“It’s almost the Wild West when it comes to marketing phrases that consumers are exposed to,” said Judith Enck, who served as a senior Environmental Protection Agency official under President Barack Obama and now heads the Beyond Plastics advocacy organization. “There’s real confusion over what is really biodegradable, what is really compostable, what is Earth-friendly.”

Just trying to define bioplastics might make your head start to spin.

Generally, materials are called bioplastics if they are partly or entirely made from plants. Some of these plastics can be broken down through composting or natural processes such as biodegradation, according to a recent report on compostable plastics from Beyond Plastics.

But bioplastics don’t always break down in the environment or compost, said Kat Knauer, a polymer scientist and senior researcher at the National Renewable Energy Laboratory. Compostable plastics are also not all plant-based, she said. They can be made from fossil fuels, but are engineered to eventually break down.

“Bioplastics are pretty diverse,” Knauer said. “They’re starting to be more than just the green compostable bag that I think we conventionally used to see.”

Here are some common types you might come across:

• Biobased plastics are made partly or fully from plant materials, such as sugar cane, sugar beets, molasses, corn and vegetable oils. They are not all compostable. Some examples include bio-polyethylene or bio-polypropylene, which are often used for food packaging and consumer goods.
• Biobased, compostable bioplastics are similarly made from plants or other natural materials, such as fungi. Most can break apart in industrial composting systems. The most common type is polylactic acid, or PLA, which is made from starches such as corn, cassava, beets and sugar cane. PLA is often used in compostable foodware, cutlery and bags.
• Compostable plastics made from fossil fuels are made from petroleum products, but have been engineered to be able to break down. PBAT is one example you might come across in the form of compostable trash bags.

With so many different types of bioplastics, it’s often difficult to parse labels and figure out whether the product you’re buying can fully and safely break down when composted.

Knauer recommends looking for items that have been certified as compostable either by the Biodegradable Products Institute, or BPI, or TÜV Austria. BPI is the lead certifier of compostable packaging in the United States, and TÜV Austria runs a certification program owned by the European Bioplastics Association. Some products sold in the United States have TÜV Austria labels that say “OK Compost Industrial” or “OK Compost Home.”

But the recent report from Beyond Plastics raised concerns about the regulations and certifications for bioplastics. The report, in part, highlighted worries that BPI-certified compostable products could retain some toxicity and noted that the certifying organization’s board of directors includes executives from U.S. petrochemical companies.

Beyond Plastics is urging the EPA to research bioplastics and is calling on the Federal Trade Commission to update and expand its guidance on environmental marketing claims involving these types of plastics. In the meantime, Enck suggested people look for products with other verified independent eco-labels, such as GreenScreen Certified or Cradle to Cradle Certified.

BPI pushed back against the report. In a statement, the institute said that its certified products must meet baseline requirements, and that the group “requires compostability tests including strict heavy metals limits, plant toxicity, and biodegradation in compost.”

“Claims that BPI’s certification has a conflict of interest due to its Board’s configuration are unfounded,” the institute said, adding that its certification decisions are made entirely by DIN CERTCO, an independent group based in Germany.

Be wary if a product is labeled compostable but lacks certifications, Knauer said. You should also avoid putting any of these plastics in your backyard compost unless the label specifies that it can be broken down in home composting setups.

Most compostable plastic can typically break down only in industrial systems that maintain high temperatures for extended periods of time, said Muhammad Rabnawaz, an associate professor at Michigan State University’s School of Packaging who researches sustainable materials.

But not all commercial composters will accept these products. In Oregon, for example, local composters say they generally do not want compostable packaging or serviceware items because the “materials compromise our composting programs and limit many of the environmental benefits of successful composting.” Among the reasons, they noted that not all certified compostable items “will actually compost (break down) as fully or quickly as we need them to.”

“The result is a finished compost that is contaminated with bits of partially degraded ‘compostable’ material,” they wrote in a public message. They also raised concerns that some packaging could contain chemicals that transfer into finished compost.

The city of Berkeley, Calif., however, does accept compostable products including bags, utensils, cups and containers, as long as they are clearly labeled “compostable” and “BPI-Certified.”

“It is incredibly difficult to be an ‘ethical’ consumer and make the most sustainable choices,” Knauer said. “It is so challenging, and especially in the plastic space where things are very confusing in terms of labeling.”

It’s critical to learn about your local community’s waste collection system, Knauer said. What is and isn’t recyclable or compostable will vary based on where you are.

“Once you have that foundation, then you can start making really educated decisions on what will be the most effective, sustainable packaging for you and your family to use,” she said.

Just because a product is compostable or designed to break down naturally doesn’t necessarily mean it’s the most planet-friendly option. Research hasn’t provided conclusive answers, and questions still remain on long-term sustainability, experts said.

“There may be innovation in the future, but I would say the jury is still out,” Enck said.

Compostable items are also often more expensive, Enck added. Sometimes they can cost up to five times as much as non-compostable alternatives.

If you need to buy single-use products such as disposable plates or cups, she suggested considering nonplastic materials, such as paper.

It’s also important to prioritize reducing and reusing rather than fixating on the details of what type of material might be better for the planet, Knauer said.

Consumers have become dependent on plastics because of their convenience and cheap cost, which does not factor in their environmental impact, Knauer said. Hopefully, she added, we can “move more toward a conscientious world where we are trying to reduce and reuse as much as possible.”