prior to TEM analysis. This will allow for concentrations to be translated from a dry weight basis (the analysis output units) to wet weight basis (the units necessary for evaluating human ingestion exposures).
