January 2, 2025 – Over the past few months, Harvard Chan faculty have been sharing evidence-based recommendations on urgent public health issues facing the next U.S. administration. Shruthi Mahalingaiah, an assistant professor of environmental, reproductive, and women’s health, offered her thoughts on the challenges posed by microplastics and the need for more public awareness about the surprising sources of a stealthy and growing hazard that demands multifaceted and creative solutions.
Q: Why are microplastics a pressing public health issue?
A: For a long time, oceanographers and marine biologists have focused on the threat to oceanic life for good reason. We have a floating garbage patch of plastic halfway between Hawaii and California that covers an area that is twice the size of Texas. And that is just the largest of five offshore plastic accumulation zones in the world’s oceans. The terrible impact on marine and wildlife species is clear.
What people may not realize is that microplastics are also a pressing human health issue. These plastics are showing up everywhere, including throughout our bodies—and even within the human reproductive system, not only in placentas but also in testes and semen. What is worse, we don’t know what the accumulation of these plastics in our bodies might mean for us. Research points to potentially serious issues, including vascular disease, cancers, respiratory disorders, inflammatory bowel disease, as well as dizziness and neurological symptoms. We have much more to learn. We know microplastics and their impacts vary based on composition, size, and surface area. The smaller the particle, the deeper it can go into the body.
There are many important questions to answer. For instance, in the human system, how do the chemical properties of the nanoparticles within the microplastics interact with nutrients and normal repair processes that prevent disease and slow aging? Is the way we produce and recycle plastic helping—or are these processes increasing unsafe exposures? It’s essential that we ask these types of questions and do the research to find out.
Q: What are the biggest challenges facing the next administration around microplastics?
A: It will be challenging to correct the deeply entrenched idea that consumer diligence in recycling plastics can or could ever solve the plastic waste and pollution crisis. The reality is that only about 9% of the world’s plastic is recycled—it’s often not economically or technically possible to recycle the rest and the vast majority of plastics end up in landfills or get incinerated or dumped into the environment.
It is encouraging that the California attorney general has filed a lawsuit against ExxonMobil, the world’s largest producer of polymers, which are materials used to create single-use plastics, including plastic utensils, drink bottles, and packaging. The lawsuit alleges that the company for decades has used marketing campaigns to create a “myth” around the impact of recycling, leading consumers to buy more single-use plastic than people would if they knew most plastic never goes away.
To make real impact, we need to be more strategic. In 2022, member states in the United Nations endorsed a resolution to end plastic pollution and forge an international legally binding agreement by 2024. It focuses on moving government and businesses away from single-use plastics. In late November, the fifth session of the negotiating committee to develop that treaty, which includes about 175 nations, met in South Korea. I hope a treaty will be adopted soon.
It’s important that we expand both the public conversation as well as scientific research to investigate all sources of microplastics. For instance, a surprising source of microplastics is wear and tear on tires. When you drive your car, how fast you go and how often you accelerate and decelerate ultimately makes an impact. Research shows that tire wear-and-tear contributes up to 10% of the plastics that end up in our oceans and enter our food chain—an issue that requires both our awareness and creative action—including carpooling, using public transportation, increasing walking to close by areas, and so on.
The challenges ahead are multifaceted. We have to understand all the sources and the complex ecosystem of microplastics for our mitigation efforts to work. We have to understand the full scope of the health impacts of microplastics. And as we work to address the problem, we have to take care not to introduce another threat, a different downstream effect created by substituting a microplastic with something that ultimately also poses health risks—so we can’t have blinders on, we must always look at the big picture in order to mitigate wisely.
Q: What are your top two to three recommendations for policies to address microplastics?
A: It’s important for relevant industries to consider the concept, “First, do no harm.” We need the wide range of industries that produce plastics as waste to take responsibility and develop creative solutions to shift away from the use of plastics.
For instance, the medical-industrial complex uses a lot of single-use plastic. As a physician, I know that routine surgeries generate a bag or more of plastic trash and time-intensive surgeries yield up to six bags. And when harm is noted, as is the case with microplastics, we owe it to our patients, community, ecosystem, and to planetary health to move to ameliorate the impact. We need a wave of creative solutions across the medical-industrial complex. For example, we can create greener labs by adopting sustainable practices that minimize plastic use. All of us must start somewhere and act.
And we must individually work to reduce microplastics in ways that extend far beyond recycling. We must be aware that microplastics are all around us, that tiny fragments of plastics exist in car tires, clothing, bedding, and all kinds of textiles, including the microplastics stripped off our clothing by friction and turbulence in the washing machine that end up in our wastewater. One solution to the latter example involves installing a filter on your washing machine to stop microfiber pollution.
Q: What’s the evidence supporting these recommendations?
A: There is a lot of evidence that single-use plastic is a problem and, as mentioned earlier, only 9% of plastic gets recycled.
We know that people are consuming and breathing a lot of plastic. One analysis shows that Americans ingest and inhale up to 121,000 microplastic particles every year, and people who drink bottled water may be ingesting an additional 90,000 microplastics per year. Put another way, scientific research shows we probably ingest the weight of a plastic credit card every week without realizing it.
I highly recommend a book by science journalist Matt Simon, A Poison Like No Other, which details a lot of the scientific research about the ubiquity of microplastics and their ability to penetrate into so many things, including our food chains and our bodies.
Q: What do you hope could be accomplished in this field in the next four years?
A: My big hope is that we get rid of single-use plastic. I want to see innovation in packaging, food storage, and especially in the medical sector where we should be rethinking single-use items and moving toward the use of sterilization of reusable equipment. Overall, I hope to see major systems across diverse sectors re-engineered in innovative ways, with the urgent reduction in microplastics a top priority.
