Guadalupe corridor transportation project asbestos health risk assessment, San Jose, California

Our plain-English summary of Guadalupe corridor transportation project asbestos health risk assessment, San Jose, California, by W.E. Steiner, J.L. Koehler, W.W. Popenuck (The Science of the Total Environment, 1990).

The study

• Authors: W.E. Steiner, J.L. Koehler, W.W. Popenuck
• Journal: The Science of the Total Environment
• Published: 1990;93:115-24
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A study was conducted to assess health risks and identify a set of appropriate mitigation measures to control airborne emissions of natural asbestos from construction of the Guadalupe Corridor Transportation Project, a highway and light-rail construction project in San Jose, California. This study supported a state-mandated Environmental Impact Report. Communication Hill, along the project route, is known to contain natural chrysotile asbestos-bearing rock. The study described in this paper estimated potential asbestos emissions, identified and evaluated mitigation measures, and evaluated air pathway exposure and health risks. With mitigation, estimated risks were found to be acceptable by the regulatory agency, and construction proceeded.

In plain English

This paper described a health risk assessment, completed in March 1988, for a highway and light-rail project in San Jose, California. Part of Communication Hill, which contains serpentinite rock bearing natural chrysotile asbestos, was to be excavated, and residents had raised concerns. The study estimated asbestos emissions from the earthwork, modeled how the fibers would spread through the air to nearby residents, and estimated lung cancer and mesothelioma risk from breathing them. The stated goal was to bring modeled cancer risk below one in a million for the maximally exposed individual and below one excess cancer case in the exposed population. Laboratory dust tests suggested that asbestos fibers were about 4 times more likely to become airborne than other dust in site soil and rock. The paper listed the dust-control measures adopted. These included ripping instead of blasting, frequent watering, and covering or sealing exposed serpentinite each work day. The paper did not report final numerical risk estimates. The authors reported that, with these measures, the estimated risks were acceptable to the Santa Clara County Transportation Agency and construction proceeded.

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: Health risk assessment for a state-mandated Environmental Impact Report. It combined emission estimates, air dispersion modeling and population data to estimate incremental cancer risk, considering both lung cancer and mesothelioma.
• Who was studied: People living around the Communication Hill excavation area in San Jose, California, in a 5-month study completed in March 1988. The Inner Study Area was divided into over ninety residential subareas. Census-tract data were used for the Outer Study Area, which extended 10 km beyond the excavation area centroid.
• Exposure: Airborne natural chrysotile asbestos released by excavating, hauling and filling serpentinite rock during construction. The excavation was about 38 m deep at most and 2.4 km long. Exposure was assumed to last the 130 days during which serpentinite would be exposed, 24 hours per day.
• Main results:
  • The assessment's target (an objective, not a reported result) was a modeled cancer risk below one-in-a-million for the Maximally Exposed Individual and fewer than 1 excess cancer case in the exposed population.
  • In laboratory dustiness tests on site rock and soil, asbestos appeared to be preferentially emitted during handling by an average factor of 4. Emission estimates were multiplied by this factor.
  • According to the authors, a preliminary risk assessment using existing fugitive dust emission factors overestimated cancer risk and population burden. This led to the development of project-specific emission factors.
  • Preliminary dispersion modeling produced a one-in-ten-million individual cancer risk contour (isopleth). This contour was used to set the boundary of the Inner Study Area.
  • Selected mitigation measures included limiting serpentinite excavation, ripping instead of blasting, and frequent watering and dust palliatives on roads. Serpentinite areas were also to be covered or sealed by the end of each work day, speeds limited to 24 km/hr, and a geologist kept onsite.
  • With the mitigation measures, the regulatory agency found the estimated (modeled) risks acceptable, and construction proceeded. The paper did not give final numerical risk estimates.
• The authors' conclusion: The authors considered the mitigation measures that contributed to acceptable health risks to be the study's main findings. They noted that few projects could afford such a study, and stated that the U.S. EPA expects to use it as a model for risk assessment protocols for construction-related natural asbestos emissions.
• Limitations the authors state:
  • Representative asbestos emission factors for this type of earthwork were not found in the literature. Existing dust emission factors were adjusted instead.
  • No particle size data were available. All asbestos emissions were therefore assumed to be transported without depositional loss and to be respirable.
  • Indoor and outdoor concentrations were assumed to be equal.
  • The level of spatial detail for demographic data and the dispersion modeling grid was chosen subjectively.
  • The exposure duration was conservatively assumed to be the entire serpentinite excavation period (130 days), 24 hours per day.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile.

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• The contribution of environmental monitoring in the epidemiological assessment of exogenous risk. The experience of ARPA in the Emilia-Romagna Region of Italy — A. Zavatti, P. Lauriola (1999)
• Asbestos problems in Montana and California — C. Maynard (2004)

Browse more research in The Science of the Total Environment, or return to medical research.