Document LJ2RDpeVLm8QnGqwgg8pNYg0g

/ * - .v/ /V / / - January 5, 1961 Mr, Paul D. Halley Director of Industrial Hygiene American Oil Company 910 South Michigan Avenue Chicago 00, Illinois Dear Paul: In answer to the question in your letter of January 3 con cerning possible ohollnesteraBe inhibition from exposure to Pydraul AC, I am sure that if real acute exposures were severe enough or if less acute exposures were repeated long enough, there could be oholinesterase inhibition. Perhaps thiB could be said for any of the triaryl phosphates. Several years ago, Kettering looked at a mixed triaryl, phos phate formulation for us and compared it with & competitive produot. A copy of the Kettering report is attaohed for your review. At the same time this work was under way, Kettering carried out a study with human volunteers in whioh known amounts of these materials were applied to the skin and allowed to remain for specified perlodB eaoh day for fifteen days. Joe Treon reported the results of the human studies at the 1957 AIHA meeting in St. Louis, His draft of a final report (which wo had hoped he might submit for publication) is still in the pile of reporta sitting on the desk of Dr. Kehoe in Cincinnati, even though Joe has not been with Kettering for several years. Essentially, Joe's work showed no significant cholinesterase inhibition in the volunteers when 0.25 milliliters was main tained in contaot with the skin for two hours in the morning and again two hours In the afternoon, five days a week for several weeks. Although this may not sound like a large amount from a praotical standpoint, we felt it represented a reasonable exposure. If you can envision this same amount of glycerin being applied to the skin and allowed to remain, you will have an idea of the amount of oily material involved. In other words, we felt that workmen doing any kind of a Job would bo unlikely to tolerate suoh amounts of material on the skin or would be unable to perform their Jobs because of slippery hands. OSW 018716 STLCOPCB4005260 Mr. Paul D. Halley - Page 2 - January 5, 1961 I am sure you have Been the work reported by the Navy In which men using triaryl phosphate hydraulic fluid aboard an air craft carrier were studied (Archives of Industrial Health. Volume 20, page 25O, 1959). Here again,'phosphate.oil or fluid which caused significant cholinesterase inhibition in the laboratory investigations caused no effect in aircraft carrier personnel. The report points out that exposure was limited. It Is our impression that any normal exposures to Pydraul AC would not cause cholinesterase inhibition. As far as abnormal or unexpected exposures are concerned, we would not expeot any significant cholinesterase inhibition without other symptoms of toxioity. If the exposure was such that there might be cholinesterase inhibition without any symptoms due to unusual exposures, it is our feeling that the inhibition would be transient and of no great consequence. Sincerely yours. EPWjdh Enclosure Elmer P. Wheeler Assistant Director Medical Department DSW 01871? STLCOPCB4005261