Document VGMgmMOj203nY4LVRXo3679nw

I SUIIMARY OF THE XXTIOXAL SAFETY COUSCIL STUDY OF BENZOL POISOMXG* C.-E. A. WINSLOW,DR.P.H. Professor of Public Health, Yale School of 411cdi&c; Chdrman, Committee on Benzol of the National Snjctu Council INT~ODUCTION Progress reports of the Committee HE Committee on Benzol* was were presented 3t the Buffalo Safety organized as a result of a Congress in 1923, the Louisville Safety discussion of the hazard in- Congress in 1924, snd the Cleveland volved in the use of the solvent in Safety Congress in 1925. The final question which was presented 3t the report of the Committee was published 1922 Sation31 Safety Congress held in May, 192G, as a pamphlet of 128 in Detroit. The work of the Com- pages for the Chemical and Rubber mittee vas made possible through Sections of the Kational Safety Coun- the appropriation of S5,OOO by the cil by the National Bureau of Casualty National Bureau of Casualty and and Surety Undermiters. Surety Underwriters; through the Before considering in detail the assignment by the Surgeon-General conclusions of the Committee it seems of the United States Public Health desirable to bring out two points in Service of Dr. Leonard Greenburg regard to its sctivities which seem to work on the problem for almost to the m i t e r to be of somewhat more a whole year; through the Iosning of than passing significance. professional personnel for shorter pe- The first point which may be noted riods by the Massachusetts State is that we have here a somewhat Board of Lzbor and Industries (Mr. eshaustire study of an industrial John R. Dexter) and by the Hood poisonous hazard which has been Rubber Company (Dr. J. N.Shirley) ; conducted primarily by and for an and through assistance or materials organiation representing industry it- furnished by the Aetna Life Insur- self. It is true that the United States ance Company, by Dr. N. B. Herman of Johns Hopkins University, by the Public Health Service, the Massachusetts State Board of Labor and Yale School of Medicine, and by the Industries, and the universities have Weirton Steel Company. generously co-operated in the task. Yet the initiative for the whole *Presented at the Fifteenth Annual Safety Congress of the Xational Safety study has come from the National Council at Detroit, Oct. 28, 1926. Re- Safety Council, a group of industrid- ceived for publication Oct. 30, 1926. C.-E.A. \\'inslow, Chairman, Leonard ists federated for the safety of the Greenburg, Vice-chairman, W. S. Paine, worker on the ground that the human Secretary H. Bradshaw, J. V. S. Brady, A. C. Fieidner, C. F. Horan, L. E. Weber, element is a primary factor in pro- and J. M. Xeiss. duction; and the fact that this body Vol. 9 No. 2 61 62 THE JOURKAL OF INDUSTRIAL HYGIESE with its long and splendid record of physiologic tests suitable for the achievement in accident prevention detection of latent and incipient should have now definitely entered damage to the human body such as the allied field of industrid poisoning threatens the subsequent development is cause for profound satisfaction. of active clinical disease. In Europe the whole program of Since this benzol study was made, industrial hygiene is essentially a two other investigations in this coun- governmental one. In the United try have been conducted along States, on the other hand, a major essentially similar Lines-the work of part of what has been accomplished the United States Public Health for industrial safety and sanitation Service on tetraethyl lead, and the has been accomplished by the initiative work on spray coating by the Pennsyl- of broad-minded employers of labor. vania State Bureau of Labor and by This benzol study is a new demonstra- the Committee on Spray Coating of tion of the readiness of industrial the National Safety Council. These leaders to learn the facts and then to three studies, all involving the prin- apply all available knowledge to the ciples outlined above, seem to the promotion of health and efficiency. miter to embody a relatively new Nest, I would call your attention and highly promising contribution to what I believe to be a second to the technic of industrial hygiene. somewhat notable fact about this With these preliminary remarlis we investigation-the method by which may proceed to a summary of the it was conducted. Nearly all previous main conclusions reached by the work on industrial poisons has been Committee on Benzol; the body of of what may be termed a qualitative supporting evidence must be sought type. It has dealt with a relatively in the full report of the Committee small number of instances of poisoning itself. which have come, one by one, to the notice of physicians, and such cases, Chemistry of Benzol from the nature of the situation) have been as a ivle of a more or less aggravated type. In this benzol study there has been for the first time a conscious and definite effort to pick out a representative group of apparently normal workers in a given industry and to make a quantitative study of: a. Mechanical conditions affecting Benzol or benzene (CsHs) is a colorless liquid, boiling a t about SO'C.,? obtained from the distillation of coal tar and from the strippings of coke oven gas. It is highly insoluble in water, slightly soluble in alcohol, and completely miscible with ether, acetic acid, carbon disulphide, and a large number of organic substances. a possible poison hazard; b. Analytic data indicating the de- gree of atmospheric pollution by the poison in question; and c. Physical findings including delicate chemical, microscopic, and The usual figure given in the textbooks is S0.2"; but it may be noted that a sample of very ure benzol_nnalyzedfor the Committee siorved that t O per cent. of the material came off between 59.5 and 59.9'. The International Critical Tables repared by the Xational Resenrch Councir give 79.6') which is undoubtedly correct. J. I. H. Feb.. 1927 BEXZOL POISON1P;G 63 There are many substances commer- chemical industries, including oil ex- cially known as "benzol," some of traction, dye and dye intermediates, which contain benzene, while others manufacture of paints, varnishes, and do not. All of them are, of course, stains, and of paint and varnish to be shnrply distinyishcd from removers, benzol is used in large benzine w h i h is a petroleum product quantities, but the very nature of the (a mixture of CsH14and C,HIS). industry demands that it be kept in Benzol was discovered by Faraday 3 closed pipe line system, any open- in 1825 in the liquid produced by the ings representing 8 loss of valuable compression of illuminating gas ob- vapors, and making the system an tained from certain oils. In 1865 inefficient one with a correspondingly KekulB announced its structural large financial loss. formula. hfansfield studied its In a second group of processes commercial production from coal tar represented by the use of benzol (a) in 1849, and twenty years later Caro in the rubber industry, (b) in artificial Clemen and Engelhorn patented a leather manufacture, (c) in sanitary process for its recovery from illumi- can manufacture, ( d ) in dry cleaning, nating gas. Only, however, with the and (e) in connection Kith the handling work of Carves, of von Hiissener, of paints, varnishes, and stains, ben- and of Brunck on the production of zol is employed chiefly as a solvent benzol from coke oven gas, between or a vehicle, and as a part of the 1884 and 1887, did this substance process it must be removed so as to come t o play a really important leave the originally dissolved sub- part in industry. stances in place. The method of removal of the benzol is usually to Industrial Uses of Benzol permit it to evaporate; in most w e s The commercial uses of benzol grew gradually and steadily from 1890 to 1915; but the development of benzol production during the war in connection with the manufacture of this is done in the cold, in some cases, however, the compound may be warmed-a procedure which naturally removes the benzol with greater rapidity. explosives led to an increase in the manufacture of benzol which has in Benzol Poisoning turn opened the way for a rapid As in the case of many other toxic broadening of the field for the com- substances used in industry, benzol mercial uses of this substance. poisoning eshibits itself in two quite In considering the practical problem distinct forms, acute and chronic, of the use of benzol in industry it is according as esposure is brief and important to remember that two intense on the one hand or moderate very distinct types of processes are and prolonged on the other. .. ,- involved. In such industries as (a) Acute.-Occasional instances of the distillation of coal and coal tar in acute benzol poisoning may be found 4, the production of benzol, (b) the in medical literature extending back blending of motor fuels, and (c) the to 1862. In our reviek of the litera- Pol. 9 No. 2 .1 I: ' I '1 ,. ,i .I '! ness) of the lips and finger tips; (c) feeble and rapid pulse; ( d ) breathlessness and D feeling of tightness in the chest, sometimes culminating in immediate death from respintory paralysis; (e) visual disturbances, with nervous excitation, tremors, and convulsions, and more rarely mznis or delirium; (f)reddish spots on the skin and internal surfaces due to small hemorrhages in the tissues; and (8) where the substance has been taken in by the mouth, symptoms of acute gastro-intestinal irritation. Death m y occur within five minutes after esQosure or the patient may epparently recover and succumb seven1 days later. There appear to be marked individual variations in susceptibility to benzol; and the effects of a given atmospheric condition may probably be increased by vigorous muscular exertion, 3s suggested by the fact that D mnn fvst rendered unconscious by the inhalation of benzol vapors may often recover while those overcome while engaged in rescuing him may die. The treatment of acute benzol poisoning involves, first of all, prompt restoration of the respiratory function by artificial respiration. Chtonic.-Chronic benzol poisoning, resulting from continuous or repeated es;posure to benzol fumes in concentrations too low to produce marked narcotic effects is, of course, 3 condition much more obscure, and much more likely to be overlooked, than is acute poisoning. It is particularly likely.to occur in the second group of industries alluded to above, in which benzol is used 3s a solvent and to 3 greater or less estent evaporated into the sir of the workroom. Chronic benzol poisoning w&s first described by Santesson, in 1897, in workers in a rubber factory in Uppsala, and mas first reported in the United States by Selling in 1910, as occurring in the coating room of 3 tin can plant. The more commonlyobserved symp toms of chronic benzol poisoning may be summarized as follows: (a) general systemic disturbance aa evidenced by headache, dizziness, mealiness, loss of appetite, and loss of weight; (b) pallor, shona ?)y blood esamination to be due to true anemia; (c) m r k e d reduction in white blood cells (revealed of course only by microscopic examination); ( d ) bleeding from nose, gums, vagina, and bowels, with the development of purplish spots caused by small hemorrhages within the tissues; (e) sore and spongy yms, and burning of eyes J. I. H. Fcb.. 19Z7 BEKZOL POISONING - and throat; (j)shortness of breath and tightness of chest; (9) sometimes, abdominal pains, nausea, and vomiting; (h) somctimes, slight tremors, visual disturbances, and abnormal sensitiveness to touch; rarely, conmlsions and delirium; (i) rarely, rashes and skin eruptions. Detection of chronic benzol poisoning in its early stages, with prompt removal from esposure, generally leads t o complete recovery. If the case of chronic poisoning be a severe one, however, certain of these symptoms may persist for 3 long time after exposure has ceased; and nearly one in five of the cases reported in the literaturc has ended fatally. Toxic dction of Benzol Benzol introduced into the body (vhich in practice ordinarily occurs a~ a result of the inhalation Of its fumes) exerts three more Of less distinct major effects on the body. It p h p the part Of an anesthetic O f WrCOtiC leading t o dizziness, faint- and Coma- It is at the same time, however, a neNe irritant p r e ducing characteristic spasmodic movemerits, and actual damage to nerve c o r n and death may also RSdt from this neurotosic action aS Well from the narcotic action Of benzol. Above all, however, this substance P o ~ e ~aedsefinite and specific destructive power for the blood cells and for those organs which produce these cells. Herein lies its most universal and most characteristic effect. Effect ora Blood Cek-At first there may be a slight increase in white blood cells but this is really due to a destruction of the white cclls in the circulating blood, overbalanced by the compensatory pro- duction of more white cells by the blood forming organs (the lymph nodes, spleen, and bone marrow). This condition is exceedingly transient, however. Very shortly the blood forming organs themselves are in- jured, particulsrly in respect to their power to produce the special liinds of white cells known 3s polymorpho- nuclear leukocytes 3nd lyrnphocytes. The total white cell count falls rapidly, producing the condition known as leukopenia. The tissues which produce the red cells of the blood zre less readily d e c t e d and a normal or increased red cell count may persist for some time, parallel with a great decrease in white cells. ultimately, hol\.ever, the blood forming organs are so seriously damaged that the n m b e r of red cells, too, falls off, producing a pronounced anemia. A decrease in the white cells of the blood is therefore the first indim tion of early chronic benzol poisoning, and the effect is so f a f i r that hen- zo] has been therapeutically for the treatment of &eases char- acterized by an excessiveconcentration of white blood cells. Our studies indicate that a fall from a normal value of 7,500 to 9,000 white cells per cubic millimeter of blood to 5,600 or less m y be taken 89 a fair index of the presence of this disease. Of c o u ~ e ,conditions other t b n benzol poisoning may cause leukopenia, but with a history of exposure to benzol and in the absence of symptoms of certain acute communicable diseases or of certain other industrial intoxi- 1'01. 9 No. 2 , :iq '8 1 ...' 1 *.'# t ,i r .I , ,(I .! v-, j .'V. .:Si i I ! ! i i j 'I 1 I .I 66 THE JOURSXL OF IXDUSTRIAL HYGIESE cations which may be associated persons were esposed to benzol, eleven, with leukopenia, the diagnosis may or nearly hdf, reported cases of be made on this basis with rea- poisoning, while of six plants in sonable accuracy. This reduction in which Mty or more employees were white cell count generally precedes exposed, all but one had had cases any other symptoms of benzol poison- of poisoning. ing and may therefore exist in persons During the last year of our work mho mould be considered normal by we made no attempt to estend this the ordinary clinical tests. survey of the extent of the benzol The seriousness of benzol L u k e hamrd; but a t least seven fatalities penia is emphasized by the obser- from this cause were brought to our vations msde by a number of investi- attention during the first nine months gators that resistance to pneumonia of 1925; and during the five years and other bacterial infections is greatly ending June, 1923, there were in the reduced by such a condition. state of Ohio, alone, twenty-nine cases of benzol poisoning, so ob- ESTEST OF BESZOLPOISOXIKING vious as to receive the benefits of AXERICLS ISDCSTRY industrial compensation. In order to gain some ides of the It is therefore clear that the hazard estent of the benzol hazard in Xmeri- of benzol poisoning in American in- can industry we sent out a question- dustry is a serious one and consti- naire in 1923 to a group of 324 in- tutes one of the major problems of dustrial establishments which, from industrial hygiene. the nature of their products, might be expected t o use benzol. Of these FIELD STUDY establishments, 140 replied; and, of Conditions in Industries Empl q i n g the 140, eightyfour were found to Benzol.-In order to determine the be making use of this substance in actual extent of the benzol hazard greater or less amount. The largest under various industrial conditions, amounts of benzol mere apparently we selected, after a preliminary sur- used in the chemical industries, in vey of industrial establishments, the can seal industry, in the rubber eighteen workrooms in twelve different industries, and in the manufacture of plants for further intensive study. artificial leather, but in the chemical Most of these were rubher factories trades the material is generally used of various sorts, but dry cleaning, in enclosed processes and the number sanitary can manufacture, and arti- of employees esposed is small. ficial leather manufacture were also From the results of this question- included. naire and from our subsequent field The workrooms mere studied from studies made in 1924 we collected a an engineering standpoint, with r e list of Gfteen fatal and eighty-three gard to the conditions under which nonfatal cases of benzol poisoning the benzol mas used and particularly occurring during the years immediately the type of eshaust ventilation pro- preceding. Out of twenty-three es- vided; analyses of the air were made tablishments in which ten or more under both summer and winter condi- J. I. E. Feb.. 1927 BESZOL POISOSISG G7 tions, in order t o deterniine the cstent individual analysis in 3 compound of the resulting contamination of the' mising room and 4,140 parts in a atmosphere. For nir analysis, we dry cleaning cstsblishment). Five of used the charcoal absorption method the eighteen rooms gave average which gave y,not benzol nlonc, but figures above the value of SSO parts the total contcnt of solvent vapors. which Legge found associated with For convenience, however, the results clinical poisoning. On the other have been espressed in terms of hand, with efficient local eshaust benzol. Whether other solvent ~ a p o r s ventilation, nnd careful management were actually present or not is of of all details of the processes involved, course indicated in each instance. it seems sometimes possible to use With small amounts of benzol in benzol in coating and mising rooms, use and with no ventilation, or with and in sanitary can manufacture, general ventilation only (which our with an atmospheric pollution emount- studies indicate is wholly inadequate ing to less than 100 parts of solvent to cope with the benzol problem), vapors per million parts of air. Our we found average concentrations of nest step wns to determine whether 100 to 1,360 parts of benzol per this degree of protection was suffi- million parts of air. With large cient to avoid danger to health. amounts of benzol in use, under similar conditions, we found average Extent of Early Benzol Poisoning values from 340 to 1,800 parts per million. On the other hand, in plants using large amounts of benzol but with enclosed systems of local eshaust ventilation, me found averages only between 70 and 500 parts per million. The plant which had the most efficient systems of local exhaust gave us average values lying between 70 parts in summer and 90 parts in winter. It appears from this study that some of the workrooms investigated at times approached the concentrations of benzol which have been found t o cause acute poisoning (Lehmann states that 0.015 gm. per liter, or 4,700 parts per miilion,5 msy produce confusion in half an hour, and we found 2,640 parts in one Results of Clinical Tests and Bhod Ezaminations.-The crux of our problem was the esamination of workers esposed to benzol under various industrial conditions, using the white blood cell count as our indes of early benzol poisoning. We were ultimately able to make tests of this kind on eighty-one workers in the eighteen workrooms discussed above (see Table 1): and we found that tment,y-six of the persons examined, or 32 per cent., showed clear evidence of blood cell destruction, as indicated by a white count below 5,500 (or in one instance 3 borderline white count of 5,800 with a very low red cell count). In seventeen instances the white count was below 5,000, in ten instances below 4,000, and in three J The factor (313) for converting milli- instances below 3,000. In only ten grams per liter of benzene into parts per million is taken from U. S. Bur. Mines, instances, however, was the red cell Tech. Paper 218, Table 8, p. 52. count below 4,000,000. Control ex- VOl. 0 KO. 2 s ' .I/ .:!Ii 1;',; L' .it I, !:.I', *. ; :-$Q !( . . 1. yg !i' .a 9 I:P 68 THE JOURXXL OF IXDUSTRWL HYGIESE amination of some fifty workers not The results of these blood esamina- exposed to benzol failed to shorn any tions are distinctly disconcerting. c such abnormal blood pictures. Not only did about one-third of the TABLE l.--SUiMPrlARY OF BLOOD FIXDINGS IN EIGHTY-OXE WORKERS -POTESTIALLY EXPOSED TO BENZOL .- ...-__- GROUP ROOU LOCAL VENTIL4TION AVERAGE BESZOL IN AIE BLOOD FINDINGS Jumbei jum- Win- E-- mer ter ined -- (81) Small amount of benzol used 1 No local ventilation Low benzol content in air 150 B 60 27 A 1.p.m. p.p.m 100 ... 150 ... 110 .. . 9 1 2 2 0 1 Small amount of benzol used No local ventilation ]I-, High benzol content in air 27 B 59 61 A 61 B Large amount of benzol used Local ventilation Low benzol content in air I11--4 78 A 150 A 75 B i00 150 130 1,360 ... 210 210 560 i o 90 90 ... loo ... 2 9 12 1 0 1 3 0 1 0 1 0 1 1 Large amount of benzol used Local ventilation 111-B High benzol content in air Largc amount of benzol used No local ventilation High benzol content in air 91 50B 50 A 75 A 75 B 23 53 95 1so 400 ..... 430 ..... 500 130 330 340 ... ..... ... 620 ... 1,sooi ... 5 3 4 10 1 6 9 3 0' 1 1 1 0 2 0 2 1 Three clinical cases, one fatal since tests mere made. In only nine cases out of the twentysix was it possible to obtain a fairly complete medical examination; and of these nine, five gave a history more or less clearly suggestive of chronic benzol poisoning (including two or more of such symptoms as headache, dizziness, pallor, loss of appetite, digestive disturbance, spongy gums, and nosebleed). eighty-one workers eshibit clear evidence of early benzol poisoning, but, what is still more serious, the evidence of poisoning was clear even with good exhaust ventilation and low atmospheric contamination. In the group of workrooms using large amounts of benzol without local ventilation, ten out of nineteen workers gave a positive pictqre; in the group of J. I. H. Fcb.. 19?7 - BESZOL POISOXISG 69 rooms d i e r e only small amounts of benzol were used without local ventilation, eiewn out of thirty-sk workers were positive. in the group using large amounts of benzol but with local exhause ventilation, only five out of twenty-six workers were positive. Thus, local eshaust ventilation reduced the proportion of workers afiected from nearly one-hnlf to less thm ooe-fifth; but even one-fifth remains a pretty high figure. Unfortunately we irere unable (after repeated efforts) to make blood examinations in the can factory costing room which gave the best analytic results; but in a coating room with local ventilation, shoning only 90 parts of benzol in the air in summer, the single worker eqosed proved positive; and in a mising room in an artiiicial leather factory, with only 100 parts of benzol in the air in summer, one out of three men proved positive. We are forced to conclude that the control of the benzol hazard (except where the substance is used in completely closed systems) is esceedingly difficult; that, in practice, systems of exhaust ventilation capable of k e e p ing the concentntion of benzol in the atmosphere below 100 parts per million are estremely rare; and that, even when this is accomplished, there remains a decreased, but substantial, hazard of benzol poisoning. Xecomnwndations i n Regard f o the Use of Benzol In Enclosed Systems.- As has already been pointed out, benzol is used in industry under two more or less distinct sets of conditions. In the nmnufncturc of benzol from coal and coal tar, in the blending of motor fuels, znd in the chemical industries, the solvent is necessarily handled in closed containers and pipe systems. Here, chronic poisoning is unlikely to occur and the chief hazard arises from acute poisoning due to carelessness in the cleaning of tanks, breaks in the apparatus, and similar accidents. W t h regard to this type of process, it seems certain that with proper care in construction, maintenance, and operation the use of benzol a n be made suficiently safe to warrant its employment. It is true that fatal accidents have occurred, and nil1 no doubt continue to occur, in these processes, just as such accidents occur, and will continue to occur, from the use of steam boilers. The danger is, however, in both instances a controllable one to be met by careful attention to safety provisions and not by the abandonment of the use of the substance or of the device in question. The chief measures of protection which should be enforced in industries of this type are: a. Regular and systematic inspection of apparatus to insure against breaks or accidental leakage. b. The greatest possible care in freeing t a n k or other receptacles which have contained benzol from all traces of the substance before they are entered for cleansing or repairing. c. The protection of workers entering enclosed spaces liable to contain benzol fumes by the use of positive pressure air helmets or hose masks; and the conduct of all such work by VOl. 9 No. 2 . .I C teams of two or more men who are certain enclosed processcs direct ven- familiar with the dangers involved. tilation (from the enclosure) with A s a So1uent.-In the rubber in- upward draft may be indicated. dustry, in artificial leather manu- b. Where locnlized heat is applied facture, in sanitary can manufacture, in the evaporation of the benzol, in dry cleaning, and in the use of hoods or enclosures should be pro- paints and varnishes, benzol is em- vided with up draft. local eshnust. ployed as a solvent or vehicle under This draft should be sufficiently in- conditions which, almost of necessity, tensive and applied so closely to the permit more or less evaporation of point of origin of the evaporating the solvent into the atmosphere. benzol as to insure the cotnplete Herc, there is relatively little danger removal of all of the benzol before of acute benzol poisoning, but very the heated surface is removed from great danger of chronic poisoning, the hood or enclosure. This recom- arising from prolonged or repeated mendation deals with specific proc- exposure to the fumes. esses where sufficient upward air In order to minimize such hazards movement is created by the heated as far as possible, there are two surface t o overcome the natural general types of precautions which density of the benzol vapor. should be taken, tending respectively Masks and respirators should not to decrease the degree of esposure be relied upon to protect the worker and to detect and control incipient against ordinary routine exposure to poisoning in its earliest possible stages. benzol fumes, since such devices 1. To diminish esposure, enclosed cannot be made efficient without a t processes should of course be used the same time making them too wherever possible and, whenever con- uncomfortable tobe worn continuously. tainers are cleaned or apparatus re- 2. To detect incipient benzol poison- paired, the special precautions ing a t a stage when its effects can be discussed in the preceding section minimized, it seems essential to the' dealiig with enclosed systems and Committee that all workers to be the danger of acute poisoning should employed in processes where esposure be observed. Wherever employees to the fumes of this solvent is involved are liiely in the course of their work should be given a thorough medical t o be exposed to benzol fumes, as esamination before employment and in the ordinary solvent and evapora- should be reexamined, with systematic tive processes or in handling the blood counts, once a month thereafter. products of such processes, they should In addition to this routine reesamina- be protected by the most effective tion, absence from work should be local eshaust ventilation designed promptly followed up by some person according to the following general conversant with the symptoms of principles: benzol poisoning; and the employees a. Where benzol is evaporated a t themselves should be made familiar room temperatures, air removal by with the symptoms which are most local exhaust ventilation with down likely t o occur. draft is recommended, although in No worker should be employed J. I. H. Feb.. 1927 c! F L BEXZOL POISONING - 71 in 3 benzol process who shows signs of: 3. Organic disease of heart, lungs, or kidneys. b. Hemorrhagic tendencies. c. Anemia or any unusual blood picture. c Any worker who, on reesamination, shows any of the following symptoms should be promptly escluded from benzol esposure and transferred to some other department of the industry: a. Hemorrhages from the mucous membranes of the nose, mouth, or other organs. b. Decrease of more than the fol- lowing amount from the employee's n o m 1 blood picture (normal condi- tions will be obtained from previous examinations of the individual em- ployee): white cells, decrease of 25 per cent.; but in no case should an employee' with a white cell count of less than 5,000 be continued in ben- zol processes; red cells, decrease of 25 per cent.; hemoglobin, below 70 per cent. LABORATORY STUDY Relative Toxicity of Benzol and its Higher Homologues of the subject are somewhat conflicting, probably because of the uncertain composition of the materials used by certain workers and of the lack of clear discrimination between the various types of toxic action produced. In general, however, the more careful work has suggested that benzol is more dangerous than its higher homologues. Our own investigation was conducted with d u l t white rats which were kept on a standard diet and subjected to preliminary study t o determine the normal range of var& tion in the blood count of each animal. The substances used for our tests were four in number: pure benzol (boiling point 80');' toluol (boiling point 111'); xylol (boiling point 139");and Hifiash naphtha (boiling point chiefly between 165" and 185"). The influence of these solvents was studied in three m e r e n t ways: by intraperitoneal injection; by subcutaneous injection; and by inhalation in a chamber specially arranged so as to make possible n close control of the proportion of solvent in the atmosphere. Inttapen'toned I n j e c t i o n . - The .. "..-.;1 . *. . 'I .. 1 ; 72 THE JOURSXL OF IKDCSTRIAL HI-GIESE treme weakness. With doses in escess of 1 C.C. per kilogram of body weight the temperature of the animal dropped 3" to 8C. At times paralysis of the extremities was practically complete. The animals always recovered from doses up to 1 c.c., but 2 C.C. per kilogram of body weight always proved fatal. I t is of special interest to note that in the animals which recovered neither the white nor the red blood cell counts were materially afTected. This is in accord with conclusions from the clinical study of human cases which indicate that acute and chronic benzol poisoning are quite distinct phenomena and that acute benzol poisoning, which is due to violent irritation of the nerve centers and consequent asphyxiation, fails entirely to produce the effect on the cell content of the blood which is characteristic of chronic poisoning. The other three solvents studiedxylol, toluol, and Hiflash naphthawhen injected intraperitoneally, showed a wholly different picture. Xylol up to 0.75 c.c., and toluol up to 0.75 C.C. per kilogram of body weight, produced no symptoms mhatever except slight apathy. Hitlash naphtha in doses of 0.5 C.C. produced some limpness and paresis and a lowering of body temperature. In larger amounts all these three substances produced deranged equilibrium and weakness, culminating in loss of power of movement and u l t h t e l y in complete narcosis with fall in temperature, but the effect in the case of toluol and xylol was rehtively lacking in the symptoms of toxic stimulation of the nerve centers and was of the nature of a narcosis, rather than of a nerve irritation. Subcutaneous Injeclion.-In view of the fact that the present study was concerned mainly with chronic poisoning, we have laid chief stress upon our subcutaneous injections. Here, doses of 1 C.C. per kilogram were injected under the skin of the abdomen or back (mixed with equal parts of olive oil to decrease local irritation and delay the mte of absorption). Injections were repeated daily for a period of four to twenty-two days. This mode of treatment leads to a gradual absorption of the injected substance, entirely comparable with what occurs in human casea of chronic industrial poisoning. In the case of benzol it caused obvious constitutional symptoms, including apathy and weakness, loss of weight, and twitchings and tremors, indicating a toxic effect on the central nervous system and culminating in death when the injections were long continued. The white blood cells were promptly nffected, the red cells more slowly, as in human clinical experience, and ultimately white cells almost disappeared from the blood. On the other hand, the animals treated by subcutaneous injection with toluol, xylol, and Hiflash naphtha showed no constitutional symptoms whatever, aside from slightly lessened activity and slight loss in weight. The white cells were not permanently nffected at all and the red cells suffered only 3 slight and transient reduction. The relative effectsof the four solvents studied are summarized in Table 2. Inhalation.-Finally, our inhalation experiments brought out the relative effects of the four solvents with even greater clearness. The results are summarized in Table 3. J. I. H. Fob.. 1927 - BENZOL POISONING 73 JVe see from this table that, when proved fatal while 2,440 parts of animals were esposed for eighteen to benzol did not. This is due entirely T.4BLE ?.--EFFECT O F INJECTION OF VARIOUS SOLVENTS SOLVEST IDAILY SCBCUTAPI'EOUS ISJECTIOX OF 1C.C. PER LILOGRAX OF BODY WEICIIT' I ISTRAPERI- Average Ktimbcr Average Averqc Reduction in of Loss in TONEAL INJECTION LETHAL Injec- Weight \vhite Red tions Cells Cells ~~ % ?& 5% C.C. p e r Hg. Benzol.. ............................ 13 26 91 25 1.25-2 .o Toluol.. ............................ 16 6 0 5 1.25-2.0 Xylol. .............................. 10 3 0 10 2.00-?.5 Hiflash naphtha.. ................... 11 4 0 5 2.5 1 Five of the animals treated Nith xylol received 2 C.C. instead of 1C.C. per day. TABLE 3.-EF'FECT I- OF INHALATION O F VARIOUS SOLVENTS MODERATE COSCES- TRATION' Low CONCENTIUTIoNa 8 0 ac1 m8, %% Benzol......... -2s 63 marked, mod- %% -15 91 prac- neuro- erate tically toxic Toluol.. ........ -21 0 narcosis, slight none +I 15 none Xylol.......... -10 death 9 narcosis, slight +3 4 none death Hitlash naphtha .... . . . . . . . . . . . . slight --2 -9 none 'Benzol 2,440 p.p.m.; toluol 1,600 p.p.m.; xylol 1,800 p.p.m. * Benzol 815 and 1,035 p.p.m.; toIuol 1,100 and 1,2jo p.p.m.; xylol 960 p.p.m.; Hiflash naphtha 567 p.p.m. 'Benzol 460 p.p.m.; toluol 620 p.p.m.; xylol 620 p.p.m.; Hiflash naphtha 312 p.p.m. twenty hours a day for seven days to high concentrations of benzol, toluol, and xylol, toluol and sylol were more toxic than benzol, since 1,600 parts per million of the former solvents to the narcotic influence of the solvents in question and is in accord with the general fact that narcotic action often increases with added methyl radicles. On the other hand, toluol Vd.9 No. 2