Assessing Directives and Outcomes of Microplastic Study Bills in the U.S.

What if one of the most widespread pollutants on Earth was already in your body? You may have consumed microplastics today without realizing it. They could have been in your bottled water, floating through the air, or shed from the clothes on your back. Once considered a distant ocean pollution issue, microplastics are now found in Antarctic ice, deep ocean trenches, mountain peaks, and even in human blood and brain tissue.

While scientists race to understand the risks, lawmakers across the United States are still trying to answer a more basic question: How do we regulate something so widespread and yet so difficult to monitor, define, and measure?

This question became the foundation of our policy clinic project with Ocean Conservancy. Our team analyzed nine state and federal laws focused on researching microplastics. Our goal was to understand what these laws accomplished, what gaps in policy remain, and what future lawmakers can learn from them.

Our Approach to Assessing Early Microplastics Policy

Microplastics are an emerging issue. A common first step legislators can take when regulating a novel pollutant is to pass a law requiring an agency or entity to assess the existing scientific landscape and provide policy recommendations; these are often known as “study bills.” Ocean Conservancy tasked us with learning more about these efforts to date on microplastics.

In 2025, Ocean Conservancy released a “United States of Plastics” report, which assessed state-level efforts to address plastic pollution. Study bills relating to microplastics were one of several policy approaches reviewed in their report. Building on that work, we produced a report that analyzed eight study bills identified in the United States of Plastics report and one additional federal law, as shown in Figure 1. The purpose of our report is to communicate insights to legislators, NGOs, and governmental agencies interested in addressing microplastic pollution. Rather than treating study bills as the only next step, our report helps legislators, NGOs, and government agencies see where existing studies already provide enough direction for more targeted action.

Methods for Preparing the Report

In producing this report, we started by conducting research on the laws of interest. This phase of the project involved identifying legislative directives embedded in each law. From there, we collected data on the outcomes of each directive by reading and analyzing publicly-available reports. These reports helped us identify whether the requirements of the laws were met, not
met, or if the agency/entity needed additional support to comply with the legislation. We then sorted the bills into thematic categories: comprehensive strategies, drinking water, microfibers, and food systems to compare different legislative approaches.

During the final stages of developing our report, we presented our preliminary findings to Ocean Conservancy staff and received feedback, which we incorporated into our conclusions.

Completing the Project: Takeaways From Our Report

• Upstream action is a commonly recommended solution: Nearly all of the reports that we reviewed identified source reduction as a solution to pollution. In these solutions, producers and consumers aim to reduce plastic contamination before it enters the environment, including the ocean and freshwater systems. Such source reduction approaches can range from reducing plastic production to adding filters to washing machines.
• Clear reporting deadlines may increase accountability: Legislation that included clear benchmarks and due dates appeared to increase likelihood of implementation. For instance, In California, clear implementation deadlines for a statewide microplastics strategy offered more accountability over a long time period. 
• While study bills can be a first step, they are not a prerequisite: Although some study bills have led to the development of microplastics policy, it may not be the best approach for every state. Some states may be able to bypass the step by looking at existing reports and assessments to determine what policies are priorities to directly regulate microplastics.
• Reports identified that a lack of standardized testing can be a bottleneck: Several agencies identified that the lack of standardized methods for testing, monitoring, and risk assessment — especially at the national level — made it challenging to adopt microplastic policies and regulations. While this was true across many of the reports, it’s important to note that at least one of the laws we reviewed (SB 1422, California 2018) resulted in a standardized definition and methodology for monitoring microplastics in drinking water.

Why Our Project Matters

Microplastics are a widespread contaminant and require a suite of policy solutions to prevent further pollution and harm. Our report delivers three crucial functions to facilitate future regulation of microplastics pollution:
 

1. Streamlining information: A major goal of this report was to produce a resource that compiled and streamlined scattered information about state-level microplastic policy efforts.
2. Informing future legislation: Understanding the dynamics of existing efforts to address microplastics could help future lawmakers craft stronger policy around this issue.
3. Highlighting efforts: State-level environmental policy often builds upon sustained momentum in other states. By communicating and analyzing existing laws, our report could encourage and inspire future action.

How EPM Prepared Us

The Policy Clinic experience helped us practice what we learned in the classroom and prepare for our next steps as environmental decision-makers. In addition to coursework geared toward completing this report, we participated in a prep seminar last fall that helped us develop project management skills, navigate client relationships in a consultant capacity, and collaborate as a
team. We hope that the report reflects the team skills we have developed and applies our technical knowledge and analytical tools in a way that addresses emerging environmental policy.

This article is the third in a series of seven that highlight Policy Clinic projects completed by EPM masters students in collaboration with our partners. On behalf of the Graduate Program of Environmental Policy and Management, we'd like to give special thanks to Angela Noakes and Anja Brandon with the Ocean Conservancy for their partnership on this project.

The views, opinions and recommendations expressed in this article and report are those of the authors and do not necessarily reflect the official policy or position of the Graduate Program of Environmental Policy and Management at UC Davis.