Madeline De Leon
Contributing Writer
Are we actually eating microplastics, and are they truly everywhere? The heavy use of plastic material in agriculture is a concern to Yuki Floyd and her colleagues at the Bren School of Environmental Science & Management at UC Santa Barbara. In her fourth year as a PhD candidate, Floyd works alongside Trace Martin and Rebecca Reynolds, researching microplastics in agriculture. Floyd is looking for a connection between microbial degradation, soil health, and the extent of plastic pollution based on different measurements.
“The first paper that ever published the word microplastics, and started looking at microplastics was only twenty years ago. Commercial plastic production has kind of been around since the ‘40s. … At this point it’s everywhere,” says Floyd in an interview with The Bottom Line. Now one might ask, Has there been any human that has yet to be exposed to microplastic consumption? Floyd says, “Probably not.” While touring the lab, Floyd points to a muffle furnace, used to turn microplastics and other contaminants to ash at around 900 degrees Celsius. She explains that even before obliterating anything on their glassware with the furnace, they “regular wash,” then acid rinse, then rinse with nanopure water. If only there was a less lethal but equally effective sterilization process for us humans.
Floyd explains that microplastics are in fact visible under a 40x microscope (enough to see down to five microns), but there are even smaller contaminants to be concerned with: nanoplastics. Where microplastics are defined as 100 nanometers to 5 micrometers (5 micrometers is like the top of an eraser at the end of a number two pencil), nanoplastics are much smaller and behave very differently. But how do you see microplastics? What do they actually look like? Floyd comments on how she is often just looking for incohesive properties in the medium being observed. “It’s really kind of like you’re guessing at that point, right? … If it’s something bright blue or, like, red, those aren’t really natural soil colors.” Namely we talk about cellulose acetate (cigarette filters), and how they are abundant in her soil samples. This is a big issue with the first step of their analysis, considering cigarette filters tend to look a lot like the natural parts of soil. Other troubling findings include fishing lines and microbeads. All are big environmental no’s. There goes your weekend.
The question is, are these contaminants biodegradable at this point? Floyd would say biodegradable means different things to different people. Floyd suggests that a chemist might have a bit of a different perspective, mainly hoping for chemical recycling rather than complete degradation. Floyd and other researchers are less optimistic on that front. To Floyd, biodegradable means fully integrating plastic back into the natural world, through cell growth, mineralization, or even respiration byproducts (something like CO2). Yuki says, “…if you talk to someone who’s a chemist, to them degradation means a larger polymer being broken down into monomers or a ligament… Just a smaller piece.” Floyd continues, “Chemical recycling has a lot of pros and cons. It can be very expensive, and it’s very energy intensive. And on top of that, a lot of plastics aren’t able to be completely recycled. … you do have to add some new feed stock anyway. … So, you’re still consuming virgin plastics. It’s not in the process of recycling. It’s just not really feasible for a lot of plastics.”
The success of the non-biodegradable plastic industry is antagonistic in nature. Not all companies involved in the plastic industry are stagnant in the race for sustainability. Over the last couple of years, Floyd was part of the team working with BASF, the largest chemical producer in the world. For the last couple of years, BASF has had a strong interest in the production of biodegradable plastics and polymers. These are mainly used in adhesive products such as tape, sticky notes, and paints. Floyd and Reynolds worked together with BASF, essentially composting plastic, and then using a gas chromatograph (another large red box), which measures the concentration of CO2 that had been produced. If there is an increase in CO2, this indicates that the microbes are able to use the substrates given and then break them down into respiration byproducts.
Fortunately, there’s work being done at the lab looking into developing new forms of biodegradation; Floyd will test multiple plastics and see if they pass the standards set by the effect of natural conditions on other potentially biodegradable materials. Others in the lab test different factors that align with real world conditions (water, wind, change in temperature, etc.), but Floyd works with photo oxidation, which is widely considered as the most important factor in natural conditions.
While some are for the elimination of plastic from industries tied to human consumption and health, Floyd points out some general benefits of plastic use. The first is water retention. Plastic films are laid over soil and then act as a barrier that reduces water evaporation and conserves water. This is particularly important in drought-stricken California. Plastic use also greatly aids in pathogen control, playing a crucial role in soil fumigation. Without the use of a sort of plastic cover, the fumigant would release into the surrounding ecosystem.
Floyd again offers her understanding of the pros and cons of agricultural plastic use. “I don’t believe that we will ever just completely get rid of plastic. … it becomes kind of almost like a social justice issue when you’re taking away goods that are available to people when they don’t have other options, right? So, I don’t think it’s like we can completely villainize it. … So, there’s always a trade-off.”
Reynolds offers a take on the research being done at Bren, and more broadly on what the research ought to be. “Obviously everyone has their own biases. … from an agricultural perspective, if microplastics increase water retention in your soils, that’s not considered a bad thing. … If you’re looking at it from an ecotoxicology perspective, microplastics and soils, the takeoff of them increasing water holding capacity is not worth the potential pollution that they cause. So it’s about reporting the facts, but doing it in the context of society and policy… disciplinary differences, full picture.”
The research being done by Yuki Floyd and those at the Bren School encourages both caution of plastic usage and the improvement of the industry. While this microplastic research develops, they hope to lessen the complexity of our relationship with the plastic industry, and ultimately strengthen the environment.