Childhood exposure to Libby amphibole asbestos and respiratory health in young adults

Our plain-English summary of Childhood exposure to Libby amphibole asbestos and respiratory health in young adults, by P.H. Ryan, C.H. Rice, J.E. Lockey, et al (Environmental Research, 2017).

The study

• Authors: P.H. Ryan, C.H. Rice, J.E. Lockey, B. Black, J. Burkle, T.J. Hilbert, L. Levin, C. Brokamp, R. McKay, C. Wolfe, G.K. LeMasters
• Journal: Environmental Research
• Published: 2017;158:470-479
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Vermiculite ore containing Libby amphibole asbestos (LAA) was mined in Libby, MT, from the 1920s-1990. Recreational and residential areas in Libby were contaminated with LAA. This objective of this study was to characterize childhood exposure to LAA and investigate its association with respiratory health during young adulthood.

Methods: Young adults who resided in Libby prior to age 18 completed a health and activity questionnaire, pulmonary function testing, chest x-ray and HRCT scan. LAA exposure was estimated based on participant report of engaging in activities with potential LAA exposure. Quantitative LAA estimates for activities were derived from sampling data and literature reports.

Results: A total of 312 participants (mean age 25.1 years) were enrolled and reported respiratory symptoms in the past 12 months including pleuritic chest pain (23%), regular cough (17%), shortness of breath (18%), and wheezing or whistling in the chest (18%). Cumulative LAA exposure was significantly associated with shortness of breath (aOR = 1.12, 95% CI 1.01-1.25 per doubling of exposure). Engaging in recreational activities near Rainy Creek Road (near the former mine site) and the number of instances heating vermiculite ore to make it expand or pop were also significantly associated with respiratory symptoms. LAA exposure was not associated with pulmonary function or pleural or interstitial changes on either chest x-ray or HRCT.

Conclusions: Pleural or interstitial changes on x-ray or HRCT were not observed among this cohort of young adults. However, childhood exposure to LAA was significantly associated with respiratory symptoms during young adulthood. Pleuritic chest pain, in particular, has been identified as an early symptom associated with LAA exposure and therefore warrants continued follow-up given findings of progressive disease in other LAA exposed populations.

Copyright © 2017 Elsevier Inc. All rights reserved.

In plain English

This study examined young adults who lived as children in Libby, Montana, where vermiculite ore containing Libby amphibole asbestos (including winchite, richterite and tremolite) was mined. A total of 312 people, average age 25.1, enrolled, and each completed at least one part of the study: a questionnaire, breathing tests, chest X-rays or HRCT (detailed CT) scans. The authors estimated each person's childhood exposure from the activities they reported. In the previous 12 months, 23% reported pleuritic chest pain, 18% shortness of breath, 18% wheezing and 17% regular cough. No pleural or interstitial changes were seen on X-ray or HRCT in the 300 people imaged, and exposure was not linked to lower lung function. Each doubling of estimated cumulative exposure was associated with shortness of breath (adjusted odds ratio 1.1, 95% CI 1.0 to 1.3). Activities near Rainy Creek Road, close to the former mine, and heating vermiculite to make it pop were also associated with symptoms. The authors concluded that childhood exposure was associated with respiratory symptoms and that pleuritic chest pain warrants continued follow-up. They noted that childhood memories may be inaccurate, and that awareness of contamination in Libby may have raised reports of chest pain.

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: Epidemiologic health study (the CHIEFS study) of young adults, with a questionnaire, spirometry, chest x-ray and HRCT done at a clinical visit; childhood exposure was estimated from reported activities
• Who was studied: 312 young adults (average age 25.1 years, 54% female, 99% Caucasian, born 1980 to 1992) who lived in the Libby, Montana area before age 18. Each completed one or more parts of the study. 300 had imaging, 304 had spirometry data and 311 had complete questionnaire data. 75% had previously taken part in the 2000 to 2001 ATSDR medical screening.
• Exposure: Childhood (birth to age 18) environmental exposure to Libby amphibole asbestos (LAA), a mixture of amphibole fibers including winchite, richterite and tremolite in Libby vermiculite. Exposure was estimated from self-reported activities, such as playing in vermiculite piles, digging in yards, spending time in attics with vermiculite, fishing and recreation near Rainy Creek Road, cutting firewood, and heating vermiculite ore to make it pop. Other measures were sharing a household with a W.R. Grace worker or contractor and living in a home with visible vermiculite. Exposures were expressed as ever/never, frequency, and estimated cumulative exposure in f/cc-months.
• Main results:
  • In the previous 12 months, participants reported shortness of breath (56, 18%), wheezing or whistling in the chest (57, 18%), regular cough (51, 17%) and pleuritic chest pain (72, 23%).
  • No pleural or interstitial changes were observed on chest x-ray or HRCT among the 300 participants who had these tests, so no statistical analyses were done for these outcomes.
  • 93% of the cohort had normal spirometry (284 of 304 with spirometry data). No significant associations were found between estimated LAA exposure, by any measure, and decreased lung function.
  • The median estimated cumulative exposure across the 12 activities was 4.99 f/cc-months (range 0.01 to 114.3 f/cc-months).
  • Each doubling of estimated cumulative LAA exposure was significantly associated with shortness of breath: adjusted odds ratio 1.1, 95% CI 1.0 to 1.3, adjusted for sex and smoking.
  • Ever sharing a household with a W.R. Grace worker or contractor was significantly associated with pleuritic chest pain (aOR 3.2, 95% CI 1.3 to 7.8). Other activities with significant associations with pleuritic chest pain were recreation along Rainy Creek Road (aOR 1.9, 95% CI 1.1 to 3.4), cutting or collecting firewood near Rainy Creek Road (aOR 3.1, 95% CI 1.5 to 6.4) and heating vermiculite ore to make it pop (aOR 1.8, 95% CI 1.0 to 3.2).
  • Ever engaging in recreational activities near Rainy Creek Road was significantly associated with shortness of breath (aOR 2.8, 95% CI 1.5 to 5.2). The same was true for fishing on the Kootenai River near the mouth of Rainy Creek (aOR 2.7, 95% CI 1.4 to 5.2) and cutting or collecting firewood near Rainy Creek Road (aOR 3.2, 95% CI 1.5 to 6.8).
  • Each doubling of the number of times a participant heated vermiculite ore to make it expand or pop was significantly associated with regular cough (aOR 1.3, 95% CI 1.1 to 1.5).
  • No activity was associated with wheezing or whistling in the chest.
• The authors' conclusion: The authors concluded that childhood environmental exposures to LAA, both before and after mining ended, are associated with respiratory symptoms among young adults. They said the high prevalence of self-reported pleuritic chest pain warrants continued follow-up and surveillance.
• Limitations the authors state:
  • Exposure was based on participants' recall of childhood activities, and some recall error is expected, especially for younger ages.
  • The high prevalence of pleuritic chest pain may partly reflect participants' awareness that LAA exposure occurred in Libby.
  • No personal or area air sampling was possible, so activity exposure estimates may over- or underestimate true exposure.
  • Heating vermiculite and living with a W.R. Grace worker or contractor could not be given quantitative exposure estimates because of lack of data.
  • The odds ratios from logistic regression may overestimate risk for outcomes that were more common.

Topics

Medical terms in this study, explained in our Lexicon: Libby amphiboles, vermiculite, Chest X-Ray, High-Resolution CT (HRCT), Pleuritic Chest Pain, Interstitial.

Related studies

• Childhood exposure to Libby amphibole during outdoor activities — P.H. Ryan, G.K. LeMasters, et al. (2015)
• Pulmonary abnormalities as a result of exposure to Libby amphibole during childhood and adolescence-The Pre-Adult Latency Study (PALS) — J. Szeinuk, C.W. Noonan, et al. (2017)
• Determining satisfaction with access and financial aspects of care for persons exposed to Libby amphibole asbestos: rural and national environmental policy implications — C.A. Winters, W. Hill, et al. (2011)
• HRCT/CT and associated spirometric effects of low Libby amphibole asbestos exposure — J.E. Lockey, K. Dunning, et al. (2015)
• Low levels of exposure to libby amphibole asbestos and localized pleural thickening — K.Y. Christensen, T.F. Bateson, et al. (2013)
• A review of scientific literature examining the mining history, geology, mineralogy, and amphibole asbestos health effects of the Rainy Creek igneous complex, Libby, Montana, USA — B.R. Bandli, M.E. Gunter (2006)

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