The plastic bottles, straws and grocery bags that wash ashore on beaches are some of the most visible signs that society’s intoxication with plastic is taking a toll on the environment. But scientists say there is another source of plastic pollution that is just as pervasive and even more difficult to clean up — and it’s hiding in our clothes.

Most clothing contains synthetic fabrics such as polyester or nylon that are essentially constructed from thin plastic fibers. These fabrics have become fixtures in closets around the world because they are durable and cheap to make. Stretchy, sweat-wicking workout clothes, water-resistant rainwear and fleece sweaters are all made of synthetics — not to mention many T-shirts, dresses and jeans that contain a cotton-synthetic blend.

These tiny bits of plastic pose a daunting environmental challenge. As so-called microfibers shed off clothing, they eventually end up in the ocean, where they can be ingested by fish and other seafood that humans eat.

“This is the microplastic pollution that we don’t talk about as much because it’s unseen, but these microfibers are everywhere,” said Sarah-Jeanne Royer, a postdoctoral research fellow at the Scripps Institution of Oceanography in La Jolla, California. “We’ve sampled them at the North Pole, in Antarctica, at the top of mountains and even at the bottom of the Mariana Trench — everywhere in the world.”

Getting at the source

Most microfiber pollution occurs when people wash their clothes. A 2016 study by researchers at the University of Plymouth in the U.K. estimated that up to 700,000 microfibers could be released in a single load of laundry, roughly equivalent to the surface area of a pack of gum.

Royer said these microplastic particles — anything measuring 5 millimeters or smaller — bypass filters at wastewater treatment plants, which means they can end up in recycled “biosolids” that are used as fertilizer or they get pumped directly into waterways. And unlike plastic bottles or candy wrappers that can be picked up and disposed of, the spread of these tiny fibers is much more difficult to control.

“Once microplastics get into the environment, you can’t sieve the entire ocean,” said Emily Woglom, executive vice president of the Ocean Conservancy, a nonprofit environmental group based in Washington. “The focus has to be on doing as much as you can to prevent the waste in the first place.”

Some in the apparel industry are heeding this call to action, with companies that specialize in outdoor gear, such as Patagonia, Mountain Equipment Co-op and Arc’teryx, leading the charge.

Patagonia, based in Ventura, California, worked with researchers at the University of California, Santa Barbara, in 2014 to explore the extent of microfiber pollution. That research, which culminated in a study published in the journal Environmental Science & Technology in 2016, examined microfiber shedding from four synthetic fleece Patagonia jackets and one from another brand.

The scientists found that when the garments were washed, an average of 1.17 grams of microfibers were released. The study also found that the amount of shedding was influenced by the type of washing machine used: Top-load machines saw seven times as many microfibers released compared to front-load washing machines. This was because front-load washing machines tend to use less water and the tumbling motions are less rigorous, according to Stephanie Karba, who co-authored the study as a graduate student at the University of California, Santa Barbara, and was subsequently hired by Patagonia as an environmental researcher in 2016.

Finding solutions

Patagonia shared these results with its customers in a 2016 blog post and recommended products that could be used in existing washing machines to collect some of the synthetic fibers from each load of laundry — akin to conventional lint traps. One such product is a reusable washing bag called “Guppyfriend,” developed by a nonprofit organization called Stop! Micro Waste. Consumers can place their fleece jackets and other synthetics inside the Guppyfriend and then toss the bag, which retails for about $30, into the washing machine, where it collects some of the released microfibers.

In addition, Patagonia is working with its manufacturers and material suppliers to investigate ways to develop fabrics that lose fewer microfibers, Karba said. But so far, there’s no perfect solution. While organic materials like cotton are biodegradable, growing cotton uses much more water than manufacturing synthetic fabrics, and it also requires land that can compete with food production.

“No matter what material you use, there will be some impact,” Karba said. “If it’s synthetic, we have to worry about microfiber pollution; for cotton, there will be some impact with water consumption; if it’s wool, there are difficulties in terms of animal husbandry. That perfect bio-based, biodegradable, nonresource-extractive material is a unicorn in the apparel industry.”

Another challenge is that the science of microfibers — and microplastic pollution in general — is a relatively new field, and there are still many unknowns.

“The research is so young that each study that comes out ends up answering one of 100 questions but then has 200 more questions that come up,” said Royer, the Scripps researcher. “Other subjects in science have years or decades behind it, so it’s hard to make conclusions right now.”

The road ahead

One of the big unknowns is precisely how much microfiber pollution has already seeped into the environment.

The most commonly accepted estimate for the amount of plastic that ends up in the ocean each year is 8 million metric tons. Of that, microplastics are thought to make up an estimated 1.5 million tons, and a 2017 report by the International Union for Conservation of Nature estimated that about 35 percent of microplastics that enter the world’s oceans comes from synthetic textiles. The next largest source of microplastics is the rubber shed from vehicle tires, with city dust, road markings, paint from ships, plastic pellets from manufacturing and personal care products making up the rest, according to the report.

Microplastics are of particular concern because they are small enough to be blown across landscapes by the wind or carried to different ocean depths by currents. This means they are virtually impossible to clean up, and these plastic particles could affect animals that unknowingly ingest them.

Studies have not only found small plastic fibers in the digestive tracts of whales and sharks, but also in a variety of fish and shellfish that people consume. Experts say there isn’t enough scientific research yet to know whether these microplastics could affect human health when eaten.

But finding plastic in so many different environments, including in the food people eat, “can’t be a good thing,” said Michael O’Heaney, executive director of The Story of Stuff Project, an environmental nonprofit based in Berkeley, California.

He added that although public awareness about some forms of plastic pollution, such as straws and grocery bags, has successfully led to bans in some cities, microplastics will most likely be trickier to legislate against because of how pervasive they are.

“Once you start to peel away the easy stuff like disposable cups or straws or bags, then you start to get into the bigger problem of how plasticized our economy has become,” O’Heaney said.

Woglom, of the Ocean Conservancy, said these challenges also present opportunities for innovation, whether the initiative comes from manufacturers, big corporations, environmental groups or consumers.

“The bottom line is that it’s going to take a suite of different things to get at a complete solution,” she said. “There isn’t going to be just one thing to do. This is going to require all hands on deck.”

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