Potters engaged in the glazing of common pottery and tiles, workmen in file-factories, workers on colored papers and in enamels, especially in glass enamels, brushmakers for the reason that the bristles are sometimes colored by lead preparations, and those engaged in sewing coarse goods because the thread is sometimes treated with a preparation of lead in order to add to its weight, are likewise liable to chronic lead-poisoning. The introduction of lead into the body through the respiratory tract is a subject of the greatest importance in the trades. Inadequate ventilation of working-rooms, living or sleeping in apartments connected with or contiguous to factories in which lead is largely used, and particularly in lead-factories, is attended with serious dangers, as is also the habit of eating food in such apartments or drinking water that has been standing in them. The possibility of lead-poisoning by way of the respiratory tract has been questioned. In view of existing knowledge as to the readiness with which carbon in minute states of subdivision finds its way into the connective lymph-channels of the lung, there can be no doubt that the habitual respiration of an atmosphere loaded with the dust of lead or its preparations in a minute state of subdivision may give rise to chronic lead-poisoning. At the same time, the experiments of Hassel4 render it probable that less absorption takes place directly by means of the pulmonary mucous membrane than by way of the mucous membrane of the mouth and throat. It must be borne in mind that none of the preparations of lead are volatile. This affection is also occasionally observed in clowns and others upon the stage or elsewhere, who habitually use cosmetics containing lead. The use of cheap tinfoil, into the composition of which lead enters largely, as a wrapper for tobacco and snuff is said to occasionally produce chronic lead-poisoning. It is stated by Naunyn that mattresses filled with horse-hair died black by lead compounds have occasioned this affection. The same authority states that a proof-reader was poisoned by reading printed proof for many years. Chronic lead-poisoning is pre-eminently a disease of the industrial arts. The means of obviating or diminishing the dangers of those exposed by their occupation to the preparations of lead will be considered under the head of Prophylaxis. The quantity of lead absorbed is of less importance than is its continuous introduction. As stated in the definition, the phenomena of chronic lead-poisoning are those brought about by the gradual accumulation of lead in the system, the amount absorbed into the blood in any given cases being comparatively small, even where large quantities are ingested. Hence prolonged exposure to small amounts of lead is attended with greater danger than a comparatively brief exposure to larger quantities. It is stated that the members of the household of Louis Philippe at Claremont manifested the symptoms of chronic lead-poisoning after the lapse of seven months in consequence of drinking water which contained a mere trace of lead. On the other hand, several grains of acetate of lead may often be administered medicinally to patients for a week at a time without inducing the phenomena of this affection, although, in view of the idiosyncrasy of many individuals, the exhibition of lead preparations for prolonged periods is not advisable.
4 The Inhalation Treatment of the Diseases of the Organs of Respiration, including Consumption, London, 1885.
According to Heubel,5 the blood and internal organs contain but very small amounts of lead—.02 per cent. in the maximum. It is probable, therefore, that the more insoluble of the lead compounds may yield a sufficient amount of absorbable lead to produce the characteristic constitutional effects.
5 Pathogenese und Symptome der Chronic Bleivergiftung, Berlin, 1871.
So long as the urine remains free from albumen, it serves for the elimination of a mere trace of lead. In albuminous urine the amount is larger. Lead is found in the bile and feces in small quantities.
SYMPTOMATOLOGY.—The general description of chronic lead-poisoning must include a great number of symptoms that do not always occur in regular order or sequence. According to the prominence of certain of these symptoms in particular cases the specific effects of lead may be grouped under the following five heads: (1) disturbances of nutrition; (2) the colic; (3) the arthralgia; (4) the paralysis; and (5) lead encephalopathy.
1. Disturbances of Nutrition—After the long-continued introduction of lead into the system the signs of impaired nutrition manifest themselves in almost all cases. The appearance of the patient is changed; he becomes thin, anæmic, and of a somewhat peculiar yellowish complexion. This hue of the skin, to which the term icterus saturninus has been applied, is not due to the deposition of bile-pigments. The wasting of the tissues of the body seems to implicate the muscular to a much greater extent than the adipose tissues. In the majority of cases a dark or bluish-black line is observed at the border of the gums. This line is more strongly marked in the upper than in the lower jaw. It is, as a rule, more plainly developed in persons of careless habits, whose teeth are the seat of deposits of tartar, but the teeth in such individuals are often discolored and appear to be elongated in consequence of the retraction of the edge of the gums. This bluish or violet-black gingival line is due to the deposit of particles of sulphide of lead in the substance of the gum, in consequence of the reaction between the sulphuretted hydrogen formed by the decomposition of particles of food and the lead particles present in the mouth. According to Tanquerel, this color may extend over the greater part of the gum or even to the mucous membrane of other portions of the mouth. If due care be exercised, there is little danger of confounding the lead-line with the livid border of the gums frequently seen in people whose teeth are in bad condition. The occasional absence of this line in otherwise well-characterized cases of chronic lead-poisoning is to be noted. It does not occur when the teeth have been lost, and is slight if they are kept clean.
Patients complain of habitual dryness of the mouth and of an insipid, mildly astringent, sweetish, or faintly metallic taste; the tongue is coated, the breath fetid. There are nausea and occasional vomiting. Constipation is common. The patient is now liable to attacks of lead colic, joint trouble, and the specific palsy, or to cerebral disturbances of grave character. Of these affections, colic is the most frequent; the joint affection is next in order; the paralysis far less common, and the cerebral disturbances comparatively rare. Continued exposure results after a time in an intensification of the malnutrition, either with repeated attacks of colic or the other specific disturbances, or occasionally in their absence, although at length the positive lead dyscrasia is established, characterized by obstinate dyspepsia, constipation, and intensification of the curious earthy or yellowish color of the skin, which is succeeded by the pallor of profound anæmia. Loss of muscular power with transient œdema now shows itself. The patient becomes apathetic, irritable, and morose. As the condition of cachexia deepens muscular tremor occasionally shows itself. After a prolonged period of profound ill-health the patient succumbs to some complication, among the more frequent of which are tuberculosis, pneumonia, and chronic interstitial nephritis. Gout is a very common complication of chronic lead-poisoning.
2. Lead Colic; Colica saturnina; Colique de plomb; Bleikolik.—This affection is also known as painter's colic, Devonshire colic, colica pictonum, the last term being derived from Poitou. It occasionally develops abruptly without previous symptoms. In the majority of cases, however, the earlier disturbances of nutrition before pointed out precede the attacks, often by a period of weeks or months. An increased tendency to constipation with transient recurrent abdominal pains, occurring sometimes immediately after food, more frequently at irregular intervals, often characterizes the prodromic period. There is, moreover, an intensification of the other symptoms of chronic lead-poisoning. The appetite is decidedly impaired, so also are the powers of digestion; the foul condition of the mouth becomes more annoying, and the peculiar taste alluded to more persistent and more marked. Constipation occasionally alternates with diarrhœa. The colicky pains which constitute the attack are of variable intensity, but usually severe. They are of the nature of true colic. Pressure over the seat of pain almost invariably gives relief, particularly in severe attacks. During the remission pressure is grateful to the patient. The position of the pain varies. Its most common seat is in the region of the umbilicus. It may occupy the epigastric and hypochondriac regions or the lower part of the abdomen, extending from side to side above the level of the pubic bone. These colics are of some minutes' duration, recurring after short intervals, which are characterized by a certain amount of continuous cramp. Tenesmus is frequent. It may be accompanied by strangury or retention of urine, with pain in the course of the ureters, the spermatic cord, or in the penis. Shooting pains in the breast also occur. The abdomen is retracted, and scaphoid to such an extent in some instances that the prominence caused by the bodies of the vertebræ is apparent in the median line of the abdomen. It occasionally happens, however, that retraction does not occur, the belly, on the other hand, remaining prominent. As a rule, to which there are few exceptions, the bowels are constipated. This condition is often stubborn. In rare cases, however, the colic is accompanied by diarrhœa. Nausea is of common occurrence. Vomiting is sometimes violent and distressing, being ushered in by repeated attacks of retching. The vomited matters are usually discolored by bile, and icterus of slight degree usually occurs. The pulse is invariably diminished in frequency, sometimes as low as 40 or even 30, per minute. It is at the same time full and tense. The pulse-frequency is occasionally variable within comparatively brief periods of time. Respiration is increased in frequency during the attack. The urine is small in quantity and of high specific gravity, and frequently contains small amounts of albumen. It is sometimes entirely suppressed. Fever is absent, and the slight increase of temperature occasionally observed is attributable to the restlessness of the patient. The intellectual condition usually remains clear, but in violent cases it is characterized by excitement. The paroxysms of pain are more severe in the latter part of the day and during the night. The course of the attack is irregular. Relapses, which may occur in the course of some days or even weeks, are frequent. The duration of the attack does not, as a rule, exceed a week, but the illness is often protracted by repeated relapses, and in continued exposure to the cause the tendency to colic may become chronic. The termination of the attack is in most instances as abrupt as its onset, and with the cessation of the colic the associated symptoms, such as retraction of the abdomen, constipation, vomiting, and diminished frequency of the pulse, rapidly subside. Lead colic is not unfrequently associated with the other affections of chronic lead-poisoning. The prognosis is favorable, the mortality being about 2 per cent.
3. The Arthralgia; Arthralgia saturnina.—The tissues entering into the formation of the joints and the muscular masses contiguous to them are frequently the seat of intense paroxysmal pains, which appear more or less suddenly, either with or without prodromes, and run a course similar to that of lead colic, exhibiting violent exacerbations and occasional more or less complete remissions. These pains are accompanied by painful contractions of the muscles. They are somewhat relieved by pressure and friction and aggravated by exercise and exposure to cold. Swelling and redness over the affected joints, ligaments, and tendons are absent. These pains do not follow the course and distribution of the nerve-trunks, and lack the tender pressure-points of true neuralgias. They are more common in the lower extremities, the knee being especially apt to be affected. When they affect the upper extremity the elbow and shoulder suffer more frequently than the other joints. The flexor muscles are much more frequently attacked than the extensors. The muscles of the back, especially the great masses of long muscles in the lumbar region, whose function is to sustain the equilibrium of the body, are frequently implicated. The intercostal muscles and the muscles of the neck are also frequently affected. The small joints and the muscles of the hands and feet as a rule escape. The pain is tearing and burning in character, and very often severe. It is occasionally associated with tremor. The derangement of the alimentary canal, especially constipation, which is so characteristic of lead colic, is often absent. Fever does not occur.