Document 1yQKjKxYDbo9k6EQdN2N3QVRj

Inin Company To: J. Harwood cc; A. E. Anderson D. Block T. Cole W. D. Compton J. U. Damian S. Gratch C. ijelvin Scientific Research Staff April 10, 1973 J. V. Fetrocelli W. Pierson V. Sussrnn P. Toth 8. Weiner S. We Instock Subject: Visit to Mount Sinai School of Medicine re: Ford Grant for Asbestos Toxicology Research The Environmental Sciences laboratory of the Mount Sinai School of Medicine (The City University of New York) received a Ford Motor Company grant of $5>000 for the academic year 1972-1973 in support of their research program on asbestos toxicology. On March 27, 1973, I visited their labora tory to revlev the status of this work. The discussion was held exclusively with the main investigator, Arthur H. Lange?, a Ph.D. is mineralogy. The work identified as being supported by the Ford grant is the examination and characterization of brake drum dust with respect to the physical and chemical nature of both the fibrous and non-fibrous components. Dr. Longer examined samples of'the drum dust from a 1969 Dodge Dart at a mileage of 20,000 miles. While asbestos fiber was not visible by polarized light microscopy, nor was chrysotile identified by X-ray diffraction, an appreciable amount of what appears to be asbestos fiber was observed by trans mission electron microscopy at magnifications in the range of 3600-20,ooox. 2 was given some photomicrographs of these samples and observed some directly. A copy of an informal interim report prepared by Dr. Longer it attached. While no quantitative determination of asbestos content was attempted, the appearance of appreciable amounts of fiber in drum dust is in sharp dis agreement with electron microscopic observations previously reported in the literature (J. R. Lynch, "Drake Lining Decomposition Pioducts," Journal of the Air Pollution Control Association, Vol. 18, December 1966, pp. 624-826), and with our own previous observations of drum dust, although some other investi gators have- reported observing as much as 1 to 3# asbestos in drum dust by optical microscopy or X-ray diffraction. The result is also greatly differ ent from the results of our examination of airborne brake wear dust. In which we found very little asbestos. Since it Is desirable to determine the reason 007934 PRODUCED BY FORD SCF-FORD-1029 J. Harwood -2 April 10, 1973 for these differences, I am sending to Or. Danger, for comparison In his ' laboratory, a sample of drum dust in which ve had seen little asbestos, and samples of ndllipore filter from our airborne disc brake wear dust experiment for him to compare airborne dust with drum dust. Samples of these filters had previously been Bent to Dr. W. Nicholson at the same laboratory, and he had indicated that the asbestos content was not inconsistent with what be would expect for ordinary urban air samples, although he did not provide any quantitative results. Dr. Danger plans to examine dust from different kinds of brakes and sizes of vehicles and at different mileages. He plans initially to characterize the fiber components and look for chemical and physical changes in the chrysotile brought about by the braking action. He also intends to characterize the other components in the wear debris. The Environmental Sciences Laboratory of the Mount Sinai School of Medicine is carrying out a competent and useful study and it is recommenoed that their grant be renewed for the next academic year. HLO-.ao Chemical Engineering Department 007935 PRODUCED BY FORD STUDY OP DnAKE-DIUIM DECOMPOSITION PRODUCTS - September 1072 - March 1073 Drake--drum dusts were obtained and examined by polarized light microscopy, x-ray diffraction and by transmission electron microscopy. Examination by polarized light microscopy failed to disclose the prosence of fibrous components. Few crystalline materials were present as indicated by the lack of birefringence on observed particles. These same materials were subjected to x-ray diffraction analysis. No serpentine peaks were visible (chrysotile}.' However, some strong quartz lines were observed as well as lines which compared with an iron phase. These dusts sere prepared for transmission electron microscopy by sonification m distilled water and pipetted onto formvar coated 200 mesh EM grids. These were carbon coated and examined. Cundlcs of short chrysotile fibers are the predom inant identifiable phase. Many other components are also present, but their identity is presently unknown. On the basis of preliminary results wo observe the following the fiber present in brake-drum dusts are in the main too small to be resolved by light microscopic methods; most of the additional phases are either non crystalline, or too small to show characteristic birefringence; x-ray diffraction is too gross a technique to characterize a brake dust for the presence or absence of chrysotile fibar; transmission electron mi croscopy should be used to determine the prescnco of fiber. Many fibers and fibrils are present in brake-drum dusts. Some preliminary selected area electron diffraction studies show the 007938 PRODUCED BY FORD presence of some clay phaseb In the brake dusts. The other phases must be characterized both on a morphological and a micro-chemical basis. A study of the available literature on the thermal and physical reduction of chrysotlle indicates that the brake dusts are likely composed of a mixture of 'chrysotlle; partially dehydroxylated chrysotlle, dehydrox yl at ed chrysotlle, forsterlte, emrtatlte, and silica in the form of amorphous silica or a recryatallized phase, The biological activity cf brake dusts and their components should be further studied. The nature of the decomposition products should be studied in detail as well. 007937 i V PRODUCED BY FORD