ROCKLAND, Maine — Dozens of activists brought whistles, noisemakers, skull-and-crossbones signs, bee costumes and babies to the streets of Rockland on Saturday afternoon as they joined in an international March Against Monsanto.

Leslie MacDonald, an herbal apothecary from Hope, blew vociferously into a conch shell as she walked down the coastal city’s sodden streets.

“I don’t want any [genetically modified organisms] in my food,” she said. “It’s hard to find food without GMOs. Everything’s changing because of this crap. It would be sad on our planet if we lost everything due to the stupidity of our chemicals and the polluting we’re doing — and our technology.”

The 70 or so marchers came from around the midcoast for the grassroots activist event — despite the at-times torrential downpour — to lodge their fears and anger about Monsanto, a global agribusiness company that has provoked the ire of environmentalists and food activists who are concerned about the company’s business and technology practices. Another march in Portland reportedly drew more than 200 people.

According to the website for the March Against Monsanto, the overall goals of the day included bringing attention to Monsanto’s corporate subsidies and political favoritism, showing that the company’s genetically modified seeds are harmful to the environment and might be tied to the widespread bee population collapse and advocating positive solutions such as buying organic food.

“It’s the tip of an iceberg, but it’s really dangerous,” Bill Eberle of Thomaston said of Monsanto’s practices.

But Benildo de los Reyes, a University of Maine molecular genetics professor, said that it is frustrating that many people have such negative views about science that they don’t fully understand.

“A very powerful tool is being wasted because of misconceptions in the public domain,” he said Friday. “It’s very upsetting, to tell you honestly.”

He said that humans have been selecting and domesticating wild plants in what he termed “genetic manipulation” since the beginning of agriculture and civilization. Scientists using modern technology can use genetic engineering to transfer genes from one organism to another to add desirable traits and features, he said. Genetic engineering has been used to develop controversial crops such as Monsanto’s Roundup Ready soybeans, which are tolerant of the Roundup agricultural herbicides.

“In my view, that is bad,” de los Reyes said.

But other examples of genetically engineered crops are designed to be beneficial, including golden rice, which has added vitamin A, which was developed to combat a common deficiency among children in South Asia. The professor said that future uses of the technology might include developing crops that can withstand drought conditions and unpredictable weather patterns connected to climate change.

“That’s using science to address a problem for humanity,” de los Reyes said. “The technology is not bad. But depending on the motivation or the goal of the technology — that’s what can make it bad.”

However, his views are not universally held.

“Humans have been breeding and selecting plants for thousands and thousands of years, but humans have never been able to introduce traits into a plant across taxonomic lines until genetic engineering,” Logan Perkins, the coordinator for the Maine Organic Farmers and Gardeners Association’s right-to-know labeling campaign, said this week. “This stuff is fundamentally different … when we start breaking open DNA chains, we’re doing something that’s never been done before.”

A Monsanto spokesperson said in an email sent to the BDN Friday that the company was aware that some local groups were promoting events but didn’t know why.

“Monsanto is primarily a seed company,” spokesman Tom Helscher wrote. “Agriculture and its uses are important to each of us. Among the challenges facing agriculture are producing food for our growing population and reducing agriculture’s footprint on the environment. While we respect each individual’s right to express their point of view on these topics, we believe we are making a contribution to improving agriculture by helping farmers produce more from their land while conserving natural resources such as water and energy.”

Perkins said that one of the critiques of Monsanto is that it has fundamentally changed the face of agriculture. The company’s claims that genetically modified foods are safe are not believable to many, she said.

“It makes people skeptical,” Perkins said.