June 2, 2016 6:02 AM EDT

THE NEW STUDY

Researchers exposed rats to cell-phone radiation for about nine hours a day and found that male rats were more likely to develop cancerous tumors.

THE EARLIER STUDIES

Observational studies in humans show limited evidence of cancer, though the World Health Organization says there’s not enough research to rule it out.

THE TAKEAWAY

It’s possible that the long-term effects of cell-phone radiation on human health are yet to be seen. More research is needed, and the study’s authors say they’ll release more findings in 2017.

This appears in the June 13, 2016 issue of TIME.

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