Document jmd7kmZOBvrg723K61RNJdR5Q

FILE NAME: US STEEL (USS) DATE: 1959 July 1 DOC#: USS003 DOCUMENT DESCRIPTION: Memo f $ I l * ,**| 1-410-448-2368 410-448-2368 FfOI: david eg1Ban (425)699-7033 Via eFax.coa Pg 1/ 1 12-20-00 02:55PM CST Mr. C. H. ftailly bisector of Safety Rational Tube Division 10119116 Kenneth X. Morsa, Director Industrial t n i t M Toxic H a l t As par your request, easy I suggest you consider 3 including the following Information with your transmission ^ - of eba one Losad bles of "Threshold Limit Values fox 1958." f The enclosed list of '`Threshold Limits" are known under variety of asase, such as "maximum allowable con centrations," "toxic limits," etc. They are not exact delinea tions between hasaxd and aoa-hasasd conditions, since they ere derived from e variety of sources. #see era besad upon studies with human subjects, others upon opinions derived by interpo lating from anleal experimental data, while still others are based ns rely upon unsupported opinions frota industrial nodical end hygiene authorities- However, tine feet remains that these 1laics ere often incorporated into ataca codes or used by State Inspectors SS asset numbers above which a condition is dangerous. Therefore, In actual practice. It is important to maintain air concentrations of these gases, vapors, dusts or aists within such levels where possible or protect workers by approved respiratory devices. These date are the maxi m m degree of air contamination to which one should be exposed upon a continuous 8-hour daily and 40-hour weekly basis. The date, therefore, are degrees of air contamination which will prevent the development of chronic poisoning arising from continuous day to day exposures. It is our opinion chat short-term expoeures also should be maintained within such liaits where practicable, because of the absance of good date cm safe concentrations for preventing acute (sudden) poisoning. This approach is considered to be the best course f action because the human body doss not respond In a direct arithmetic relationship with the amount of contaminant In the air. 2a other words. It would not be prudent to expose an individual for one hour to eight times the values shewn in the enclosed table without respiratory protection, furthermore, tete inspectors would no doubt consider such exposures as' hseardous to health. B tf USEI00106 03/26/00 16:40 TX/RX NO.0292 P.001