After dueling reviews of research studies, scientific panels from the U.S. government and the World Health Organization can’t agree on whether the popular weedkiller RoundUp, or glyphosate, can cause cancer, Iowa Public Radio reported.

The U.S. Environmental Protection Agency is reviewing the safety of glyphosate for the first time since 1993. As part of its scheduled review, the agency examined dozens of glyphosate studies and decided that it is “not likely to be carcinogenic to humans at the doses relevant to human health.”

Last year, however, IARC — the International Agency for Research on Cancer, which is part of the World Health Organization — classified glyphosate as a probable carcinogen.

Why the discrepancy?

One difference is in the evaluation of “risk.” The EPA puts an emphasis on deciding whether glyphosate is likely to cause cancer at normal exposure levels. IARC wants to know if cancer is possible, even at very high, experimental doses.