Making Biodegradable Plastics Out of Bugs

“Paper or plastic?” asks the grocery store clerk. For me, that question is never easy. I tend to choose paper when it comes to grocery bags or drinking cups and straws, but I’m finding out that my choices aren’t always the most eco-friendly.

For example, like plastic grocery store bags, paper ones have a heavy environmental footprint—one that we often don’t consider when comparing it with a plastic bag’s petroleum origins. According to California’s Stanford University alumni magazine, manufacturing a paper bag takes about four times as much water as it takes to produce a plastic bag, plus the chemicals and fertilizers used in producing paper bags create additional harm to the environment. For a paper bag to neutralize its environmental impact compared to that of a plastic bag, the paper bag would have to be used at least three times.

Replacing single use plastic cups with paper ones is problematic, as well. Recently, researchers have shown that a paper cup that ends up in nature can cause damage, too, as they also contain toxic chemicals. And, what’s labeled as “eco-friendly paper drinking straws” contain long-lasting and potentially toxic chemicals.

There seems to be no right answer to the question of which kind of bag is better for the health of the planet. But what if I told you that we could use insects as a source for making plastics that will biodegrade later—with the help of those very same types of bugs?

Impossible, you say? Well, that concept is closer to reality than you might think.

Paper cups: moving away from a disposable lifestyle

Reports of plastics pollution contaminating all parts of the Earth and in all living things has accelerated a shift to alternative materials. The latte you take with you from the corner coffee shop now comes in a paper cup; sometimes, even, with a paper lid. But that paper cup that you feel good about carrying around could cause harm to organisms if it ends up in nature. Researchers at Sweden’s University of Gothenburg proved this in a study that was published in the journal Environmental Pollution in August 2023. They tested the effect of disposable cups made of two different materials on the larvae of butterfly mosquitoes.

The University of Gothenburg researchers left paper cups and plastic cups in water and wet sediment for a few weeks and followed how the leached chemicals affected the larvae. No matter the material, all the cups negatively affected growth.

You might have expected that result with the plastic cups. But paper is neither fat- nor water-resistant, so paper that is used in food packaging materials needs to be treated with a surface coating. This coating is a thin, plastic film that protects your hand from the hot coffee you’re holding. Nowadays, the plastic film is often made of polylactide (PLA), a type of bioplastic. Bioplastics are produced from renewable resources—such as corn, cassava or sugarcane—rather than from fossil fuels, which is the case for 99% of plastics on the market today. While PLA is often regarded as biodegradable, meaning that it can break down faster than oil-based plastics under the right conditions, the University of Gothenburg study shows that it can still be toxic. Bioplastics do not break down effectively when they end up in water in the environment. That means that there is a risk that bioplastics remain in nature, resulting in their being ingested by humans and other animals, just as other plastics are. And bioplastics contain at least as many chemicals as conventional plastics.

The Swedish researchers say that when disposable products first appeared on the market after World War II, large campaigns were needed to teach people to throw such products away, since disposable items seemed so unnatural to us. Now, we need to move back and away from our disposable lifestyles. It’s better for all of us if you bring your own mug when buying take-out coffee, or pause for a time and drink your coffee from a porcelain mug while sitting in the coffee shop.

Currently, the United Nations is negotiating a binding agreement with the world’s countries to end the spread of plastics in nature and in society. A council of scientists, known as SCEPT (Scientists’ Coalition for an Effective Plastics Treaty) contributes scientific evidence to the negotiations. The council calls for a rapid phasing out of unnecessary and problematic plastics, as well as vigilance to avoid replacing one bad product with another. SCEPT is also calling for transparency requirements within the plastics industry that forces a clear reporting of what chemicals plastic products contain.

Paper straws: shifting toward drinks without them

As with cups, straws made from plant-based materials, such as bamboo and paper, are often advertised as being more sustainable and eco-friendly than those made from plastic. A growing number of nations, including the United Kingdom and Belgium, have banned the sale of single-use plastic products, including drinking straws; and plant-based versions have become popular alternatives. But a new study, published in the journal Food Additives and Contaminants in August 2023, shows that paper drinking straws contain long-lasting and potentially toxic chemicals.

Researchers in Belgium recently tested 39 brands of drinking straws made from five different materials—bamboo, glass, paper, plastic and stainless steel—and mainly obtained from fast-food restaurants, shops and supermarkets for the presence of a group of synthetic chemicals known as perfluoroalkyl and polyfluoroalkyl substances (PFAS). PFAS are used to make everyday products, from nonstick pans to outdoor clothing, that are resistant to heat, stains and water. They are, however, potentially harmful to the environment, people and wildlife. PFAS break down very slowly over time and can persist for thousands of years in the environment, a property that has led to them being known as “forever chemicals.” These chemicals have been associated with several health problems, including lower birth weight, an increased cholesterol level, kidney cancer, liver damage, lower response to vaccines, testicular cancer and thyroid disease.

PFAS were found in most of the straws tested, with 18 different PFAS detected in total. The PFAS were most common in straws made from bamboo (in four out of five brands tested, or 80%) and in paper straws (in 18 out of 20 brands tested, or 90%). PFAS were found in three out of four (or 75%) of the plastic straw brands and in two out of five (or 40%) brands of glass straws. They were not detected in any of the five types of steel straws tested.

The PFAS found most, perfluorooctanoic acid (PFOA), has been banned globally since 2020. Also detected were trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid (TFMS), “ultrashort-chain” PFAS, which are highly water soluble and so might leach out of straws and into drinks.

However, the PFAS concentrations were low; and since most people tend to use straws only occasionally, they pose a limited risk to human health. However, PFAS can remain in the body for many years, and concentrations do build up over time.

The researchers say that it isn’t known whether the PFAS were added to the straws by the manufacturers for waterproofing or whether they were the result of contamination. Potential sources of contamination include the soil the plant-based materials were grown in and the water used in the manufacturing process. However, the presence of the chemicals in almost every brand of paper straw means that it is likely that the PFAS were being used as a water-repellent coating and that the paper straws (as well as the bamboo) are probably not biodegradable.

Since no PFAS were detected in stainless steel straws, the scientists advise using that type of straw or avoid using straws completely.

Soldier flies: going with a biodegradable source of plastics

For 20 years, a research group at Texas A&M University has been developing methods to transform natural products—such as glucose obtained from sugarcane or trees—into degradable, digestible polymers that don’t persist in the environment. But those natural products are harvested from resources that are also used for construction, food, fuel and transportation. So, the group began searching for alternative sources that wouldn’t have these competing applications.

That’s when the Texas A&M scientists hit on leftover waste products from farming black soldier flies, an expanding industry. The larvae of these flies contain many proteins and other nutritious compounds, so the immature insects are increasingly being raised for animal feed and to consume wastes. However, the adults have a short life span after their breeding days are over, and then they are discarded. But, it was thought, those adult carcasses could become new starting material for the Texas A&M team.

Chitin is a major component of dead flies. This biodegradable, nontoxic, sugar-based polymer strengthens the shells (or exoskeletons) of crustaceans and insects. Manufacturers already extract chitin from crab and shrimp shells for various applications; and scientists have been applying similar techniques using acidic demineralization, basic deproteinization, bleach decolorization and ethanol rinses to extract and purify it from insect carcasses. Obtaining chitin from flies could avoid concerns over seafood allergies. Currently, some other researchers isolate chitin or proteins from fly larvae, but the A&M team is the first to use chitin from discarded adult flies, which—unlike the larvae—aren’t used for foods.

While the Texas A&M group continues to refine extraction techniques, others have been converting purified fly chitin into a polymer—known as “chitosan”—by stripping off chitin’s acetyl groups. That exposes chemically reactive amino groups that can be functionalized and then cross-linked. These steps transform chitosan into useful bioplastics, such as superabsorbent hydrogels, which are 3D polymer networks that absorb water.

So far, a hydrogel that can absorb 47 times its weight in water in just one minute has been produced. This product could potentially be used in cropland soil to capture floodwater and then slowly release moisture during subsequent droughts. And because the hydrogel is biodegradable, it should gradually let go of its molecular components, which would act as nutrients for crops.

Now, the Texas A&M team is beginning a project to break down chitin into its monomeric glucosamines. These small, sugar molecules will then be used to make bioplastics, such as polycarbonates or polyurethanes, which are traditionally made from petrochemicals.

Black soldier flies contain many other useful compounds that the group plans to also use as starting materials, including DNA, fatty acids, lipids, proteins and vitamins. The products made from these chemical building blocks are intended to degrade when they’re discarded, so they won’t contribute to the current plastic pollution problem. Ultimately, the scientists would like the insects to eat the waste plastic as their food source, and then they would harvest the bugs again and collect their components to make new plastics. So, the insects would not only be the source materials for the plastics but also the end consumers of them.

Decisions: finding a new answer to an old question

Paper or plastic? It’s not always easy which one to pick—or even if those should be the only choices.

But I believe that if we could make a biodegradable plastic that isn’t derived from a natural product that’s needed for other essential items, I could be convinced to quickly answer “plastic.”

Here’s to finding your true places and natural habitats,

Candy