New Microplastics Study

As Many as 4,000 Metric Tons of Synthetic Microfibers Pollute California Environment Per Year

A study quantifying the amount of synthetic microfibers released into the environment from washing machines and wastewater in California.
Microfibers A study quantifying the amount of synthetic microfibers released into the environment from washing machines and wastewater in California. © Casey Fleser

First-of-its-kind study from The Nature Conservancy and UCSB finds a staggering number of microfibers enter state’s natural systems annually--more synthetic fibers than there are stars in the Milky Way galaxy 

As concerns over the global plastic pollution crisis mount, researchers are unearthing a different but equally important component of the problem--microfibers. The Nature Conservancy and world-renowned industrial ecologists at the University of California Santa Barbara recently unveiled a study quantifying the amount of synthetic microfibers released into the environment from washing machines and wastewater in California. The study estimates that approximately 1,700 metric tons of synthetic microfibers enter natural systems each year. Scientists note that this number could be as high as 4,000 metric tons or the equivalent of more than 80 million rubber duckies. 

Microfibers are the most common type of microplastics, tiny plastics that are less than 5 millimeters in size, found in the environment; they are generated during the manufacturing, processing and laundering of commonly worn clothing and other textiles made from synthetic materials. Apparel washing has long been established as the major source of primary microplastics polluting our oceans (35%). However, prior to this study, reliable data did not exist to quantify the magnitude of microfibers flowing into lands and waters off California. 

“Microfibers are so small that they can be ingested by organisms of almost any size. Their removal in wastewater treatment plants is no real solution, since it mostly just diverts them from aquatic to terrestrial ecosystems,” said Roland Geyer, co-author of the study and professor at the Bren School of Environmental Science and Management, University of California Santa Barbara.

The sheer number of microfibers is staggering with 13.3 quadrillion fibers entering our waterways and ocean from California, each year. A quadrillion is 1,000 trillion. UCSB scientists also found the volume of microfibers entering California’s lands and waters has been trending upward over the last five years. If actions are not taken around the globe to address this problem, over two times as many microplastics could leak into the world’s oceans.   

“We are faced with the challenge of tackling a massive pollution problem that is largely invisible,” said Alexis Jackson, fisheries project director for The Nature Conservancy. “Fortunately, there are immediate steps both consumers and manufacturers can take, coupled with bold policy actions, to preserve the health of our oceans, freshwater and terrestrial systems, and support conservation efforts worldwide. Failure to act now could spell catastrophe for people and nature.” 

Synthetic microfibers, found in coastal and deep ocean waters off the coast of California, work their way up the food chain, soak up other toxins, and are ingested by a wide range of marine animals from tiny plankton to fish and seabirds. They have been found in California’s seafood supply, introducing serious questions about the microfibers’ long-term impacts to human health. 

Wastewater treatment is commonly seen as the solution to address microplastics pollution. The study revealed, however, that although wastewater treatment has helped stem the flow of microfibers into waterbodies, large and unexpected amounts of microfibers still leak into the state’s lands and waters despite important improvements made in wastewater treatment plant infrastructure and practices. Specifically, scientists found that microfibers captured in the sludge from waste treatment plants are often spread onto the land and re-enter the environment. These findings demonstrate that, while wastewater treatment solutions are essential, they alone cannot prevent the flow of microplastics into the environment. “Solutions are needed upstream of wastewater treatment facilities to stop the flow of microfibers into our environment,” said Jackson.

The Nature Conservancy is exploring science and policy-based interventions to stem the flow of microfibers during the manufacturing and laundering processes. In addition to exploring design and policy solutions to reduce the volume of microfibers produced during the laundering processes, The Nature Conservancy is also exploring solutions to reduce microfiber leakage and shedding in manufacturing and creation of apparel and textiles to stem the flow more readily at the source.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world’s toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 76 countries and territories—37 by direct conservation impact and 39 through partners—we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.