3. Its application to the surface of the body in the form of ointment, plasters, cosmetics, and hair-dyes.
4. Drinking water impregnated with lead, from being stored in leaden cisterns or conveyed in leaden pipes.
“The action of water upon lead is much modified by the presence of saline substances. It is increased by chlorides and nitrates, and diminished by carbonates, sulphates, and phosphates, and especially by carbonate of lime, which, held in solution by excess of carbonic acid, is a frequent ingredient of spring and river water. But water highly charged with carbonic acid may become dangerously impregnated with lead, in the absence of any protecting salt, in consequence of its solvent power over carbonate of lead. In general, water which is not discoloured by sulphuretted hydrogen may be considered as free from lead; but there are few waters which have passed through leaden pipes, or have been retained in leaden cisterns, in which a minute analysis will not detect a trace of the metal; and were it not for the great convenience of lead, iron pipes and slate cisterns would, from a sanitary point of view, be in all cases preferable.
“Another case of contamination by lead may arise from electric action, as where iron, copper, or tin is in contact with or soldered into lead; and in these cases, owing to the action of alkaline bases as well as of acids upon the lead, danger may occur when it is thrown into an electro-negative as well as into an electro-positive state.
“Cisterns are sometimes corroded and their bottoms are perforated by pieces of mortar having dropped into them, the lime of which has caused the oxidation of the metal and a solution of the oxide.”
5. Lead may also find its way into the system by means of the food. Farinaceous foods, chocolate, and tea may become contaminated if lead wrappers be used; and confectionery from the use of lead chromate as a colouring agent. The use of leaden vessels in the manufacture of cider is attended with danger, and also the keeping of pickles in glazed earthenware jars. The celebrated “Devonshire Colic” was the result of cider-making in leaden vats. Beer may be contaminated with lead if allowed to stand in leaden pipes overnight. Rum has been known to have been dangerously impregnated with lead, leaden worms having been used attached to the stills. Many tobacconists are in the habit of using lead foil to wrap up their tobacco and snuff; this practice has resulted in several cases of chronic lead poisoning. Soda and Seltzer waters may contain lead when kept in syphons with leaden caps or valves.
6. Acute and subacute cases of poisoning occur from the taking of lead in the form of diachylon pills to procure abortion.
Symptoms of Poisoning by Lead
Acute.—A metallic taste in the mouth, accompanied with dryness in the throat and intense thirst, is experienced by the patient soon after the poison is swallowed. In some cases, however, two or more hours may elapse before the effects of the poison begin to show themselves. Vomiting may or may not be present. Twisting colicky pains are felt in the abdomen, relieved in some cases by pressure. The paroxysms of pain may be separated by intervals of ease. The bowels are, as a rule, obstinately confined, and the fæces are of a dark colour, from the formation of the sulphuret of lead. The skin is cold, the pulse quick and weak, and there is considerable prostration of strength. In some cases the patient suffers from cramps of the calves of the legs, and sometimes, in protracted cases, paralysis of one or more of the extremities may supervene. The effect on the nervous system, headache, temporary blindness, is marked by giddiness, and stupor, in some cases delirium even resembling acute mania, terminating in coma, or convulsions and death. Albuminuria may occur.
Chronic.—This form of poisoning generally occurs among painters, manufacturers of white lead, pewterers, and others. The early symptoms are those of ordinary colic, only more severe. The patient generally complains, in the first instance, of feeling unwell, and of general debility. He then suffers from pain of a twisting, grinding nature, felt in the region of the navel, the abdomen being retracted and hard. The bowels are obstinately confined. The appetite becomes capricious, and may be entirely lost. The mouth is parched, the breath fœtid, the countenance sallow, the skin dry, and general emaciation sets in. A nasty sweetish metallic taste in the mouth is present in most cases. Not infrequently the subjects of lead poisoning experience a peculiar form of paralysis of the upper extremities, well known as “dropped hand.” It appears that this condition is the result of paralysis of the extensor muscles of the wrist, the long supinator escaping. In other cases the muscles of the shoulder girdle or pelvic girdle and legs may be affected. Acute general paralysis has occurred in workers with lead, and may prove fatal. Optic neuritis and optic atrophy occur in some cases. Persistent headache may be present in others. The muscles undergo a form of fatty degeneration. The lead appears to act primarily on the muscles, then on the nerves, and lastly on the nerve centres. The absorption of lead causes marked anæmia with degeneration of the red corpuscles, which show marked punctate basophilia. One other symptom of importance has yet to be noticed. The gums, at their margins where they join the teeth, present a well-marked blue line, absent where a tooth has been removed. This is not present in all cases, but it should be looked for. Chronic lead absorption produces cardiovascular changes with arterio-sclerosis, valvular degeneration, cardiac hypertrophy, and chronic renal changes with albuminuria. Closely associated with these conditions are saturnine arthritis and gout. The effects upon the vessels may predispose to cerebral hæmorrhage or lead encephalopathy. Cicconardi suggests as a method of diagnosis in lead poisoning, where the cause of the colic is uncertain, to paint the skin with a 6 per cent. solution of sodium sulphite. If lead be the cause the painted part will become darkened in colour.