Silica exposure and silicosis among ontario hardrock miners: II. Exposure estimates

Abstract

An epidemiological investigation was carried out to determine the relationship between silicosis in hardrock miners in Ontario and cumulative exposure to silica (free crystalline silica-a quartz) dust. This second report describes a side-by-side air-sampling program used to derive a konimeter/gravimetric silica conversion curve. A total of 2,360 fi lter samples and 90,000 konimeter samples were taken over 2 years in two mines representing the ore types gold and uranium, both in existing conditions as well as in an experimental stope in which dry drilling was used to simulate the high dust conditions of the past. The method of calculating cumulative respirable silica exposure indices for each miner is reported.

A Comparison of Sampling and Analytical Methods for Assessing Occupational Exposure to Diesel Exhaust in a Railroad Work Environment

“…For example, in Ontario hard rock mines (i.e., gold, uranium, and nickel), respirable dust concentrations typically range from 0.5 mg/m 3 to 2 mg/m 3 and higher, and the combustible dust is only about 10 percent of the respirable dust concentrations. (34,35) The EC method, on the other hand, is both sensitive and selective. Birch and Cary (17) reference an unpublished 1985 report by D.P.…”

Particle Size Distribution and Particle Size-Related Crystalline Silica Content in Granite Quarry Dust

“…For example, particle size distributions (e.g., mass median diameter) vary across tasks and processes within a workplace (1) and across workplaces, (2) but the nature and extent of such variations have not been widely documented. Likewise, the silica content of dust has been shown to vary according to the process by which it is formed, but this also has not been well studied.…”

“…It seems that the relationship between empirically derived particle counts and mass determinations are not constant within mines, across mines, or across ore types. (1,2) Unfortunately, only limited amounts of published empirical data describe these relationships. Accordingly, the authors undertook the following preliminary field study to better characterize the relationships between particle size distributions, particle size-related silica content, and differing work tasks and environments in the quarries of Barre, Vermont.…”

Silica exposure and silicosis among ontario hardrock miners: III. Analysis and risk estimates

“…The basic methodology of this survey has been described in parts I and II of this series of reports Verma et al, 1989]. Of miners who joined the hardrock mining industry in Ontario between 1940 and 1959, data from 2,109 who met the criteria for inclusion in this study were examined to determine the incidence of silicosis in relation to cumulative respirable silica exposure.…”