The application of dustiness tests to the prediction of worker dust exposure.
ABSTRACT Laboratory bench tests, known as dustiness tests, have been used to evaluate and compare the potential of various powders to cause occupational dust exposure. Dustiness tests are used to develop products with reduced dust emissions. The correlation between dustiness test results and dust exposures was evaluated at two bag dumping and bag filling operations. At one bag dumping and one bag filling operation, there was evidence of a relationship between dustiness test results and dust exposures. In one case, regression analysis showed that dust exposures could be predicted to within nearly one order of magnitude. The variability in this prediction was caused by the inherent variability in the occupational dust exposures. In the other case, there was evidence of a correlation after the data had been adjusted for the effect of varying drop height. At the remaining two operations, no correlation between dust exposures and dustiness test results were observed. These results indicate that the relevance of dustiness tests to occupational dust exposure needs to be evaluated at each site. Because a better option does not exist, manufacturers should continue to use empirical dustiness tests to develop better products in the laboratory. The conclusions reached in the laboratory need to be validated by dust exposure measurements in the field, however.
- [Show abstract] [Hide abstract]
ABSTRACT: A standard rotating drum with a modified sampling train (RD), a vortex shaker (VS), and a SSPD (small-scale powder disperser) were used to investigate the emission characteristics of nano-powders, including nano-titanium dioxide (nano-TiO2, primary diameter: 21 nm), nano-zinc oxide (nano-ZnO, primary diameter: 30–50 nm), and nano-silicon dioxide (nano-SiO2, primary diameter: 10–30 nm). A TSI SMPS (scanning mobility particle sizer), a TSI APS (aerodynamic particle sizer), and a MSP MOUDI (micro-orifice uniform deposit impactor) were used to measure the number and mass distributions of generated particles. Significant differences in specific number and mass concentration or distributions were found among different methods and nano-powders with the most specific number and mass concentration and the smallest particles being generated by the most energetic SSPD, followed by VS and RD. Near uni-modal number or mass distributions were observed for the SSPD while bi-modal number or mass distributions existed for nano-powders except nano-SiO2 which also exhibited bimodal mass distributions. The 30-min average results showed that the mass median aerodynamic diameter (MMAD) and number median diameter (NMD) of the SSPD ranged 1.1–2.1 μm and 166–261 nm, respectively, for all three nano-powders, which were smaller than those of the VS (MMAD: 3.3–6.0 μm and NMD: 156–462 nm), and the RD (MMAD: 5.2–11.2 μm and NMD: 198–479 nm). For nano-particles (electric mobility diameter < 100 nm), specific mass concentrations were nearly negligible for all three nano-powders and test methods. Specific number concentrations of nano-particles were low for the RD tester but were elevated when more energetic VS and SSPD testers were used. The quantitative size and concentration data obtained in this study is useful to elucidate the field emission and personal exposure data in the future provided that particle loss in the generation system is carefully assessed.Journal of Nanoparticle Research 01/2012; 14(4). · 2.28 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Dust exposures are observed in some production departments of pharmaceutical industries, especially in tablet manufacturing processes. This dust generally includes a portion of therapeutic material. The development of an adequate industrial hygiene monitoring strategy is therefore required to evaluate these specific exposures. The first step for a proper health risk assessment consists of establishing adequate exposure limits for each drug of interest. Second, the dust must be sampled to quantify the drug exposure. This monitoring often requires the development of analytical methods for each pharmaceutical active of concern. However, the development of analytical methods for some drugs is a procedure too expensive for many industries, especially where industrial hygiene resources are limited. These difficulties would be avoided if the proportion of drug in the total dust could be estimated without direct chemical analysis of the drug. Over a three-year period, two types of granulation processes were monitored in one pharmaceutical industry. Total dust exposure levels and drug ratios in the recipe were compared with drug exposures obtained with direct drug analysis. The data suggest that a direct comparison was possible between total dust air sampling results and drug concentrations, depending on the manufacturing process used. Tartre, A.: An Industrial Hygiene Monitoring Strategy for Dust in the Pharmaceutical Industry. Appl. Occup. Environ. Hyg. 7(11):764–771; 1992.Applied Occupational and Enviromental Hygiene 11/1992; 7(11):764-771.
- [Show abstract] [Hide abstract]
ABSTRACT: A bench-top apparatus was designed and built to investigate factors that affect dust generation. The apparatus allows the investigation of process variables, material properties, and the size distribution of generated dust, thus addressing the limitations of other bench-top dustiness testers. The controlled testing of hazardous materials is also possible in this air-tight device. The apparatus consists of a dust generation section and a dust measurement section. Materials are introduced to the generation section at various drop heights and flows by an injection slide. Dust is generated by the impact of the falling material and the release of air entrained with the falling stream of material. The generated dust is drawn through an elutriator, which removes particles 25 μm and greater in aerodynamic diameter. The size distribution of the residual dust is measured for particles between 1.4 and 15 μm in aerodynamic diameter with a cascade impactor.The effects of material drop height, mass flow, and moisture content were investigated for four granular materials: ground limestone, titanium dioxide, glass beads, and lactose. For each material, a simple model was developed to describe the size-specific dust generation rate. Increases in material drop height caused a roughly proportional increase in the dust generation rate for all four materials. Material flow had little effect on dust generation. Changes in moisture content, which affect the interparticle binding forces, strongly influenced the dust generation rate. Decreased dust generation was found in all cases where material moisture content increased. Although an increase in dust generation normally results from reductions in moisture content, some dried samples showed a decrease in the dust generation rate. This could have occurred due to the formation of solid, interparticle bridges of soluble materials, or due to increased electrostatic effects, as the material dried.Applied Occupational and Enviromental Hygiene 07/1993; 8(7):624-631.