An environmental lobby group has published a list of the relative amounts of electromagnetic radiation given out by mobile devices.
The Environmental Working Group (EWG) said in a statement that while there is no conclusive link between mobile phone use and incidence of cancer, consumers could use the comparitive list to "make informed decisions".
"We would like to be able to say that cell phones are safe," said Olga Naidenko, EWG senior scientist and lead author of the list. "But we can't. The most recent science, while not conclusive, raises serious issues about the cancer risk of cell phone use that must be addressed through further research. In the meantime, consumers can take steps to reduce exposure."
EWG compiled the list of phones using technical information supplied by manufacturers.
Results of studies into phone use and links to cancer are inconclusive.
For example, one Institute of Cancer Research study in 2006 found no conclusive links between phone radiation and the most common type of brain tumour, glioma.
Another Institute of Cancer Research study, in 2005, also found no conclusive links between phone use and acoustic neuroma, a nervous system tumour that occurs close to where mobile phones are held to the head.
However, in the case of acoustic neuroma and other types of cancer, mobile technology is still too new to be able to gauge its long-term health effects, according to Institute of Cancer Research professor Anthony Swerdlow.
"The results of our [acoustic neuroma] study suggest that there is no substantial risk in the first decade after starting use," said Swerdlow. "Whether there are longer-term risks remains unknown, reflecting the fact that this is a relatively recent technology."