Urinary asbestos fibers and inorganic particles in past asbestos workers

Our plain-English summary of Urinary asbestos fibers and inorganic particles in past asbestos workers, by S. Zaina, G. Mastrangelo, M.N. Ballarin, et al (Archives of Environmental & Occupational Health, 2016).

The study

• Authors: S. Zaina, G. Mastrangelo, M.N. Ballarin, L. Scoizzato, G. Carradori, U. Fedeli, S. Capella, E. Belluso
• Journal: Archives of Environmental & Occupational Health
• Published: 2016;71(3):129-35
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To assess the validity of the procedure as a test of asbestos exposure, we compared urinary asbestos fibers with occupational and environmental exposure data in a random sample of 48 subjects with high past asbestos exposure. Occupational and environmental exposure was estimated on questionnaire, pleural plaques were diagnosed with computed tomography, and inorganic fibers and particles were identified by scanning electron microscope with an energy-dispersive spectrometry. Few urinary asbestos fibers (in 15% of workers and 17% of cases with pleural plaques) and high amount of urinary silicate (particularly nonfibrous particles) were detected. Asbestos undergoes dissolution in lung tissues, but the secondary minerals are largely unknown. These materials, possibly nonfibrous silicates or metals, could be excreted with urine. Therefore, another study including a control group is warranted to discriminate the occupational origin of minerals in the urine.

In plain English

This exploratory study asked whether testing urine for asbestos fibers could show past exposure in former asbestos workers in Venice, Italy. From 273 workers with high past asbestos exposure and bilateral pleural plaques or unilateral pleural thickening seen on CT, examined 2000 to 2011, the authors randomly chose 55; 48 agreed to take part. Their past work exposure, estimated by questionnaire, was heavy; 42 of the 48 had pleural plaques. Urine was examined by scanning electron microscopy with energy dispersive spectrometry. Asbestos fibers were found in the urine of 7 of 48 workers (15%) and 7 of 42 workers with pleural plaques (17%). These were chrysotile-antigorite in four (the method could not tell chrysotile from antigorite) and tremolite-actinolite asbestos in three. No statistically significant differences in age or recorded work-exposure measures were found between the 7 workers with and 41 without urinary asbestos fibers. Most urinary material was nonfibrous particles, many of them silicates. The authors concluded that urine analysis could not reliably indicate past asbestos exposure or effect, and called for a further study with a control group.

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: Exploratory study of urine samples from a random sample of former asbestos workers, compared with questionnaire-based exposure estimates
• Who was studied: 48 former asbestos workers who agreed to take part, out of 55 randomly sampled from 273 workers with high past asbestos exposure and bilateral pleural plaques or unilateral pleural thickening diagnosed with low dose computerized tomography. All 273 had been examined from 2000 to 2011 in the Occupational Health and Safety Department of Venice (Local Health Authority No. 12, Veneto Region, Italy).
• Exposure: Past occupational asbestos exposure, estimated by questionnaire using a stepwise semi-quantitative procedure (fiber types handled at work not specified). Mean length of exposure was 26.7 years (standard deviation 6.8). Mean cumulative exposure was 245.7 fiber-years per ml (standard deviation 112.5). Environmental exposure was also asked about and was described as sporadic.
• Main results:
  • Urinary asbestos fibers were detected in 7 of 48 workers (15%) and in 7 of 42 workers with pleural plaques (17%).
  • Among the 7 workers with urinary asbestos fibers, chrysotile-antigorite was found in four and tremolite-actinolite asbestos in three. Chrysotile and antigorite could not be told apart with this technique, so the authors grouped them and counted them as asbestos.
  • No statistically significant differences were found between the 41 workers without and the 7 workers with urinary asbestos fibers in age, length of exposure, cumulative or peak exposure, or years since first and last exposure. For example, mean cumulative exposure was 242.0 fiber-years per cc in the workers without fibers and 267.5 fiber-years per cc in those with fibers (p equal to 0.609).
  • In the urine of the 48 workers, fibers made up only 7.5% of the elements detected (405 fibers per ml against 4970 particles per ml).
  • The concentration of nonvitreous nonfibrous silicates, especially phyllosilicates, in the workers' urine was 10 times higher than that of the fibrous forms.
• The authors' conclusion: The authors concluded that this urine analysis could not be a reliable indicator of past asbestos exposure or of asbestos effect. They said the high amount of silicates found in urine deserves further investigation, on the hypothesis that some non-asbestos silicates could come from occupational exposure.
• Limitations the authors state:
  • There was no control group. The authors said a future study should include one, to tell occupational from environmental sources of minerals in urine.
  • The technique could not distinguish chrysotile (asbestos) from antigorite (non-asbestos).
  • Tremolite and actinolite asbestos could not be told apart by this analysis, so they were grouped together.
  • The sample size was small, because the study was exploratory and the microscopy was difficult and expensive.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Environmental Exposure, Pleural Plaques, Silicate.

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