Evaluation of take-home exposure and risk associated with the handling of clothing contaminated with chrysotile asbestos

Our plain-English summary of Evaluation of take-home exposure and risk associated with the handling of clothing contaminated with chrysotile asbestos, by J. Sahmel, C.A. Barlow, B. Simmons, et al (Risk Analysis, 2014).

The study

• Authors: J. Sahmel, C.A. Barlow, B. Simmons, S.H. Gaffney, H.J. Avens, A.K. Madl, J. Henshaw, R.J. Lee, D. Van Orden, M. Sanchez, M. Zock, D.J. Paustenbach
• Journal: Risk Analysis
• Published: 2014;34(8):1448-68
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The potential for para-occupational (or take-home) exposures from contaminated clothing has been recognized for the past 60 years. To better characterize the take-home asbestos exposure pathway, a study was performed to measure the relationship between airborne chrysotile concentrations in the workplace, the contamination of work clothing, and take-home exposures and risks. The study included air sampling during two activities: (1) contamination of work clothing by airborne chrysotile (i.e., loading the clothing), and (2) handling and shaking out of the clothes. The clothes were contaminated at three different target airborne chrysotile concentrations (0-0.1 fibers per cubic centimeter [f/cc], 1-2 f/cc, and 2-4 f/cc; two events each for 31-43 minutes; six events total). Arithmetic mean concentrations for the three target loading levels were 0.01 f/cc, 1.65 f/cc, and 2.84 f/cc (National Institute of Occupational Health and Safety [NIOSH] 7402). Following the loading events, six matched 30-minute clothes-handling and shake-out events were conducted, each including 15 minutes of active handling (15-minute means; 0.014-0.097 f/cc) and 15 additional minutes of no handling (30-minute means; 0.006-0.063 f/cc). Percentages of personal clothes-handling TWAs relative to clothes-loading TWAs were calculated for event pairs to characterize exposure potential during daily versus weekly clothes-handling activity. Airborne concentrations for the clothes handler were 0.2-1.4% (eight-hour TWA or daily ratio) and 0.03-0.27% (40-hour TWA or weekly ratio) of loading TWAs. Cumulative chrysotile doses for clothes handling at airborne concentrations tested were estimated to be consistent with lifetime cumulative chrysotile doses associated with ambient air exposure (range for take-home or ambient doses: 0.00044-0.105 f/cc year).

© 2014 Society for Risk Analysis.

In plain English

This was a chamber simulation, not a study of people's health. The authors released Grade 7T chrysotile around mannequins in new work clothes at low, medium and high target airborne levels. A person then handled and shook out the clothes for 15 minutes, then remained 15 minutes without activity. Measured by asbestos-specific TEM, the handler's average chrysotile levels during active shaking were 0.014 to 0.097 f/cc. For medium and high levels, the handler's calculated eight-hour average was 0.2% to 1.4% of the matching simulated workplace average (0.03% to 0.27% weekly). These averages assumed zero asbestos outside the 30 to 45 minutes of each activity. PCM, a general fiber count, read 2 to 50 times higher than TEM, which the authors attributed largely to clothing fibers. Assuming weekly handling for 25 years, estimated cumulative doses (0.00044 to 0.0047 f/cc year) were at or below estimated lifetime ambient chrysotile doses. The authors concluded that, under similar conditions, such handling would not measurably raise asbestos-related disease risk above background. They noted chamber ventilation may have exceeded a home's and that relevance to amosite is unclear.

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: Experimental exposure simulation in a sealed test chamber. Air was sampled during clothing contamination ('loading') and during later clothes handling and shake-out, followed by estimates of cumulative dose.
• Who was studied: No disease outcomes were studied. Work clothing on six mannequins per loading event was contaminated in a sealed chamber (stated as RJ Lee Group, Monroeville, PA). There were six loading events in total. Each was followed by a matched 30-minute handling and shake-out event performed by a study participant acting as the clothes handler, with area samples at simulated bystander positions 6 to 12 ft away. Study dates are not given.
• Exposure: Airborne Grade 7T chrysotile at three target loading levels: low (0 to 0.1 f/cc), medium (1 to 2 f/cc) and high (2 to 4 f/cc). Two loading events were run at each level, each lasting 31 to 43 minutes. Each loading event was followed by 15 minutes of active clothes handling and shake-out plus 15 minutes of no activity.
• Main results:
  • Mean TEM chrysotile concentrations during the simulated workplace (loading) events were 0.01 f/cc for both low events, 0.88 and 2.42 f/cc for the medium events, and 2.38 and 3.30 f/cc for the high events.
  • Clothes handler, 15 minutes of active handling: mean TEM concentrations were 0.014 f/cc for the low events, 0.068 f/cc for Medium #1, and 0.097 and 0.085 f/cc for the high events. Medium #2 had only 30-minute samples.
  • In the 15 minutes of no activity that followed, mean TEM concentrations fell by 86–87% for the Medium #1, High #1 and High #2 events (to 0.009–0.014 f/cc). Only one chrysotile fiber was detected across all samples from that second period.
  • Over 30 minutes, for the Medium #1, High #1 and High #2 events, bystander (area) TEM concentrations were 0.006–0.011 f/cc, compared with 0.021–0.063 f/cc for the clothes handler.
  • PCM concentrations, which count all fibers, were 2- to 50-fold higher than TEM chrysotile concentrations for all handling and shake-out events. The authors interpreted this as showing that many or most fibers counted by PCM were clothing fibers.
  • The eight-hour and 40-hour TWAs were calculated rather than measured over full days or weeks. The calculation assumed zero asbestos for the rest of the day or week outside the approximately 30–45-minute loading or handling periods.
  • For the medium and high events, the clothes handler's calculated eight-hour TWA chrysotile concentrations were 0.2% to 1.4% of the matching calculated eight-hour loading TWAs (0.0004–0.0040 f/cc vs. 0.0976–0.5491 f/cc, TEM).
  • On a calculated 40-hour (weekly) TWA basis, the clothes handler's concentrations were 0.03% to 0.27% of the matching loading TWAs.
  • For bystanders, calculated eight-hour TWAs were 0.1% to 0.5% of the matching loading TWAs, and 40-hour TWAs were 0.01–0.1%.
  • For the two low loading events, all of the clothes handler's personal samples were nondetects, so no ratio was calculated.
  • The authors assumed handling once a week (52 days per year), 0.5 hours per day, for 25 years. On that basis, estimated cumulative doses for the clothes handler were 0.00044–0.0047 f/cc year. The authors' estimated lifetime ambient chrysotile doses were 0.0035–0.105 f/cc year.
• The authors' conclusion: The authors based their conclusion on comparing their dose estimates with ambient doses and with published epidemiological studies. They concluded that chrysotile workplace exposures at the concentrations tested (up to 0.55 f/cc as an eight-hour TWA) would not measurably increase the nonoccupational risk of asbestos-related disease above background for people at home handling chrysotile-contaminated clothing under conditions similar to this study.
• Limitations the authors state:
  • The chamber ventilation rate may have been higher than in some homes. The authors said this may have affected the bystander results and the no-activity period results.
  • The mannequins did not move during loading, unlike workers. This may have left more fibers on the clothing.
  • The study did not consider other ways fibers are lost from clothing, such as contact with surfaces or commuting.
  • Fiber release from clothing may not be proportional to how long the clothing was loaded.
  • Take-home chrysotile exposures were not measurable at some of the loading concentrations tested.
  • How the data apply to amosite is unclear.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Take-home Exposure, Chrysotile, Asbestos Exposure, Air Sampling, Fibers per Cubic Centimeter (f/cc), NIOSH.

Related studies

• Evaluation of take-home exposure to asbestos from handling asbestos-contaminated worker clothing following the abrasive sawing of cement pipe — A. Abelmann, J.R. Maskrey, et al. (2017)
• Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature — E.P. Donovan, B.L. Donovan, et al. (2012)
• A study of airborne chrysotile concentrations associated with handling, unpacking, and repacking boxes of automobile clutch discs — G.C. Jiang, A.K. Madl, et al. (2008)
• Commentary on 'evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature', Donovan et al.1 — D.S. Egilman, N.M. Druar (2013)
• Simulation tests to assess occupational exposure to airborne asbestos from artificially weathered asphalt-based roofing products — P. Sheehan, F. Mowat, et al. (2010)
• Measured removal rates of chrysotile asbestos fibers from air and comparison with theoretical estimates based on gravitational settling and dilution ventilation — J. Sahmel, H.J. Avens, et al. (2015)

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