Correction appended: March 27, 2015.

In an interview with the French television station Canal Plus, an advocate for genetically modified foods said Roundup, a weedkiller that is manufactured by chemical giant Monsanto, is safe for human consumption but refused to drink the herbicide when offered a glass by an interviewer.

Patrick Moore says he leads a campaign in support of “golden rice,” a genetically modified grain that contains high amounts of vitamin A. In the interview, which Moore says he believed would focus on “golden rice,” he says the active ingredient in the herbicide, glyphosate, is not causing cancer rates in Argentina to increase.

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“You can drink a whole quart of it and it won’t hurt you,” he said.

But when the reporter told him that they had prepared a glass and invited Moore to drink it, he refused, saying “I’m not stupid.”

“So, it’s dangerous?” the interviewer asked.

“It’s not dangerous to humans,” Moore replied.

He insisted that people “try to commit suicide” by drinking Roundup but “fail regularly.” Moore then walked out of the interview.

Last Friday, the World Health Organization’s cancer-research arm, the International Agency for Research on Cancer, classified the widely used herbicide as “probably carcinogenic to humans.”

Correction: The original version of this story identified Moore as a paid lobbyist for Monsanto. In a statement published Friday, Monsanto said Moore “is not and never has been a paid lobbyist for Monsanto.”

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Write to Helen Regan at helen.regan@timeasia.com.