Document mmQvkxNq7yOqyE7dXqBo0EVY0

DOW CHEMICAL U.S.A. April 15, 1987 LOUISIANA DIVISION P. O. BOX ISO PLAQUEMINE. LOUISIANA 7076B-01B0 S04 389-8000 I. H. Contacts cc: Mike Nevill, 3502-E Henry Bell, 4701 Dr. Currier, 2303 Lester Poirrier, 4109 Ray Kemp, 4109 1.1.1- TRICHL0R0ETHANE TOX STUDY The attached telex was recently recived from Midland. It concerns a recent animal study -where exposure was to an aerosol rather than a vapor. In the study, rats died at lower levels (1375 - 12000 ppm) than in previous studies. However, the levels causing death were well above the current TLV of 350 ppm. It is believed that the increased toxicity was related to the aerosol droplets. Please pass this information along to your plant maintenance people and review any operations in your area where 1.1.1- trichloroethane (Chlorothene) is used as a fine mist or spray to make sure exposures are being kept below the TLV. William E. Ledford Industrial Hygiene sb AN OPERATING UNIT Of THE DOW CHEMICAL COMPANY DO 106744 CONFIDENTIAL 31 MARCH 1987 ACUTE TOXICITY -- 1*1*1-TRICHLOROETHANE PRELIMINARY RESULTS OF ACUTE INHALATION STUDIES OF AEROSOLIZED 1*1*1-TRICHLOROETHANE* SPONSORED BY THE 3M CORPORATION* HAVE COME TO OUR ATTENTION. THIS INFORMATION HAS BEEN SUBMITTED TO THE U.S. ENVIRONMENTAL PROTECTION AGENCY. RATS WERE EXPOSED FOR 4 HOURS BY INHALATION TO 1*11-TRICHLOROETHANE WHICH WAS INTRODUCED INTO THE CHAMBER IN AEROSOL FORM. RATS DIED AT ALL LEVELS TESTED* 7510 TO 65*500 MG/CU. METER. EARLIER STUDIES OF 1*1* 1-TRICHLOROETHANE * CARRIED OUT IN A SIMILAR WAY SHOWED LOWERTOXICITY WITH AN LC50 OF ABOUT 76*400 MG/CU. METER. FURTHERMORE* `A DOW STUDY OF FULLY VAPORIZED 1*1*1-TRICHLOROETHANE WHERE ANIMALS WERE EXPOSED EVEN LONGER* 7 HOURS* GAVE AN LC50 OF 77*800 MG/CU. METER <14*250 PPM). IT IS NOT CLEAR WHY THERE IS SO MUCH DIFFERENCE BETWEEN THE MOST RECENT AND THE EARLIER STUDIES. IT MAY BE BECAUSE OF THE WAY THE MATERIAL WAS DISPENSED* LEADING TO HIGHER LEVELS OF AEROSOLIZED DROPLETS OF 1 * 1 *1-TRICHLOROETHANE. WE ARE NOT SUGGESTING ANY CHANGES IN WORK PRACTICES AT THIS TIME. HOWEVER* WORK SITUATIONS WEHRE AEROSOLS OF 1 * 1 * 1-TRICHLOROETHANE MAY BE ENCOUNTERED SHOULD BE REVIEWED TO ENSURE EXPOSURES TO THE MATERIAL ARE MAINTAINED BELOW THE CURRENT ACGIH TLV OF 350 PPM <1900 MG/CU. METER) ADDITIONAL STUDIES OF 1 * 1 *1-TRICHLOROETHANE TO RESOLVE THESE DIFFERENCES IN APPARENT TOXICITY ARE BEING PLANNED AND CARRIED OUT. YOU WILL BE KEPT INFORMED OF ADDITIONAL INFORMATION AS IT BECOMES AVAILABLE. L. W. RAMPY DIRECTOR* INDUSTRIAL HYGIENE 517/636-6260 J. M. LANHAM CHIEF MEDICAL 517/636-210 OFFICER DOWCHEM C PLAQ 1067*5