Document dnNjKJ2eN2y90mpKpRV76pNDb

Preliminary Dust Survey for Asbestos Textile Institute June, 1947 19 STATISTICAL STOPBa OF MEDICAL BBOQKPS There ere two very important questions concerning the physiological nature of asbestos that have not yet been answered, by eny published Invest!- ' gallon: 1. What la the expectation of asbestosls In vortors exposed more than 15-20 years to low concentrations of asbestos duet? . Among the 500-odd vortero vho composed the subjects In the TJ.B. Public Health Service study, . there were abnormlly few vho had been exposed for more then* 15 years end^ practically none over 20 years. These facts seriously affected the ccnelu-' elcma that could be drawn. 2. Is there a progression to advanced asbestosls after exposure of an Individual has been discontinued or. has been reduced to very low levels, due toectdon of dust deposits from earlier exposure? *0110 question, is of very great importance to intelligent medical supervision of vortors In these plants. It Is virtually certain that statistical Investigations of existing records would throw valuable light on these questions, * Sane of the plants visited during this Inquiry have sufficiently extensive and systematic records to provide satisfactory answers to these questions, but the medical department of Metropolitan Life Insurance Company, under Dr. A. J. Lanza, have x-rays of a number of men obtained In the early 1930's which could provide the nucleus of some useful information, depending > on how many of the original group axe available for re-x-ray.