Use of quantitative analysis of urine to assess exposure to asbestos fibers in drinking water in the Puget Sound region

Our plain-English summary of Use of quantitative analysis of urine to assess exposure to asbestos fibers in drinking water in the Puget Sound region, by E.S. Boatman, T. Merrill, A. O'Neill, et al (Environmental Health Perspectives, 1983).

The study

• Authors: E.S. Boatman, T. Merrill, A. O'Neill, L. Polissar, J.R. Millette
• Journal: Environmental Health Perspectives
• Published: 1983;53:131-41
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

An earlier epidemiologic and electron microscopy study of drinking water in the Everett area of Washington State indicated large numbers of naturally occurring chrysotile asbestos fibers in the water. The purpose of the present study was to determine whether significant numbers of asbestos fiber could be demonstrated in the urine of donors residing in that area for less than 3 yr and over 20 yr where the tapwater contained about 200 X 10(6) fibers/L. A control group was obtained from Seattle where the tapwater asbestos fiber content was 100 times less. Urine samples, filtered control water, tapwater samples, and additional controls were processed for transmission electron microscopy by the use of the Nuclepore membrane filter-Jaffe wick procedure. Interference by mucus in the urine was reduced by treatment with hydrogen peroxide. Samples were taken over a period of 21 months. At no time during this period did the asbestos content of the urine samples consistently exceed that of the control waters. There was a significant difference (p less than 0.05) in the asbestos content of urine samples from subjects with less than 3 yr residence times versus greater than 20 yr. Asbestos concentration in urine samples from Everett residents as a whole did not differ significantly from that in samples from Seattle residents. Variable degrees of chrysotile contamination of control water samples and of Nuclepore membrane filters presented a problem. At present, the data are inconclusive but would suggest no relationship between high concentrations of fibers in drinking water and the numbers estimated for voided urine.

In plain English

This study looked for asbestos fibers in urine of people whose tap water carried naturally occurring chrysotile. The exposed group was seven male staff of the Everett Public Health Laboratories, Washington State. Four had lived there 24 years or more, three under 3 years; their tap water held about 200 million fibers per liter. Four Seattle and Bellevue residents from the University of Washington were controls; their measured tap water averaged 2.36 million fibers per liter. Urine, filtered control water and tap water were examined by electron microscopy over 21 months. No urine count was consistently and significantly higher than control water counts. Long-term Everett residents had higher urine counts than short-term residents (p = 0.05, one-tailed test). One long-term donor's urine count exceeded those of all other Everett donors; the authors said the means were otherwise similar. Everett urine overall did not differ significantly from control urine. Mucus in urine and chrysotile-contaminated filters hampered the work. The authors called the results inconclusive but said they suggested no relationship between high chrysotile fiber numbers in drinking water and the numbers estimated for voided urine.

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: Small exploratory study measuring chrysotile fibers in urine, filtered control water and tap water by transmission electron microscopy, comparing residents of a high-exposure area with low-exposure controls
• Who was studied: Seven male staff of the Everett Public Health Laboratories, Washington State. Four had lived in the Everett area 24 to 30 years and three less than 3 years. Four controls were personnel of the School of Public Health, University of Washington, living in Seattle or Bellevue. None reported kidney disease or occupational asbestos exposure. Samples were taken November 1979 to August 1981.
• Exposure: Naturally occurring chrysotile asbestos in drinking water. The study was designed around Everett tap water of about 200 x 10^6 fibers/L, compared with a Seattle-area control supply averaging 2.0 x 10^6 fibers/L. The measured tap-water means appear in the results.
• Main results:
  • Over the 21-month sampling period, no donor's urine fiber concentration was consistently and significantly higher than the concentration in the control waters.
  • For the Seattle/Bellevue controls, the measured tap water had a mean of 2.36 x 10^6 fibers/L (SD 0.98, 12 samples). Their urine had a mean of 0.83 x 10^6 fibers/L. Measured Everett tap water had means of 285 x 10^6 fibers/L for long-term residents and 278 x 10^6 fibers/L for short-term residents.
  • Urine fiber counts differed significantly between Everett donors with less than 3 years' residence and those with 24 or more years' residence (p = 0.05, one-tailed t-test). Mean urine counts were 0.51 x 10^6 fibers/L for short-term and 1.23 x 10^6 fibers/L for long-term residents.
  • The authors noted that donor No. 102 had a higher urine count than all other Everett donors. Otherwise, mean concentrations for long-term and short-term residents were similar.
  • Urine from all Everett donors combined contained 0.97 x 10^6 fibers/L. This was not significantly different from urine of Seattle/Bellevue control donors, whose drinking water had at least 100 times fewer fibers.
  • Urine 'spiked' with a known amount of chrysotile gave a mean count of 5.0 x 10^6 fibers/L, which was 57% of the asbestos control without urine (8.9 x 10^6). This is a 43% reduction in counts.
  • Filtering through 0.2 micrometer pore membranes gave about four times as many fibers as filtering through 0.1 micrometer membranes.
  • Fibers found in urine had a mean length of 0.9 micrometers, with a range of 0.5 to 1.2 micrometers.
• The authors' conclusion: The authors concluded that the results were inconclusive. They said the results would suggest no relationship between high numbers of chrysotile fibers in drinking water and the numbers estimated for voided urine.
• Limitations the authors state:
  • Mucus residues prevented filtering large volumes of urine, even after hydrogen peroxide treatment. This limited detection, and fibers could be masked by the residues.
  • The 0.2 micrometer Nuclepore filters contained chrysotile contamination of their own, and samples were sporadically contaminated from the environment during processing.
  • Under the counting method used, counts below 5 fibers per 20 grid openings are not considered statistically significant. The urine differences in Table 2 were largely in this range.
  • The donor group was small. The authors said detecting a significant difference between test and control values would need a considerably larger number of donors.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Transmission Electron Microscopy (TEM).

Related studies

• Cancer incidence in relation to asbestos in drinking water in the Puget Sound region — L. Polissar, R.K. Severson, et al. (1982)
• A case-control study of asbestos in drinking water and cancer risk — L. Polissar, R.K. Severson, et al. (1984)
• Cancer risk from asbestos in drinking water: summary of a case-control study in western Washington — L. Polissar, R.K. Severson, et al. (1983)
• Additional notes on the case-control study in western Washington on the cancer risk from asbestos in drinking water — L. Polissar, R.K. Severson, et al. (1983)
• Engineering and operating approaches for controlling asbestos fibers in drinking water — G.S. Logsdon (1983)
• Asbestos-contaminated drinking water: its impact on household air — J.S. Webber, S. Syrotynski, et al. (1988)

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