Naturally occurring asbestos: a recurring public policy challenge

Our plain-English summary of Naturally occurring asbestos: a recurring public policy challenge, by R.J. Lee, B.R. Strohmeier, K.L. Bunker, et al (Journal of Hazardous Materials, 2008).

The study

• Authors: R.J. Lee, B.R. Strohmeier, K.L. Bunker, D.R. Van Orden
• Journal: Journal of Hazardous Materials
• Published: 2008;153(1-2):1-21
• Type of article: Review
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The potential environmental hazards and associated public health issues related to exposure to respirable dusts from the vicinity of natural in-place asbestos deposits (commonly referred to as naturally occurring asbestos, NOA) have gained the regulatory and media spotlight in many areas around the United States, such as Libby, MT, Fairfax County, VA, and El Dorado Hills, CA, among others. NOA deposits may be present in a variety of geologic formations. It has been suggested that airborne asbestos may be released from NOA deposits, and absent appropriate engineering controls, may pose a potential health hazard if these rocks are crushed or exposed to natural weathering and erosion or to human activities that create dust. The issue that needs to be addressed at a policy level is the method of assessing exposures to elongated rock fragments ubiquitous in dust clouds in these same environments and the associated risk. Elongated rock fragments and single crystal minerals present in NOA have been construed by some as having attributes, including the health effects, of asbestos fibers. However, the Occupational Safety and Health Administration (OSHA), Mine Safety and Health Administration (MSHA), and the Consumer Products Safety Commission (CPSC) found that the scientific evidence did not support this assumption. As in many environmental fields of study, the evidence is often disputed. Regulatory policy is not uniform on the subject of rock fragments, even within single agencies. The core of the issue is whether the risk parameters associated with exposures to commercial asbestos can or should be applied to rock fragments meeting an arbitrary set of particle dimensions used for counting asbestos fibers. Inappropriate inclusion of particles or fragments results in dilution of risk and needless expenditure of resources. On the other hand, inappropriate exclusion of particles or fragments may result in increased and unnecessary risk. Some of the fastest growing counties in the United States are in areas where NOA is known to exist and therefore this issue takes on national significance. This ongoing national dilemma has raised public and business concerns. There has been continuing political and scientific debate and widespread miscommunication over perceived versus actual health risks, the validity of various analytical sampling and testing methods, the questionable necessity and escalating costs of remediation procedures, and the combined negative impact on numerous commercial and public interests. Thus, conflicting research and regulatory positions on the distinctions between and hazards of true asbestos and ordinary rock fragments is all that is presently available to the public until the differing scientific communities and government agencies arrive at a consensus on these issues. The risk assessment methodology and the analytical technology needed to support inferences drawn from existing research are available, but have not been organized and implemented in the manner needed to resolve the NOA controversy. There should exist nationally adopted and peer-reviewed NOA standards (developed jointly by the scientific community, health risk professionals, and government regulators) that establish: (1) a scientific basis for risk evaluation and assessment of NOA and rock fragments; (2) accepted analytical protocols for determining if NOA actually exists in a given area and for separating NOA from related non-asbestos rock fragments and single crystal minerals; and (3) effective public policies for managing NOA, minimizing potential hazards, and protecting public health. This article will review some of the key issues involved with the current NOA debate, propose improved analytical methodologies, describe potential solutions for dealing with NOA, and outline the benefits to be gained by creating a practical national NOA public policy.

In plain English

This article was a review and policy commentary, not an original study. The authors discussed the U.S. debate over naturally occurring asbestos (NOA), centering on whether elongated amphibole rock fragments, construed by some as having the health effects of asbestos fibers, should be counted as asbestos. After reviewing risk models and laboratory methods, they argued the standard light-microscope counting rule is not valid for mixed mineral dusts. They proposed screening steps and wider use of scanning electron microscopy, and described several NOA sites. A 2006 U.S. Geological Survey study said that, had an EPA study at El Dorado Hills, California been an enforcement action, classifying its amphibole particles as actionable would be inappropriate: the majority were prismatic, not fibrous, and approximately 40% were magnesiohornblende, a non-regulated mineral. An EPA Inspector General report said cleanup in Libby, Montana could not be verified as effective after more than $100 million spent. Dust controls in Fairfax County, Virginia were estimated to add 10–20% to construction costs. The authors concluded the nation should develop a rational NOA public policy based on scientific, engineering, and medical principles.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review and policy commentary; no original data were collected
• Who was studied: No study population. The review discussed U.S. locations with naturally occurring asbestos concerns: Libby, MT; El Dorado County, CA; New Idria, CA; Clear Creek Management Area, CA; Fairfax County, VA; and Sparta, NJ
• Exposure: Airborne dust from naturally occurring asbestos (asbestiform amphibole and serpentine minerals), compared with non-asbestiform elongated rock fragments (cleavage fragments) and single crystal minerals of the same minerals
• Main results:
  • The authors argued that the phase contrast microscopy counting rule (a minimum 3:1 aspect ratio for particles longer than 5 micrometers) is not valid for mixed mineral dusts, because too many non-asbestos particles fit that definition
  • The authors proposed scanning electron microscopy as a possible screening technique for identifying long, thin fibers in mixed mineral environments
  • Reported from a 2006 U.S. Geological Survey study (not the authors' own work): if the EPA's El Dorado Hills, CA study had been an enforcement action, it would be inappropriate to classify the amphibole particles there as an actionable material, because the majority of those particles were prismatic, not fibrous, and approximately 40% of them were magnesiohornblende, a non-regulated mineral
  • Reported from a December 2006 EPA Office of Inspector General report: the EPA still could not verify the effectiveness of its amphibole asbestos cleanup in Libby, MT
  • Reported from another study (Pan et al., not the authors' own work): in California, the odds of having mesothelioma fell by 6.3% for every 10 km farther a person lived from the nearest naturally occurring asbestos source. The authors described criticisms of this study, including the absence of air sampling near residences and the lack of lifetime residential histories
  • In Fairfax County, VA, the expense of reasonable dust controls for construction in NOA deposits was estimated to add 10–20% to construction costs
• The authors' conclusion: The authors concluded that the nation should develop a rational NOA public policy based on scientific, engineering, and medical principles. They called for nationally adopted, peer-reviewed NOA standards and an independent national review of the science on how NOA is defined and measured.
• Limitations the authors state:
  • The authors stated that a detailed review of the results of the Berman–Crump risk assessment protocol was outside the scope of the article

Topics

Medical terms in this study, explained in our Lexicon: naturally occurring asbestos (NOA), El Dorado Hills, Engineering Controls, Single Crystal, OSHA, MSHA.

Related studies

• Community responses to naturally occurring asbestos: implications for public health practice — M.R. Culley, J. Zorland, et al. (2010)
• Asbestos: scientific developments and implications for public policy — B.T. Mossman, J. Bignon, et al. (1990)
• Asbestos-associated diseases. Science, public policy, and litigation — H. Weill (1983)
• Asbestos in New York City public school buildings--public policy: is there a scientific basis? — R. Wilson, A.M. Langer, et al. (1994)
• Evaluation of public and worker exposure due to naturally occurring asbestos in gravel discovered during a road construction project — R.A. Perkins, J. Hargesheimer, et al. (2008)
• Banning asbestos in Asia: campaigns and strategies by the Asian Network for the Rights of Occupational Accident Victims (ANROAV) — S. Pandita (2006)

Browse more research in Journal of Hazardous Materials, or return to medical research.