Document 7Rp3xy0gRe2Y2zrQgO3Dga99g

CQMTDEMTIAL TO: DR. J.W. BARRETT. DVMH/teEB . c.o. Dr. J.A. Gardner. Dr. W.KoG. Morgan. Mr. W.2. Hamer. Mr, C.G. Wickham Dr. H.R. Reman Dr. D.S.P. Roebuck Mr. J.S. Hunter Mr. E.L. Pixton Mr. H.G.H. Thomas. Mr. J.A. Brindle. 6th Deoenber 1955 AROCLORS TOXICOLOGICAL EXAMLNATIQK * Since communication of 19th August 1955, when I sunned up the poeition confronting ue following the receipt of the reports of the Kettering Laboratory/ Dr. Hevman has discussed with Dr. Kelly the significance of the Kettering results in relation to M.C.C. thought and policy. M.C.C.'s immediate action is to submit the reports to the American Conference of Governmental Industrial Hygienists in support of a claim that the offieial table of naxinun permissible vapoure concentrationsdbould include the. items:* I 42 Chlorinated Diphenyl (Aroclor 1242) 54% * * (Aroclor 1254) 2 agrms./3 1 ngrn./n^ ' The Kettering results indicated in brief that prolonged exposure to Aroolor 1242 vapour at 1.9 ngim./n' gave no sign of danage to the test animals but that'Aroclor 1&54 *t 1.5 ngr*./n3 caused slight but positive signs of injury.'- Iou will note that M.C.C. do not introduce a safety factor in translating these animal test results to hunan beings, and in faot regard such a faotor as unnecessary in animal tests of such thorough ness as those carried out st Kettering. It will be sometime before we know the decision. In ay view it would not be unreelietie to assign a value of 2 ngm./iK te Aroolor 1242 but the ease for setting the limit at 1 mgra./m^ for Areolor 1254 Is not so logical. After all 1254 can oause slight but perceptible danage at 1.6 mgi*./*3 and who oan say whether it would be harmless at MONS 095188 TOWOLDMONOQ46080 - 2- 1 mgrm./m^. However, if the M.C.C. recommendations are accepted there will be an implication that Aroolor toxicity increasee with chlorine content, a reversal of the position suggested in M.C.C. technical literature. M.C.C. Application Data Bulletin No. P-115 states "If Aroclore are used at elevated temperatures such as 200 or 300C. in open systems methods must be designed to ezhauet any vapours arising from these open systems. This applies especially to lover chlorinated Aroclore where experimental work on animals indicates that the maximum safe concentration in workrooms is in the range of 0.5 - 1.0 milligrams per cubic meter of air. In the case of more highly chlorinated Aroclors such as Aroclor 1268 the allowable limit is about 10 milligrams per euhie meter of air and accordingly. Aroclors of this type are believed to be of a much lover order of toxicity. Whatever the outcome, there will be no impact on H.C.C. policy regarding the use of Aroclors in paints since M.C.C. have long ceased to recommend the use of Aroclors for this purpose. However, M.C.L. has oontinued to offer Aroclors for use in paints on the basis that the evidence for rejection was slim, and that the risk is reduced by resorting to the use of more highly ohlorinated Aroclors. ThiB was thought to have the duel advantage of using a material of (a) lover intrinsic toxicity (b) lower vapour pressure. It is now clear that toxicity increases with degree of chlorination and that this effect may cancel or even outweigh the.advantage due to deoreaaed vapour pressure. Ue have tended to draw a distinction between the use of Aroclors in latex paints on the one hand and in conventional paintb on the other, the ooncensuB of opinion being that the rate of volatilisation from the former is greater than from the latter, and aa a result we are no longer recommending Aroclors for latex paints. Tbs deoision now before us is whether we should continue to sell Aroclors for use in conventional paints. On tills issue, the reoent decision by I.C.I. to discontinue their usage of Aroolors in ordinary paints ie considered to be aa indication of the line that may veil t?e taken by our other customers. Broadly speaking the main objections are that the paint manufacturer oaxrnot ocntrol the paint user who may apply in the form of spray, and may use on hot surfaoes. In either ease a degree of risk must be admitted. As to bow serious the risk may be it depends naturally on the total time for which any individual is exposed during his life time. There must dearly be circumstances under which the use of Aroolor containing paints will con stitute a health haaard, particularly to individuals who for one reason or another are constitutionally less resistant than the nor*. The I.C.I. decision must have been influenoed quite materially by a letter from Dr. Kelly to Mr. Hoy Wltternhein (dated 15.7.55.), a eopy ef which reached them through Canadian Industries Ltd. The relevant passages are as follows;- - HONS 095189 TOWOLDMONOQ46081 Arodor should not be sprayed on the job la an industrial plant where there are plant personnel who can breathe the vapours. there is no danger at all if the material is brushed on, and there is no danger in spraying it if the workers use a booth or ubs an approved respirator and no one inhales the spray. Arodor fanes at rooa temperature very probably would not present any hazards. Mist or spray, however, is another problem entirely and that is the reason for the above recommendation. After all, the toxicity of Arodor oust take into ocosideration how much oan get into the air. It is our belief that at room temperature not enough can get into the air to cause any trouble. At elevated temperatures and if the material is dispersed as a mist or aerosol a different Interpretation has to be placed on its toxicity*. The passages of particular significance to l.C.I. Faints are underlined and mey be considered to be reflected in their conclusions which 1 now quote below:- In brief (a) The spraying of Arodor paintb appears to involve precautions which would be so inconvenient as to limit unduly their application by this method. (b) Apart from questions of spraying there appear to be cases where Aroclor-containing points would involve toxic hazards either during appli cation or subsequently, and where cautionary advice wcwld be appropriate. The need for special precautions would limit the use of Aroclor paints in -these caBes. (c) As far as the paints in question are oonceraed it is impossible to know how eny particular oan may be eventually used, so every can would need to show the warnings and precautions for all foreseeable eventualities. The preaenoe of these warnings would tend to deter people from using the paints even in oases where no special precautions ware needed.* With referenoe to the impression generally given that cold Arodors are safe, recent determinatione of vapour pressure (Southern Research Institute Final Report to M.C.C. on Projeot 526 by W.M. Rolan) permit the saturated vapour ocnoentrationa to be calculated as follows:- Vapour.Concentration fagm./m?) Arodor 1242 Aroolor 1248 Arodor 1254 20C. 4.7 2.1 0.8 A 8.2 3.0 1.1 HONS 095190 TOWOLDMONOQ46082 -4- Henoe air Batura tad with cold Aroclor ie at or above the maximum permissible conoentration. In general we have to accept Dr, Kelly's leading remarks and the conclusions of 2.C.I. Paints, but any consideration of the risk under a given set of conditions must involve the total exposure factor as well as the concentration. It is in this area that constructive answers could be made if the necessary background of data were available. However, the issue before us is whether M.C.L. should align its policy on the use of Aroclors in paint with that of M.C.C., and as I see it we have little alternative when M.C.C. can be quoted against us. The use of Aroclors in paints based on chlorinated rubber warrants special consideration in view of the following circumstances (a) Aroclors are of such value for the purpose that the manufacturers might well be * embarrassed if we withdraw our recommendation (b) they are not used for ordinary decorative and protective purposes in domestic and industrial premises, but to protect metals from corrosion, (o) they are not applied to hot surfaces under conditions whioh would constitute a hazard to nearby personnel. ' My recommendations are accordingly as follows:- 1. M.C.L. continues to Bell Aroclors for ubo in the manufacture of paints based on chlorinated rubber. 2. M.C.L. continues to sell Aroclors for production of paints intended for exterior application. M.C.L. discontinues the sale of Aroclors for use in the manufacture of all other paints. D.V.N. HARDY MONS 095191 TOWOLDMONOQ46083