The popular-yet-controversial weed killer Roundup, blamed for causing users to develop non-Hodgkin lymphoma, may also be partly responsible for killing bees around the world, according to a study conducted by researchers at the University of Texas at Austin.
Roundup was introduced by Monsanto in the 1970s, and is now the most used herbicide in the world. It contains the active ingredient glyphosate, which in 2015 the World Health Organization’s International Agency for Research on Cancer (IARC) listed as “probably carcinogenic to humans.” Monsanto has never warned consumers of this risk nor has it placed warnings on the product’s labels.
According to the new study, glyphosate can also destroy gut bacteria in bees, rendering them defenseless to infection and death from harmful bacteria. As a result, Roundup may be contributing to so-called colony collapse disorder that has been killing off honey bees and native bees for more than 10 years, the researchers said.
“We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide. Our study shows that’s not true,” said Erick Motta, one of the researchers on the project.
Monsanto was recently acquired by Bayer AG, which responded to the study, which was published in the journal Proceedings of the National Academy of Sciences. “No large-scale study has ever found a link between glyphosate4 and honey bee health issues,” Bayer said in a statement, adding that the study’s small sample of individual bees does not meet regulatory research criteria on pesticides.