Microplastics: Small Particles, Bigger Questions
By Kevin Westerling,
@KevinOnWater
For years, the water industry’s conversation around microplastics has been largely geographic. Where are they? How much of them are there? How are they entering our waterways, our treatment systems, and our drinking water supplies?
The answers have become increasingly unsettling. Researchers have identified microplastics in rivers, lakes, oceans, bottled water, wastewater streams, and even human tissues. The particles seem to be everywhere we look. But another question has lingered. What do they actually mean for health?
New research from Columbia University and the University of California, Berkeley may bring us closer to an answer.
Published October 14 in Nature, the study found that common microplastics can spontaneously generate reactive oxygen species when immersed in water. These include hydroxyl radicals, which can damage biological molecules. The researchers also demonstrated effects involving proteins and cells in laboratory experiments.
The work identifies a potential mechanism through which microplastics could cause harm. It does not establish the health risk from drinking water containing them. That distinction matters — but so does the finding itself.
More Than A Counting Exercise
Plastic is generally considered chemically durable. That’s part of the reason we use so much of it. We make something out of plastic expecting it to hold up. Breaking it into smaller pieces might seem to leave us with the same material, just considerably harder to collect.
As plastic breaks down into smaller particles, however, more surface becomes exposed relative to its volume. The researchers found that interactions at the boundary between microplastics and water can trigger chemical reactions, with greater activity associated with more water-repellent plastics. As a result, chemical activity that might be insignificant in a larger piece of plastic becomes more relevant when that plastic breaks into smaller particles.
According to Columbia’s explanation of the research, this activity could help explain how microplastics contribute to biological damage. The study’s findings raise questions about effects in the water-rich environments where particles may be found, from aquatic ecosystems to the human body.
For water professionals, the finding adds another dimension to the microplastics question: These widespread particles may interact with water in ways researchers are only beginning to understand.
The findings also suggest that particle counts may not tell the whole story. Understanding the potential effects of microplastics may require more information about the particles themselves and the conditions in which they occur.
From Presence To Potential Harm
Concern about microplastics is hardly new. Their persistence and prevalence have made them a subject of research and public attention for years. Finding them in more places, however, has not necessarily answered the question of what their presence means.
That is where this study makes a contribution. It gives researchers a potential way to connect exposure with biological effects — an explanation to examine more closely as they work to understand whether, and under what circumstances, those effects translate to harm.
There is still a considerable distance between a laboratory finding and a reliable assessment of risk. Concentration, exposure, particle characteristics, and the conditions in which reactions occur all matter. The study does not tell a utility that microplastics in its finished water are causing disease, nor does it establish a safe or unsafe concentration.
But uncertainty should not be mistaken for a reason to dismiss the finding. The evidence gives substance to a concern that has been difficult to resolve. Tiny particles may do more than persist in water and accumulate in living organisms. Under the conditions studied, they can also participate in chemical reactions with the potential to damage biological material.
A Water-Sector Question
For the water industry, the study adds another layer to an issue that spans more than drinking water. Microplastics can enter and move through watersheds and wastewater systems, creating questions about exposure for people and aquatic life as well as how particles are measured, managed, and removed.
As discussed in a recent Water Online article on source water protection, microplastics have been something of a “known unknown” for the sector. Research has indicated that conventional treatment processes can remove many particles, but questions remain about measurement and long-term health effects.
The new study does not prescribe a treatment response. It does, however, make the work of understanding microplastics more consequential. Better measurement can help establish what is present; further health research can help determine what those findings mean. Both are needed before utilities can make informed decisions about risk and treatment.
The research may also have implications beyond removal. The Berkeley researchers suggest that understanding the surface chemistry could eventually help inform the design of plastics with less potential to produce harmful reactions. That possibility puts some attention where it belongs: on the materials entering the environment, as well as the systems tasked with managing them.
Customers may have questions as this research reaches a wider audience, and utilities will need to be clear about what is known and what remains uncertain. For the moment, the finding is also worth the industry’s attention on its own merits.
The concern around microplastics has never been simply that the particles are small or widespread. It is what their presence might mean for living things. This study does not provide the final answer, but it offers researchers a more concrete place to look for one.