Partial findings in a US study to determine whether cellphones cause cancer have been released, although the study is allegedly not finished yet, according to NBC News. The bit of results released by the US National Toxicology Program are claiming that in their experiment, male rats exposed to constant, heavy doses of the certain types of radiation emitted by cell phones developed brain and heart tumors while female rats did not. A puzzling aspect of the study is that the male rats that developed the tumors lived longer than the control rats who were not exposed to radiation. When rats are used in a study they are considered of only partial reliability.

There has not yet been shown a link between humans and risk of cancer or tumors from using cellphones, although findings like this breathe new life into that debate. The full report is due out next year.

Past studies also found mixed results, with NBC News citing one that concluded a cell phone held next to the head might warm up brain cells but found no consequences.