Plastics are found in waterways throughout the world. Over time, they break down into tiny pieces not easily seen by the naked eye—smaller than 5 millimeters in size—and become microplastics, which may pose a risk to humans and wildlife.

Everyday items like straws, water bottles and takeout containers can be sources of microplastics. Humans and wildlife can be exposed to microplastics by inhalation, ingestion and skin contact. This exposure can occur as microplastics are lifted into the air by the wind, absorbed into soils, or enter waterways through runoff.

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As a result of the inextricable link between human, wildlife and ecosystem health, microplastics can even make their way into the food web. Microplastics can be mistaken for food by wildlife. When animals whose bodies contain microplastics are consumed, microplastics move throughout the food web.

Microplastics have been found in the stomachs of both humans and wildlife, as well as within human blood and placenta.

In the past decade, scientists have only just begun to understand where microplastics come from and how they affect humans and wildlife. What we know about microplastics is still just the tip of the iceberg, and many questions remain unanswered.

Scientists at the U.S. Geological Survey are helping to uncover how microplastics move and transform through ecosystems. In the Pacific Northwest, USGS scientists evaluated microplastic ingestion in Chinook salmon, which are a significant fish species in the region. USGS research from the Great Lakes explored the relationship between the occurrence of microplastics and watershed attributes, such as population density.

To meet the growing demand to fill critical gaps in what we know about microplastics, USGS scientists identified what’s next for short- and long-term science opportunities related to microplastics in a new report. 

The recently published report outlines a strategy for USGS and partners to address gaps in our knowledge of microplastics to achieve the following: 

• Provide actionable information to natural resource managers for decision-making. 
• Build coalitions of research partners. 
• Serve as an information resource for people interested in microplastics research.

One important gap highlighted in the report is the lack of standardized methods for collecting microplastic samples in water. The USGS is already taking steps toward developing sampling protocols that can fulfill that need. In a collaborative effort among four USGS water science centers, USGS scientists are using a new method to collect water samples for microplastics analysis.

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The new approach has USGS scientists using plastic-free equipment to collect water samples at multiple locations across a stream. This allows the scientists to capture a more representative sample compared to typical sampling methods done at a single location.

“If we can collect water samples for microplastics in a uniform way, more in line with the way we collect water quality samples for chemical analysis, then we can standardize our approach across our Water Science Centers,” said Shawn Fisher, a USGS hydrologist involved in this effort. “We can also provide more robust datasets that can be used to understand microplastic loads in the future.”

With the broad geographic footprint of USGS science centers across the country, our multidisciplinary natural science expertise and our laboratory and field capabilities, the USGS is poised to be a leader in advancing microplastics science.

Read the full report here.