§ 789. Elimination of Lead.—When a large dose of acetate or carbonate is taken, part is transformed into more or less insoluble compounds—some organic, others inorganic; so that a great portion is not absorbed into the body at all, but passes into the intestines, where, meeting with hydric sulphide, part is changed into sulphide, colouring the alvine evacuations black. Some of the lead which is absorbed is excreted by the kidneys, but the search often yields only traces. Thudichum[853] states that in fourteen cases of lead-poisoning, in two only was obtained a weighable quantity from a day’s urine; in the remaining twelve lead was detected, but only by the brownish colour produced in an acid solution of the ash by hydric sulphide.
[853] Pathology of the Urine, p. 550.
The elimination of lead by the kidneys is favoured by certain medicines, such, for example, as potassic iodide. Annuschat found in dogs poisoned by lead from 3·8 to 4·1 mgrms. in 100 c.c. of urine; but, after doses of potassic iodide, the content of lead rose to 6·9 and even to 14 mgrms. Lead appears to be eliminated by the skin, being taken up by the epithelial cells, and minute, insoluble particles coming away with these cells. If a person who has taken small doses of lead for a time be placed in a sulphur water-bath, or have his skin moistened with a 5 per cent. solution of sodium sulphide, the upper layer of the epidermis is coloured dark; but the perspiration excited by pilocarpin or other agency contains no lead.
§ 790. Fatal Dose—(a.) Sugar of Lead.—It may almost be said that it is impossible to destroy human life with any single dose likely to be taken or administered. In three cases an ounce (28·3 grms.) has been taken without fatal result. Although it must be allowed that repeated moderate doses, extending over some time, are more dangerous to health and life than a single large dose, yet there seems to be in some individuals a great tolerance of lead. Christison has given ·18 grm. in divided doses daily for a long time without any bad effect, save the production of a slight colic. Swieten has also given daily 3·9 grms. (60 grains) in ten days without observing toxic effects. That, in other cases, less than a grain per gallon of some lead compound dissolved in drinking-water, or in some way introduced into the economy, causes serious illness, is most inexplicable.
(b.) The Basic Acetate in solution is more poisonous apparently than the acetate—60 c.c. (11⁄2 drms.) have caused serious symptoms.
(c.) The Carbonate of Lead.—Doses of anything like 28 grms. (an ounce) would probably be very dangerous to an adult; the only case of death on record is that of a child who took some unknown quantity, probably, from the description of the size of the lump, about 10 grms. (21⁄2 drms.).
§ 791. Antidotes and Treatment.—Soluble sulphates (especially magnesic sulphate) have been given largely in both acute and chronic cases; in the acute, it stands to reason that it is well to ensure the presence of plenty of sulphates in the stomach and intestines, in order to form the sparingly soluble lead sulphate, should any residue remain; but to expect this double decomposition to go on in the blood and tissues is not based upon sound observation. The chronic lead-poisoning is best treated by removal from the source of mischief, the administration of large quantities of distilled water, and medicinal doses of potassic iodide.
§ 792. Localisation of Lead.—In a dog, which was killed by chronic lead-poisoning, Heubel found in the bones 0·18 to 0·27 per 1000 of lead; in the kidneys, 0·17 to 0·20; liver, 0·10 to 0·33; spinal cord, 0·06 to 0·11; brain, 0·04 to 0·05; muscles, 0·02 to 0·04; in the intestines traces, 0·01 to 0·02; in the spleen, the blood, and the bile, he also only found traces. Ellenberger and Hofmeister found in the kidneys of the sheep, 0·44 to 0·47; liver, 0·36 to 0·65; pancreas, 0·54; salivary glands, 0·42; bile, 0·11 to 0·40; bones, 0·32; fæces, 0·22; spleen, 0·14; central nervous system, 0·07 to 0·18; blood, 0·05 to 0·12; flesh, 0·05 to 0·08; urine, 0·06 to 0·08; and in the unstriped muscles and the lungs, 0·03 per 1000 of lead.