Chapter XXIX

THE LESIONS RESULTING FROM THE MANUFACTURE AND
USES OF POTASSIUM AND SODIUM BICHROMATE

Peculiar lesions--erosion of the septum of the nose and the production of ulcers on the skin--are caused by bichromate of potassium or sodium. Erosion of the septum is found only among persons engaged in the manufacture of the salts, but ulceration of the skin of exposed parts, principally the hands, although most severe and most frequently met with among the same class of operatives, may be detected among persons engaged in the many industries in which the salts are used in solution.

Bichromate of potassium and sodium, commercially known as “bichromes,” are used largely--

1. In the manufacture of colours, such as the various chrome yellows, by the interaction of lead acetate and bichromate of potassium.

2. In dyeing and calico-printing. In dying cotton yarn the material is soaked in lime water, and, after wringing, is transferred to a vat containing lead acetate. It then passes through a solution of bichromate which develops the yellow colour on the fibre.

In calico printing potassium bichromate is used in the indigo blue discharge style, when it may be printed from a paste containing 40 per cent. of bichromate, which will discharge the colour from the blue material after suitable treatment. Or it may be used for the production of chrome lead colours by first printing the desired pattern on the calico with a paste containing acetate of lead, and subsequently passing this through a 2 to 5 per cent. solution of bichromate.

Potassium bichromate is the most important mordant for wool. The mordanting bath is prepared with 2 to 4 per cent. potassium bichromate (of the weight of the wool) and the necessary quantity of water, amounting to from 50 to 100 times the weight of wool.[103]

3. In photography. The carbon process depends on the fact that gelatine and potassium bichromate combine under the influence of light to form a compound which is insoluble in hot water. The strength of the bichromate solution for this process does not exceed 5 per cent.

4. As an oxidising agent for the manufacture of coal tar colours, for the bleaching of oils, etc.

The first full account of the lesions arising in the course of the manufacture of bichromate was given by Bécourt and Chevallier in 1863.[104] In 1854 Heathcote published in the _Lancet_[105] an account of obstinate ulceration of the tonsils and pharynx observed in a worker in a bichromate factory. No such extensive ulceration as he describes has been recorded since.

A very complete description of the processes and of the clinical symptoms shown by the persons employed, together with suggestions for improving the conditions of working, was given in a joint paper by Delpech and Hillairet[106] in the years 1869 and 1876. They believed that any part of the skin might become ulcerated if exposed long enough to the action of the dust. In no case did they find that the ulcers penetrated into the joints, or that the bones of the nose were attacked. They believed that the action of the dust set up in some cases bronchitis and asthma.

In 1893 the effect of bichromate on the health of the workers was referred to in the Report of a Departmental Committee of the Home Office on the conditions of labour in chemical works, and, as a result, special rules prescribing protection of vessels containing bichromate in solution, respirators, due means for the removal of dust, waterproof gloves, and lavatory accommodation, were drawn up.[107]

In 1895 the conditions found in the German bichromate factories was made the subject of an interesting official report by Dr Wutzdorff,[108] assisted in the chemical part by Dr Heise. Following upon the recommendations made by Dr Wutzdorff, stringent regulations were drawn up to govern the industry in Germany.

In 1899 considerable stir was created in Glasgow by the publication by the _Labour Leader_ of a series of pamphlets directed to show, among other things, that in certain factories in Scotland the conditions of work were still unhealthy. In that year I visited all the factories in this country, and a code of special rules printed elsewhere in this volume now governs the industry.

Potassium bichromate is made by roasting a mixture of chrome ironstone, potash and lime, lixiviating the fused mass with water, and adding enough sulphuric acid to convert the neutral chromate into bichromate. The reaction may be represented as follows:--

Cr_{2}O_{3} + 3O = 2CrO_{3}
CrO_{3} + K_{2}CO_{3} = K_{2}CrO_{4} + CO_{2}
2K_{2}CrO_{4} + H_{2}SO_{4} = K_{2}SO_{4} + K_{2}Cr_{2}O_{7} + H_{2}O.

Sodium bichromate is made in practically the same way, sodium carbonate taking naturally the place of potassium carbonate. In the crushing and grinding of the chrome ironstone much dust permeates the air, but this mineral dust does not give rise to the peculiar lesions associated with the bichromate.

After having been ground to a fine impalpable powder the chrome ironstone, mixed with lime and potash, is introduced into a furnace and roasted for about three hours. When withdrawn from here the fused mass or “batch,” as it is called, consisting of neutral chromate of calcium and potassium, after being allowed to cool, is broken up and shovelled with evolution of much dust into large vats or “keaves.” Water and potassium sulphate in solution are added, and at this stage, owing to the slaking of the uncombined lime, much steam, carrying with it particles of chromate dust, arises. The solution, when concentrated by passing through successive keaves, is pumped into evaporating pans, which are almost invariably entirely covered in and communicate with the outside air by means of a shaft running through the roof. Sulphuric acid is next added, forming potassium sulphate and potassium bichromate. The former is withdrawn, and the latter, when sufficiently concentrated, is pumped into lead-lined tanks, where crystallisation is usually completed within three weeks. The crystals form beautiful large adherent masses on the sides and floor of the tanks. They are broken up by a pick, removed on barrows to be washed, dried in open stoves by hot-air or steam-pipes, and finally packed in barrels.

Sodium bichromate does not usually crystallise, but forms a solid cake which requires to be broken up.

The particular lesions associated with the manufacture are found among all classes of men employed, from the moment the fused mass is removed from the furnace, until the crystals are headed up in the barrels. Inasmuch, however, as all the processes are carried out in one large common shed, it is a little difficult to determine the relative degree of danger attaching to each operation.

The rafters immediately above the keaves are coloured a canary yellow, from the neutral potassium chromate carried up by the steam; a sheet of cardboard suspended at a height of 2 feet above an evaporating pan becomes covered in a short time on its _upper_ surface with innumerable small brown specks of bichromate--a precipitation which must result from the cooling of the steam; a stranger present for only a few minutes while the packing is being done has the mucous membrane of his nose acutely inflamed for hours or even days afterwards. These facts show how permeated the atmosphere in the shed can become from the dust and fumes from the bichromate. Breaking the crystals is the source _par excellence_ for the development of chrome sores.

Dr Heise, in the paper already referred to, estimated quantitatively the amount of bichromate dust in the air where the different processes were carried on. Thus he found 1 cubic metre of air near to the place where three men were breaking up a cake of sodium bichromate contained 6.30 milligrammes. One cubic metre taken during the fifteen minutes during which packing was done contained 1.57 milligrammes. As regards the steam, he found 1 cubic metre taken at a height of 45 centimetres above the level of the evaporating pan contained 0.736 milligrammes of sodium bichromate. In general, considerably less bichromate was found in the air over the evaporating pan than where the dusty processes were carried on.

The following is the result of an examination I made of 176 men exposed to work at one time or another in the chrome house:

+---------+-------+-----------+----------+--------------+-------------+ | | | | |Sense of Smell| Number with | | Number |Septum | Septum | Septum | Lost or | Unhealed | |Examined.|Normal.|Perforated.|Ulcerated.| Impaired. |Chrome Sores.| +---------+-------+-----------+----------+--------------+-------------+ | 176 | 30 | 126 | 20 | 16 | 39 | | 100 | 17.0 | 71.6 | 11.3 | 9.9 | 22.1 | +---------+-------+-----------+----------+--------------+-------------+

In most of the cases where the septum was found ulcerated but not perforated, the duration of employment had not been sufficiently long for the ulceration to proceed to perforation.

In none of the 30 men in whom the septum was found to be normal was the immunity attributable to shortness of employment. Six were connected with the management, 6 were blacksmiths or coopers, 10 were furnacemen, 4 were engaged at the keaves, and 4 in the crystal house. One-half of them had been employed for upwards of ten years.

There can be no doubt that the mucous membrane covering the septum is attacked more readily in some persons than in others, and I incline to the view that an immunity may be acquired if the first few months are passed without ulceration taking place.

The rapidity of its onset is remarkable, as is shown by the following table:--

Duration of Employment where the Ulceration had not
progressed to Perforation.

+------------+------------+---------+--------+----------+
| 2 Weeks or | 2 Weeks to | 3 to 12 | 1 to 3 | Over |
| less. | 3 Months. | Months. | Years. | 3 Years. |
+------------+------------+---------+--------+----------+
| 3 | 7 | 5 | 4 | 1 |
+------------+------------+---------+--------+----------+

Perforation was noted as having already occurred in one instance where the duration of employment had been seven weeks, and in two others it had been less than three months. Usually, it appears to take place between the sixth and twelfth month after commencing work. Most of the men examined worked in the crystal house, and all except the four mentioned had either ulceration or perforation of the septum. The majority of the furnacemen also had perforation, but in them the septum was found normal more frequently than was the case with the men employed in the crystal house.

_Nature of the Perforation._--The cartilaginous framework of the nose consists of five pieces, the two upper and the two lower lateral cartilages, and the cartilage of the septum. The two upper and the two lower lateral cartilages give the nose much of its shape, and form the alæ nasi. The ulcerative process due to bichromate dust never attacks them. The cartilage of the septum is somewhat triangular in form, and thicker at its margin than at its centre. Its anterior margin, thickest above, is connected from above downwards with the nasal bones, the front part of the two upper lateral cartilages, and the inner portion of the two lower cartilages. Its posterior margin is connected with the perpendicular lamella of the ethmoid; its inferior margin with the vomer and the palate processes of the superior maxillary bones. The seat of election for the ulceration to commence is a point about a quarter of an inch from the lower and anterior margin of the septum, and it extends in a direction upwards and backwards.

The limitation of the perforation to the cartilage of the septum is accounted for by the fact that the mucous membrane covering it is adherent, forming the perichondrium, and is far less vascular than the mucous membrane lining the rest of the nasal fossa. Once the mucous membrane is destroyed, the blood supply to the cartilage is cut off, and necrosis ensues. The ulceration having progressed upwards as far as the junction of the septum with the ethmoid and backwards to the vomer, becomes arrested. Healing then takes place, the bone not being attacked, and the cicatrix usually becomes covered with an ecthymatous crust of mucus.

In no instance was the anterior or lower border of the septum destroyed. Consequently, the rigidity of the parts is maintained, and deformity, so prominent in other ulcerative processes attacking the nose, absent.

The onset of the morbid process is ushered in by sneezing and the ordinary symptoms of nasal catarrh. The pain accompanying the ulceration appears to be insignificant. It had never been severe enough to necessitate absence from work or to call for medical treatment.

Once the perforation is established, the only inconvenience which results is the formation of plugs of mucus in the nasal passages. The general health is in no way detrimentally affected by the condition. Considering the extent of the lesion, the number found with marked impairment of the sense of smell is not large. Mucous deposits and white patches were occasionally noted on the pharynx, but definite ulceration, such as has been described in bichromate workers, was in no case detected. Asthma, noted by the French writers on the subject, Delpech and Hillairet, was found in one instance--that of a partner in one of the works. In his case there was a family predisposition to it, but the first definite attack dated from contact with bichromate.

_Ulceration of the Skin._--In 39 out of the 176 men engaged in chrome processes, one or more unhealed ulcers or “chrome holes” were observed. In these and in several others, numerous scars marking the site of bygone ulcers were noted.

A chrome hole is a sluggish ulcer. It results from a cut or abrasion of the skin coming into contact with bichromate in the form of crystals or solution. The seat of election is either on the knuckles or at the base of the nail, but they may occur on any part of the hands or forearm. In two cases they were observed on the neck, once in the groin, and once on the foot. The tissues around are raised, thickened, and indurated; the centre is filled by a slough, usually covered by a scab, and the whole resembles a large boil. When the slough has been removed the floor of the ulcer is seen to consist of greenish-yellow granulation tissue. In the majority of cases the central scab is not more than ⅛ inch in diameter, in a few it is ¼ inch, and the largest that I have seen measured, ¾ by ½ inch. Chrome holes occur principally among men engaged in the crystal house and at the keaves, and only rarely among the furnacemen. The amount of pain and inconvenience they cause is considerable. Sometimes they necessitate absence from work, but they are never a menace to life. At one works six men were absent during 1898 for periods varying from three to nine weeks, on account of chrome holes. Even when their severity is not such as to necessitate absence from work, months may elapse before they heal.

The treatment adopted by the men is of the most elementary description, and naturally under these circumstances they prove intractable.

The conditions found by Dr Wutzdorff in the German bichromate factories were very similar. Ulcers of the external skin were found most frequently on the fingers, hands, and arms, then on the feet and legs; once an ulcer was found in the external auditory meatus and three times on the eyelids. The ulcers penetrated deeply into the soft parts, and required, in consequence, a long time to heal. In no case had they penetrated as far as the tendons, or into the joints. Ulceration and perforation of the septum was found in workers in several factories, and ulceration of the gums and pharynx of slight extent was observed twice. The general condition of the workpeople was apparently good--at all events no worse than that of chemical workers generally.

The preventive measures necessary in the manufacture of potassium or sodium bichromate will be found stated in the regulations printed elsewhere in this volume. They resolve themselves generally into removal of dust and fumes, cleanliness, and medical supervision periodically of the workers, and the covering up of cuts and abrasions with suitable dressings. When in solution the salt does not attack the unbroken skin. Indiarubber gloves are sometimes worn by the men in dye-works who are constantly engaged in processes in which bichromate is used in dilute solution, but in view of the difficulty of enforcing their use, and the fact already stated, that unless there is an abrasion of the skin a chrome hole will not be developed, the wearing of indiarubber gloves, while a thing to be recommended, can hardly be made compulsory. It is advisable that in all dye-works the foreman should be made responsible to report all men suffering from abrasions of the skin, or from chrome holes, to the manager, in order that they may have proper treatment, and be put to other work until such time as healing has taken place.

In photographic processes involving the use of bichromate, if there is any tendency to the development of eruptions on the hands, careful washing and subsequent treatment, when thoroughly dried, with lanolin or glycerine should be tried. If this fails, rubber gloves must be worn.

T. M. LEGGE.