The Right Hon. NEVILLE CHAMBERLAIN, M.P., Minister of Health. SIR, INTRODUCTION. 1. We have the honour to report that we have now considered the question which you referred to us, and that we think it desirable to make an Interim Report. Our Terms of Reference were as follows: "To enquire into the possible dangers to health resulting from the use of motor spirit containing lead tetra-ethyl or similar lead-containing compounds and to report what precautions, if any, are desirable for the protection of the public or of individuals in connection with the use or handling of such motor spirit.' 2. Our enquiries have shown that Ethyl Petrol is the only motor spirit on the market containing any lead compound, and this Report accordingly deals only with Ethyl Petrol. 3. We have read the accounts which appeared in Hansard of the two debates in the House of Lords in regard to the use of lead tetra-ethyl in motor spirit. We have held four meetings in public. At the first of these Dr. T. Carnwath of the Ministry of Health acted as deputy for Sir George Buchanan, having previously informed the Committee of the steps which had for some time been taken to keep that Department informed of developments in this matter. We have examined the following witnesses: Dr. Graham Edgar, Ph.D., Director of Research of the Ethyl Mr. A. M. Maxwell, Vice-President and Sales Manager of Mr. H. S. Tegner, B.A., A.M.I.A.E., A.M.I.P.T., of the Mr. Myer Coplans, D.S.O., O.B.E., M.D., D.P.H. Sir William Pope, K.B.E., F.I.C., F.R.S., Professor of Professor H. B. Baker, C.B.E., M.A., D.Sc., LL.D., Professor G. I. Finch, M.B.E., Department of Chemical We have also had the advantage of a personal conference with Surgeon-General Cumming, head of the United States Public Health Service, who was good enough to make arrangements to meet us when passing through London. 4. Ethyl Petrol has only been in use in this country for a very few months and then only to a limited extent. It has, however, been used extensively in the United States for some years, and we therefore considered that in the first instance we should investigate the experience in the United States and examine the validity of the evidence on which the Public Health Department of that country had based their decisions. BRIEF HISTORICAL STATEMENT. 5. For some years numerous investigations have been carried out with a view to improving the efficiency of internal combustion engines by providing a fuel which would allow of a higher compression in the cylinders. Large numbers of different materials have been tested, and up to now, we are informed, lead tetraethyl has proved to be the most effective. In 1923 a fuel known as Ethyl Petrol was placed on the American market. This fuel consists of a mixture of petrol and Ethyl Fluid, the Ethyl Fluid being composed of lead tetra-ethyl, ethylene dibromide and monochlornaphthalene. The amount of Ethyl Fluid added to the petrol varies according to the nature of the petrol, but in no case does the amount of lead tetra-ethyl in Ethyl Petrol sold for ordinary commercial purposes exceed 1 part in 1300 parts by volume or about 1 in 650 by weight. Lead tetra-ethyl is a very poisonous substance and its manufacture, its blending with the other materials to produce Ethyl Fluid and the mixing of the latter with petrol, must be carried out with very great care. Sufficient precautions were not at first taken in the manufacture and handling of lead tetra-ethyl, and in 1924 a number of deaths resulted in the United States. These deaths naturally created considerable anxiety, and Surgeon-General Cumming accordingly decided to call a conference in the spring of 1925 "To determine whether or not there is a public health question in the manufacture, distribution or use of tetraethyl lead gasoline." This conference was numerously attended by Public Health Officers, Professors of the Universities of the United States, Representatives of the Trade, and others. After considerable debate the following resolution was unanimously passed by this conference "It is the sense of this conference that the SurgeonGeneral of the United States Public Health Service appoint a Committee of seven recognized authorities in clinical medicine, physiology, and industrial hygiene, to present 67495 A 3 to him, if possible, by January 1 next, a statement as to the health hazard involved in the retail distribution and general use of tetra-ethyl lead gasoline motor fluid; and that this conference endorses as wise the decision of the Ethyl Gas Corporation to discontinue temporarily the sale of ethyl gas; that the investigation shall be paid for exclusively out of public funds; and that the results of this investigation shall be reported back to a public conference called for the purpose by the United States Public Health Service, at which labour shall be represented." 6. In compliance with the request of this conference, the Surgeon-General appointed a Committee constituted as follows: A. J. Chesley, M.D., St. Paul, Minn., Executive Health David L. Edsall, M.D., Boston, Mass., Dean of the Medical Reid Hunt, M.D., Boston, Mass., Professor of Pharmaco- Walter S. Leathers, M.D., Nashville, Tenn., Professor of Julius Stieglitz, Ph.D., Chicago, Illinois, Professor of Charles-Edward Amory Winslow, M.S., New Haven, Conn., 7. The composition of this Committee, which numbered amongst its members some of the most eminent scientific men in the United States, was such as to command general confidence. The Committee held their first meeting on June 15, 1925, and at their second meeting on the 29th of that month certain lines. of investigation were settled. All the resources of the United States Public Health Service were placed at the disposal of the Committee, and Dr. J. P. Leake, a Commissioned Officer. in the United States Public Health Service, was directed to take charge of the investigations. It will be seen that the question referred to the United States Committee was practically the same as that referred to us; they were asked to determine : What health hazards, if any, were involved in the retail distribution and general use of tetra-ethyl lead gasoline as an automobile fuel. THE OBSERVATIONS AND EXPERIMENTS MADE BY THE UNITED STATES GOVERNMENT COM MITTEE. 8. Before the Government Committee began their investigations, a large number of experiments on animals had been made, mainly by the United States Bureau of Mines in collaboration with the trade interests concerned, and the Government Committee decided that they would base their investigations chiefly on human subjects who had for a considerable period been handling and using Ethyl Petrol. It was considered that such investigations would be more likely to produce evidence which could be accepted as conclusive. Observations were made on the following groups of workmen : (A) Control group of 36 chauffeurs of cars using ordinary petrol. (B) Test group of 77 chauffeurs of cars using Ethyl Petrol only since July, 1923. (C) Control group of 21 workers in garages, at service stations, or on delivery trucks. Ordinary petrol only was handled by these men. (D) Test group of 57 workers engaged on work similar to that of group (C) except that Ethyl Petrol was used. (E) Control group of 61 workers at works where a recognized lead hazard existed, such as, e.g., accumulator works. This group was selected in order to check the adequacy of the clinical and analytical methods used. 9. The observations extended over a period of approximately six months. Each individual was subjected to a careful clinical examination, and, in addition, smears were made from his blood and a specimen of his faeces was collected. The examination of the faeces for lead was made by chemists who had been especially trained in the technique of the method; the blood examinations were also made by skilled observers, and were arranged so that the counts in each case were checked by several investigators. The clinical examination was conducted by four physicians. A careful industrial history of each subject was obtained, and a thorough medical examination, including a medical history, haemoglobin estimation, red cell count, blood pressure records, visual acuity tests, urine examinations, etc., was made. In addition a determination by a special method devised for the occasion was made of the muscular strength of the extensor and flexor muscles of the forearm. Special attention was directed to three methods which it was hoped would yield quantitative data of an objective character. These were :(1) The determination of the amount of lead in the faeces as an index of exposure to lead. (2) The estimation of the number of stippled red cells which, in the absence of other causes, might be considered as an index of lead absorption, and (3) The measurements of the strength of the extensor muscles of the forearm as an index of lead poisoning. The first two methods yielded results of positive value, but this was not so in regard to the third. RESULTS OF INVESTIGATIONS MADE BY THE UNITED STATES GOVERNMENT COMMITTEE. 10. The indications of exposure to lead were found to be practically the same among the chauffeurs of cars using ordinary petrol and the chauffeurs of cars using Ethyl Petrol. The chauffeurs of the cars using Ethyl Petrol had been using the material continuously since July, 1923. As regards the garage workers, the indications of exposure to lead were very slightly greater in the case of workers in garages in which Ethyl Petrol only had been used since July, 1923, than in garages not using this material, but in both cases the indication of exposure was small and far less than that found in the workers employed in the manufacture of electric accumulators, for whom recognised lead risks exist. The indications from the examination of the blood for stippling followed very closely those for the examination of faeces. The clinical examination of the men using Ethyl Petrol did not disclose any symptoms of ill-health indicative of lead poisoning. 11. The investigators found that an appreciable amount of lead was present in the faeces of garage workers in garages in which Ethyl Petrol had not been used, and accordingly examined the faeces of ten workers in the Government Laboratory who had had no known exposure to lead. Lead was found in the faeces of such workers in quantities not appreciably different from the amount found in the faeces of garage workers. We may observe that some preliminary experiments which our colleague Mr. Chaston Chapman has kindly made for us have shown lead to be present in measurable quantities in the urine. of laboratory assistants in this country with no known exposure to lead. Mr. Chaston Chapman's experiment gave results |