Document dadEKopEmyGMqgDwb5ZZ4JL5R

Mortality information of this nature would be more meaningful if complete information were made available on the work history of each worker in the study. On reviewing the history of the fibrous glass manufacturing indus try. the Bureau of Occupational Safety and Health believed that useful data would result from a records study as covered above, of the workers in this industry. We have already duplicated over 20, 000 records of em ployees in the fibrous glass insulation and textile manufacturing industry. A large number of the workers have been in the industry 25 years and longer. To back this up, we are doing limited environmental studies within each of these plants to get a parameter of the nature and the extent of exposure to fibrous glass, and are characterizing the fibers as to physical dimensions of diameter and length. We feel that for the most useful data we must extend this type of a study to include also workers manufacturing fibrous glass textile materials. We would also like to extend the study to the manufacture of micro fibers if we can get a large enough group to study. DISCUSSION FROM THE AUDIENCE: Would you say a few words about microfibers as relates to insulation vs. weaving applications? DR. KONZEN: For textile fibers, the average range is about 14 hundred thousandths of an inch which is four microns. The diameter ranges from about 12 to 18 hundred thousandths of an inch (by dividing by 4 you can come into microns). This technical data is reported in Dr. Eldred P. Heisel's study in the November, 1968 issue of the Archives. We have to make a differentiation here between textile and wool fiber. Further you have to break it down as to how much is produced in each category of fiber. The vast majority of wool fibers (that used for insulation) are 6 to 6 1/2 microns or more in diameter. FROM THE AUDIENCE: Can we make any statement as to the chron ology of the introduction of these different sizes of fibers? It seems to me this is important in the study, such as what Dr. Cooper was talking about; what was going on 25 years ago, 10 years ago, 5 years ago. DR. CRALEEY: We are getting that information as part of our environ mental study. This is going to be a retrospective -- and then converted into a longitudinal--cohort study, and we expect along the line that some smaller diameter fibers will be introduced into processing. 17.