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Conversion of particle number to beryllium particle number concentration.

Berakis-M; McCawley-M; Kent-M
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana. Fairfax, VA: American Industrial Hygiene Association, 2001 Jun; :9
Previous work has hypothesized that beryllium particle number may be the proper exposure metric for inhaled dose. The difficulty has been in obtaining an estimate of the beryllium number concentration. We are now able to obtain the beryllium mass and total mass using a polycarbonate substrate material for Microorifice Uniform Deposit Impactor (MOUDI) stages. The polycarbonate substrates are weight stable, unlike MCE filters which are prescribed for beryllium sampling. After they are postweighed the polycarbonate can be digested and analyzed for beryllium. By dividing beryllium mass by total mass on the filter we can obtain the percent beryllium for each size range from the MOUDI. A Submicrometer Particle Sizer (SMPS) was used to derive count data, but in narrower size ranges than the MOUDI, 100 increments in all. These much smaller particle count size increments are clustered together to match the MOUDI range and the percent beryllium is applied to the clustered range. However, the overall range for values of beryllium content only extended from a little less than a tenth of a percent to a little over one percent. For the size range in which most of the particle counts actually occur, the beryllium content range averaged around 0.1 % +/- 0.05%. The beryllium content can therefore be considered constant for that size range. By applying these percentages to measurements in areas in which workers were found to have chronic beryllium disease, beryllium particle number concentrations were found to extend from 10/cubic centimeter to over 10,000/cubic centimeter. This information is to be used in an epidemiological investigation to determine the risk of disease in a study population.
Beryllium-compounds; Particulates; Weight-factors; Weight-measurement; Filters; Sampling-methods; Sampling-equipment; Samplers; Sampling; Analytical-processes; Analytical-instruments
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American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana