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1 DONALD HUNTER. LECTURE 1. Lead. Tetraethyl lead. Arsenic. Arseniuretted hydrogen. Phosphorated hydrogen. In ?Iicsi* lour lectures it has been my purfwise to review from the point of view of the 'iinici.m the broad problem of disease in relalion to occupation. I have given special emphasis to the mechanism by whieh poisoning occurs and the means of prevention used. It has been ue<vssary oft-n to approach the sub ject historically in order to show what has hern achieved or what yet requires to be done, t wisii it to he .dear that I am not concerned solely with what happens in this country; my review takes into account oceupational disease in any part of the world. It follows that I have recorded certain descriptions of working conditions and diseases which I have not* had the opportunity to study personally. TXm*STRlAL LEAD POISOXINU. HtSTOBY. White lead and red lead are amongst the oldest pigments known, and it is possible to traee their history with some accuracy over a period of at least two thousand years. (Klein. 19131. The i-arliest prototype of white lead was the native earbnnate of lead known ;s eerussiuy Xenophon (400 B.C.) makes what is probably the earliest reference to this material whieh he describes as cerussa and records that it was used as a cosmetic. Vitruvius (15 B.C.) referring to red lead as sandaraea states that it was discovered by accident in a cosmetic jar of white lead which had been exposed to heat in the burning of a house at Pineus. Early in the Christian era it was made by roasting ceruse. It was not until much later that the method of manufacture from lead or litharge was discovered. The many symptoms of plumbism were noted long before they were ascribed to the action of lead. Gradually, however, physicians 'First of a scries of four lectures given to the Derby Medical Society in May. t?s5. came to appreciate the cause of these distur bances ami the syndrome was designated satur nism, for lead was called saturn by the alchemists because it absorbs and devours, so to speak, all other imperi'eef mends. Hippo crates (370 li.t'.i was probably the rirst of the ancients to recognise lead as the cause of the symptoms, at least he describes a severe attack of colic in a man who extraeted metals. The relationship of constipation, colie. pallor, paralysis, and ocular disturbances to the action of load on the body was observed by Xleamler in the second century B.<Pliny (23-79 A.D.l states that the ancients painted their ships with native ceruse, that lead poison ing was known in his day, and that the workers in lead products tied up their faces in loose bags lest they should inhale the pernicious dust. Dioscorides (100 A.D.l knew that ingestion of lead compounds caused colic, paralysis, and delirium. He states that in his time white lead was made artificially from lead ami vinegar. This is probably the earliest record of the arti ficial muunfactuiv of white lead, 'hi' of the earliest references to its use in Rmrbmd is found in the <'!*< RiuN (Kdward 1. 1274. where an account is rendered for painting materials supplied for the deroratim :>f the Painted Chamber. I'ntil the 17th century the Venetians apjiear to have been the principal manufacturers of white lead, and after that date the process was largely developed in Holland. Probably the earliest record of lead poisoning amongst white lead workers in England is that of Vernatti {167^ -- 'The Accidents to the workmen arc. immediate pain in the Stomack, with exceeding contortions in the Guts, and Costiveness that yields not to Cathartieks, hardly to often repented Clysters ............ And these we find effected principally by the mineral steams in the easting of the plates of lead, and by the dust of tin* flakes ............ Next, a vertigo, or dizziness in the head, with continual great pain in the brows.  CLINICAL SUPPLEMENT insusceptible animals as mice. He was able to show that the active growth of the bacilli did not depend merely on the necrosis of the tissue, but was due to the actual presence of silica. ASBESTOSES. electrical, building, chemical and other trades with materials of very great utility. These include a wide range of insulation products, as well as cement sheets for building work, brake and clutch linings, electrodes for welding, acid resisting filtering cloth, packings, jointings, and wrappings for steam pipes. The asbestos industry is 2,000 years old. Herodotus (450 b.c.) relates how the Romans mined it in the Italian Alps and Ural Mountains, using it for enshrouding their corpses before cremation to permit of easy collection of the ashes for burial. They named it "amianthus." meaning undefiled, pure, incor ruptible. Pliny (a.d. 501 refers not only to difficulties in the weaving of asbestos. but also to the use of respirators to avoid the inhalation of dust. Strabo (30 b.c.) and Plutarch (a.d. 70) refer to the wicks of the lamps of the vestal virgins as "asbesta."--the unquenchable, in extinguishable. or ineonsumablc. It is stated that Charlemagne possessed a tablecloth made of it, which was cleansed by passage through fire. Raw* asbestos in crude and fibre form is imported chiefly from South Africa, Canada and Russia, and stored in sacks in open sheds. The crude asbestos, as required, is carried to a rotary mill and opened, two or three sacks at a time by hand. This process is dusty The operation which follows is that of crushing, to separate the rock from the fibre, which then passes by vacuum suction into a dosed-in machine for fiberisiug. This machine delivers fiocculent, soft, fibrous material, free from grit. It is the custom in the trade to blend the material and this involves emptying out a number of sacks upon the floor and raking the material over to mix it thoroughly (fig. 421. However, though asbestos occurs in every country, it is only within the last 50 years that it has been used for industrial purposes. In 1880 the annual world production totalled only 500 tons, a figure which had risen to 434.938 tons in 1929. The term asbestos is a collective name applied in commerce to a variety of silicate minerals which differ from each other in chemical composition and physi cal properties, but resemble one another in their' finely fibrous nature and flexibility. Their value depends uti the fa-ility with which they can be split into long and short flexible fibres, their resistance to aeid>. and their insu lating properties with respect to heat and fleetricity. Most of the asbestos in commerce is either fibrous serpentine such as ehrysotile. or a fibrous mineral of the hornblende group, of which the most important are croeidolite and amosite. Chrysottle is essentially a hydrated silicate of magnesium, containing little iron and practically no calcium. The hornblende varieties contain less magnesium and usually more aluminium, and iron, croeidolite ami amosite being mainly silicates of iron. Capable of being spun into yarn and woven into cloth, or of mixing with cement, rubber, resin, bakelite. or graphite, to form a variety of useful products, it provides the engineering. Fig. 42.-- Method used to apply exhaust ventilation for blending of crushed asbestos. The draught acts directly above the middle of the heap. Such a method is hopelessly inad.quate. < 00 Conference* cODeeroios Mrtliorir for iuppwsiug Dust in Textile Factories 13JH. For the manufacture of yarn and doth cotton is often incorporated with the fibre before carding. The carding machine consists of large fast-running cylinders, covered with innumerable minute wire hooks to ensure that the fibres are laid parallel (fig. 43). From the end of this machine the material is received as a sliver or rope. Stripping the carding machines (fig. 44) and cleaning the cylinders with a wive brush is a very dusty occupation. 59  LONDON HOSPITAL GAZETTE ortable vacuum plant for cleaning asbestos aiding machine. Note the revolving brush tted with a cover and connected to a vacuum leaner. ill] ('oufti'i'iii'ii co'"'*-1 iiing .\]<-tbolf forSii|"|uMriui: :itt iu A*lw*.o* TvXiilc Fv.'Wtl**, I'.tSt >. doubling. and weaving follow the ' carding. Dry weaving is usually tor wet weaving has the disadvanisting certain fittings on the maehin- mm-textiles. such as milHwards. a hs is employed. Fibcrised asl>estos is h elav. cement. ami water and run series of sedimentation tanks to finest of the pulp. This pusses along aie as sin emulsion, becoming drier doughy on its way. until it is eventu- out upon a cylinder. From this it loved, and dried in the drying room. 1 operations, such as sawing, grindig. and polishing, give rise to much nlating mattresses are made almost .y hand from lengths of asbestos ace filled with fibcrised asbestos by l>. or shovel, levelled by Iteating and sewing. igers of asla-stos remained for Jong d. They have come to light with a disconcerting suddenness. The first U'stosis known in this country was tn 19(10 and the second in 19*24 chronic pulmonary asbestosis as a definite clini cal entity (Merewother and Price, 1930). From that time the view that dust from silicates is comparatively innocuous was no longer tenable. It is now suggested that when the silicates of aslx-stos are dissolved in the lung tissue silicic real is liberated and acts as a chemical irritant to which connective tissue is particularly sensi tive. Regulations lutve now been applied to the industry by the Home office. The principle of locally applied exhaust ventilation is enforced to prevent the escape o;' asbestos dust into the air of any room in which jKMsons work. Hand cleaning of the cylinders of carding machines is prohibited while any other (tcvson is present, nor may it Ik* done by hand strickles or other hand tools. Those cleaning cylinders, filling insulating mattresses, and entering chambers containing loose aslH'stos should he provided with an efficient apparatus by means of which they can breathe air free from dust. These i; regulations have stirred up other countries so that interest in the matter is now world-wide Reports o! a heavy immienee of asltcslnsis have been made recently in some (ierm iu factories, especially in Dresden (Kruger. J931- and Berlin {(lerbis and I'cko. 193*2'. In five years 3" workers in asbestos have attended my out-patient department: 25 were women and 12 were men. Of these 30 were judged to be suffering from pneumonokoniosis due lo the inhalation of asbestos. Seven of these have since died: and in four autopsy showed that the pneumonokoniosis `was com plicated by pulmonary - tuberculosis. Many had worked in more than one department, hut the principal occupations in order of frequency were as follows:--spinner, weaver, disintegra tor. mixer, mattress maker, card cleaner, store keeper, slab maker, pressor, maehin'st. The average length of exposure Imm'ojv the ousel of syniptoTiis was seven years! tt the patieiits who died, one was a weaver who had been exposed for IS months and another a store keeper who had ln*en at work for 19 year.:. It; nianv cases there was a long interval lh*tween removal from exjmsure and the onset of symp toms: the longest such interval was eight years. The presenting symptom was dyxpncpa. This ^ \V;w ohvIv stud eonvm'-nioiv ................................. .  CLINICAL SUPPLEMENT # Pig. 44.--Stripping an asbfstos machine before a modern type of exhaust ventilation was locally applied. 1 By kind perniitJioo of British Belting and AcbettM, Lt<lA was uoa riy always associated with nonproduedye cough. as many as lt< oases having little or no sputum. Ila-muptysis never occurred in fiu- absence of pulmonary tuber culosis.- it was round in throe eases. lu lh cases pain occurred between tile shoulders, under the scapula, or behind the sternum; it was never more than slight, lu two eases a diagnosis of acute pleurisy had l>ern made during the period oi employment in axhvxioa but in no ease had a pleural effusion occurred. A history of warts was obtained in Id eases, of laryngitis in three, and of conjunctivitis in two. The patients were usually well nourished. Clubbing of the fingers was present n six cases. Cyanosis was occasionally noticed but was only slight. Kxammatiou of the chest showed limitation of the respiratory excursion on both side's. The percussion note was never seriously impaired, but di-du dullness was sometimes found at the buses. The breath sounds were vesieufar. and auscultation sonictunes revealed scattered, nn-diu!!.. crepitant rules, often with a melailie tone, aid situated especially at the bases. Added '-unds were ahsent on repealed examination in ten ease.-, b'or obvious reasons the condition is not uni lateral. and therefore displacement 0: the heart and other mediastinal structures was not found. Thirteen cases showed axbestosi> bodies in the sputum. These are golden-yellow structures of elongated licaddike form, often with bulbous ends (1'ookc and Hill. 19271. Tin- appearance of fully formed bodies has been anpared to In-ads on a necklace. The beads vary in size, and make up an irregularly segmented body. These bodies have been found to vary in length from 2d to over 200 microns. An asbestos fibre fornw the central core in each body <(Moyne. 61 i LONDON HOSPITAL GAZETTE icy ;i re Ik*ki seen with an oil immerand show up clearly without staining yellow structures (fig. 45). They can d hy lueinatoxylin. The tubercle as round in the sputum of five of the as**, and already four of those have -1 fibrosis develops more rapidly. With continued exposure to high concentrations of dust the fibrosis may be fully developed in seven years, and may cause death after about 13 years' exposure. It must be remembered that the existence of a clinically recognisable degree of asbestos fibrosis in any individual Ls an addi tional adverse factor in the prognosis of any acute infection of the lungs such as pneumonia or broncho-pneumonia. Precise information as to the incidence of pulmonary tuberculosis amongst asbestos workers cannot be obtained, but there is reason to believe that the out standing susceptibility to this complication in silicosis does not apply to the same extent m asbestosis. The fibrosis in asbestosis is much more diffuse than that due to silica. In silicosis it occurs in the form of numerous more or less isolated foci, but in asbestosis as a fine network throughout the lungs. In radiograms it is so fine as to resemble ground glass (fig. 46). Homogeneous opacities of this nature are seen at both bases, and may later fo-mme more sbestosis bodies from the lung juice in a case asbestos pneumonokoniosis (x 6oo). A girl f 2i who had been employed in the spinning epartment of an asbestos factory for four ears. Abnormal signs were present in both mgs, and asbestosis bodies and tubercle bacilli ere found in the sputum. At autopsy asbestos oeumonokoniosis and pulmonary tuberculosis ere found in both lungs. --A.B.. woman, aged 27. Worked from in tiie spinning department of an asbestos - tie protection from dust was poor. D92S: : shortness of breath, and occasional t side of chest on breathing. On examina* warts on fingers, the largest 3 by ] mm. of fingers. Pyspnma, but no cyanosis, tot displaced, heart sounds normal. Dimimeat of hasp of right lung, with slight miinislied breath sounds, and extensive euritic sounds. A few crepitations at No sputum. X-ray: heart normally situhomogeneous opacities resembling ground ** of both lungs (fig. 46). 1935: Shortness worse: dry cough. On examination: no igers. Physical signs in chest unchanged. 4iMalritn the fortieth nf time which obv: loba the havzom but 193: star: nod adv pro P si lie / ( ii \ I I: mas ) ine pai one sub tilit vap hig: pri< moi lan boh eve: ear> gre. the Ion-. I mat elec ! nea Hu mu11 in his risl res> his usi' fro ])e: res  CLINICAL SUPPLEMENT obvious as a fine punctate stippling. The inter lobar pleura is usually thickened. Ultimately the fine punctate mottling can be observed to have spread beyond the limits of the lower zone to the middle and even the upper zone, but the apices usually remain free (Ellman, 1933). This fine, diffuse, punetate mottling stands out in definite contrast to the coarse nodular mottling seen in silicosis. In tact in advanced asbestosis the degree of shadowing present would have little significance if seen in silicosis (Timmermans. 1931). FLUOROSIS. In the middle of the nineteenth century many chemists attempted the isolation of fluor ine from hydrofluoric acid, and more than one paid with his life for handling too frequently one of the most dangerous of known chemical substances. The danger arises from the vola tility and extremely corrosive nature of the vapour of the anhydrous acid. Even when highly diluted with air it causes an intolerable prickling and burning sensation in the nose, mouth and eves. If inhaled it attacks the larynx and trachea giving rise to burning pain behind the sternum, cough, ex(>ectoration, and even hemoptysis. Unless handled with extreme care it may get under the finger nails causing great pain, and if a drop comes in contact with the skin it lias a caustic effect producing pro longed and painful ulceration. It is said that C. Knox lost his voice per manently during his early experiments on the electrolysis of the acid, and that T. Knox nearly died of its effects (Louyet. 1846). Humphrey Davy wrote that he had suffered much from the dangerous effects of hydro fluoric acid, and it is said that he abandoned his attempts to isolate fluorine because of the risk involved. P. Louyet, who continued the researches of the Knox brothers, described how his own health was profoundly altered from using the acid, and how it caused him to suffer from cough and hemoptysis. According to Debrav (1886) the death 6f Louyet was a result of his work but no medical details are available. In 1869 J. Nickles died from the effects of accidentally inhaling the vapour of concentrated hydrofluoric acid (Core. 1869). In spite of these deaths the search for tho fourth halogen went forward, until in 1886 H. Moissan isolated the element fluorine during the electrolysis of a solution of |>otassium fluoride in anhydrous hydrofluoric acid, in an apparatus made wholly of platinum. In this way was solved one of the most difficult prob lems iu modern chemistry. Comj>ounds of fluorine have been increasing in im|>ortance in industry of late years. Hydrofluoric acid is used for clouding electric light bulbs, etching glass, pickling metal and wire, and cleaning sandstone and marble. Owing to its corrosive properties it must bo handled with every precaution. The fluorides enter into the composition of artificial fertili sers. and insecticides and fumigants used in agriculture. Feil (1930) has recently empha sised the danger of poisoning from hydrofluoric acid in the manufacture of aluminium by the electrolysis of cryolite. (udjonsson has unearthed a new horror of modern industry, namely, fluorosis of the bones and ligaments in cryolite workers. Working with Professor P. Flemming Moller in the Occupational Hygiene Bureau of the Labour Inspectorate in Copenhagen, he was at first concerned with the incidence of pneumonokoniosis among workers in dusty trades. In the vicinity of Copenhagen cryolite is crushed and refined for use in the manufacture of alu minium. Cryolite is a double fluoride of sodium and aluminium, containing as much as ")4 |>er cent of fluorine. In the crude state it is mixed with a considerable amount of quartz. and there is thus an added risk of pneutnonokoniosis. Moller and Gudjonsson (1932) examined 78 employees, all of whom had been working in a cryolite factory for more than two years. They found the following four distinct lesions. 1. Pneumonokoniosis. This was present in various stages in half the subjects examined, the diagnosis being based on radiograms of the chest. The conclusion is unavoidable that the disease of the lungs was due to the quartz laden dust in the factory. 2. Fluorosis of bones and liganu nts. As the radiographic investigations of the lung condi tion proceeded, it was found that the shadows of the ribs, clavicles, and cervical vertebrae showed unusual density and abnormalities in /