In the United States alone, more than 8 trillion plastic microbeads enter aquatic habitats each day — often with dire consequences to wildlife — researchers from 7 different institutions suggest in a newly published study.

As small as a grain of sand, the tiny plastic beads are commonly used in personal care products such as toothpaste and body wash, adding a hint of grittiness to products intended to scrub, clean and exfoliate.

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Because of their extremely small size, the beads aren’t caught by filtration systems, leaving them to wash freely through sewage treatment plants and back into the ocean. The beads are not biodegradable and often end up being ingested by wildlife.

“We’ve demonstrated in previous studies that microplastic of the same type, size and shape as many microbeads can transfer contaminants to animals and cause toxic effects,” study lead author Chelsea Rochman explains in a news release.

“We argue that the scientific evidence regarding microplastic supports legislation calling for a removal of plastic microbeads from personal care products.”

A dozen states have already taken steps to remove plastic microbeads from personal care products, although Rochman and her colleagues point out that there are still legislative loopholes that need to be closed.

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The Microbead-Free Waters Act of 2015 was introduced in Congress earlier this year; the proposed federal legislation would “ban cosmetics that contain synthetic plastic microbeads” beginning in 2018.

According to Environmental Advocates of New York, several leading producers of personal care products have already taken steps to remove microbeads from their products.

Editor's Note: This story has been updated for clarity.