AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Characterization of the Dust from Sawing Preservative-Treated Woods
CHAOLONG QI, Alan Echt, NIOSH
Abstract Number: 655 Working Group: Health Related Aerosols
Abstract The use of copper compounds as wood preservatives has been growing rapidly. However, the increasing use of copper nanoparticles in wood treatment raises the concern of workplace exposure to these nanoparticles.
In this study, we conducted laboratory experiments to characterize the dust from sawing wood treated with different copper preservatives. The dust generation rate, size distribution of the dust, and copper content in the particles of different sizes were characterized in details.
In an evaluation of saw dust generation, in the aerodynamic particle size range from 0.5 and 20 µm, the mean particle generation rates (10 tests) for Micronized Copper Azole Ground Contact (MCA-GC) treated wood and Copper Azole, Type C Ground Contact (CAC-GC) treated wood were significantly higher (p<0.0001) than all other types. Additionally, those values for untreated wood and Micronized Copper Azole Above Ground (MCA-AG) treated wood were significantly higher (p<0.0001) than 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one-Imidacloprid-Stabilizer Above Ground (EL2-AG) treated wood.
In the range of particle mobility diameters from 5.6 to 560 nanometers, statistically significant differences were observed in the mean particle generation rates among the wood types. CAC-GC and MCA-AG mean particle generation rates were significantly (p<0.0001) higher than all the other wood types (untreated, MCA-GC, and EL2-AG). MCA-GC mean (10 tests) particle generation rate was also significantly (p<0.0001) higher than EL2-AG and untreated wood, and EL2-AG wood was in turn significantly higher (p<0.0001) than untreated wood, which had the lowest value among all types.
Analyses of the copper content of wood dust showed that statistically significant differences in copper content were only observed in two dust sizes, 7.5 µm (p=0.02) and 0.7 µm (p=0.019). Tukey’s multiple comparison test showed that MCA-GC and MCA-AG had significantly more copper in both the 7.5 µm-size and 0.7 µm-size samples than CAC-GC.