Asbestos at Superfund Sites: Technical Resources

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Framework for Investigating Asbestos-Contaminated Superfund Sites

Framework for Investigating Asbestos-Contaminated Superfund Sites (PDF)(71 pp, 849 K)
OSWER Directive 9200.0-68, September 2008.

This framework implements the 2004 OSWER Directive (9345.4-05) for addressing asbestos at Superfund sites, recommending a risk-based, site-specific approach for site evaluation based on current asbestos science. The framework provides a flexible approach to investigating and evaluating asbestos contamination at Superfund removal and remedial sites. It also provides remedial project managers, on-scene coordinators, site assessors and other decision makers with information to assist in the evaluation of asbestos risks at Superfund sites. It includes information to facilitate decision making at sites with incomplete characterizations and addresses the varied nature of environmental asbestos contamination.

Major Elements of the Framework

  • Flow diagram for site assessment and removal action and remedial action decisions.
  • Application of activity-based sampling (ABS) to evaluate the exposure potential at a site in support of risk-based removal and remedial decisions.
  • Resources for sample collection and analysis.
  • Definition of phased contrast microscopy equivalent (PCME) structures for estimating exposures for site risk assessment.
  • Age- and duration-specific cancer inhalation unit risks (IURs) to address early-lifetime and less-than-lifetime exposures to asbestos.


The framework is part of many recent efforts to make sure that new developments regarding asbestos are used to better assess exposure and risk (e.g., EPA efforts to update cancer and non-cancer assessments for asbestos). The framework provides a process that supplements other EPA guidance concerning exposure and risk assessment (e.g., EPA’s 1989 Risk Assessment Guidance for Superfund) and is specific to assessment of sites contaminated with asbestos. Because there are unique scientific and technical issues associated with the investigation of human exposure and risk from asbestos, it is important for risk assessors and risk managers to understand these issues when assessing asbestos sites. This framework discusses specific strategies based on the best available science and recommends common industrial hygiene methods for characterizing exposure and risk from asbestos.

Asbestos fibers in outdoor soil, indoor dust or other source materials typically are not inherently hazardous, unless the asbestos is released from the source material into air where it can be inhaled. If inhaled, asbestos fibers can increase the risk of developing lung cancer, mesothelioma, pleural fibrosis and asbestosis.

The relationship between the concentration of asbestos in a source material and the concentration of fibers in air that results when that source is disturbed is complex and dependent on a wide range of variables. To date, no method has been found that reliably predicts the concentration of asbestos in air given the concentration of asbestos in the source. Additional research is ongoing to characterize this relationship.

This framework emphasizes an empirical approach to site characterization; models to predict airborne asbestos concentrations from soil concentrations have not been validated. Concentrations of asbestos in air at the location of a source disturbance are measured rather than predicted.

This framework does not provide direction or guidance on risk management decisions that may be required during a site assessment. Typically, the key management decision at asbestos sites is how to interrupt or eliminate the complete inhalation exposure pathway. As always, risk management issues should be evaluated by the site manager, with input from the site’s scientific teams, stakeholders, Regional management and legal staff, as appropriate.

Other Site Investigation and Environmental Sample Resources

Investigation of Indoor Environments at Asbestos-Contaminated Superfund Sites (PDF)(17 pp, 305 K)
OSWER 9200.3-101, March 2015.

The TRW Asbestos Committee developed this document to provide clarification to the Framework for Investigating Asbestos-Contaminated Superfund Sites (U.S. EPA, 2008) for indoor environments. This document provides recommended sampling methods and strategies for evaluating the nature and extent of asbestos contamination in indoor environments at Superfund sites. The sampling strategies and methods discussed are those currently employed by the Agency to estimate exposures and the associated health risk in support of risk management decisions for asbestos in indoor environments. This document is intended to provide supplemental information at sites where indoor contamination by asbestos may be of concern.

Standard Operating Procedures for Activity-Based Sampling (PDF)(29 pp, 323 K)
OSWER's Environmental Response Team's Standard Operating Procedure #2084, Revision 0, May 2007.

ERT Helpful Hints for Activity-based Sampling for Asbestos in Air (PDF)(8 pp, 48 K)

The Standard Operating Procedures (SOP) for Activity-Based Sampling outlines a highly structured approach to activity-based sampling (ABS) to provide a consistent approach at sites (e.g., raking in a circle and turning a quarter-circle every 15 minutes). Based on extensive review of ABS activities at sites and ongoing evaluation and discussion of best practices by EPA’s Environmental Response Team (ERT), the Helpful Hints document provides a more flexible approach to ABS. It recommends that sampling teams attempt to replicate activities known or expected to occur at the area being sampled. The emphasis is on realistic scenarios rather than rigid, methodical actions.

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Laboratory Analysis for Asbestos in Soil and Bulk Materials

CARB Method 435: Determination of Asbestos Content of Serpentine Aggregate (PDF) Exit(19 pp, 1.2 MB)

The California Air Resources Board's 1991 method for determining the asbestos content in serpentine aggregate, based on polarized light microscopy. Sampling techniques are provided. Recommended modifications to this method include increasing the particle size for analysis and reporting asbestos observed through visual estimate or a field of view. Samples should be milled to a particle size for analysis of about 250 micrometers in size. Visual estimate and field of view are used to reveal structures possibly missed by point count in soil samples.

Polarized Light Microscopy (EPA 600-R-93-116): Method for the Determination of Asbestos in Bulk Building Materials (PDF)(46 pp, 3.9 MB)

While developed primarily for analysis of asbestos-containing material (such as building materials) as defined in NESHAPs, this method has detected asbestos from building materials in site soils. However, this method is limited. It is not recommended for characterization activities at Superfund sites. The Framework for Investigating Asbestos-Contaminated Superfund Sites recommends use of CARB Method 435 as augmented by Appendix C of the framework.

ASTM Method D7521-13 Standard Test Method for Determination of Asbestos in Soil Exit

The American Society of Testing Materials (ASTM) has developed a new method for analysis of asbestos in soil and bulk materials. EPA is evaluating this sampling method for its applicability to Superfund site characterization.

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Laboratory Analysis for Asbestos in Air Samples

ISO Method 10312: Ambient Air - Determination of Asbestos Fibers - Direct-Transfer Transmission Electron Microscopy Method Exit

This complex analysis method requires laboratories to record detailed information about asbestos structure type and size using transmission electron microscopy (TEM). It is considerably more difficult than other TEM methods. Suggested modifications to this method include using a 3:1 aspect ratio for counting of all structures and the use of 0.25 microns as the lower width limit for counting of polarized light microscopy equivalent (PCME) structures. Filters for analysis by this method should not exceed 25 percent loading.

ISO Method 13794: Ambient Air - Determination of Asbestos fibers - In Direct Transfer; Transmission Microscopy Method Exit

This companion method to ISO 10312 provides an alternative preparation for overloaded filters. Filters that exceed 25 percent loading may be analyzed by this method. However, results from using ISO 13794 may differ from those that would have been achieved using ISO 10312 on an appropriately loaded filter. The use of ISO 13794 should be avoided to the extent possible through field techniques that minimize filter overloading.

NIOSH 7400: Asbestos and Other Fibers by Polarized Light Microscopy (PCM) (PDF) Exit(15 pp, 949 K)

The National Institute of Occupational Safety and Health (NIOSH) developed this method for measuring worker exposures in occupational environments where asbestos is present. This method should be used when monitoring worker exposure and evaluating compliance with OSHA standards. However, the PCM instrument cannot distinguish between asbestos and non-asbestos fibers. NIOSH Method 7402 is a companion method using TEM to determine if the fibers viewed by PCM are asbestos fibers.

Due to the limitations of PCM, EPA does not recommend this method for evaluating environmental exposures (See the Framework for Investigating Asbestos-Contaminated Superfund Sites (PDF))(71 pp, 849 K)

NIOSH 7402: Asbestos by Transmission Electron Microscopy (TEM) (PDF)(7 pp, 37 K)

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Accreditation of Laboratories for Asbestos Analysis

The National Institute of Standards and Technology (NIST) runs an accreditation program for laboratories conducting asbestos analyses. Laboratories in the National Voluntary Laboratory Accreditation Program (NVLAP) meet minimum standards for conducting polarized light microscopy (PLM) and TEM analyses. Laboratories should be further evaluated prior to selection to determine their capability to perform methods recommended in the framework, which are more complex than the basic methods evaluated through NVLAP.

NVLAP-accredited Laboratories for the PLM Test Method are accredited to analyze bulk samples for asbestos using polarized light microscopy. NVLAP accredits laboratories for the 1982 procedure, Interim Method for the Determination of Asbestos in Bulk Insulation Samples, found in 40 CFR Part 763, Appendix E to Subpart E (formerly Appendix A to Subpart F). Additionally, "laboratories may request to be assessed to the Method for the Determination of Asbestos in Bulk Building Materials (EPA 600/R-93/116; 1993)." NIST also states that "NVLAP will not accredit a laboratory for the 1993 method alone; all laboratories must maintain accreditation for the 1982 test method (EPA 600/M4-82-020).”

NVLAP-accredited Laboratories for the TEM Test Method are accredited to identify and quantify asbestos using transmission electron microscopy. NVLAP accredits laboratories for the interim test method found in 40 CFR, Part 763, Subpart E, Appendix A, Interim Transmission Electron Microscopy Analytical Methods – Mandatory and Nonmandatory – and Mandatory Section to Determine Completion of Response Actions.

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National Asbestos Data Entry Spreadsheets (NADES)

This EPA data management tool facilitates the recording and transmittal of sampling results for asbestos for the methods most often employed in Superfund work. National Asbestos Data Entry Sheets (NADES) are provided for PLM analysis of bulk materials air and dust analysis using TEM and air samples using PCM.

NADES include checks and error codes to guide data entry and allow for the sorting of structures into size bins. NADES provide a tool to generate standardized electronic data deliverables for import into Scribe software or other data management tools.

Instructions and additional information concerning use of Scribe software for asbestos sites Exit

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Risk Assessment

Information Risk Information System (IRIS) Assessment for Asbestos (cancer)

This Web page provides EPA's IRIS cancer assessment for asbestos. EPA has classified asbestos (CASRN 1332-21-4) as a human carcinogen and established an inhalation unit risk to estimate cancer risk from exposure to asbestos.

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Presentations and Training

Asbestos Site Assessment Framework Self-guided Training (PDF)(95 pp, 5.5 MB) EPA's TRW Asbestos Committee developed these training slides to provide a broad overview of the framework. The slides include asbestos definitions and morphology, asbestos sampling recommendations, examples of activity-based sampling, asbestos laboratory analysis recommendations and asbestos risk assessment recommendations.

Activity-Based Air Sampling for Asbestos Exit (CLU-IN presentation)

NARPM Presents: An Overview of Asbestos – Health Effects, Regulations, Sampling and Analysis, and a Case Study Exit (CLU-IN presentation)

Sample This! Asbestos in Soil Exit (2013 Brownfields Conference)

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