Cellphones might cause brain cancer, a World Health Organisation agency (WHO) said yesterday, citing a review of studies.

Exposure to radiofrequency electromagnetic fields from handsets was greater than that from phone towers and base stations, said Robert Baan, a scientist in charge of the International Agency for Research on Cancer (IARC) report on the subject. The fields were “possibly” carcinogenic, the same category as diesel fuel, chloroform and working as a firefighter, according to the IARC, in France, which classifies cancer risks.

This was the first time an agency working group had surveyed research on radiofrequency electromagnetic fields to make a definitive classification, the IARC said on Monday. The agency did not issue guidelines for cellphone use and said more study was needed after finding some evidence for an increased risk of glioma, or brain cancer.

“It’s not at the moment clearly established that the use of mobile phones does in fact cause cancer,” said Kurt Straif, the head of the IARC Monographs Programme, adding that the research pointed to ways in which risks might be lowered. “For example, the highest exposure is from voice calls. If you use text messaging or headsets, this will lower the exposure.”

Concerns have risen in recent years that cellphones might be harmful to the health of people using them, according to the WHO agency, which said there were 5 billion wireless subscriptions worldwide. The US Federal Communication Commission has said devices with a specific absorption rate, the amount of radio-frequency energy absorbed by the body, within a set limit are safe.

The IARC considered studies in its reviews that might have flawed data, John Walls, the vice-president of public affairs for the CTIA wireless industry trade group in Washington, said on Monday. The classification did not mean cellphones caused cancer.

Nokia, the largest maker of cellphones by the number of units sold, said yesterday that its products complied with international exposure guidelines and limits set by public health authorities.

Apple, the maker of the iPhone, didn’t respond to requests for comment.

“It is important to note that the IARC has not classified radio-frequency electromagnetic fields as definitely nor even probably carcinogenic to humans,” Finland-based Nokia said in a statement. The agency had “only concluded that, based on limited evidence, it may be possible that there could be some increased risk for certain cancers”.

The working group of 31 scientists from 14 countries met for seven days last month to study exposure to radio-frequency electromagnetic fields from cellphones, radar, microwaves and radio, television and wireless signals. By classifying cancer risks, the IARC aims to provide scientific advice to government authorities.

The most recent research considered dated to 2004, and exposure levels from handsets had dropped over time, said Jonathan Samet, a professor and the chairman of the working group.

The age of the studies also means the participants had used their phones for no more than 10 to 15 years, leaving open the question of the effect of longer-term exposure.

The agency said the evidence was limited, and it might re-evaluate yesterday’s recommendation once more recent research was available.

A quarter of the 900 agents evaluated were determined “possibly carcinogenic.”

The IARC lists substances as carcinogenic, probably carcinogenic, possibly carcinogenic, not classifiable and probably not carcinogenic. Half the substances it has reviewed are listed as not classifiable.

The categorisation that cellphones were possibly carcinogenic to humans was appropriate, said Malcolm Sperrin, the director of medical physics at the Royal Berkshire Hospital in England.

“The justification for such a risk indicator respects the anecdotal evidence,” Sperrin said. “The publication of more data along with a comprehensive justification of any conclusions is eagerly awaited, especially in relation to children.” – Bloomberg