REFERENCES.
[ [1] Zinn: Berl. Klin. Woch., No. 50, 1899.
[ [2] Collis, E. L.: Special Report on Dangerous or Injurious Processes in the Smelting of Materials containing Lead, p. 6. 1910.
[ [3] Grissolle: Thèse, Paris, 1835.
[ [4] Meillère, G.: Le Saturnisme, p. 122. Paris, 1903.
[ [5] Amino: Archiv. Ital. di Clin. Med., 1893.
[ [6] Chatin: Province Méd., Lyon, No. 4, 1892.
[ [7] Harnack: Deutsch. Med. Woch., 1897.
[ [8] Mayer: Virchow’s Archiv, 1881.
[ [9] Hunter, John: Observations of the Diseases of the Army in Jamaica. London, 1788.
[10] Mott, F.: Archives of Neurology and Psychiatry, vol. iv., p. 117.
CHAPTER VIII
EXCRETION OF LEAD
Symptomatology and Diagnosis (Continued)—Excretion of Lead.
—The two chief channels for excretion of lead are the urine and the fæces, while some include the saliva and the sweat.
In the case of the sweat there is not much evidence, but a few observers, mainly French, claim to have discovered traces of lead in the skin of lead-workers. In such a case, however, it is exceedingly difficult to eliminate the question of surface contamination; and although brisk peripheral circulation and transudation may possibly carry off a certain amount of lead, the chance of this is highly improbable.
There seems rather more evidence that the salivary glands may eliminate lead, as a number of other substances are undoubtedly passed in this way. Mercury certainly undergoes excretion through the salivary glands and the mucous glands of the mouth, and it is therefore not improbable that a metal so closely related in its chemical, and perhaps physiological, relations may be excreted in a similar fashion. Meillère[1] cites three instances of parotitis which were considered to be of lead origin, and further quotes an instance where, in chemical examination of the salivary glands after death, lead was found in small quantities.
Chronic parotitis is not infrequently cited as a symptom in cases of reported industrial lead poisoning, and may owe its origin to impairment of the salivary gland by the passage of the metal. Chronic parotitis, or even tenderness of the parotid glands, does not occur frequently among lead-workers with symptoms of lead absorption. Excretion, however, of lead through the salivary glands is not of great importance, except from the occasional complaint of a metallic taste in the mouth in chronic lead poisoning, and in such instances possibly definite excretion of lead is taking place through the parotid glands. A case may be cited which rather supports the view that lead may be excreted through the salivary glands. A certain worker engaged in a dangerous lead process from time to time, but never as a constant symptom, showed distinct pigmentation in the internal surfaces of both cheeks in the region of the buccal papillæ of the parotid duct. The pigmentation was intermittent; at times a large patch of deep blue-black pigmentation was found in the situation on both sides, with no staining of the cheeks around or of the gum margins, although his teeth in these regions were coated with foul tartar. If the lead in this instance gained access through the mouth, why should it have been deposited merely upon the cheek in this one situation, despite the fact that several other situations in the mouth exhibited the same conditions of bacterial decomposition for the production of sulphuretted hydrogen? We have not observed this pigmentation in the neighbourhood of the ducts of the submaxillary and sublingual glands, but only in the parotid.
By far the most important organ in the excretion of lead, from the point of view of symptomatology and diagnosis, is the kidney. Lead is not uncommonly found in the urine of lead-workers and in the urine of those suffering from lead poisoning. The quantity present is usually small and in a form in which it is exceedingly difficult to detect. Yet very pronounced changes in the kidneys may take place, with little evidence in the urine itself that pathological changes are taking place.
The urine of workers in lead factories is frequently high-coloured; in fact, as a general rule the degree of pigmentation is greater than is normal, and in those persons who show some degree of icterus, with the curious yellowish-brown colour of the conjunctivæ, hæmatoporphyrin may be detected on applying suitable tests.
In well-established cases of chronic poisoning, albuminuria as a rule is found, together with certain alterations in the other constituents of the urine, such alteration frequently making its appearance before the definite onset of albuminuria. Further, the changes in the eye, referred to under a special heading, have been frequently described as albuminuric retinitis of lead origin, it being true that eye changes are often associated with chronic changes in the kidney.
In acute poisoning lead is generally found in the urine, but in chronic poisoning it is by no means a common occurrence. From time to time small quantities are excreted, and in the chemical analysis made of the kidneys in cases of fatal lead poisoning a certain amount of lead has frequently been noted. Wynter Blyth[2] found in the kidneys of two white lead workers a total of 0·003 gramme. Peyrusson and Pillault[3], quoted by Meillère, found a similar quantity, 0·003 gramme, while in experimental animals Meillère himself found considerably less, only 0·0001 gramme; Stevenson, in a case reported by Newton Pitt[4], 0·0086 per cent. of lead in the cæcum and colon. Notwithstanding a small quantity of lead which may be determined by chemical methods as present in the urine or the kidney, very definite nephritis is set up in these organs, obviously due to the irritative effect of the metallic poison.
The Kidneys.
—Kidney disease of several types has been described as associated with poisoning by lead, particularly with chronic lead poisoning, where large quantities of a soluble lead salt have been ingested. Very considerable strain is thrown upon the kidney, with the result that the lead salts themselves are passed through; but, as has been pointed out when dealing with acute poisoning, the passage of lead through the kidneys does not continue for any considerable time, and in lead poisoning of an industrial and chronic nature no lead at all has been found in the urine in undoubted cases. Even when present, it may be difficult to detect unless the electrolytic method is used (see [p. 174]). At the same time kidney disease undoubtedly does occur in a very large number of workers.
All heavy metals, of which silver, mercury, iron, zinc, and finally lead, may be quoted as examples, appear to be eliminated by the kidney when they are present in the body in toxic doses, and often when in small non-toxic doses, but in the latter case to a greater extent through the bowel than through the kidney. The lead circulating in the blood, in common with other heavy metals, may be found chemically in the kidney, but the quantity recovered is not as large as one would expect from the considerable amount of inflammation often present.
In the experiments on animals, subjected to poisoning over considerable periods, the condition of the kidney in every instance showed distinct histological changes; and the longer such animals had been subjected to the poisonous effects of the metal, the more advanced were the signs of degeneration in its structure. In the earliest cases the disease partook much more of the nature of an interstitial nephritis, and it was in the later and more chronic stages only that changes in the glomeruli and fibroid degeneration were to be found, but in even these earliest cases of poisoning definite minute interstitial hæmorrhages were to be found scattered about the kidney. These minute hæmorrhages did not cause symptoms of hæmaturia, as in none of the experimental animals was bloody urine observed. On the other hand, besides definite small areas of hæmorrhage, patches were discoverable, indicative of hæmorrhage which had undergone fibroid change. Even in the illustrations given by Glibert[5], there appears to be evidence that hæmorrhage had taken place and had undergone fibroid degeneration, and there is very little doubt that in cases of kidney disease, the preliminary action of the poison determines small local yieldings of the vessel walls, with leakage, often hardly amounting to true hæmorrhage, at such spots. There is nothing opposed to the theory in the findings of other observers; in fact, if the preliminary gross effect be leakage of the description given, all the other lesions described by various observers follow as a corollary.
In the kidney, as in the other regions of the body, the venioles rather than the arterioles appear to be the preliminary site of destruction, and microscopical observation of the sections leads to the view that the intima of the vessels and not the media or the muscular coat is the one affected in the first place. Capillary hæmorrhages under these conditions are easier to understand than if the arterioles themselves or their muscular or middle coats were primarily affected. As degenerative changes progress, the whole of the vessel—external and middle coats and intima—undergoes change, ultimately resulting in the extreme narrowing and consequent blocking of the vessels themselves. Further shrinkage taking place in this area produces the shrunken sclerosed kidney.
Zinc in the form of oxide behaves in very much the same way upon the kidney as does lead. An experimental animal, which was given 0·2 gramme of zinc oxide per kilogramme body weight by hypodermic injection in the muscles of the back, died in fifteen days, and the kidneys showed extensive hæmorrhages—not merely the minute and capillary hæmorrhages found in lead poisoning, but hæmorrhages extending right through from the cortex.
Clinically, kidney disease, unless albumin be detected in the urine, is not a prominent symptom during the progress of an attack of chronic lead poisoning, and is to be regarded as a late symptom, developing as the result of long-continued irritation. The difficulty of eliminating alcoholic complication has been discussed, and there are no specific symptoms or post-mortem signs which enable one to distinguish alcoholic nephritis from the nephritis of lead poisoning.
In the chapter on [Pathology], the effect of alcohol on the kidney was cited as a common predisposing cause of kidney disease in lead-workers, and the effect of alcoholic excess in the case of a person who is already the subject of chronic lead absorption may determine the change from absorption to definite poisoning, because of alteration in the excreting-power of the kidney. So long as the ratio between ingestion and excretion is maintained the balance is kept up, and, although the tissues of the body may show signs of a certain amount of degeneration, no definite disease is produced; but the gastric irritation and the work thrown upon the kidney in removing from the blood large quantities of alcohol may be sufficient to alter this absorption-excretory balance and determine the attack of poisoning.
Acute nephritis is rare, and cannot be regarded as a sequela of chronic lead poisoning. Acute nephritis occurring in a lead-worker, with the associated symptoms of general œdema of the face, eyes, hands, feet, is of the gravest possible moment, and such a sudden appearance of nephritis is almost invariably fatal. In chronic nephritis, to which most of the lead cases belong, the usual signs are to be found in the urine. Pain is rarely a symptom; and although pain in the back is often complained of by lead-workers, examination rarely suggests that the backache is of kidney origin, but rather the lumbago type associated with chronic constipation. Care, however, must be taken, when backache is complained of, in eliminating kidney disease as a possible origin of the pain. A quantitative examination of the urine, with reference to the total acidity and phosphate excretion, may assist; and although this is not possible in a routine examination of cases of lead absorption, it may be useful in cases of suspected poisoning, especially where there are evidences of a good deal of blood-destruction.
For convenience of description, it is better to consider the action of lead upon the blood under two headings:
1. That of the corpuscular and other changes.
2. The action on the vessel walls, and pathological changes secondary to disease of the vessels.
The Anæmia of Lead Poisoning and Saturnine Anæmia.
—From the early days of medicine it has been known that lead produces poverty of the blood, and the white or yellowish-white appearance of persons who have been subjected to long-continued inhalation of lead dust or fumes constitutes striking evidence of blood-alteration. At the same time it is a common fact that the facial pallor does not always go hand in hand with diminution in the hæmoglobin. The conjunctiva may be observed as a test for colour, and here may be seen the curious vaso-motor disturbances which are partially responsible for the facial pallor.
Facial pallor in some forms of lead cachexia owes its origin to interference with the nerve-supply to the vessel walls, and it is a noticeable fact that a lead-worker whose face shows unmistakable signs of pallor rapidly flushes when spoken to suddenly or if mentally disturbed. The anæmia of lead poisoning is, however, a very definite fact. All observers are agreed that a marked diminution in the hæmoglobin of the blood takes place, to as low, often, as 35 per cent., without necessitating abstention from work, and without any serious interference with respiration, even when performing heavy manual labour.
In persons in whom the hæmoglobin is diminished there is frequently a yellowish or icterous hue of the skin, particularly the conjunctiva, due to staining of the tissues with altered blood-pigment. The hæmoglobin derivative—hæmatoporphyrin—can also be found in the urine of persons suffering from a marked degree of reduction in the blood-pigment, and may be taken as confirmatory evidence of destructive or hæmolytic anæmia. The symptom is, however, a later one than is frequently stated by the French observers, and can only be regarded as a later and confirmatory symptom, and not as an early one of diagnostic importance.
As would be expected from the destruction of blood-pigment, the morbid process leaves its imprint upon the individual red cells, and basophile staining of a number of the red corpuscles is to be found in a very large proportion of persons poisoned by lead. Moritz[6] first pointed out that these alterations in the red cells were present in lead poisoning. The basophile granules are by no means confined to lead anæmia, but are to be found in any severe secondary anæmia where hæmolysis has taken place, as in nitrobenzene and aniline poisoning, carbon bisulphide, etc. In addition to the basophile-staining granules in the blood-cells, the whole corpuscle may take on a bluish-grey tint when stained. The best stain to demonstrate these bodies is Leishman’s modification of Romanowski’s, and there is no occasion to stain the blood in the fresh condition, as the presence of the granules may be demonstrated easily, even after two or three months. Schmidt[7] thinks that if the basophile corpuscles reach 100 per million red cells the cause is undoubtedly lead poisoning.
Alterations are also to be observed in the structure of the red blood-cells in addition to the basophile staining. Distinct vacuoles appear, but as a general observation—first noted by Glibert[8]—the blood appears to be more resistant to damage when making the films, and the red corpuscles themselves seem to be more elastic than normal (increased viscosity). Alteration in the shapes of the corpuscles also takes place, and not only small varieties—microcytes—but also the large macrocytes are to be found. Nucleated red cells are rare.
The diminution in the number of the red cells is not so pronounced as would be supposed from the diminution in the quantity of hæmoglobin; but in the later stages, as in other secondary anæmias of toxic origin, the total quantity of red cells sinks to a count of a million or less per cubic millimetre.
According to Garrod, etc., the alkalinity of the blood is decreased in lead absorption.
The white blood-corpuscles do not show any change in their structure by the ordinary methods of staining, but they apparently show, as do the red cells, more resistance to injury in spreading blood-films—that is to say, the viscosity of the blood, which is apparently increased in lead poisoning, is also exhibited by the white cells. In the early stages of lead poisoning, more especially in acute lead poisoning, distinct leucocytosis may be observed, such a leucocytosis showing itself rather in relation to the lymphocytes than to the polymorphonuclear cells. In addition, the large mononuclear cells are also greatly increased, and a differential blood-count from a case of lead poisoning which also shows the presence of basophile granules in the cells invariably brings to light a definite increase in the percentage number of lymphocytes, and a decrease in the number of polymorphonuclears, and this even when the total leucocyte count is not outside the ordinary limit of normal variation. On the whole, the number of leucocytes present in the blood of persons suffering from lead absorption will always be found to tend rather towards the higher than the lower limit of normal variation.
At times a considerable increase in the number of eosinophile cells is found in films made from persons suffering from lead poisoning, particularly when there has been prolonged obstinate constipation. The count is never high, and is rarely more than 5 or 6 per cent. It is not usual to find any of the other forms of white cells in the blood, and in this way the anæmia of lead poisoning may be easily differentiated from the other forms, such as pernicious anæmia, lymphatic leucæmia, spleno-medullary lymphocythæmia. By examining a number of blood-films derived from persons subjected to lead absorption, and shuffled with a number of films from normal persons, one of us (K. W. G.) has been able to separate out, by the above method, the blood-films taken from the suspected persons. The criteria in the determination were—
1. The presence of basophile granules.
2. Total basophile staining and size of corpuscles—poikilocytosis.
3. Differential count, showing increase in a number of lymphocytes and large mononuclear cells.
Determination of the presence of lead poisoning from the examination of the blood, therefore, receives considerable support; but at the same time it is open to some objection from the fact that it is not in lead poisoning alone that basophile granules make their appearance in the blood. Any cause producing destruction of the red blood-cells, and even their depletion by prolonged hæmorrhage, is followed by an increase in the output of the red cells from the bone-marrow[9]. During this output of extra blood-cells from the bone-marrow, numerous cells gain entrance to the blood, in which the nuclei are not entirely degenerated; and it is these particular cells which give the phenomena of basophile staining, and their presence is rather indicative of the increased blood-formation that is progressing, following blood-destruction, rather than direct evidence of blood-destruction itself.
In a number of forms of anæmia—in fact, in almost all forms of severe secondary anæmia, and certainly all forms of anæmia associated with hæmolysis—the presence of basophile granules may be demonstrated. They are commonly found in pernicious anæmia, secondary septic anæmia, and the anæmia of malaria. Practically, the use of basophile granules in the presence of the blood of lead-workers is being utilized in Leipzig for the early detection of lead poisoning. By means of the Zeiss eyepiece enumeration disc the relative number of basophile granule cells to normal red cells is determined; and when the number of red cells containing basophile granules exceeds 100 per million red cells, the individual from whom the blood is derived is regarded as in a presaturnine condition, and given proper treatment. By this means it has been found possible to diminish the number of persons actually suffering from lead poisoning.
The adoption of such a method has some drawbacks, especially in view of the fact that substances other than lead may cause the basophilia. At the same time there is no doubt that, if all persons employed in lead trades who showed basophilia were suspended from their employment at the present time, a very large number of persons would be dealt with. Yet the practical application of this method is by no means impossible under industrial conditions, and would at any rate give a definite test upon which diagnosis could be made, though it would be quite impossible to expect the general practitioner or the certifying surgeon to estimate the basophilic content. All such estimations would necessarily have to be performed at some properly equipped pathological laboratory, such as at the present time many municipal authorities possess.
These facts are of importance, as a differential count of the white cells, together with a careful inspection of a blood-film for basophile staining and alteration in the red cells, as well as other phenomena noted, together with an estimation of the hæmoglobin contained in the blood, are to our mind of considerably more value in the diagnosis of lead poisoning than is the quantitative estimation of the red or white cells. The following tables give a certain number of enumerations, etc., made from the blood of lead-poisoned persons:
BLOOD-EXAMINATION OF LEAD ANÆMIA—DIFFERENTIAL COUNT PER CENT.
| No. | Hb. | R.B.C. | W.B.C. | Index. | A. | B. | C. | D. | E. | F. | G. | H. | I. | J. | K. | Work. | Notes. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Per Cent. | |||||||||||||||||
| 1 | 60 | 3,460,000 | 7,000 | 0·7 | 63 | 20 | 6 | 3 | 8 | 0 | + | - | + | - | + | Paint mill | 5 years. |
| 2 | 45 | 1,707,000 | 9,000 | 1·4 | 46 | 38 | 8 | 1 | 7 | 0 | + | + | + | + | + | Paint mill | 10 years. |
| 3 | 55 | 2,620,000 | 20,000 | 1·0 | 58 | 32 | 4 | 2 | 4 | 0 | + | - | + | - | + | Paint mill | 7 years. |
| 4 | 60 | 1,334,000 | 10,000 | 3·0 | 55 | 35 | 8 | 0 | 5 | 0 | + | - | + | + | + | Packer white lead | 5 years. |
| 5 | 54 | 3,210,000 | 8,000 | 0·9 | 52 | 41 | 4 | 2 | 1 | 0 | + | + | + | - | + | Grinder | 6 years. |
| 6 | 60 | 1,347,000 | 10,000 | 3·0 | 59 | 32 | 3 | 2 | 3 | 1 | + | + | + | + | + | White lead | 8 years. |
| 7 | 65 | 3,760,000 | 9,000 | 0·9 | Press and stoves | 8 years. | |||||||||||
| 8 | 65 | 2,200,000 | 10,000 | 0·7 | + | + | Zinc distillation still | 20 years; double wrist-drop 2 years. | |||||||||
| 9 | 50 | 3,860,000 | 8,000 | 0·6 | - | + | + | White lead beds | 10 years. | ||||||||
| 10 | 60 | 3,420,000 | 9,000 | 1·0 | 76 | 16 | 13 | 3 | 0 | 0 | + | + | Packer |
- A = Polymorphonuclears.
- B = Lymphocytes.
- C = Large hyaline.
- D = Eosinophile.
- E = Transitional.
- F = Basophile.
- G = Microcytes.
- H = Megalocytes.
- I = Poikilocytes.
- J = Nucleated red.
- K = Plehn’s bodies.
- Corpuscles, Thoma-Zeiss.
- Hæmaglobin, Haldane’s instrument.
- Films, stained Leishman.
The form of lead inhaled is immaterial, and definite poisoning with alteration in the blood may be occasioned, not only with white lead and lead fume, but also even with lead sulphate and lead silicate.
The following table gives the result of blood-counts performed upon the blood of persons employed in the manufacture of a paint erroneously supposed to be innocuous, as the base consisted of lead sulphate and oxysulphate:
Differential Counts per Cent. of Blood-Films from Lead Sulphate Workers.
| No. | A.[A] | B. | C. | D. | E. | F. | G. | H. | I. | J. | K. |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 55 | 16 | 5 | 1 | 0 | + | + | - | + | + | + |
| 3 | 57 | 16 | 26 | 1 | 0 | + | + | - | - | + | - |
| 6 | 67 | 23 | 9 | 1 | 0 | + | + | + | + | + | + |
| 7 | 72 | 18 | 5 | 5 | 0 | + | - | - | - | + | + |
| 8 | 65 | 26 | 7 | 2 | 0 | + | + | - | - | + | + |
Sand-papering surfaces of painted objects, walls, coaches, etc., also throws a definite amount of lead dust into the air whenever the sand-papered paint contains lead. The following table gives the differential counts of the blood of persons employed in the furniture-painting trades:
Differential Counts per Cent. of Blood-Films from Furniture-Makers (Sand-Paperers).
| No. | A.[A] | B. | C. | D. | E. | F. | G. | H. | I. | J. | K. |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 48 | 39 | 11 | 1 | 1 | + | + | + | + | + | + |
| 13 | 54 | 35 | 9 | 2 | 0 | + | + | + | + | + | - |
| 15 | 53 | 32 | 13 | 1 | 1 | + | - | - | - | - | - |
| 16 | 58 | 30 | 9 | 3 | 0 | + | - | - | + | - | - |
| 19 | 56 | 31 | 12 | 0 | 1 | + | - | - | + | + | - |
- A = Polymorphonuclears.
- B = Lymphocytes.
- C = Mononuclears.
- D = Eosinophiles.
- E = Myelocytes.
- F = Basophiles.
- G = Microcytes.
- H = Megalocytes.
- I = Poikilocytes.
- J = Vacuolated red cells.
- K = Normoblasts.
Circulatory System.
—A very large number of the symptoms referable to chronic and well-defined lead poisoning are referable to circulatory lesions, and, as has been elsewhere pointed out, the ultimate nerve degeneration occurring in various parts of the body is probably but a final symptom of the earlier hæmorrhage which has taken place. Certain symptoms are, however, more closely related to the circulation than others, and may therefore be more conveniently grouped together under the present heading. The smaller changes, many of them connected with special organs (such, for instance, as the eye) or particular regions (as the mesenteric vessels), have been already referred to in dealing with colic and eye changes. Vaso-motor changes precede the actual change in the vessel walls themselves. On the other hand, the alterations in the structure of the liver, lung, spleen, and more especially the kidney, are secondary to change in the structure of the walls of the vessels themselves.
Vaso-motor disturbances may or may not be of nervous origin, although the former view is probably correct, and it is also equally possible that the direct affection of the vessels is associated with the nerve irritation. On the other hand, direct inflammation of the vessel walls, resulting in obliterative arteritis, in arterio-sclerosis, and degeneration and exudation in the kidney, lung, and liver, are practically due to degenerative changes either in the intima or the middle coats of the finer vessels. The common symptoms of arterio-sclerosis, vertigo, headache, and pulsation in the vessels, and of the persistent headache already referred to, all suggest changes taking place in the vessels complicated by œdema. In the early stages of kidney degeneration, however, it is common to find an interstitial nephritis due apparently to exudation from the vessel walls. Such an hypothesis is to some extent supported by the somewhat allied condition of engorgement and fibroid change in the liver and lung, and to a lesser extent in the spleen. In the lung, even in persons not exposed to inhalation of lead, and in animals, as pointed out by Glibert, secondary changes in the lung follow lead intoxication, such changes taking the form of emphysema and generalized fibrosis; whilst the liver is engorged with blood, and later undergoes similar degenerative changes. The bloodvessels in these organs are found to have lost a considerable amount of their elasticity, to have yielded here and there, and in other places to be completely closed by obliterative arteritis. Microscopical hæmorrhages are to be found mainly in the veins leading from the capillaries. In the kidney such vessel changes as are outlined are the precursors of disease, and albumin is found in the urine, but the quantity is rarely very large. Casts are not common, and the amount of lead present in the urine may be exceedingly small, difficult to trace, and in many cases entirely absent.
In the later stages of chronic saturnism the heart may show degenerative changes. Microscopical examination of the heart muscle shows that alteration of the fibres of the muscles takes place in a manner similar to that of the voluntary muscles. Disease of the heart valves is uncommon; alterations in the heart sounds are infrequent; the clinical picture of the cardiac condition is that of a “flabby” heart.