Pf. Gao et al., Estimating factors to convert Chinese 'total dust' measurements to ACGIH respirable concentrations in metal mines and pottery industries, ANN OCCUP H, 44(4), 2000, pp. 251-257
Historical data on the dust exposures of Chinese workers in metal mines (ir
on/copper, tin, tungsten) and pottery industries are being used in an ongoi
ng joint Chinese/United States epidemiological study to investigate the exp
osure-response relationship for the development of silicosis, lung cancer,
and other diseases. The historical data include 'total dust' concentrations
determined by a Chinese method. Information about particle size distributi
on and the chemical and mineralogical content of airborne particles is gene
rally not available. In addition, the historical Chinese sampling strategy
is different from a typical American eight-hour time-weighted average (TWA)
sampling strategy, because the Chinese samples were collected for approxim
ately 15 minutes during production so the sample could be compared to their
maximum allowable concentration (MAC) standard. Therefore, in order to ass
ess American respirable dust exposure standards in light of the Chinese exp
erience, factors are needed to convert historical Chinese total dust concen
trations to respirable dust concentrations. As a part of the joint study to
estimate the conversion factors, airborne dust samples were collected in 2
0 metal mines and 9 pottery factories in China during 1988 and 1989 using t
hree different samplers: 10 mm nylon cyclones, multi-stage 'cassette' impac
tors, and the traditional Chinese total dust samplers. More than 100 sample
s were collected and analysed for each of the three samplers. The study yie
lded two different estimates of the conversion factor from the Chinese tota
l dust concentrations (measured during production processes) to respirable
dust concentrations. The multivariate analysis of variance (MANOVA) reveals
that, with a fixed sampling/analysis method, conversion factors were not s
tatistically different among the different job titles within each industry.
It also indicates that conversion factors among the industries were not st
atistically different. However, the two estimates consistently showed that
conversion factors were the lowest in the pottery industry. Average convers
ion factors were then calculated for each of the estimates across the indus
tries studied. A pooled mean conversion factor, 0.25 +/- 0.04, was then der
ived for all the job titles and industries. Respirable dust levels were est
imated from the historical 'total dust' concentrations collected between 19
52 and 1992 by adopting the American standard. (C) 2000 British Occupationa
l Hygiene Society. Published by Elsevier Science Ltd. All rights reserved.