Comments on "Dimensions of elongated mineral particles with implications for pathogenicity and classification as...

Roggli and Green have reported their study of the dimensions of fibers extracted from the tissues of cases examined in their laboratory, and have drawn conclusions about the pathogenicity of Elongated Mineral Particles and their classification as asbestiform versus cleavage fragments. There are aspects of their methodology and discussion that would benefit from examination. Roggli and Green have relied upon a paper by Harper et al. for their definitions of asbestiform and cleavage fragments. Unfortunately, they have misinterpreted the work of those authors who have concluded that the best criterion is a particle width <1μm. Roggli and Green conclude that 'Our findings demonstrate the lack of pathogenicity of fibers less than 10 μm long or likelihood of cleavage fragments for fibers less than 10μm long and greater than 1.0μm in diameter has little or no effect on the classification of commercial amphibole fibers using our analytical methodology. On the other hand, both lack of pathogenicity and likelihood of cleavage fragments apply to a significant proportion of noncommercial amphiboles identified using our counting scheme.' This is not true. The study of Roggli and Green was a simple fiber counting study with no control population. The design of such a study does not allow the investigator to draw any conclusions about pathogenicity, or lack thereof.