Document gDK7qZwD791dO6RvXmZ72rzne

OR-670t * -- > E. I. d u Po n t d e N e m o u r s 2* C o m p a n y INCORPORATED W i l m i n g t o n 98, D e l a w a r e ORGA N I C CH EM I CA L S D EPA RT M EN T PET ROL EU M CH EM I CA L S D I V I SI ON February 24, 1961 Lir. C. L. Risso-Gill Associated Ethyl Company Limited 23 Berkeley Square. London, W.i, England Dear Charlie: I am attaching a reprint of an article presented by a group of our people at the American Industrial Hygiene Association meeting in August, 1958. It is the only piece of literature that we give to customers that contains a reference to the figure of 4 raicrograms of lead per cubic foot of air as the safe limit. Ke did at one time have this figure in the domestic version of our Tank Talk booklet. It was never in the export version. We have since deleted it so that one booklet would serve for both domestic and foreign use. ^ a' ^ ^ While this booklet is the only publication given to customers that mentions this figure in writing, we, as well as the Ethyl Corporation, have verbally advised customers that in tank entry work and work around the refineries 4 -.aicrograms of lead per cubic foot of air is the safe limit for an 8 -hour day. While we have used the 4 microgram figure in connection with tank entry v.-ork and work around lead blending plants in our customer refineries, we have always used half that amount, or 2 micrograms of lead per cubic foot of air, in our plant operations. I talked to Hank Ball today to confirm this, after reading the extract from Dr. Kehoe'a letter to`you. Hank advises that they have in their records in black and white, going back a number of years, the figure of 4 micrograms as the safe limit for use in connection with tank entry work. I can only assume that in writing you Dr. Kehoe was thinking only about plant operations, in which case his comments are quite correct. A copy of this letter is being sent to Dr. Kehoe and also Hank Ball, in order that this question can be resolved. We think it extremely Important, especially in view of new manufacturers that are coming into the field, that we all pass on to the customers the same figure so far as safe concentrations of lead in air are concerned. With best regards, BGC :mlra Attachment cc: Dr. Kehoe H. K. Bali B. G. Crane Manager of Operations KE OO638