Heavy metal draws sting from ulcers

Bismuth, which sits next to highly toxic lead in the periodic table of elements, is increasingly being used to calm ulcers - and it plays an important role in cancer and medical diagnostic equipment.

Whereas lead can seriously harm health, heavy metal bismuth has been treating stomach ulcers and disorders, as former Iranian leader Ayatollah Khomeini and Pope John Paul, who both suffered from internal bleeding, could testify.

Now, bismuth medicines can combat the bacteria which specialists say cause peptic ulcers, and with bismuth-based alloys being used in x-ray screening and magnetic resonance imaging scanners, prospects for the metal are healthy.

"The use of bismuth will not grow wildly in the pharmaceutical sector in the future," says Yves Palmieri, secretary-general of the Brussels-based Bismuth Institute.

"But there is a place for it, and that place could be greater and more important."

Pharmaceuticals - medicines and diagnostics - account for about 10 per cent of the 5000 tonnes-a-year global bismuth market. Although rare, bismuth is a metal that has been used since antiquity and traces have been found in Roman coinage.

But it is only in the last 200 years that usage has become widespread. Other alloying uses include steel cutting tools and iron castings, while compounds are also used in electrochemistry, ceramics, plastics and pigments.

In the medical field, research now suggests that bismuth compounds before treatment reduce the lethal toxicity of some cancer therapies, and may even combat Aids, although rapid progress will not happen in these fields.

"Development is slow, because we are talking about human beings - you cannot take chances where people are concerned and it takes a long time before everybody is convinced," Mr Palmieri said.

Nevertheless, latest medical thinking on ulcers indicates that a bacteria which aggravates these stomach conditions can be tackled by bismuth medication.

"People tend to think that ulcers are induced by stress, which increases acidity and causes heartburn," he said. "That is not so with a peptic ulcer - it is bacteria.

"There is a germ called helicobacter pylori, which makes the lining of the stomach more sensitive to acid. These germs grow in the ulcers in the lining of the stomach and prevent them from healing.

Even if the acid in the stomach is reduced, the ulcers generally will not heal as long as the helicobacter pylori germs are present.

"As long as we have this bacteria we try to cover it up with antacids. The more antacid you take, the more acid it produces," Mr Palmieri said.

Sufferers from helicobacter pylori not only included Khomeini and the Pope, but in all probability former US President George Bush and Imelda Marcos, wife of the former Philippines president, the Helicobacter Foundation says.

Bismuth acts like an antacid, but it is not one. By taking bismuth-based medicines, a coating is formed which protects the stomach lining against the acid.

"By using bismuth you are reducing the effects of the other medications on your stomach, as these antibiotics are extremely strong. With bismuth-based premedication you soften the blow, then the antibiotics take over," Mr Palmieri said.

Outside the body, bismuth alloys and crystals are making steady inroads in oncology treatment and MRI scanner diagnosis.

Bismuth germanium oxide crystals are at the heart of scanners. Their use was kick-started several years ago when the European Organisation for Nuclear Research built its gigantic multiple-particle accelerator.

Steady growth is assured where bismuth is concerned in scanners, as any future crystal developments will still depend on this metal.

Bismuth germanium oxide crystals neutralise lethal gamma rays, as well as improve overall imaging, and there are no viable technological alternatives on the immediate horizon, nor is there any financial stimulus, as metal prices have a track record of stability.

"I do not see any reasonable substitute to bismuth germanium oxide, or eventually bismuth silico oxide, as it usually takes 10 to 15 years before people come up with a substitute," Mr Palmieri said.

Bismuth alloys, which are used in the protective radiation shields in oncology centres, are likely to see similar steady growth rates.

These are solid castings, sometimes cut into complicated shapes, that are placed on certain parts of the body that need shielding from radiation during cancer treatment.

Each shield will be different, depending on the patient, says Glyn Morgan, of alloy-producers Mining & Chemical Products.

The advantage of bismuth alloys is that they can be cast in polystyrene moulds - a cheaper process.

"The alloy is totally reusable," Mr Morgan said. "When it is used the block is recycled and then used for another patient."

Because of this, explosive growth is unlikely, unless more oncology centres are built.

- REUTERS