A number of these cures have been found to be effective. The mechanism of their curative properties is understood, and they are now incorporated into modern practice. Among the more benign are the uses of iron to cure anaemia, magnesium salts for constipation and indigestion and iodine as an antiseptic and for problems with the thyroid gland.
However, some remedies are known to have been ineffective, while a few were quite dangerous.
Elements From the Poisoner’s Armoury
The poisoner’s favourite, arsenic, has been used to treat illnesses as diverse as TB, diabetes, malaria, rheumatism and syphilis. Its close relative, antimony, was used to cure skin complaints, and to induce vomiting. As tartar emetic, it may have been responsible for the premature death of Mozart.
Another element favoured by murderers, thallium, was employed during treatment for ringworm, one symptom of its toxicity being hair loss, which exposed the infection and thus made it easier to treat.
Mercury compounds were often used in ointments, yet this deadly metal can be absorbed through the skin.
Medical Uses of Other Poisons
Despite the dangers, modern medicine continues to employ toxic elements in cases where there appear to be no safer alternatives.
The soluble salts of barium are poisonous, and if swallowed, cause vomiting, diarrhoea and ultimately, paralysis. On the other hand, barium sulphate is almost entirely insoluble, and will pass safely through the digestive system as a suspension of solid particles, which is opaque to X-rays. If a patient is given a ‘barium meal’, X-rays can then be passed through the stomach to reveal ulcers or tumours that would otherwise be invisible.
Bismuth belongs to the same family group as arsenic and antimony, and though it salts can cause liver damage, it is much less poisonous. As the nitrate and carbonate, and more recently the citrate, it has been used to treat stomach ulcers. It appears to work by killing bacteria that cause ulcers and by protecting the stomach wall against enzymes that otherwise attack it.
Elements of the Aluminium Family
Some compounds of aluminium, such as the alums, have been used for nearly 2000 years to stop bleeding. Other elements in the same group, such as boron and gallium also have their uses. Boron atoms can be attached to chemicals which, when injected into the body, concentrate in tumour cells, particularly those in the brain. When exposed to a beam of neutrons, these boron atoms become radioactive, giving off alpha rays, which kill the tumour cells. As alpha rays cannot travel far in dense material (they can be stopped by a sheet of paper), they do minimal damage to surrounding healthy cells.
A radioactive form of gallium also concentrates in tumours that occur in soft tissues of the body, such as the liver, spleen or lymph nodes, and can be used to diagnose such tumours, which would otherwise be difficult to detect. It is also used to treat skin cancers, like melanoma and to monitor the treatment of bone tumours in children. A non-radioactive compound of gallium has recently shown promise in treating malaria when more traditional drugs have failed.
A radioactive isotope of yttrium can be attached to antibodies that attack cancer cells in the colon, bones, ovaries and pancreas, and can be used to destroy these cells.
Technetium is an element that is always radioactive, and can only be made in nuclear reactors. It is used in the diagnosis of cancers and to show up damage resulting from a heart attack. The residues formed by the decay of technetium are only mildly radioactive and are quickly eliminated from the body.
Lanthanum, a Rare Earth Metal
Despite its classification, lanthanum is more abundant than metals like lead and tin. Its carbonate is often added to the diets of patients with kidney disease to prevent the absorption of phosphates through the gut. The excess of phosphates that might otherwise be absorbed can cause painful bone deformities, as calcium phosphate is the main constituent of bone.
Precious Metals in Medicine
Sixty tons of gold each year are used in dentistry. Gold compounds are also employed to treat rheumatoid arthritis, though the side effects, which include diarrhoea and skin rashes, mean that the treatment has to be discontinued after a few years.
Platinum is even more expensive than gold. Cis-platin, a complex of platinum with chlorine and ammonia, combines with DNA in cells and prevents replication. Because of this, it is used to kill cancer cells. Unfortunately, it has the same effect on healthy cells and can cause breathing problems and vomiting. Nevertheless, cis-platin brings about a 90% cure rate for some cancers.