Document 1gz6JrVxBMVvMkaQkQqwE60yo

x> PLAINTIFF'S EXHIBIT JPo CJSM-258 March 2, 1967 I. letter traa Division of Industrial Safety / State of California -- Ra: Asbestos Dust I t Daring the dust test on March 1, Mr Bradley v&s asked to read the above letter acme of his cements wares )- Hie Division of Industrial Safety is an organization Chich is concerned with accidental injury only. They are not qualified to make the statements in the letter and the information they gave they got second hand. The authority for this type of - * statement would cose from the California State Department of Health only. The MAC for asbestos is 5 million parts per cubic foot of particles below 10 sic. is disaster. With the normal microscope one can see down to 1 micron. Therefore, ve count only the particles, froa 1 to 10 nicrons. The standard light field technique neons the field in which the particles are is lit up, and this is done by shl ntng light up through the. slide into the microscope Under certain conditions the particles have the same index of refraction as the water mediua, and therefore the particles cannot be seen. When this occurs, the dark-field technique is used, which means there is a disk placed directly under the slide so tha light does not go through the specimen but around tha perimeter, and essentially, lig,' is reflected off the particle rather than passing through the particle. The term * phase contrast* means there is a contrast difference between the particle and the liquid phase. In general, one gets about the same particle count with either method. * It is known that there are smaller particles below 1 micron, and these can be oeasured by higher magnifying microscopes such as the electron microscope - but so wh; In all cases when one reports the particles below 10 microns, it is assumed therefore many smaller particles that are normally not visible. The only real testing done has been with animals which were given dosages of dust with the 10 micron size down, and these animals always got the very small particles also. Mr. Bradley said that If one tested air by itself they would find m,; many of the line partieles that are normally not reported. /Pttr. Bradley does not know of any case of lung cancer related to asbestosis and he said asbestos chut causing mesothelioma is very rare. Mesothelioma is essentially irritation of the lung linings- which- goes away when the-dust condition is removed. . I think if the Association plans to reply to this letter it should be written by son- one of authority such as Hr. Bradley, or Hr. Bradley should draft the letter for SKIM.' In this case, any specific statements made should bo qualified with references to sub stantiate the technical facts. ' IMS/eo cc: / 7. CSouxka