DEVELOPING A RISK ASSESSMENT METHOD FOR TEM ANALYSIS

The current TEM method of choice used by risk assessors at NOA and/or CERCLA sites is the ISO 10312 method that utilizes transmission electron microscopy (TEM) techniques to define, classify and characterize fibrous minerals by energy dispersive spectroscopy (EDS), diffraction and highly resolved, transmitted images. This method is over 19 years old without any modifications nor any new changes are in sight for the near future. In addition, individual laboratory interpretations of these counting rules can vary widely, leading to variations in reported concentrations from different laboratories on very same sample.

Regulators are requesting better methodology for these sites using current, more advanced techniques that are not covered in the ISO method. A new ASTM Work Item WK43720, An Analytical Method Designed for Risk Assessment, has begun to address these issues.

This presentation will provide risk assessors, toxicologists, and others interested in asbestos-related sites an overview of the characterization of complex structures common to sites with fibrous amphibole and serpentine mixtures