Environmental scientists highlight the role of paints in microplastic pollution

Plastic waste is recognized as the main cause of environmental hazards. Products such as water bottles, plastic bags and clothing fibers are recognized as major contributors to plastic pollution, but research by University of Toronto environmental scientists shows that another source deserves more attention.

A study published in the Journal Environmental Toxicology & Chemistry shows how paints are being studied seriously when it comes to research on microplastics, researchers from the Faculty of Arts and Sciences.

Microplastics, defined as plastic particles with a size of less than 5 millimeters, are known to accumulate in the air, water, food, and even the body over time, and have been shown to have toxic effects on both marine life and human health.

Researchers say paints are severely underrated as microplastic pollutants because they can be difficult to identify.

“In many cases, when you characterize microplastics, paint appears as “an artificially unknown,” says Zoe Diana, a postdoctoral researcher who co-authored the research with Assistant Professor Chelsea Rochman and master’s program Yuin Chen. “Researchers wonder what such particles are and assume that paints can be involved in most of them based on computer modelling.”

To further explore this, researchers looked into existing literature to determine where paint contamination came from. They found that around 800 studies have been published in 2019 on microplastics, but only 53 focused on paints, resulting in significant research gaps.

Paints have traditionally been considered a type of plastic, but on average, 37% of them are made up of synthetic resins that bind pigments.

To fill in the gaps in her research, Diana is creating a spectral library. This is a technique for identifying the molecular structure of unknown fragments.

She points out that there are many measures being adopted to reduce microplastic pollution. For example, rain gardens and landscape sites that absorb rainwater.

“Rain Gardens installed by major San Francisco highways have been shown to reduce downstream microplastic emissions by 91%, which is a very high success rate,” she says. “You can also install a filter in a washing machine that captures microfibers before being handed over to a wastewater treatment plant.”

When paint is involved, existing measurements include a special vacuum that can prevent paint emissions from penetrating into the environment during the construction of the building.

Diana says it is important to devise and deploy more measures to reduce paint pollution, given the ubiquitous nature of paints.

“There’s paint from the boats. There’s paint on the buildings and our roads. When you walk around town, you start to see it everywhere,” she says.

She is also optimistic that the Global Plastics Treaty will be signed in the near future. “It’s something in the work and, as we’ve seen, I’m looking forward to where it lands to reduce microplastics.