Document nj9EX9VDwKJVZ5dkMjG824g6

0^u ' * March 25, 1969 Mr. W, J, ilahn United Fire and Casualty Co. 49 30 W. 77th St. Minneapolis, Minn. 55435 Dear Mr, Hahn: Your letter of :tarch 18, 1969 to John Vyve'rberg of our Hew York, office nas been referred to ae for- reply. Enclosed are several reports of medical research studies and investigations that were conducted for the purpose of determining the biological effects of exposure to fibrous 3lags particles. Fibrous glass has not demonstrated, during the past thirty years, that it has properties th3t cause lung disease, it does not cause asbestosls and, to our knowledge, no case of silicosis has resulted from exposure to air-borne fibrous glass, this last statement frequently surprises those who are unfamiliar with the phyaical structure and chemical makeup of glass. Glass is a silicate and does not contain free silica. Silica does cause silicosis. Glass is amorphous, whereas silica and asbestos are crystalline in structure. The crystalline materials have been shown to be more pathogenic than the amorphous substances. Moat of the fragmented and air-borne glass particles from the glaas insulations are too large to enter the lungs. If the particles cannot enter the lungs, tney cannot cause lung disease. On the other hand, should the glass particles be milled or impinged to form very small particles capable of being inspired by laboratory animals (see "Glass Duat: A Study of Its Biologic Effects", page 34/22, Summary and Conclusions), no serious lung or bronchial disease was demonstrated. J) Mr. W J. Hahn -2- March 25, 1969 Therefor*, exposure to fibrous glass can b* dismissed a* being a contributing factor in this case. Did Mr. Herkal actually handle or Install Kaylo or other asbestos containing product* during the period from May, 1960 to August, 1961? If so, how such of hia time was spent with these products and was he subjected to high concentrations of dust? Objective ayraptoma of aabestoais are seldoa demonstrable in less than 12 to 15 years of exposure and may require as much as 30 to 35 years. Kaylo is a'.-hydrous calcium silicate containing approximately 15Z asbestos. The asbestos is contained in the calcium silicate atatert'Bfl and very little of the asbestos fiber'vill be released except when tha product i* saved into desired snapej or stripped from pipes, boilers, etc. A typical composition is: quicklime, tripoli, diatomite, clay, calcium chloride and asbestos. These material* are mixed with water and then indurated in an autoclave at 400*F and 250 p.s.i. for three hours. If there are additional questions, please call or write. Sincerely, FilE/am F. H, Edwards Director of Health & Hygiene