Saturday, November 26, 2005

Remember, Wood Dust is known to be a human carcinogen

[BrooklynDodger is having trouble with fonting in Firefox. Please excuse]

Wood Dust is one of the several human carcinogens completely ignored by OSHA. There isn't even a pre-1970 vintage PEL. The IARC summary will be posted separately. Natural doesn't mean non-toxic, or non-carcinogenic. Nasal cancer is most prominent among people; this suggests large particle exposure. Wood dust exposures are generated by low energy processes [compared to sawing concrete] without combustion, also a construct for large particles. [Nasal cancer and not other sites might be an artifact of the low population risk for nasal cancer, thus a smaller attributable risk could achieve statistical significance compared to lung. Do human lung tumors arise from the parenchema or from the bronchial tree?]

The investigators cite another paper for descriptions of where samples came from and how generated. The Dodger welcomes this least publishable unit approach which provides for another easy but useful post.

Bottom line: the IOM [open faced] sampler measured about 2x the mass of the 37 mm cassette, and the samples overall were 10 times normal workplace measurements.

"Table 1 Comparison of sampler means for all samples, samples not
containing ultra-large particles, and samples containing ultra-large
particles. Note that these values are about a factor of ten higher than
normal workplace measurements"


Journal of Environmental Monitoring, 2004, 6(1), 18 - 22
DOI: 10.1039/b312883k

Comparison of wood-dust aerosol size-distributions collected by air samplers

Martin Harper, Muhammad Zabed Akbar and Michael E. Andrew

A method has been described previously for determining particle size distributions in the inhalable size range collected by personal samplers for wood dust. In this method, the particles collected by a sampler are removed, suspended, and re-deposited on a mixed cellulose-ester filter, and examined by optical microscopy to determine particle aerodynamic diameters. This method is particularly appropriate to wood-dust particles which are generally large and close to rectangular prisms in shape. The method was used to investigate the differences in total mass found previously in studies of side-by-side sample collection with different sampler types. Over 200 wood-dust samples were collected in three different wood-products industries, using the traditional 37 mm closed-face polystyrene/acrylonitrile cassette (CFC), the Institute of Occupational Medicine (IOM) inhalable sampler, and the Button sampler developed by the University of Cincinnati. Total mass concentration results from the samplers were found to be in approximately the same ratio as those from traditional long-term gravimetric samples, but about an order of magnitude higher. Investigation of the size distributions revealed several differences between the samplers. The wood dust particulate mass appears to be concentrated in the range 10–70 aerodynamic equivalent diameter (AED), but with a substantial mass contribution from particles larger than 100 µm AED in a significant number of samples. These ultra-large particles were found in 65% of the IOM samples, 42% of the CFC samples and 32% of the Button samples. Where present, particles of this size range dominated the total mass collected, contributing an average 53%(range 10–95%). However, significant differences were still found after removal of the ultra-large particles. In general, the IOM and CFC samplers appeared to operate in accordance with previous laboratory studies, such that they both collected similar quantities of particles at the smaller diameters, up to about 30–40 µm AED, after which the CFC collection efficiency was reduced dramatically compared to the IOM. The Button sampler collected significantly less than the IOM at particle sizes between 10.1 and 50 µm AED. The collection efficiency of the Button sampler was significantly different from that of the CFC for particle sizes between 10.1 and 40 µm AED, and the total mass concentration given by the Button sampler was significantly less than that given by the CFC, even in the absence of ultra-large particles. The results are consistent with some relevant laboratory studies.

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