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Particle size fraction -Response: Letter to the Editors
Citation:
GILMOUR, M. I., H. TONG, J. K. MCGEE, S. H. Cho, Q. T. KRANTZ, AND R. W. BALDAUF. Particle size fraction -Response: Letter to the Editors. ENVIRONMENTAL HEALTH PERSPECTIVES. National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, 118(9):A380, (2010).
Impact/Purpose:
would like to comment on the article by Cho et al. (Cho et al. 2009), which was published in the November 2009 issue (volume 11, number 11, page 1682-1689) of Environmental Health Perspectives.
Description:
To the Editors: We, the undersigned, would like to comment on the article by Cho et al. (Cho et al. 2009), which was published in the November 2009 issue (volume 11, number 11, page 1682-1689) of Environmental Health Perspectives. We read the paper with great interest as the discussion of size-dependent effects of particulate matter is of great importance and has not yet been definitively clarified. When discussing the size-dependent effects of particles, it is essential that the size distributions of the applied particle solutions are known, as well as the specific particle size fractions administered. The study by Cho and colleagues (Cho et al. 2009) does not use a direct inhalation exposure, which is the most relevant exposure route for airborne particles (Oberdorster, Oberdorster, and Oberdorster 2005). The particulate matter was sampled, resuspended in methanol and saline and administered via pharyngeal aspiration to mice (50lll saline containing 25 or 100 ug particulate matter). Due to the extremely high effort that the inhalation of the sizefractionated airborne particulate matter would require, it is understandable that the particles were collected and resuspended. However, the fact that no analysis of the size-fraction in the suspensions was performed is regrettable. It is known that particles react in suspensions, especially by forming aggregates, and are dependent upon the specific composition of the suspension liquid (Teeguarden et al. 2007). Statements therefore, concerning particulate size effects which are made without taking into consideration the characteristics of the particle suspension used for aspiration are, in our view, a significant drawback. This aspect should have been clearly addressed in the discussion. It is to our surprising that the reviewers did not highlight this point. We are interested in studies which pay attention to the size effects of particles, both environmental and engineered, which consider direct exposure as well as other exposure modes. It is our hope that your journal, Environmental Health Perspectives, may take this into consideration during the peer-review process in the future.
