Clothes manufacturers should stop using potentially carcinogenic formaldehyde, a leading toxics expert has warned, after nurses given new uniforms containing the chemical reported side effects.

Gwynne Lyons, until recently a member of the Government's Advisory Committee on Hazardous Substances, said it was "highly likely" that scores of nurses in Wales who last month reported severe skin rashes after starting to wear new uniforms had had an allergic reaction to formaldehyde resin used to make the tunics crease-resistant.

Alexandra plc, of Bristol, one of six companies which supplies clothing to NHS trusts, said the skin irritation affecting the nurses related to "an isolated batch of fabric" from Carrington Career and Workwear, its Lancashire-based supplier, which had been treated with a low level of formaldehyde.

The chemical is used by clothes manufacturers to prevent creasing and mildew during transit. Workers in the industry are warned by the Health and Safety Executive that it can cause skin, eye, nose and throat irritation. Long-term exposure to high levels has been linked with nasal and lung cancer.

Dr Lyons, director of the Chemicals, Health and Environment Monitoring Trust, said it was likely the skin irritation was caused by formaldehyde. She added: "But there is also a bigger picture, in that many experts consider that formaldehyde is a known human carcinogen when inhaled over time. Therefore, whenever possible, it is high time that safer substances were used instead of formaldehyde."

Alternative uniforms are being made available to nurses in Wales while the problem is investigated. Similar problems have been reported in Scotland. Carrington said that its fabrics worn close to the skin typically had half the permitted level of formaldehyde resin.