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AMERICAN INDUSTRIAL HYGIENE ASSOCIATION QUARTERLY .,c =o.q I Forty Years in the Poisonous Trades ALICE HAMILTON, M.D. r A M a f r a i d t h a t t h e title of m y paper may T h e most difficult obstacle I found was I give the impression that I mean to in- the universally held doctrine that the only ddulge in t h e vice of old a g e and waste my way to prevent industrial poiso ing was time on tales of the far- distant past. I to keep the skin clean, t o scrub the-hands will not do t h a t b u t I cannot resist t h e and especially t h e fingernails. I have been temptation t o give YOU of . t h e later gener- reading over some of t h e papers' I wrote ation something of a picture of what in- before the F i r s t World War a n d in all of dustrial medicine was 40 years ago. F o r them I plead with physicians a n d employers only if you look at i t can you appreciate to give up the clean fingernail doctrine and the remarkable record your country has face the fact that a lead worker eats only made in t h a t really brief period, a record three times a day and even then h e does not starting in ignorance almost complete, and wa:;h his hands in his soup o r coffee, bnt willfully so, to a position of what we may he breathes 16 times a minute a n d if there almost call world leadership, the countries is lend in the air, he will get it no m a t t e r which f o r so long led u s being now unable how often he scrubs his nails. R u t it was to keep pace because of \var destruction uphill work, for I u x s trying to upset a and poverty. cherished myth. I remember the hend siir- When I entered this field in 1910, a f t e r geon of a prent Coloritdo smelting compitny two years study of all the available English saying in a public meeting: " It is not t h e and German material, industrial medicine lend :I miln ilbsorbs d u r i n g his \wrk t h a t did not exist in t h e U.S.A. and industrinl poisons him but \\.hilt he carries home on surxery was rather discredited. I think you h i s skin." I remember the physician in could have counted the published articles charge of a L t n h smelter telling me he ai- on iiidustrial poisoning on the fihgers of ivays instructed the men- blast fum:w one hand. T h e r e were of course men in in- tenders, flue iind bnghouse cleaners-to dustry, foremen especially, who had a lot scrub their nails carefully. of' practical experience, and :i few doctors .At t h a t time we believed t h a t the lead really studied their cases, but the prevail- which was inhaled reached the stomach by in K ;itt i t ude was ost rich-li ke. Americnn being mised with the saliva and s\v;ilio\ved factories were so much better thnn Euro- and the only reason why men working ill pcan. American. workmen so much better fumes and dust were intoxicated so much lwusctl a n d fed thnn E u r o p e a n that thc more rnpidly and severely thmi those hand- industrial dise:iscs described by foreign ling solid lead ( a fact noted by T;inquercl nuthoi-ities simply did not esist over here. tics P h n c h e s :ilmost a century ago wis I remember t h e shocked surprise I felt t h a t the clu;intity e n t e r i n g t h e body w;w' when 1 visited the model town o f K s s ~ i i . g r t u t c r . K . R. 1.chniann. thcn onc of our ' -;!ftcl. 1 h;l(! SCCll SOllth I<<thlL'hC'Rl. x:rc;ttt~s;t:ttrthoritics:, thought h e h:id provtvi this by :i few questionable hurn:in csperi- Prawcntrcl n.r the- Cumminps Mvrtii~riitl I.cc*turv iit :hr merits. I t w:is not until *J. C. A u b m:ide Ninth t\nnrini % f w t i n g of t h e A M K R I ~ . A S I S I ~ I ' S T K I A I . lliirtiiii.IIYCIESK , ~ S S ~ I ( * I A T I I ~AS i.bvil I . I!l.lS. !4:iss:i- rhuwrt3. his studies in the twenties thnt we under3t ood thc (I i ffcrcticct twt wcri iilworpt ion 7 I I i . cl'll,ql- I N I>U S T R I A I, IIY G I E N E QUARTER1,Y Murclc, 1.948 t h 1.OU x h t h e ~ : ttsro-i ntes t i ti id t ract, \vi t h its many natural defenses, and that through the almost completely defenseless respira- toi'y tract. These studies really revolution- izcd the attitude of physicians and of prac- tical rncn towards the protection of lead ivorkers. For many years I believed that the body cleanliness story was a thing of the past and then not long ago I picked up a publication of one of our governmen- tal industrial hygiene outfits, and read : "In the prevention of benzol poisoning the most important element is tlodily cleanliness." Sometimes it seems ;IS if :t lie crushed to earth n-ill rise again. Imagine a man who Ilils t o breathe benzol fumes protecting him- self by bathing. T h e earliest method of protection against severe exposure to an industrial poison was to shorten the time of exposure and the first such measure of which we know was introduced in 1556 in the Austrian mercury mines of Idria. T h e working day was shortened by Ian. to sis hours. In Spain, i n the g r e a t quicksilver mines of Almnden as late as 1921 30 hours constituted a month's work and in England in 1899 strip- pers of the white bed in white lead works Dr. A l i c e Hamilton, Cummings Lecturer f o r the w e r e forbidden t o do t h a t work on more N i n f h Annual M e e t i n g of the American Industrial than two successive days. Practically the only method of prevention I found before the First World War in lead smelting and in the production of white lead and in roasting oxides was to rush the dangerous jobs and then discharge the men. I t was always a matter for the foremen to decide. Hygiene Association, i s the world's foremost woman industrial hygienist. Whenever workers have been subjected t o poisonous matorials in their trades, Dr. Hamilton has brought the facts t o light b y visiting the plants and talking with the affected workers. She has coniinually f o u g h t f o r c o n t r o l o f industrial hcalth hazards through legislation, b y convincing managemont t o take action, and through education. Her t h e management kneu- nothing about i t investigations have included the lead industries, vis- except that there was an enormous labor turnover. B u t in those days t h a t was a matter for pride. Foremen would boast of having to b r i n g in from 30 t o 50" c new men every pay day. In that way, they thought, not many n.ould get severely 1e:tded. Of course there were always plenty of nen-ly arrived immigrants to fill the cose rayon production, potteries, steel mills, mining. The first woman on the faculty of Harvard Medical School, the only woman t o serve on the H e a l t h C o m mitiee of the League of Nations and to receive the American Public Health Association's Laster Award f o r c o m b J t t i n g causes o f disease and death, Dr. Hamilton is author of several books on industrial toxicology. She i s an active m e m b e r o f the Comm i t t e e on Permissible Limits of Dusts, Gases, and yanks. Vapors of the American Standards Association. Her * Even now t h e shortening of exposure work over t h e past forty years has done much to m:iy be : d o p t c d :is t h e only practical u-ay demonstrate the nocessity o f vigorous, scientific con- of ;tvoiclinK serious trouble. There ;ire emergencies, such as accidental spillage. (,is breakage, 01- unusiial repair work. which have to be dealt with at once. I t may be trol of poisonous materials incident t o the occupation. The Cummings Memorial Lecture is given annually by an outstanding personality in the field of industrial E.hygiene i n c o m m e m o r a t i o n of Donald Cumminqs, Past-President of the A m e r i c a n Industrial H y g i e n e As- , t h a t t h e only possible way to manage is sociation, killed i n a plane crash en route t o control t o let no individual work in the poisoned an occupational disease situation ieopardiring pro- air for q o r e than a few minutes. duction of a critical war material. INDUSTRIAL HYGIENE QUARTERLY Two subjects that in the early days bothered u s a great deal were the special danger to young people f r o b industrial poisons and the special danger to women. As to t h e first, t h e great susceptibility of youth is admitted and the Federal Childrens' Bureau has for some years examined the industries employing minors and secured gentlemen's agreements to rule out minors from possibly hazardous jobs. When it comes t o t h e over-susceptibility of women, a theory which has prompted some quite foolish legislation, careful observation of large groups in the poisonous trades has not given proof of it. We still hold t h a t plumbism is more harmful in a woman because i t is a poison to the germ cell and although t h a t is t r u e too of the*male germ cell, still in t h e woman there is t h e additional injury to the fetus by the lead in the mother's blood while she is carrying the child. T h i s i s probably t r u e also of mercury. As to benzol we still believe that it is more h a r m f u l t o menstruating girls t h a n to young men, though we are not so strongly convinced now as we used t o be. Certainly t h e r e is no ground for forbidding women to work in jobs that espose them to carbon monosicte or to silicosis. Statistics seem to point the other way. Lead I T Is in t h e industrial control of lead poisoning t h a t we see, I think, the greatest advitnce over the situation that obtained in this country up to the First World War. Let me give briefly a few pictures of t h e chief lead industries as they were then, reminding yoti that whxteser statistical informittion we had was based on personal surveys including interview with physicians;, labor leilders, soci:d workers. druggists. and on hospital records, not on routine medical examination of the individuals in lead work. Th+ production of white 1e:d a i d o f t h e oxides was t h e most notorious o f t h e lcad trades ant1 in every c m t e r i t w:is possible 1`6 pick u p reports of pnlsics. encephdopathics, deaths from $evere intosic:ttiori. That industry has been revolutionized. thc dusty processes controllctl, the ~vorkcrs kept under medic:rl supervision. I n the old days, Phi1:idelphi:i :md Chic:igo h : d so many 3 ci\ses of plumbism f rum white 1e:td and red lead plants t h a t Cook County Hos- pital and old Blockley listed them under t h e name of t h e plant, not under lead poison- ing- that was taken for granted. Pottery glazing and decorating was an- other notorious source/for we used white lead unchanged in the &laze and the colors and made no effort to cbntrol the dust. It was then t h a t I came across my first cases in women, dippers' helders and lithotrans- fer makers, - and convinced myself that women are more susceptible than men to cerebral plumbism. Then I went to Eng- land and Germany and saw what could be done with good exhausts and with wetness everywhere I c`aw how t h e English c!ianged soluble white lead in the glaze by fritting it to insoluble disilicate. We had in 1922 a r a t e of 22 to 23`~; of plumbism among potters, the English had a rate of O.!lCc. Now we frit our glazes and we practice good housekeeping in our potteries, so Ohio, New Jersey and West Virginia ;\re no longer happy hunting grounds for the student of plumbism. An equally g r e a t re- form hi\s occurred in t h e making of smi- tary ware. That used to seem to me the worst of t h e lead trades. The enamelers scattered a powder containing up to 20c( soluble lead over red hot iron sinks and bathtubs, the men and all surfaces were dust-covered. In one Pennsylvania plant employing 130 enamelers, doctors and hos- pital records showed that in two years there had been 72 c;<ses of severe plumbism, with five of palsy, two of encephalopathy :;nd three deaths. Sow we use a lei\<iless cnamel on clay bi\thtubs and sinks. T h e rubber industry \vas once ;1 soiirce of severe forms of plumbism. because leiid oxides and the basic carbonate were im- portant compounds and men in the com- pounding rooms and on t h e mills were ex- posed to soluble lead in t h e form of w r y fine dust. Now lead has almost vanished from the rubber industry. # The old notorious lead tr:tdes, p:iintinp, printing. plumbing. which s t v c rise to thc cspressions "paintcrs' or printers' colic : ~ n d palsy," are no longer important in thitt respect. The newer coatings, eti:\mels, liic- ((lrers. plxstics. are Icnd-free. titanium di- oside 1ispl:ices white 1~:td to i1 Kre:rt es- i en t i 11 pni 11 t , ;\11 tf i n t cri or de cor:^t ion is (innc with 1c:idless p:ii n t. P r i n t i 1'1g pliin t s ; I I Y I Y;II. t J ( * t t ( ' t ` ( a f l I I i ~ J l ) ( a ( I ;ttttI IltI*c('Iym w h - :triizcvI, p I i i n ~ t ~ ~ ih*:isi*tlly cornc! i i i c*ont:i:.t wit ti l w d c ~ s c c ~ pfto r I-:LI*C jobs. Ycnt I c w l still hc~ltls :in import:int pl:ic.c i r i tho list o f iridusti*i;il poisons for thoriKli it v:tiii.;hw from ;tri o!tl tiwlc, it may stid- t l ~ n l y:ippwir i n ;i I I P W o i i ~ . P a i n t i n g ;tuto- mot,ilos with many coFrits o f l(*itdpaint x;ive \:.a.to 1c:icl-frcri I:ic~jt~(:i-sb, ut when s t r m m - lininr: came in, the 1c;~tlproblem mritlc 11 crarniit ic. rc;tppcitl.;tncc for the sul.f:iccs o f the CitI- must l x :ihsolutctly smooth and t h i s mc:ins t h a t sc:ims must be coveiwl wit!i 1c;ttl .ioltler a n d then wntlp;ipei-etl and smoothed. `Thv s c r a p p i n g o f steel striict u r e s by the use o f intense heilt is ;in in- ciwisinK source of clanger. Recently Cott e r described some 300 cases of "lend in- toxication by inhalation" in men scriipping the elevated railroads in Ne\v York by using blow torches on the steel n-hich had had many coats of red lead paint. Even more dangerous because it is often carried on in enclosed p!aces and with extreme de- grees of heat is weldinx, ivhich is more and more replacing riveting. Tetrnethyl lead is an ever-presen t clanger, though scrupulous- ly safexuarded now. And the trade which in all industrial countries yields the, greatest number of cases of plumbism, the maki n g of storage batteries, is not only still with u s but increasing in importance. I t is a very difficult problem for the industria! hygienist. I have never seen a plant which was entirely safe, though the English sys- t e 4 of keeping everything dripping wet has much in i t s favor. Belknap of Milwaukee puts his mixers, pasters and finishers into positive pressure masks, but 1 believe that even t h i s drastic system is not entirely foolproof. We are told t h a t a new kind of lead-free storage battery, developed by the Fi-ench, is being introduced in this count r y b u t since it uses cadmium, i t is rather like leaping from the frying pan into the fire. There are questions still unsettled with regard t o lead poisoning in spite of the enormous amount of study which has been devoted to the subject: the possible relation between lead poisoning and peptic ulcer, between 1c;td poisoninr: :inti multiple sclerosis, arteriosclerotic kidney, generalized arteriosclerosis. Here the English are doing the most significant work. for they rtc;ccl not dttpciicl 011 ;mima1 experiments, the)" can follow hum;in Iced tc.orkers over ;I long period of years, men a n d women who tvorkcd in t h e 1c:itl trades its much as 50 ,ve;ti.s ;igo twfore s a n i t a r y control w a s perfected, :inti d h o ;it t h e end show t h e effects of what the English believe t o be slow, prolonKctl poisoning. T h e English law ac- cepts as occupational in character chronic nephritis with or without general arterios:lcrosis in a n old I ~ i l t lworker. 1Jnfortun;itely for us, during the .yeilrs when lead poisoning of a severe character tvits pr&zi!ent in t h i s country, no rea1 intcrest w:is taken in its study by physicians. I t was not till hyxienic reform was well under y t y :md severe poisoning cgiitrolled that we began intensive research. Mercurv IIK old familiar poison, mercury, has Theltl its place in industrial toxicology since Roman days when` the quicksilver mines of Spain were exploited, b u t the industry most notorious f o r its disilstrous effects has always been the making of felt hats. We do not know when mercury nit r a t e was first used t o help in felting f u r but we know t h a t when the Huguenots fled from France a f t e r the Revocation of the Edict of Nantes in 1685, they carried with them the secret of mercurial carrot, as we call it, t h e French still call i t le swrtt. Hatters' shakcs a n d ),,ad as a hatter are old terms f o r the mercurial tremors and psychoses of chronic poisoning as seen in this trade in every country. Studies of mercurialism in the hatters' trade in this country began with one published by J. Addison Freeman of Orange, New Jersey, i n 1860. He described some 100 hatters of Orange, who were victims of typical mercurial poisoning, b u t 15 years passed before the next record appeared, quite as shocking as the first. Nothing was done about it, little attention was paid, none by t h e medical world. Then in 1912, 34 years later, t h e public was startled by a report made by a lay organization, the National Civic Federation which had made survey of the mercuryiisiiig trades in New ,Jersey ; m i New York. Of course the cases of poisoning t h e survey brought to light were only t h e severe, conspicuous ones. Of these 94 were found, 1 IN DUSTRIAL HYGIENE QUARTERLY among them men incapacitated by palsies, four with compiete paralysis of a limb, many cases of polyneuritis, two with insanity. Xoiv t h e situation in t h e felt h a t in- dustry is completely changed. This historic trade, full of traditions and established hihits, h a s at long last abandoned t h e use of mercurial carrot ahd substituted mix- tures containing sulphuric and nitric acids, and hydrogen peroxide. The great reform \vas accomplished in a way typical of o u r country, not by law but by agreement between manufacturers and state and Federal Public Health Services, just as was the control of radium in industrial use and of tetraethyl lead. It is the only way a quick and effective reform ca\be brought about in several difYerent states simultaneously. Thus a n old and notorious source of industrial sickness has been abolished, we hope complet ely . Foreign literature is full of cases of mercurialism traced to t h e use of mercury vacuum pumps in making electric light bulbs. Nowadays we use these very sel- dom, never in electric bulb manufacture. Yet mercury is still a n important industrial element, especially in the production of dry batteries, in making thermometers and barometers, in extracting gold and silver from the richer ores and in the electrical industry. High frequency induction furnaces, the constant potential department, the manufacture of tungsten and molybdenum rods and wires, all call f o r the use of quicksilver. And now a new source of poisoning, sometimes acute and severe in form, h a s appeared, namely t h e use of or- ganic compounds as fungicides. The dimethyl compound of mercury seems to be the one most often used here, but a Cilnildian report mentions diethyl mercury. The symptoms as described by English. German, and Canadian writers difTcr from those caused by the inorganic compounds. There is no mention 'of ginfiivitis or snli- vation, t h e central nervous system is chiefly involved, peripheral 'nerves, cerebellum, cerebral cortes, and t h e onset is usunlly rapid. The most striking cases come from Germany. Koelsch writes of 22 fatal cases he was cdlect on to investigate during the war. These were in ;.n chemical plant where mercury ethyl acetone and mercury ethyl bromide were produced f o r use as fungicides. He writes thyt the illness was characterized by profound cerebral involvement. One is reminded og the similar difference between t h e action of inorganic lead and of organic, tetraethyl lead. ' 1) FCarbon Monoxide ORTUNATELY f o r ' t h e :industrial ivorker carbon monoxide poisoning hns :.nl\vays satiori. ilrltl m;my hitve involved persons of the 11ppe1-classes who had the best of medical care. As to whether chronic CO pois o t l i A K is ;L clinical entity there a r e still v:tryinK vieivs. I t is admitted by all t h a t ('0 is riot a cumulative poison f o r i t is rapidly eliminated but there is evidence thilt repeated attacks of anoxia bring about 8 itn accumulation of effects. T h e experid.ments of Leivcy and his colleagues d u r i n g the w t r point to ;i cumulative effect on t h e brain by repeated short exposures to an atmosphere devoid of oxygen. The brains of mimals which have recovered promptly and without any visible injury from such exposure have shown cell damage, first of reversible n a t u r e but later of permanent, if the anoxia was repeated. Lewey also exposed dogs to the standard concentration of 100 p.p.m. f o r five and a half hours a day, six days a week, f o r 11 weeks. T h e clogs seemed to continue in perfect health but as early as the second week electrocardiograph changes appeared and if they were killed, autopsy revealed degeneration of h e a r t muscle fibres, hemorrhages and necroses. Some of t h e dogs showed disturbances of gait and of reflexes and histological changes were found in the central cortex and in the basal ganglia. Phosphorus A N O T H E R old poison is phosphorus. It was deeply entrenched in the match indust r y f o r all t h e years between 1833 when Lorinser, a n Austrian, described 22 cases of phossy jaw which had developed among match workers in the 12 years following t h e invention of strike-anywhere matches, and the year 1908 when European countries signed the Berne Convention by which they agreed to give up the manufacture and the importation of white phosphorus matches. In t h i s country a very early case of typical phossy j a w was treated in t h e Massachusetts General Hospital in 1851, some 15 years a f t e r the manufacture of white phosphorus matches began in Springfield. This was a very severe case, ending after six months in death from toxemia. There was. however, no mention of phossy jaw in American medical literature from 1851 t o 1910, when John A n d r e w published the report of an investigation he had ma& for t h e Federal Depnrment of Commer((e of American match factories. We had always been assured /that our factories were so superior to the British and European that phossy j a w was unknown in o u r country, but A n d r e w brought to light over 150 cases, some of them quite as severe as any in foreign countries. As everyone knows, t h a t report led t o t h e passage of t h e Esch law, which placed a tax on white phos-phorus matches and 'led to the substitution of the harmless sesquisulphide. T h e Diamond Match Company held the patent for this Fren6h discovery but generously threw open to the whole country the use of the process. So one notorious dangerous t r a d e was rendeqed s a f e and we all thought t h a t phossy jaw was a thing of the past. But eternal vigilance is t h e price of industrial safety. A sudden and quite unexpected reappearance of severe phosphorus necrosis took place in 1923 when a new kind of fireworks was manufactured in three plants on the Atlantic seaboard and white phosphorus was one ingredient. The management was hoth 'ignorant and indifferent before the attentjbn of physicians and state authorities \:-as called t o t h e situation. Fourteen workers, all women but one, had developed intensive necrosis of the jaw and two had died of septicemia. T h e period of exposure in these cases was unusually short f o r the exposure was very great. T h a t source in its t u r n was abolished, and years passed before we heard any more about phosphorus poisoning in industry. However, it h a s emerged again. I n 1946 Heimann of t h e New York State Department of Labor found t h r e e cases of phosphorus necrosis of t h e j a w in men working in the production of red phosphorus, converting t.he yellow into the red allotrope. In spite of routine medical and dental ex- aminations including dental x-rays, phosphorus necrosis of the j a w appeared a f t e r exposures of two gears, eight years and 13 years. T h e miin who had been exposed only two years recovered without deform- ity, the one who had worked eight years lost all his teeth and part of t h e left m m dible, with some facial deformity; the case which was slowest in developing was much the most serious. This man lost a large portion of t h e palate bone and there were fistulous t r a c t s leading from mouth to nose \*(ll,. !I, No. 1 INDUSTRIAI, HYGIENE QUARTERLY Page* I I ;tiid nztsd sinuses. These mere still active itftcr 1s months. Heimann traces t h e trouble to the bubbles which form and burst from the water over the yellow phosphorus, for this must always be handled under water since it burns in the air. Finally there is a still more recent source of trouble f r o m t h i s very troublesome element, although so f a r no human injury has been reported. This i s t h e electro-thermal production of elemental phosphorus to be used in t h e preparation of phosphate fertilizer in the T.V.A. Fleming, Miller and Swayne of t h e T.V.A. have attempted to find t h e maximum allowable concentration of phosphorus by subcutaneous injection of animals, but such results are of little value in solving t h e problem of workers' pro- tection. Heimann's cases seem to show the prxc- tical impossibility of providing foolproof protection. These men had all had a dental esamination within one month of the development of t h e necrosis. In t h e days when white phosphorus wis still used for making matches the English took elaborate precautions in their factories. Workers were forbidden t o keep a glass of water on the work 'bench, to chew gum or tobacco while a t work o r to e a t a n apple or p u t ;I finger in the 'mouth or pick their teeth. Strict cleanliness of benches and provision ut: f u m e removal were required of the management, yet phossy jaw continued to appear and apparently i t always will so long as t h a t subtle a n d relentless poison is used. A few metxllic poisons which were formerly little used or used in ways not end;ingering health have suddenly emerged with prominence and have begun to show omirious characteristics. The most importi111t are a1u m i nu m an c? beryll i 11m. RAluminum ECENTLY Koelsch of Munich. for m;my years the foremost authority in Germiiny in this field, has sent me lib4tracts of German reports on the effect of alumilirlm dust. reports 1vhic.h were not ;Iccessiblc to us d u r i n g the war m d which arc of interest not only in connection with aluminurn workers but also with men workinJ in mines which are dusted with aluminum for t h c prevention of silicosis. Koelsch rcnt me a b s t r a c t s of four papers which dc- scribe what the authors consider it definite characteristic picture of aluminum dust poisoning in men working in an atmosIiherc of finely divided particles. T h e symptoms consist qf short breath, lessened vital capacity, stabbing pains..in the chest, slight cough and expectoratiop. The special feat u r e all note is t h e youth of t h e victims !older men are less susc'eptibb) the *shortness of exposure, t h e rapid course of t h e disease, (the latter two' in sharp contrast with silicosis) and the fact that the pro7ess may progress a f t e r exposure ceases. Two cases of pneumothorax are described, attributed to great increase of intra-alveolnr pressure, the aluminum dust impeding expiration. Two autopsies are described, the findings in which agree strikingly : exten- sive interstitial pneumonia with induration ;ind shrinking. T h e interstitial tissue had undergone hyaline-collagenous degeneralion. One author speaks of a silvery, metallic sheen on the cut surface of &e lung. According to Koelsch there was an abnormal dust exposure in these factories, caused by war-time conditions, the lack of proper eshausts, the obstructed windows. necessitated by the black-out. TBeryllium IiE newest of the industriill poisons of practical and rapidly i ~ ~ c r e a s i nimg portance is beryllium. F o r the descriptio11 of i t s sources. uses and action I a m indebted to Dr. Hnrriet Hardy f o r I have had 110 esIJerience at all in this field. I t appears t h a t descriptions of pulmonary lesions following esposure of workmen t o dust o r fumes of beryllium cornpounds were published in Germany, Italy and Russia during the thirties. T h e most extensive discussion w:ts t h a t of Gelman of B.Iosco\v who wrote the section on beryllium for the I.L.O.Ency- clopedia. Observing not only what he ciillcd "disseminated injuries to the Iting" but i r r i t i ~ t i o ~olf the mucous membranes it11(l the skin, he wrote t h a t it was not easy t 0 separate the action of beryllium fluorides from that of other fluorides. Howcvcr. in (krmi:riy !he picture in t h c ltixigs dcscribed by Gelman was found in workers exposed to beryllium compounds free from flriorine. The picture was one of disseminated scler- Iotic chi nges with s- ray findings resemblinrr mi1i ;t ry t11bercu losis. C1i n icnlly ther c \vas 1I coitKh, i*cditction of chest expansion, mild A very stranbe feature of t h e Massachu- tlyspne;~, with disproportionately severe setts experience is t h e discovery of three physic;il fitidinKs of pulmon:l1.y involvement. cases, two of them fatal, in individuals who l'hc first$ report of (in occiipational dis- were associated with, but never went into L`WC i n tho beryllium industry in this coun- a plant making fluorescent lamps. These, t r y canic .from the Cleveland Clinic in 1943. in history and autopsy findings, seem t o These first American cases were reported belong to the `same group as t h e 17. by Van Orcistrand, Hughes and Carmodv in Since the publication of t h i s report Dr. men producing beryllium oxide from beryl Hardy has had case records sent t o h e r from ore. T h c authors called the affection chem- seven different states, including Massachu- ical pneumonia. T h e following year s a w a setts. B`y April 1947, there were 40 cases similar report from Pennsylvania, this time of delayed chemical pneumonitis known t o from an industry employing a fluorescent t h e Massachuselh Division o$ Occupational powder which contained beryllium carbon- Hygiene jn workers in t h e fluorescenf lamp a t e and manganese silicate. Then the Cleve- industry. Since some 1500 workeru have dland group came back with an extensive re- been exposed, t h i s would mean a ca.e inci- port o an illness which they boldly called dence of 2.riCc but obviously t h a t figure is beryllium poisoning, and of which they f a r too lorn, based as i t is on the more o r described 35 cases with five deaths. Briefly less accidental discovery of fairly advanced summarized, the symptoms were those of cases. chemical pneumonitis, cough, dyspnea, sub- The reported cases of beryllium poison- sternal pains, anoresia, loss of weight, in- ing therefore have come from plants pro- creasing fatigue. T h e onset was insidious, ducing and casting alloys, making a n d us- lasting some three weeks, after which a ing fluorescent powders. No dependable recharacterist ic, diff use bi1atera1 haziness ap- po,rts have as yet been made of t h e amount peared in x-ray pictures of the lungs. Re- of beryllium in t h e a i r of working places moval from exposure and rest in bed with where the poisoning occurred. Chemical oxygen, as indicated by cyanosis, was fol- tests seems quite inadequate t o reveal small lowed by recovery, but if then the man re- amounts but a spectographic analysis, de- turned t o work there was a relapse and the veloped in t h e Kettering Laboratory in fataI cases were in part due to pulmonary Cincinnati and in the Massachusetts Di- edema following too early esertion. T h e vision of Industrial Hygiene, promises to autopsy findings were those of bilateral. give results. acute, organizing, atypical bronchopneu- T h e latest contribution in this field. Jnn- monia. All t h e Cleveland cases were in men w r y 19.18, comes from Martland and his exposed to beryllium oxide in processing colleagues. They discuss four fatal cases, beryl ore. In 1946 Hardy and Tabershaw published it report of 17 cases of w h a t they called "delayed chemical pneumonitis" in 14 wom- en and three men working in the fluorescent one acute, the others chronic, and include one which dates back to 1934 and has only now been recognized as a case of chronic beryllium poisoning in a worker in the fluorescent lamp industry. A most intcr- lamp industry a n d using zinc manganese esting addition t o our knowledge is the proof I~erylliumsilicate. H e r e we have ;idifferent clinical picture. one of delayed onset, the symptoms appearing from sis months to three years after the victim had left the workshop, then dramatic dyspnea, great loss of weight and a poor prognosis. Six of of t h e presence of beryllium in t h e OrgiltIs of two and in t h e skeleton of one of these two. This was shown by the spectographic method in the Kettering Laboratory. T h e importance of this new poison is xrowing rapidly, f o r i t is a n excellent in- the 17 died and the other 11 were disabled gredient for alloys, which a r e light and refrom 18 months t o over four years with sistant to strain, it is a good rcfr;ictory f o r only one known case of complete recovery. firebricks and is used not only f o r fluor- T h e pathologic lesions in the lung were csccnt lamps b u t f o r m:iny other electric those of an atypical granulomatous process appliances. To anyone who, like me, CilR 1-uplacing normal tissue, and similar lesions look h c k t o the early days of industrisl were found in liver, spleen and lymph nodes. medicine, this story of beryllium poisoning INDUSTRIAL HYGIENE QUARTERLY Page 1J is ;in itmazing thing. Here, in t h e space of some six o r e i g h t years a f o r m of industrial poisoning which was highly dubious, involving only a small number of cases, not included under compensation laws ex- cept in full-coverage states, observed by a small number of physicians, was promptly made t h e subject of thorough s t u d y w i t h full publicity. A conference was held in Boston at which t h e late Leroy Gardner of Saranac agreed to undertake animal studies with beryllium and last y e a r a symposium was held in Saranac where the data were assembled from all over the country and discussed. When I look back on the days when we were urged not to mention such a thing as T N T poisoning lest we drive all workers out of t h e plants, I can hard]? believe; it is the same country. Cadrniu rn ADMIUM is another industrial poison whose use.has lately increased, but our knowledge of i t s action has been fairly estensive for some time. However. the in- creasing use for alloys and for electric plating and recently f o r t h e production of storage batteries has added to the data formerly acquired. According to Fairhall the danger of cadmium poisoning in the electroplating process is slight. i t is in the application of heat to the plated surface with the production of t h e oxide t h a t t h e danger comes. T h e occurrence of cadmium poisoning in smelters of ore containing this element was noted by t h e German, Stockhaiiscn, as early as 1656 and thoroughly discussed by Tracinski of Upper Silesin in 1838. B y 19461Fairhallwas able to summarize t h e histories of 59 reported cases of acute cadmium poisoning with it mortality of 15'4. T h e action of the cadmium oxide is chiefly on t h e lungs, and resembles t h a t of nitrous fumes, with constriction of t h e chest, increaaing dyspnea, cough, nausea and abdominal pain. bronchopneumonin. cyanosis and pulmonary edema. As for chronic cadmium poisoninx t,here tias been ;i wide sprea4 scepticism but recently some French reports have come from plnnts producing storage batteries by the n e w method. A supposedly slow action of cadmium appeared a f t e r five to 14 years' expwure and began 8s obstinate pain in the lower back apd legs which increased till walking became impossible. By x-ray, certain bones, chiefly scapula, ilium and femur, showed lines of pseudofracture. Anemia of the iron-deficiency type was the only other definite finding except of a yellow discolor- ation of t h e teeth. H a r d y and Skinner reported five cases of w h a t they suspected to be chronic cadmium pbisoning in men exposed to concentrations. of 0.6 to 6.8 mg. per 10 cu.m. T h e illness was subacute, with anorexia, nausea, yomiting, epigastric pain, fatigue, dopeyness, tooth decay, low hemoglobin values. The most recent work is t h a t of Princi of t h e University of Col- orado, who is studying workers in a cadmium smelter where the electrolytic method is used and the men are exposed to dust of t h e oxide. The concentration of cadmium oside is sometimes a s high as 31.3 mg. p e r 10 c11.m. He confirmed t h e French experience as to a yellow line on t h e teeth and also low hemoglobin values and low red cell count. The experimental work of Prodan in 1932 is still the most valuable in t h a t field, since it was an attempt to duplicate industrial esposure. Both the oxide and the sulphide were used and both are toxic, the latter less so I ~ x a u s eof its relative insolu- bility. The attack is chiefly on t h e respirn- tory tract causing a rapidly developing pulmonary edema. or i\ pneumonia, i t h e course is less rapid. d fibrotic thickening of the alveolar \valls w c u r s , which is permanent. In animals these lasting lesions folloived even brief exposure to the fumes. Liver : ~ n dkidneys show f a t t y degeneration, both organs retaining much of t h e ingested m d m i 11m . Although not in t h e field of industrial toxicology one must not omit mention of the large number of cases of acute poisoning resulting from cadmium-plated eating utensils. According to Fairhall up to 1941 only '21 such accidents were reported, but since then no leas than 265. A curious fact noted by Church and Yrinci is worthy of mention. T h i s is t6c apparent antagonistic action of selenium o n cadmium its shown experimentally and confirmed in practice. In one cadmium smelter the workers were free from nny sign of poisoning although t h e poncentriition of cadmium i n t h e a i r was dp to 2000 or :Wi$3 times the maximum i\llo\vable con- f' celitratiori. . `I'hc: air of t is plant h a s small tr:iws of selenium.* TChr'ome :!E l o c d :rction of c h r o m i c acid droplets :tnd chrom;tte d u s t is very familiar t o ~ ~ ~ l * k m;etnIdl h;ts tJeen f o r over ;t century. (`hromc ulcers, chrome holes, perforated riiisal septit ;LIT certainly Itroublesome but rit~verreally disahling and we still feel cert a i r i that such lesioris do not undergo canccrotis change, for they have been under obswvation for over a century. But lately I'e~J`Jl'tShitve heen coming f r o m Germany of cases fJf pu1mori;try ciwcinoma in men exp(JSf?d to chromitte dust, not many cases, it is true, h u t numerous enough to make such authorities its Koelsch and Teleky beIiew t h a t there is a cxusative relation. So f a r n o such repoi-ts h;tvc heen published in t h i s country, hut of C : J U ~ S w~ e m u s t expect the same experience, t h a t is observed in Othel. countries inv;ti*i:tbly t u r n s up over h e w . T h a t t h e cases S(J f a r reported all occiiiwd i n meti exposed to chromate dust, llCJt to droplets of chromic acid, is probably due to the greater precautions taken agl;cinst t h e very i r r i t a t i n g action of t h e wid. I n`othing of the; effects to be looked f o r and sanitary engineers had no idea of t h e danger points to I be avoided. I remember a worried du Pont chemist telling me he could riot understand why a worker should be fatally p o i s h e d Lvhen there was no more than 5`1, of benzol in t h e a i r where he worked. The study made by the National Safety Council under c-E. A. Window started us on the right road a n d soon American laboratory studies and observations in the field widelied pur understanding and led t o a marked fall in the incidence of poisoning. But t h e greatest. advance was made when latex came in as a substitute f o r the various solutions gf-rubber. Here, as in the case of white phosphorus matches and of carbon disulphide vulcanization and of mercuryfree felt hat cnrrot, a safe substancedakes the place of it poison. Latex is the gum of tho rubber tree and instead of coagulating it and then dissolving it. f o r dipped, spread ant1 cemented rubber goods, i t is shipped as ;i liquid in tankers and used as a liquid. Unfortunately benzene has many other iises for which latex is not a substitute and it requires unremitting vigilance on the liitrt of the industrial physician if h e would avoid trouble. The more recent studies, tispecially those made by the Boston and Sew York groups, of workers exposed to benzene have shown that the earliest sign of intosication is not always, 8s we used to believe, a drop in the white cell count or t w i i a low polymorphonuclear count, but i t may be ;I drop in the red cell count with the appearance of large erythrocytes, ii m:irwcytiC anemia. Another important addition to our underst:intliny of the action of bcnirtie we owe to t h e w Hoston :tnd S e w York studies. No loriger do we believe that t h r attack of berizcwe is on one element only o f t h r bone m w r o w , rather we insist that any irbnorrndity in the blood picture, i f it appears in it benzene worker. must be treated its it wartiing of dzrngcr. Thnt is the o ~ ~ l > * sztfr cmlrse tu foilu\v. Still m o t h e r important finding is the fact that marrow aplasia is not ;in in\viLri:Lble finding i n stbvere be11~0l p o i s o n i ~ i ~in. deed hyptrrp1;isi;i is the characteristic tiritiiiiK in mitny cases. These observers s u ~ ~ e tshtat t h c I'cits()riu.hy we have believed women to he much niorc su?rceptiI)le to betizene than mrii m;iy be t h a t ciists with hyperp1:tstic I t I I I ! i I 1 I I c ( VOI.. !I, No. 1 INDUSTRIAL HYGIENE QUARTERLY P a g t 1.5 m:irrow were rejected, and it is t r u e t h a t neglected by the American medical pro- one c;tn find in the older literature in- fession. I came across i t first in 1914 when stiirices of such a decision. My experience I was studying the rubber industry. The with compensation boards bears this out. German, the Italian and t h e French litera- Nevertheless I still believe t h a t benzene is t u r e were full of discussions of this poison especially dangerous to menstruating to the central nervous system, f o r carbon women. disulphide .was an essential element in t h e The entrance of the methyl radical re- rubber industry in tho$e countries. Eng- moves from toluene and xylene this special land did not use it as mbch and we Amer- action of benzene on t h e bone marrow a n d icana still less. But we. did at t h a t time several extensive investigations made dur- use it for the vulcanization of thin rubber ing the war serve to confirm t h e compara- goods and I discovered cases enough in tively harmless n a t u r e of these two sol- Akron. Kot through physicians, who seemed vents. never to have heard of it, always only As to the benzene derivatives which have through foremen. Yet the cases of sudden found a place in industry, t h e i r name is maniacal attacks and then of more slowly legion and our knowledge of their action in increasing motor paralysis were dramatic many cases is founded only on animal ex- enough to attract attention. periments. Even more. numerous and m o r e , Fortunately this vulcanizing agent was complicated a r e the derivatives of t h e petro- given up by the rubber people soon a f t e r leum series, t h e chlorinated hydrocarbons, the-First World War, but then i t came back so valuable because they a r e non-inflam- in greater force when viscose rayon ap- able, a group of which the chlornaphtha- peared and it spread f a r more widely than lenes a r e t h e newest members; the glycols, it ever had in the rubber trade. Yet as late which a r e bivalent alcohols ; t h e cyclohex- as 192s t h i s industrial poison \vas practical- anes a n d hexanols; dioxan, which is di- ly ignored by American doctors. I found ethylene dioxide. These a r e all of increasing that the insane asylums to which the vic- importance and call for continued obser- tims were sent, recorded the cases with vation in practicaI the. estre e caution as due to "some esogenous poisoT' or "etiology unknown" or "possibly FORTUXXTELYMeihanol methyl alcohol is no longer ;t cause f o r apprehension. Our history in regard to t h a t poison is unique and not very cret1it:tble. First, under the infi~ienccof the 1occuphtional in origin." In those rare in- stanc s when compensation \vi\s sought. i t was ppi\rently al\\.iiYs possible to secure the scrvices of ;t professor of neurology o r o f :I sychiatrist to testify t h a t t h e r e was wood alcohol producers and the total abstin- no sukh t h i n g ;is carbon disulphide intosi- ence idvOc;tteS, we forbid the use of rev- cation/. The only l~Xpliti1ititon for this enue-free g r a i n alcohol, so t h a t the use of ost ric.\i-like :it t it u d t ~is thitt t h e pl;nits \vert. wotl iilcohol wts stronxly entrenched in litr~el).situ;tttd in stiittbs with vt'ry p(wr Amei.icitn industry at the time when iill fiictolk inspcvtioii tit~~~iirtmt*ltiit~sici stili other industrial nations iised deii:tturatc4 ~)ooi*t'c~O/n1peIlsiition systems. grain :tlcohol. Then when Prohihition ci\mcb C;irbon disulphidc is still essential in t h e in :uid reports of hlindness iiI1tl death from pi*oduktioii of viswstb rtiyon h i t ntnv t h e bootleg liquor shocked the public, w e \vent 1;IitIItsl which ustvl t o i g w w t ht, dtiiigter art' to the o t h e r extreme, forbiddinx evcn t h c : i d mi riihly si\f thgt1;r rtltvl iii1d rout i11t b mcdiiwl itdtl i t i on of W ( J O ~ I ;tlcoh ol to i nd LIst r i it 1 xi*t:i 11 t~xiimitlntionstbrvt's t o (ltbtt-ct t h t b t roubltb tit i\lcohol :IS 0 1 1 ~of th(! tfetl;itt1ritn ts. LYOOCI : I I ~ tbiii*ly stiipt1 ii11d rtbRlo\'t, t ht1 victim f r o m itlcohol still citrrics its I J i l d i*eput:ttioii it1itI fui*tfic!r t*xposurt*. `l'rt)tiblt* t h t w will al-* whtw it is uscxi, cl:thr:ttc prcwtu lions a r c \v;iys l)t* so long its ctir1)on ciisulphitlc is titktbli, p r c ~ ; i i i t i o ~ ~i sI I C\ ~ i b u l t ll i k v t o S ~ Y * iisetl. for t h e w is 110 \vny o f (Irtrcting in plit.cl to more d;ingcrotis liquids. a(lvii1ic-v which indivitlitcils will provt. to br ovtlrsuswpt ihltn. ( h i t ) good ftvttiirt) o f t tic Carbon Dirulphide \ poison is thrit llot h t tit, i w i t rril cind t tw p t v i - C A R I I O N disulphidc is ill1 iii(tiistrii11 I ) c i i s l ) A , 1 ) h t b l . i i l iitirst' injiiry 1ii.t' rtbvtbrsil)ltb. ` l ' h t b Iwhich w;is f o r rntiiiy y e ; ~ r s vuriously~ t 1 * t i ~ i ~s~t i~t v~ t~~Ci~ist'~s w h i r h \vt* fot111(l 1 0 #I )*(~:ii.:siRo nx1i*e1 1 s u ; t ~ ~iny men who were a!lowed to go hack to their f o r m e r jobs and of cfJllrsc! th;tt \voilid never happen now. poisons used :is ingredients or as solvents for synthetic rubber, besides those already mentioned. Synthetic Rubber N E of the newo' industries is the making of synthetic rubber which w;ts of very g r e a t importatice d u r i n g t h e war and is now firmly establishad. Fortunately it was developed so recently that it had no bad practices inherited from the past and from its inception the industry h i s been much under the eycs (Jf competent physicians and sanitary engineers so t h a t the risks and the w a y t o cor!trol the risks have been studied thoroughly. Of course t i e r e is no tell- i p u~-hen o u r extremely capable and inventive industrial chemists will introduce new compounds, indeed alreitdy t h e list of organic :tccelerators and anti-oxidants is formidable, but the soivcnts are ,mostly familiar to us, the coal tar solvents and t h e chlori nated hyd rocarbons . -According to Mallette of the Firestone Company there are five prin&pal types of artificial ruht)er manufactured in the L'nited States. The toxic mtterials which a r e new are not many and few of them present ;i serious tl;mger. T h e following have been tested on animals and on men : acrylonitrile, ivhich is :in oyqmir: ;cyanide, vinyl cyanide, and has the well-known cyan iiction; butadienc, a mild narcotic with an irritating effect on the eyes and the a i r pas- sages, sometimes affecting the lungs, but with no cumulative action ; monomeric styrene which is more productive of discomfort to human heings than either butadiene or toluene. The irritating effect on eyes and nose is supposed to give ample warning of d;tnx,.er, a rule xhich sad experitmce with d h e r little known poisotis has proved to be unreliablt*. In animals, heavy exposure to monomcri c' ..;t y rene c;t 11des i mmediIIt e denth f r o m :t primary itction on t h e central nervous system, delayed death from pneumonia. Such ii finding mwis t h a t a job of repairing o r cleitnirlK ilplJal.iltuS mag be fraught with great danger. The fourth one is c h l o r o h u t d i e n e , k n o ~ v n its chloroprene. It has been found to he decidedly toxic t o animals, ciiusinL( tlc*prf?ssion of the nervous system, ;i low blood pressure and severe tle- generative changes in the ,organs. Then t h e r e is it long list o f old familiitr I;TPrevenfion IS now a n accepted duty of the industria1 ; physician to examine or employment all new men a n d assign them t o various kinds /tPof work according t o their physical condi- tion, but such exam' ion will never weed out the over-suscept le. Only a close watch over the newly employed during t h e early months will do t h a t for, as is true of the infectious _diseases, the victim of lead or mercury 6r nitrous fumes may be a phy- sically perfect specimen whose idiosyncrasy cannot be detected in advance. Frequent rekxamination d u r i n g the first months is the only way the physician can detect and remove from exposure such a worker. This brings us to t h e question of alternative workers in dangerous jobs. When I ~ v i t sin EngIancl studying the storage bat- tery industry, I found that they laid great stress on this method of preventing plilmbism. We have never used it here to workmen object to it. unOf course we do remove a toxic job but we do not send it after a spell at other work. Moreover we have been told recently by the tlu Yont physicians that they have given up removinK from the job men who show, on cystoscopic examination, a condition leadi n g to wh;tt we still call ;miline tumor of the Llatltler. T h i s is-*because they found t h a t the process keeps uti a f t e r exposure ceiiscs, unless properly treated. They leave the man at work under treatment. Although no mezisures of personal hygiene will Sitve a worker from occupational (IiseiLsta i f the conditions of work ;ire bad, yet there ;ire certain rules of hygiene that are decidedly useful. Both human obser- vation and animal experiments have shown t h a t the presence of milk in the stomach inhibits to ii decided degree the iibsorption of lead. Hritish and German employers have for half a century had the habit of providing milk f o r lead workers the first t h i n g in the morning o r in the middle of Ihe morning ant1 afternoon. Studies of car- tlon tctritchioritie therapy f o r hookworm in- festation htive shown thitt H negative calcium bitlance from lack of calcium in the - I food encourages a toxic reaction, also t h a t as only slightly toxic, but wartime exper- it is possible t o defend the liver from dam- ience here and in England showed t h a t zinc age by a diet rich in sulphur-containing chloriqe in t h e form of fumes can be deadly. proteids. German and Russian writers hold 3 ) Be cautious in applying t h e results of that the obese are more susceptible to ben- animah experiments to human beings. We zene than t h e thin a n d t h a t f a t t y food fav- ors poisoning. This was confirmed by the experiments of Li and Freeman who showed that a diet low in proteins and high in f a t were misled for years by accepting the pic- fture benzene poisoning as seen in ani- mals vhere leucopenia i6 the typical sign, appea s early and is a safe warning of in- increased t h e action of benzene on rats and toxication, anemia is slight or absent. So on dogs. T h e eff'ect of alcoholism is notor- f o r ydars we depended on the white cell iously bad on poisoning from lead, mercury count bnly and missed many cases. I n car- and T N T , and pharmacologists found that bon tetrachloride poisoning in animals, i t to be true of carbon tetrachloride also. is thelattack on the liver that is conspicu- Foulger, Director of t h e Haskell Labor- oils, not t h e kidneys, in industrial poisoning atory of t h e du P o n t de Nemoiirs Company, t h e reverse is true. Animal experiments emphasizes the importance of proper food a r e ofi course very valuable but they can for workers in the poisonous trades. H e has found t h a t such workers need an opti- never serva t 1Iodon away with of human the need beings. of close obThey would Lmal content of vitamin in their daily food, never , ave helped u s to detect early mer- particularly of vitamin C and the B group. cury poisoning, with its increasing timidity It may be simpler and more effective t o and depression, or early ciirbon disulphide administer these vitamins than to t r y to poisoning. with its irritability and gloom. control t h e e a t i n g habits of the men a n d 4 ) I n making your diagnosis do not fol- women in these jobs. Foulger quotes Vis- IO\\. too s c r l ~ p ~ i l o t ~tshley typicid picture ils count Chetwynd, manager of a T X T fill- given i n the test-books. those books. with ing factory in t h e First World W:tr. as sny- which :you will be confronted when yoti go iiiK t h a t the women in the factory had f a r before the Compensation Board. I t is only more gastric disturbances than the men. in industrial cases with their unfortun:itt? On the theory t h a t this was caused by the medico-legal si'de that such ii strict demar- less substantial meals eaten by the women, cation line esists. T h e literature on blood the miinrtKement made a deduction f r o m dyscrasias is full of atypical cases but wtl their pay mid fed them well. As a result. have only lately been able t o discard t h e the complaints fell off from 11.3Cr in Sep- typical picture in berizetic poisoning. tember t o 0.7-2.0'C the following JantIiiry. 5 ) Be cautious in accepting the skitement Foulger says t h a t the night shift needs spe- of the employer as to the compounds to ciitl attention in this respect. which your patient IViIS esposed. Often he May I close with a few warnings: docs not know \\.hilt ii trade name me:uis- 1I T h e establishment of so-called mnsi- there are more than ;t dozen str:inpc I I ~ R I C S mum';tllow:ible concentrations by the X.S.X. tor ciirbon tet rachloride-or he miiy think for industri;tl poisons has given lis v~tltlilblc h e is still using t e t r i \ c h l l ) r c t h ~ l e ~:i~s eit sol- Kiiidnnce, b u t do not forget t h a t these arc vcn t \ v h e i ~t hc pu rveyor hiis wit hot1t \ViirtI- bitseti on t h e qu;intity inh;tlcd I>y a miin iiip switched over t o tetr;\chlc.trcth;iIie. O r breiithing ;it a normal r a t e for cight hours. t hc st r;\ight-run p;isolinc hc formttrly iistvi Ovcr-time and hexvy, hot work. making the hiis been c h i ~ l p t d to "crilcked giisolint%" m u 1 b r w t h e more tiecply iincl r:ipidl:\., make \vhich contains benzene. / necess:i1-y ;L lowc r stan d;t rti. ti 1 Fin;tlly \vi' must titkc with citlitiol\ thtt 21 S t a t e m e n t s ;is t o t h c tosicity of it11 s t ;t t 1%m CIIt t hitt casperi n ~ts t\vi~t h :l ccrt 11i 11 element must t x titken with c*ittltio!l for nta\v poison sho\v thitt sutticitwt \ V i \ r l I i t I r o f thew may he ;t wide diffcrencil i u thc t l i f - tl;tiigi*r will be givtw in time, by NI i r r i t a t - ferclit ctimpiincls. Thc biisic cit1.bOtl;ltc' inp ;ir*tion 011 t h r t'yt', n o w ilnd throilt. Thilt of le;tti is much m o i ~solrible i n thc body n1iiy 1 ) ~t rrlr \vhcii i~mploymetn is high i111tl yt(juices thit11 the s t i x i g h t c:ir\)oii;itc: the s111- comprn ion I;i\vs ;idt%(ltiilte. 1t cannot bt> phitttl i.s f;tirly solu\)lt~.t h c siilphitlt. vary ~lt~pt*ndtv0 1i1 tvht'ii jobs itrt' scilri*t%o r in slir;.htly SO. \Vel look upoii zinc c-onipotintls s t a t w w i t h poor 1 ; t h w lil\Vs. ,