Earth Day 2024: Planet vs. Plastics

As someone who cares deeply about the Earth and the natural habitats that it provides, you’ve heard a lot about the 30 x 30 idea—which aims to protect 30% of the planet by 2030—and the similar America the Beautiful plan, with the objective of conserving and restoring 30% of U.S. lands and waters by 2030.

Now, however, we have another measurement to aspire to that comes to us by way of the theme of Earth Day 2024: Planet vs. Plastics. For the sake of human and planetary health, this year’s subject calls for the end of plastics, with a 60% reduction in the production of plastics by 2040; or, in short, 60 x 40. The ultimate goal, according to EARTHDAY.ORG, is building a plastic-free future for generations to come.

In fact, instead of living in the Anthropocene, some have suggested that we really live in the “Plasticene.” New research bears that out: in a recently published report, researchers state that they found microplastics in all 62 human placenta samples that they tested. That means, essentially, that we are all now partially made of plastics.

So, what can be done about our planet and its ubiquitous plastics? Is 60 x 40 doable?

It just might be.

Plastic people

To achieve the 60 x 40 goal, EARTHDAY.ORG is suggesting four avenues of approach. One is that we phase out single-use plastics by 2030 and embed that commitment in a United Nations Global Plastics Treaty on plastic pollution.

A second strategy is to raise public awareness about plastic’s harm to humans and to biodiversity health. A flurry of recent studies has found that microplastics are present in virtually everything we consume, from bottled water to meat to plant-based foods. And now, to call attention to that that fact and its dangers, University of New Mexico Health Sciences researchers have found a way to measure the microplastics present in human placentas.

Plastic use worldwide has grown exponentially since the early 1950s, producing a metric ton of plastic waste for every person on the planet. About a third of that plastic is still in use, but most of the rest has been discarded or sent to landfills, where it starts to break down due to exposure to ultraviolet radiation present in sunlight. After that, it ends up in groundwater, where we and other animals can ingest it; or sometimes it aerosolizes, and we inhale it.

Many plastics have a long half-life, the amount of time needed for half of a sample to degrade. The half-life of some items might be 300 years, while the half-life of others could be 50. But between now and 300 years, some of that plastic gets degraded. The microplastics that we see in the environment today are probably 40 or 50 years old.

In a study published in the journal Toxicological Sciences in February 2024, a University of New Mexico Health Sciences research team analyzed donated placental tissues. In a process called saponification, they chemically treated the samples so that they would “digest” the fats and proteins into a kind of soap. Then, they spun each sample in an ultracentrifuge, which left a small nugget of plastic at the bottom of a tube. Next, using a technique called pyrolysis, they put the plastic pellet in a metal cup and heated it to 600 degrees Celsius, capturing the gas emissions as different types of plastic combusted at specific temperatures, creating specific “fingerprints.”

The findings revealed that there were microplastics in all 62 of the placenta samples tested, with concentrations ranging from 6.5 to 790 micrograms per gram of tissue. Although those numbers may seem small (a microgram is a millionth of a gram), the scientists say they worry about the health effects of a steadily rising volume of microplastics in the environment. For toxicologists, “dose makes the poison”; and if they’re seeing effects on placentas and the dose keeps going up, then all mammalian life on this plant could be affected. That’s not good.

The most prevalent polymer in the placental tissues was polyethylene, which is used to make plastic bags and bottles. It accounted for 54% of the total plastics. Nylon and polyvinyl chloride (better known as PVC) each represented about 10% of the total, with the remainder consisting of nine other polymers.

Previously, it had been difficult to quantify how much microplastic was present in human tissues. Typically, researchers would simply count the number of particles visible under a microscope, even though some particles are too small to be seen. With this new analytical method, more precise quantification is possible.

Traditionally, plastics have been assumed to be biologically inert, but some microplastics are so small that they are measured in nanometers—a billionth of a meter—and are capable of crossing cell membranes. The growing concentration of microplastics in human tissues might explain puzzling increases in some types of health problems, such as inflammatory bowel disease and colon cancer in people under 50, as well as declining sperm counts. The concentration of microplastics in placentas is particularly troubling because those tissues have only been growing for eight months (they start to form about a month into a pregnancy). So, other organs of your body are accumulating plastics over much longer periods of time.

The production of plastics worldwide is projected to double every 10 to 15 years. So, even if we were to stop today, in 2050 there will be three times as much plastic in the background as there is now.

And, we know we’re not stopping today.

Plant polymers

A third avenue to achieve the 60 x 40 goal is combating the environmental impact of fast fashion, which relies on the use of synthetic materials made of plastics, such as nylon and polyester.

The fourth and final approach for achieving 60 x 40 is investing in innovative technologies aimed at finding sustainable alternatives to plastics. Researchers at the University of California San Diego and materials-science company Algenesis claim to have one: they say their plant-based polymers biodegrade—even at the microplastic level—in under seven months. Their paper on the subject appeared in the journal Nature Scientific Reports in March 2024.

To test its biodegradability, the product was ground into fine microparticles. The research team then used three different measurement tools to confirm that, when composted, the material was being digested by microbes.

The first tool was a respirometer. When microbes break down compost material, they release carbon dioxide, which the respirometer measures. These results were compared to the breakdown of cellulose, which is considered the industry standard of 100% biodegradability. The plant-based polymer matched the cellulose at almost 100%.

Next, the team used water flotation. Since plastics are not water soluble and they float, they can easily be scooped off the surface of water. At intervals of 90 and 200 days, almost 100% of the petroleum-based microplastics were recovered, meaning none of it had biodegraded. On the other hand, after 90 days, only 32% of the algae-based microplastics were recovered, showing that more than two-thirds of it had biodegraded. After 200 days, only 3% was recovered, indicating that 97% of it had disappeared.

The last measurement involved chemical analysis via gas chromatography/mass spectrometry, which detected the presence of the monomers used to make the plastic, indicating that the polymer was being broken down into its starting plant materials. Scanning-electron microscopy further showed how microorganisms were colonizing the biodegradable microplastics during composting.

In conclusion, say the scientists, this material is the first plastic demonstrated to not create microplastics as we use it. It’s more than just a sustainable solution for the end-of-product life cycle and our crowded landfills. It’s a plastic that’s not going to make us sick.

Creating an eco-friendly alternative to petroleum-based plastics, of course, is only one part of the long road to viability. The ongoing challenge is to be able to use the new material on preexisting manufacturing equipment that was originally built for traditional plastic. But Algenesis is making progress. They have partnered with several companies that are able to use the plant-based polymers in making products, such as coated fabrics and cell-phone cases.

Subverter superworms

Another new, creative technology to deal with the plastics problem involves worms. A team of scientists from Singapore’s Nanyang Technological University (NTU) has developed an artificial “worm gut” to break down plastics, offering another nature-inspired method to tackle the global plastics pollution problem.

Previous studies have shown that Zophobas atratus worms—the larvae of the darkling beetle, commonly sold as pet food and known as “superworms” for their nutritional value—can survive on a diet of plastic because their guts contain bacteria capable of breaking down common types of it. However, their use in plastics processing has been impractical due to the slow rate of feeding and maintenance needed for worm farming.

But publishing their results in the journal Environment International in January 2024, the NTU scientists demonstrated a way to overcome these challenges by isolating the worm’s gut bacteria and using them to do the job without the need for large-scale worm breeding.

To develop their method, the NTU scientists fed three groups of superworms different plastic diets: high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS)—over 30 days. The control group was fed a diet of oatmeal. After feeding the worms plastic, scientists extracted the microbiomes from their guts and incubated them in flasks containing synthetic nutrients and different types of plastics, forming artificial “worm guts.” Over six weeks, the microbiomes were left to grow in the flasks at room temperature.

The scientists found that compared to the control group, the flasks which contained the gut microbiomes from the plastic-fed worms showed a significant increase in plastic-degrading bacteria. Furthermore, the microbial communities colonizing the plastics in the flasks were simpler and more tailored to the specific type of plastic than the microbes found on plastics that had been fed directly to the worms. When the microbial communities are simpler and targeted to a specific type of plastic, this translates to potential for more efficient plastic degradation when used in real-life applications.

The researchers say their proof-of-concept lays the foundation for developing biotechnological approaches that use worms’ gut microbiomes to process plastic waste that will be stable and replicable at scale.

Banishing bubbles

One low-tech way to screen out plastics from your drinking water, specifically, might be as simple as brewing a cup of coffee or tea.

A report published in the journal Environmental Science and Technology Letters in February 2024 showed that boiling and filtering calcium-containing tap water could help remove nearly 90% of the nano- and microplastics (NMPs) present. The authors of the report collected samples of hard tap water from Guangzhou, China, and spiked them with different amounts of NMPs. Samples were boiled for five minutes and allowed to cool. Then, they measured the free-floating plastic content.

Boiling hard water, which is rich in minerals, will naturally form a chalky substance known as limescale, or calcium carbonate (CaCO3). Results from these experiments indicated that as the water temperature increased, CaCO3 formed incrustants, or crystalline structures, which encapsulated the plastic particles. Over time, these incrustants build up like typical limescale, at which point they can be scrubbed away to remove the NMPs. Any remaining incrustants floating in the water can be removed by pouring the liquid through a simple filter, such as a coffee filter.

In the tests, the encapsulation effect was more pronounced in harder water; in a sample containing 300 milligrams of CaCO3 per liter of water, up to 90% of free-floating MNPs were removed after boiling. However, even in soft-water samples (less than 60 milligrams CaCO3 per liter), boiling still removed around 25% of NMPs. The researchers say that this work could provide a simple, yet effective, method to reduce NMP consumption.

Memorable measurements

The first time I heard about a popular, cultural “environmental equation” was back in 2014 when I read about renowned evolutionary biologist and author E. O. Wilson’s Half Earth theory. It postulates that the only way we can avoid an extinction event as devastating as the one that killed the dinosaurs 65 million years ago is to set aside half of the planet in permanently protected areas for the 10 million other species with whom we share the world; half for them and half for us.

Since 50/50, two more calculations have joined the lexicon: 30 x 30 and 60 x 40. These memorable measurements represent not only mathematical models but formulas for a favorable future.

On Monday, April 22, I hope you have a happy Earth Day 2024.

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

Candy