Two million people marched in protest against seed giant Monsanto in hundreds of rallies across the U.S. and in over 50 other countries Saturday.

“March Against Monsanto” protesters said they wanted to call attention to the dangers posed by genetically modified food. Founder and organizer Tami Canal said protests were held in 436 cities in 52 countries.

Genetically modified plants are grown from seeds that are engineered to resist insecticides and herbicides, add nutritional benefits or otherwise improve crop yields. But some say genetically modified organisms can lead to serious health conditions and harm the environment.

The use of GMOs has been a growing issue in recent years, with health advocates pushing for mandatory labeling of genetically modified products even though the federal government and many scientists say the technology is safe.

The ‘March Against Monsanto’ movement began when Canal created a Facebook page on Feb. 28 calling for a rally against the company’s practices.

“If I had gotten 3,000 people to join me, I would have considered that a success,” she said Saturday.

Canal said she was grateful that the marches were uniformly peaceful and no arrests were reported, despite the size of the gatherings.

“It was empowering and inspiring to see so many people, from different walks of life, put aside their differences and come together today,” she said. “We will continue until Monsanto complies with consumer demand.”

Monsanto Co., based in St. Louis, said Saturday that it respects people’s rights to express their opinion on the topic, but maintains that its seeds improve agriculture by helping farmers produce more from their land while conserving resources such as water and energy.

The Senate last week overwhelmingly rejected a bill that would allow states to require labeling of genetically modified foods.