Document 1g643Na9D9Qjo7j3vBmnrNxOa

CONFIDENTIAL TOi DR. J.W. BARRETT. dvmhAieb c.o. Dr. J.A. Gardner. Dr. W.MoG. Morgan. Mr. W.I. luar. Mr. C.G. Hiekhaa Dr. H.R. lewan Dr. D.S.P. Roebuck Mr. J.S. Hunter Mr. E.L. Plxton Mr. N.G.H. Thomas. Mr. J.A. Brlndle. 6th Deoeaber 1955 AROCLORS TOXICOLOGICAL EXAMINATION Since ey eoanunication of 19th August 1955> when I sunned up the position confronting us following the reoeipt of the reports of the Kettering Laboratory,' Dr. Newnan 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 Amerioan Conference of Governmental Industrial Hygienists In support of a claim that the official table of maximum permissible vapours concentrations should include the items;- I 42S Chlorinated Diphenyl (Aroelor 1242) 2 agras./n? innw uui* 7 b"'" - **' -eet anlaale but that-Aroelor 1254 at 1.5 mgrm./m? oaused slight but positive sign* of Injury.'' lou will note that M.C.C. do not Introduce a safety factor In translating these aninal test results to hunan beinga, and In fast regard such a factor as unnecessary in aninal testa of such thorough ness as those carried oat at Kettering. It will be acnetine before we know the deoisian. Zn ay view It would not be unrealistic to assign a value of 2 agru./V te Aroelor 1242 but the ease for sotting the Unit at 1 agra./a3 for Araolor 1254 is not so logloal. After all 1254 sen oause slight but peroeptible daaage at 1.6 ngm./m3 and who can say whether it would be harmless at MUNS 095188  - 2- 1 ngra./m^. However, if the M.C.C. recommendations are accepted there will be an implication that Aroolor toxicity inoreasea with chlorine content, a reversal of the position suggested in M.C.C. technical literature. M.C.C. Application Data Bulletin Ho. P-115 states "If Aroclors are used at elevated temperatures suoh as 200 or 300C. in open systems methods must be designed to exhaust any vapours arising from these open systems. This applies especially to lower chlorinated Aroclors 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 suoh as Aroclor 1266 the allowable limit is about 10 milligrams per cubic meter of air and accordingly. Aroclors of this type are believed to be of a much lower order of toxicity. Whatever the outeoae, there will be no impact on M.C.C. policy regarding the use of Aroolors in paints since M.C.C. have long ceased to recommend the use of Aroolors for this purpose. However, M.C.L. has continued 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. This was thought to have the duel advantage of using a material of (a) lower intrinsic toxlalty (b) lower vapour pressure. It la now clear that toxiolty increases with degree of ohlorination and that this effect may canoel or even outweigh the.advantage due to decreased vapour pressure. We have tended to draw a distinction between the use of Aroclors in latex paints on the one hand and in conventional paints an the other, the concensus of opinion being that the rate of volatilisation from the former is greater than from the latter, and as a result we are no longer reoonmending Aroolors for latex paints. The decision now before us is whether we should continue to sell Aroclors for use in conventional paints. On this issue, the recent decision by I.C.I. to discontinue their usage of Aroolors in ordinary paints is considered to be an indication of the line that may well be taken by our other customers. Broadly speaking the main objections are that the paint manufacturer oannot control the paint user who may apply in the form of spray, and may use on hot surfaces. In either case a degree of risk must be admitted. As to bow serious the risk nay be it depends naturally on the total time for which any individual is exposed during his life time. There must dearly be Clroumstanoes under which the use of Aroolor containing paints will con stitute a health hasard, particularly to individuals who for one reason or another are constitutionally lass resistant than the norm. The I.C.I. decision must have been influenced quite materially by a letter from Dr, Kelly to Mr. Hoy Wltterseheln (dated 15.7.55.), a copy of whioh reached them through Canadian Industries Ltd. The relevant passages are as follows;- MCNS 0951S9 -3- Aroolor ahottld not ba sprayed on the Job In an Industrial plant where there ara Plant person*TM! who nan breathe the vapours. There la no danger at ell If the material le brushed an, and there is no danger In spraying it if the workers use a booth or UBe an approved respirator and no one inhales the spray. "Aroolor fumes at room temperature very probably would not present any hasards. Hist or spray, however, is another problem entirely and that is the reason for the above recommendation. After all, the toxicity of Aroolor must take into consideration 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 I.C.I. Paints are underlined and may be oonaldered to be reflected in their conclusions which I now quote below: - In brief (a) The spraying of Arodor paints 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 Aroolor-oontalning paints would involve toxic hazards either during appli cation or subsequently, and where cautionary advice would be appropriate. The need for speoial precautions would limit the use of Aroolor paints in these cases. (c) As far as the paints in question are concerned it is impossible to know how any particular can may be eventually used, so every oan would need to show the warnings and precautions for all foreseeable eventualities. The presence of these warnings would tend to deter people from using the paints even in oases where no special precautions were needed.* With reference to the impression generally given that cold Aroclors are safe, recent determinations of vapour pressure (Southern Research Institute final Report to H.C.C. on Projeot $26 by W.M. Nolan) permit the saturated vapour concentrations to be calculated as follows:- Vapour Concentration (mgrm./m3) Aroolor 1242 Aroolor 1248 Aroolor 1254 20C. 4.7 2.1 0.8 3.0 1.1 MONS 095190 -4- Hence air saturated with cold Aroclor la at or above the maximum permissible eonoentration. In general vie have to accept Dr,, Kelly's leading remarks and the conclusions of l.C.I. Faints, but any consideration of the risk under a given set of conditions must involve the total exposure factor as wall 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) Aroolors 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 surfnoes under conditions which would constitute a hazard to nearby personnel. My recommendations ara accordingly as follows:1. M.C.L. continues to sell Aroolors for use in the manufacture of paints based on ohlorlnated rubber. 2. M.C.L. oontlnues to sell Aroclors for production of paints intended for exterior application. 3. M.C.L. discontinues the sale of Aroclors for use in the manufacture of all other paints. D.V.if." HARDifJ MOMS 095191