Document EvM6X7MQdgg6kR8rg4G6mOyQg

V' .r- m : ' ,, a m U m ' <J la O 270 PA'kK AVEfiUE, NEV/ YQSX, NEW YOSK 1CC17 Messrs: C. Benjamin T. F. Frangos B. E. Godard J. L. Myers J. A. Riddle --p/ N. J. Setter J. T. Sinclair J. R. Stickney W. S. Young Data C.-igj/TOMj Dcif. A "Wiring Setter dctn Sulfari April 3', 1969 Medical Department Asbestos A?R ? ;5-:3 U.C.C. CHC'L. i ELASTICS Gentlemen: Both because of changes in regulations and availability of data developed after the issuance of our report in 1964, Dr. Dernehl and I have revised the asbestos memorandum. A copy of the revision, is enclosed. The major changes are the decrease in the Threshold Limit Value from 5 million particles per cubic foot of air to 2 million particles per cubic foot of air. (There is also a provision for another method of counting but it does not appear applicable to our short fiber asbestos.) We briefly discuss mesotheliomas, but data is too scanty as yet for a definite policy to be established. It is worth mentioning that the American Conference of Governmental Industrial Hygienists considered in 1968 a requirement that airline respirators be required for all contact with crocidolite asbestos. The resolution, did not pass, but may come up again in'future meetings. Any questions or comments will be welcome. Very truly yours. KSL:lk Enclosure .. . Kf. S. Lane, M.fD. " Assistant Medical Director UCC 023218 It has been known for years that seme persons working in asbestos production were prone to develop a disabling lung disease. In time, this condition became .mown as asbestos is and was related to exposure to high concentrations of asbestos dust. With further experience, it was found that men could work with asbestos without development of lung disease if dust concentrations were kept below a certain level. It has been generally accepted that a worker will not develop asbestosis if he is exposed to no more than 5 million particles per cubic foot of air, even if this exposure con tinues for his entire working lifetime. Although no cases of asbestosis are known to have occurred when exposures have beer, maintained at or below this level, the ACGIH (which sets the threshold limit value (TLV) in the U. S. A.) has indicated they intend to lower the TLV for asbestos to 2 million particles per cubic foot in an effort to increase the safety factor incorporated in the limit. The U. S. department of Labor has already issued a regulation under the Walsh-Mealy Act placing the TLV for asbestos at 2 million particles per cubic foot for public contracts in which they have jurisdiction. This concentration of dust is generally not visible in the average work area unless a UCC 023219 f -2- bean of light causing a Tyndall effect is present. Usually the dust concentration must be from 8-10 million particles per culbc foot (n??CF) before its presence it visible in average lighting conditions. Several years ago,, it was reported that there was an increase in the incidence of cancerous tumors, especially of the lung, associated with asbestosis. Recently there have been reports of some cancers occurring in individuals exposed to asbestos dust, but 'who have not developed clinical asbestosis. It is believed by most authorities that these cases have been associated with exposures significantly exceeding the Threshold Limit Value. A type of cancer named mesothelioma has been noted to be associated with asbestos exposure in recent years. These tumors, -while rather few in number to date, may occur in individuals with histories of only slight exposures, and that as much as twenty to forty years earlier. There is considerable evidence that crocidolite is most frequently associated with mesotheliomas. From the data available it appears that the TLV of 5 MPFCF is not low enough to protect against mesothelioma, and it is quite possible that 2 M??CF is not, either. Research on the problem continues. Control of asbestos dust exposure is therefore necessary. The control methods are the standard ones applicable to a variety of dusty operations.They include closed flow systems. UCC 023220 4 i wee processes where possible, and adequate exhaust ventilation where openings in the system, are necessary. Pelletizing is sometimes used to improve the handling characteristics of otherwise dusty materials. Where satisfactory containment to stay -within- the Threshold Limit Value is impractical or impossible, efficient and reliable respirators are available for the protection of the employee. A program of environmental monitoring is highly desirable to determine that Threshold Limit Values are not being exceeded. In paper manufacturing, it would be desirable to know the dust conGenerations where the asbestos is dumped from bags info the . pulp slurry. Concentrations should also be determined where dusting occurs in finishing products. While initial dust determinations should be made at frequent intervals, once the level has been established as satisfactory, the frequency may be extended to occasional tests to assure continuation of a satisfactory condition. ?re-employment and periodic physical examination of *a -workers are desirable. These should include chest X-rays to insure that the worker has no chest condition prior to work -with asbestos and to determine that no lung changes -.-r, -Z. `''I Asuiting from work with asbestos. It is believed that the addition of asbestos at the ;sed levels during the manufacture, of paper products . -- * -------- 1SS to the consumer. Total dusting -would UCC 023221 have to bi well in excess of any levels acceptable to the cone .r for the asbestos concentrations to approach the Value. c'delusion, while asbestos dust in excess of the . Limit Value is potentially harmful, as are many 3 encountered in industry, it is as readily d as other such dusts and is can be used safely opriate orecautlons. Industrial Medicine And Toxicology Department Union Carbide Corporation UCC 023222