Roundup is the city's most heavily used herbicide. View Full Caption Mike Mozart/Flickr

CHELSEA — State Sen. Brad Hoylman wants to ban a controversial weed killer used all over the city because it is likely to cause cancer, he said Wednesday.

The World Health Organization (WHO) announced last month that the main ingredient in Roundup, glyphosate, is “probably carcinogenic to humans.”

The product was the most-used herbicide in city parks in 2013, according to a report by the city's health department using the most recent data available. It was applied 1,226 times by the Department of Parks and Recreation in 2013, including near playgrounds.

“The initial research on Roundup is extremely troubling,” Hoylman said in a statement. "Experts from the WHO have concluded the chemical glyphosate used in Roundup probably causes cancer in humans. It’s therefore prudent to protect New Yorkers potentially exposed to Roundup by halting sales until the research shows that it’s otherwise safe to use.”

Hoylman’s proposed legislation would place a statewide moratorium on the sale, distribution or use of products that contain glyphosate.

The Parks Department said they pull weeds by hand or without Roundup when they can.

"When that fails, or when resources do not allow, we spray Roundup, in complete compliance with NYC, NY State and Federal laws," spokesman Sam Beiderman said in a statement.

Beiderman said the department was conferring with regulatory agencies to see if the WHO's statement affected them. City agency use of Roundup represents only a small fraction of use by private businesses and property owners, the department added. Hoylman's legislation would suspend both public and private use.

Roundup, made by bioengineering giant Monsanto, was deemed to cause cancer in the 1980s by the Environmental Protection Agency, which reversed its conclusion in 1991.

But the WHO’s release said the herbicide is likely to cause cancer in humans.

In response, Monsanto head Hugh Grant told Fortune that “he didn’t see the issue impacting the business, and that the company will continue to support the product.”

Roundup and similar pesticides generate hundreds of millions of dollars in revenue for Monsanto each year, according to the company’s yearly report.

Monsanto stood by their product in a statement. "Because safety is our top priority, we conduct rigorous and comprehensive testing on each product. Roundup-branded herbicides are our most popular crop protection product, and we’re proud of their excellent safety record," they said.