President Barack Obama Monday afternoon signed into law legislation that will ban the use of tiny plastic beads in soaps, scrubs and other healthcare products that critics say were fouling the Great Lakes and other waters.

The bill, which passed the House and Senate earlier this month, phases out the manufacturing of plastic microbeads in the U.S. starting July 1, 2017 and bans the sale of beauty products containing plastic microbeads after July 1, 2018.

The Microbead Free Waters Act, H.R. 1321, bans plastic microbeads, including those made from so-called “biodegradable plastics,” the majority of which do not biodegrade in water. Trillions of the tiny beads were flushed through U.S. water treatment systems each year and generally not being removed, so they ended up in lakes and rivers.

Lorena Rios-Mendoza, assistant professor of chemistry at the University of Wisconsin-Superior, worked on a team that was among the first to discover the beads across the Great Lakes.

In 2012 researchers found them in Lakes Superior, Erie and Huron. In 2013 they found them in Lake Michigan and Lake Ontario. Lake Erie seems to hold the highest concentrations of plastics, she said, probably because the particles usually float downstream from the upper lakes. But researchers also found the beads buried in Lake Superior sediment.

Rios-Mendoza, who had studied plastics in oceans before arriving in the Twin Ports, said it was unclear and mostly unstudied what impact the beads might have on marine ecosystems and aquatic life that could mistake the beads for food.

"The president's signature on this legislation is a major victory for U.S. waterways and the environment," said U.S. Rep. Frank Pallone Jr., D-New Jersey, the top Democrat on the House Energy and Commerce Committee and the chief sponsor of the legislation. “Without the ban, an estimated eight trillion plastic microbeads pollute U.S. waterways each day, threatening the environment and ultimately our health. My bill is a commonsense, bipartisan solution to this little-known but serious problem.”

Minnesota and Wisconsin state lawmakers already had taken action to phase-in bans of the plastic beads in most products, as had several other states.