Document zbjDKJyL3BkdYZMXjjo2z8nxg

CONFIDENTIAL TOi DR. J.V. BARRETT. DVKH/kEB o.o. Dr. J.A. Gardner. Dr. W.MoG. Morgan. Mr. W.E. Hauer Mr. O.G. Vickhaa Dr. H.R. Heusan. Dr. D.5.P. Roebuck. Mr. J.S. Hunter Mr. S.L. Pixton. Mr. M.G.H. Thomas. Mr. J.A. Brindle. 19th August 1955. AROCLORS TOXIC (LOGICAL EIAMTHATICft Further to ay memo of 9th August, I propose to sunaariee the present position on Aroolor vapour toxicity as an essential back ground to our polioy and to our consideration of the Battelle proposal for a programme of toxic ologioal work. I have indicated in ay summary of the two reports by The Kettering Laboratory that prolonged exposure (7 hours a day for 150 days) to Aroolor 1254 vapour at 1.5 mgra,/r caused slight but positive signs of injury in tsst animals and that similar experiments with Aroolor 1242 gavs negative results at 1.9 agrm./nr. As I see it this positive result with 1254 would be construed by Public Health Authorities as an indictment of Aroolors as a olass, and the negative result with 12/,? v would not rank as a olearanoe for that particular chlorinated diphenyl. To upset the one positive result with 1254 would require much more than a simple re-inv^stigatian, sinoe It would be necessary to demonstrate * by an even more exhaustive and searching investigation that the Kettering observations were mistaken. Even then, the work would probably not be deoiaive until confirmed by an independent authority. During the near future, at any rate, our consideration of the suitability of Aroclors for speciflo applications must be governed by, this finding that prolonged exposure to Aroclor vapour mt 1.5 mgnn./ir can produce damage to the liver and kidneys of test animals. In translating this finding to the human being it ia the reoogniBed practice to employ a safety factor of 10; in other words when the maximum, safe concentrations for test animals has been located, the corresponding value for the human being is taken as one tenth of it. With 1254 we now know that 1.5 mgrm./W* i6 above the maximum permissible concentration for EXHi&fT HONS 095215 TOWOLDMON0046044 WATER_PCB-00037021 2- - * test animals so that the maximum for human beings must be placed below 0.15 mgrB./m^, and must be regarded as applying to all Aroolors, on acoount of their similar chemioal constitution. ' Our own analytical work with a room painted with Aroclor plasticised Lustrex Latex paint affords evidence that Aroclor concen trations of the order of 0.5 mgrm./m^ can prevail for a month; we have not so far attempted to develop the more refined analytical tech nique necessary to determine with reasonable preoision concentrations in the range'of 0.1-0,5 mgnn./m'. This development would be a difficult assignment and when available it would only permit ns to determine the time to reach 0.15 mgnu/m-3 and henoe the time during which a person could be ezpoeed to concentrations greater than what muet now be regarded as the maximum permissible. Previously on the basis of published work the value has been taken variously at 0.5 or 1 mgrm./sr and Monsanto has normally used the higher figure. On that baBis it oould be argued that exposure to a concentration at or above the maximum permissible would be of short duration and that any hazard waa of marginal significance. However, we now have to reckon with a fairly long exposure to concentrations above the new maximum, and hence the hazard must be rated much greater. There is yet a further consideration that is always taken into aooount by Health Authorities, and this relates to the idiosyncrasy factor. So far we have considered the average human being, but there will always be a minor proportion more susoeptible than the rest. This msy be due to the natural variability of resistance or predisposition existing among healtiyindividuals, or to functional disability, and in assessing a human hazard consideration is always given to those individuals who are more likely to suffer injury; in this oase presumably those possessing impaired livers and kidneys would be most likely to suffer first. * If the argument I have presented above is aeoepted then we must now line up with M.C.C. in withdrawing our recommendation that Aroolors be used as plasticisers in Lustrax Latex paints. As regards the use of Aroclors in P.T.A. paints, we have so far made no measurements of Aroclor concentrations in painted roqms, but I see no reason for believing that materially reduoed concentrations would be found. . We have still to examine the position of Aroolors in ordinary paints. Here I have argued that the rate of volatilisation will be greatly reduced and probably governed by the rate of migration within the dry paint. It now seems possible that a hazardous oosoentration could M0NS 095216 I TOWOLDMON0046045 WATER PCB-00037022 - 3- be attained In a room is which a large area is pointed with Aroolorcontaining paint. Certainly we oust say that these paints must not be used on hot surfaces such as radiators and hot-vater pipes. MONS 095217 TOWOLDMON0046046 WATER PCB-00037023