Blue whales consume up to 10 million pieces of microplastic every day, researchers estimated on Tuesday, suggesting pervasive pollution poses a greater threat to the world’s largest animal than previously thought.

The tiny plastic fragments have been found everywhere, from the deepest oceans to the tallest mountains, and even in human organs and blood.

Now a model study published in the journal Nature Communications has estimated how much is ingested by whales.

A US-led research team tagged 191 blue, fin and humpback whales living off the coast of California to monitor their movements.

“It’s basically like an Apple Watch, only on the back of a whale,” said Shirel Kahane-Rapport, a researcher at California State University at Fullerton and the study’s first author.

The whales fed primarily at depths between 50 and 250 meters (165 to 820 feet), where the “largest concentration of microplastics is found in the water column,” Kahane-Rapport told AFP.

The researchers then estimated the size and number of bites the whales had on a daily basis and what was filtered out, and modeled three different scenarios.

In the most likely scenario, the blue whales ate up to 10 million microplastic pieces per day.

Over the 90-120 day annual feeding season, this equates to over a billion head per year.

The largest animal to ever walk the earth is also likely the largest consumer of microplastics, eating up to 43.6 kilograms a day, the study found.

“Imagine you’re carrying an extra 100 pounds — yes, you’re a very large whale, but that’s going to take up space,” Kahane-Rapport said.

It is estimated that humpback whales eat about four million pieces a day.

While it’s easy to imagine whales ingesting massive amounts of microplastics as they make their way through the ocean, the researchers found that wasn’t the case.

Instead, 99 percent of the microplastics got into the whales because they were already in their prey.

“This is of concern to us,” Kahane-Rapport said, because humans eat this prey.

“We also eat anchovies and sardines,” she said, adding that “krill is the foundation of the food web.”

Previous research has shown that if krill is in a tank with microplastics, “they will eat it,” Kahane-Rapport said.

Now that the researchers know how much microplastic is consumed by whales, they next want to determine how much damage it could do.

“The dose defines the poison,” said Kahane-Rapport.