Tiny plastic beads commonly found in beauty products are showing up in North America's Great Lakes, sparking concerns for the health of the world's largest surface freshwater system.

Scientists have already found the particles floating in the oceans, but a non-profit California-based environmental activist group recently reported the same contamination in lakes Erie, Superior and Huron.

A team of researchers with the 5 Gyres Institute collected samples from the interconnected lakes during the past northern summer and found large quantities of round, plastic pellets - also called "microbeads", which are often less than a millimetre in diameter.

Microbeads make up the exfoliant component of such products as facial scrubs, body washes and toothpastes, and are designed to wash down a household drain.

The plastic particles found by 5 Gyres team members "matched the same size, colour, texture and shape of the microbeads found in popular consumer products," said the group's executive director, Marcus Eriksen.

The group said it had presented its research to Proctor & Gamble and Johnson & Johnson, two major manufacturers using microplastics in their products.

Mr Eriksen said the group had expected the companies to put up a fight over any attempts to pressure them to stop using microplastics.

However, he said, a Johnson & Johnson spokeswoman claimed the company had already begun phasing out the use of polyethylene microbeads and is developing alternatives.

"We won without having to go through a legislative battle, which no one wants to do," Mr Eriksen said.

Mr Eriksen said a Proctor & Gamble spokesperson told 5 Gyres that the company would phase out the use of microbeads by 2017.

Meanwhile, however, he said the plastic particles had been added to a long list of threats to the Great Lakes fish population, as they could easily confused with natural food.

Furthermore, they may also pose a health risk to humans, the group said.

"We don't know if the problem stops with the fish or if we eat the fish, the problems are with us now," said Lorena Rios-Mendoza, a chemist with the University of Wisconsin-Superior who was on the 5 Gyres boat expedition.

There was also an issue of removing the microplastic debris already in the lakes.

"Plastic doesn't biodegrade so once it's in the water, it doesn't just disappear," Ms Rios-Mendoza said.

Mr Eriksen said particles could also absorb chemicals from the water, which acted as weight, sinking the particles to the lake beds.

The lifespan of microplastics is unknown so it can take years for it to completely leave the ocean or lake, if it ever does.

The scientists said they would expand their research to lakes Michigan and Ontario this year.

They planned to publish their research in a peer-reviewed journal later this year.

Reuters