Document re3JjYo0q6eBO9KQRQXEYwX30

Cfettig c f Sins Attgtka. Jkailljr l i p r t e t i i . BUS 'nrih Spring B iz z st Hus Angelas 12, (Edifnntta April 27, 19U8 Dr. Robert A. Kehoe Kettering Laboratory University of Cincinnati Cincinnati, Ohio . . Dear D r . .Kehoet'- . ... . At a recent meeting of governmental personnel engaged in official industrial hygiene activities in California, the writer was selected to formulate an ac ceptable definition of Maximum Allowable (or Acceptable) Concentration for use in oui4work. It was felt that the fact that different persons have dif ferent concepts of the term leads to much avoidable confusion and that a standard definition is desirable. lie should therefore appreciate your views on the matter. A similar letter is going to other authorities in this field. The questions that are most often raised are (1) Are the present lists of M.A.C.*s predicated on an 8-hour daily exposure for each substance? (2) If so should not excessive peak con centrations for a short, period be given more value than would appear in an in tegrated sample? (3) Is there any why of separating the M.A.C.'s into values for those substances which are definitely toxic and those which are merely un comfortable or irritating? Gf course a sharp differential cannot be made as some irritants are also toxic. Seme of the group mentioned above felt that it would simplify the industrial hygienists1 work in the field if the M.A.C. for most substances was that figure which should not be exceeded at any time. However the majority of the group felt that we should go along with the national consensus of that subject, and for that reason authorized me to correspond with you. . Very truly yours, Roy G. Gilbert, M.D PGBtMP 0020009 Paul G. Brown Industrial Hygiene Engineer Division of Industrial Hygiene 'Please address to Paul G. Brown, Industrial Ifygiene Engineer Division of Industrial Hygiene 8o8 Horth Spring St., Suite 806 Los Angeles 12, California