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

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.