Lead poisoning and lead absorption

by Sir Thomas Morison Legge; Kenneth Weldon Goadby

When this phenomenon is present, it is always associated with a marked degree of pyorrhœa alveolaris, the gums are soft, œdematous, and pus oozes from their edges, the teeth are frequently loose, and the other symptoms of disease of the os marginum are present.

Sections made from such a case suggest still more that some excretion of lead has taken place from the bloodvessels, as the lead particles may be seen closely related to the capillaries; but here again there is little doubt that it is due to absorption from the externally inflamed surfaces of the gum rather than excretion of the vessels themselves. It is interesting to note that, in all the experimental animals, in no instance has any Burtonian line been observed, although the animals (cats and dogs) have been fed upon cat’s meat, which readily undergoes putrefaction, and organisms capable of producing sulphuretted hydrogen are invariably present in the mouths of such animals. Notwithstanding this, the blue line has not been observed, because the animals’ gums were entirely free from infection or pathological changes. By causing an artificial inflammation around the canine teeth of an animal exposed to lead infection, a definite blue line was produced in two weeks. This line had all the characteristics of the common Burtonian line.

This form of blue line with a deep pigmentation of the whole of the gums, although in itself not to be regarded as diagnostic of lead poisoning alone, rarely occurs unless the person has been subjected to such long-continued poisoning that other symptoms have already made their appearance.

The blue line, then, whichever type is observed, cannot in our opinion be regarded as a diagnostic sign of lead poisoning, but is merely an indication that the person who exhibits the phenomenon has been at some time or other subjected to lead absorption.

There is no evidence to show that lead is excreted by the salivary glands. A number of cases of poisoning certainly complain of a metallic taste in the mouth, and, judging from the analogy of mercury, it is possible that excretion of small quantities of lead may take place through the saliva; but such a point is merely of scientific interest, and has no practical bearing on the question of lead poisoning. Pigmentation in the salivary glands suggesting excretion of lead has not been observed, notwithstanding the constant presence of potassium sulphocyanide in the parotid saliva. The blue line of Burton may occasionally be observed, in other regions of the body. From time to time the intestine is found stained with a bluish-black deposit of lead sulphide, and in a case of acute poisoning following the ingestion of a large quantity of lead acetate, and in the cases described by Oliver of the ingestion of lead oxide (litharge), black staining of the intestines was peculiarly well marked. In all the animals referred to it forms a constant feature in the large intestine, and in the chapter on Pathology this blue staining of the large intestine is more minutely described. We have met with it once in the post-mortem examination of a man who died of lead poisoning, and when found it may, we think, be regarded as a diagnostic sign. Macroscopical evidence is not sufficient; it is necessary to make a histological examination of the tissues, when the stained areas are seen to be associated with the lymphoid tissue in the intestinal wall, and not only interstitial portions, but actually the interior of the cells themselves, are found to be packed with small bluish granules. Such a histological finding would be highly characteristic of an extreme case of lead poisoning.

Where considerable quantities of lead have been taken into the gastro-intestinal canal, a blue ring has occasionally been described surrounding the anus.

About 85 per cent. of cases of lead poisoning with colic show obstinate constipation as a leading symptom. The constipation generally exists for several days preceding the onset of the colic, and may persist for as long as twelve to fourteen days, while six to seven days is a common period. There is very little that is characteristic about the constipation other than its intractability; indeed, it is frequently of the greatest difficulty to relieve this symptom. No doubt the direct origin is due to the excretion of lead into the large intestine (see [p. 94]).

Palpation of the colon often shows distension, with a good deal of pain on pressure at both the hepatic and splanchnic flexures, more particularly the latter. Distinctly painful spots may be found in the length of the intestine, due to small ulcers, or more probably to the minute hæmorrhages which we have elsewhere described as associated with lead poisoning. The remaining 15 per cent. of cases have as a prodromal symptom diarrhœa. Further, diarrhœa is not uncommon amongst persons who are working in a lead factory, and who do not show other signs of poisoning; and as lead taken into the body in various ways is excreted through the fæces in common with other heavy metals, such as iron, bismuth, nickel, as well as arsenic, the occurrence of diarrhœa should suggest to the surgeon the possibility of considerable lead absorption having taken place.

REFERENCES.

[ [1] Zinn: Berl. Klin. Woch., No. 50, 1899.