Diane Batchelor, of the National Cancer Institute, Amsterdam, told the European Cancer Conference in Vienna that in the past nurses had been exposed to risk when handling powerful anti-cancer drugs which attack the body's cells and can be as dangerous as radioactive materials.

She warned that history could repeat itself with the advent of new gene therapy techniques under which genetic material is introduced into the body of cancer patients using host viruses.

An investigation by the Robert Gordon University School of Nursing and Midwifery, Aberdeen, found that nurses who administer anti-cancer drugs showed many inconsistencies in their practice.

The nurses were found to wear different kinds of protective clothing, had different ways of checking drugs, and took different actions when drugs were spilled.

Many simply had not been properly trained to handle the medications.

Urine traces

The findings were echoed by a second study by Dutch nurses who specialised in cancer care.

"We are all involved in manipulating, preparing or administering cytotoxic medication," they said.

"These drugs are all more or less irritating, carcinogenic, mutagenic or teratogenic (capable of causing birth defects), yet they can be found in the urine of health care workers."

Ms Batchelor said the European Union had now drawn up protocols for the handling of anti-cancer drugs.

She said similar regulations were needed for gene therapy.

It was possible that contamination could infect nurses with the host virus, or that there may be health risks from the introduction of foreign genetic material.

She said: "Let's not make the same mistakes that we did in the past, let's be careful with gene therapy and let's monitor nurses from the start.