Microplastic Releases
It’s never a good feeling, throwing a plastic bag in the trash. Landfills contribute in a major way to greenhouse gas emissions and by extension climate change by releasing harmful gases like methane. The materials we put into landfills also do not easily decompose, especially plastics. What we do not typically realize, however, is that those plastic bags and packaging that we are throwing away is likely turning into even more harmful microplastics. In fact, recent research by the National Institute of Standards and Technology (NIST) indicates that plastic polymer products, when exposed to hot water, release trillions of nanoparticles per liter into their surroundings.
Microplastics are tiny particles of plastic that are formed after shedding off from larger pieces of plastic that are no larger than 5mm in diameter. Many microplastics are formed by fragmenting from a larger piece of plastic, or from the plastic shedding and smaller polymers coming off of a larger part. Some products are produced in such a way that they already contain microplastics in them, like glitter products or some toothpastes. Other microplastics shed from textiles that reach the oceans, or fishing products like lines and nets that degrade over time.
We do not yet know the full extent of the human health effects of microplastics – preliminary studies indicate that cytotoxicity, adverse immune responses, and oxidative stress are just some of the common health effects that can be traced to microplastic exposure in clinical test settings. Other health effects that may occur are neurotoxicity, and some studies suggest that harm to human reproductive systems may be tied to microplastics in the body.
While the health effects of microplastics still remain uncertain, what we do know is that microplastics are already everywhere. A team of researchers estimated that there could be anywhere between 82 and 358 trillion plastic particles in the world’s oceans. The NOAA Marine Debris Program estimates that microplastics have been a concern in oceans for over fifty years. And a National Geographic report states that microplastics been found near the peak of Mt. Everest, the highest recorded discovery of the particles. The health effects may be unknown, but the ubiquity of microplastics is undeniable.
The aforementioned NIST study is of particular interest because scientists were able to isolate microplastics for analysis through a simple means of adding hot water to common products that are known to contain or produce microplastics. In the study, researchers added water heated to 100°C (212°F) to a commonly used plastic-coated coffee cup, left it in the cup for 20 minutes, and sprayed it into a fine mist. The mist was then dried, and the researchers were then able to isolate the nanoparticles from the original solution.
This picture demonstrates the process through which scientists isolated microplastic release from a hot beverage cup. Source: Zangmeister et al. 2022
This research is important because it allows the scientific community to isolate down to the nano-level what plastics may be contained within everyday products that are heated with hot water. Since coffee and tea consumption is common, this outcome might be of particular concern since microplastics are shedding from the layers within these commonly used coffee cups.
However, without knowing the extent of the health effects of microplastics, it is difficult for scientists to conclude any immediate dangers to human health. This is because the plastic that ends up tocuhing our food is highly regulated by agencies like the Food and Drug Administration (FDA), who perform extensive testing of products for approval for human consumption safety. It is important to know that large agencies like the FDA rely on research done by the scientific community to update their regulations and maintain a safe level of exposure to the US populace. For example, the US Environmental Protection Agency (EPA) did not initially have such a low threshold of exposure to Per- and Polyfluoroalkyl Substances (PFAS), also known as forever chemicals, until largescale, longitudinal research was conducted to understand that PFAS can be carcinogenic in extremely small quanities. Though we cannot predict the same will be true for microplastics, a similar level of caution should be taken when approaching potential health outcomes for these substances.
The NIST study is significant because there is no common lab test for seeing what exactly microplastic particles are made of. Such a test would help in understanding the risk profile of exposure to certain particles over others. For example, plastics that are shed from a tea bag could have different risks associated with them than plastics from PVC piping. Overall, however, the study’s results will be added to the growing body of knowledge that currently exists for microplastics, in an effort to better understand them going forward.
