Scientists may have found the answer to manufacturing plastics products that actually break down without forming into microplastics, or tiny pieces of plastics that could linger for thousands of years.

Researchers at the University of California, San Diego, and materials company Algenesis said they found a way to construct plastic with polyurethane, a “bio-based” polyurethane polymer that could compost and break down in the natural environment, compared to typical petroleum-based plastic polymers, which typically are inaccessible to biological processing, according to a study published in Scientific Reports earlier this year.

But the big question is whether the algae-based material would break down into microplastics -- microscopic pieces of plastic smaller than one micrometer in size, or less than one-seventieth the width of a human hair.

"The argument then was always put back to us, 'How do you know they're just not making microplastics?'" Skip Pomeroy, a professor in the Department of Chemistry and Biochemistry at U.C. San Diego and one of the authors of the study, told ABC News.

So the researchers set a goal to prove their substances don't make microplastics over time because they're really being broken down by the microbes in the environment, Pomeroy said.

They found a strain of bacteria in compost that could live completely off of the polyurethane-made plastics, Michael Burkart, another U.C. San Diego chemistry researcher and co-author of the paper, told ABC News.

"In the past, we thought that maybe we needed multiple different microbes working together to biodegrade these materials," Burkart said. "But no, we found a single bacterial strain that could live off these things, and so that that really means that these materials that we're making are truly, completely biodegradable."

The organisms that break down the bio-based plastic think the material is similar to leaves or wood that they would find in a normal compost, Burkart said. And the process -- from manufacturing with algae-based materials to break-down -- is 100% renewable, according to the research.

The study shows that their plant-based polymers can biodegrade past the microplastic level in under seven months. Examination of samples after 90 days of aerobic composting showed a 68% decrease in the number of particles. After 200 days, a 97% overall reduction from the starting count was observed, according to the paper.

Burkart said part of the reason why adoption of plastic made of a bio-based polymer is because people were skeptical that it could work.

"Some people didn't believe us," Burkart said. "They didn't think that what we were doing -- that we were actually making truly biodegradable materials or that or that it was even possible at all."

Accumulation of microplastics in the natural environment is ultimately due to the chemical nature of widely used petroleum-based plastic polymer, the researchers said. Microplastics can take hundreds or thousands of years to break down completely.

"We do not need to be using these materials that are going to live forever," Burkart said. "We really can now start replacing all of these materials we have around us into things that are a lot more sustainable."

However, cost is currently a prohibitive issue to widespread use, the researchers said. While petroleum is readily available to siphon from the ground, widespread infrastructure for algae farming will be needed for plastics made of the bio-based polymer to become used en masse, Burkart said.

However, the process the researchers devised can also be applied to other plant-based material, Burkart said.

The researchers hope their new process can eventually be implemented widely for food packaging, Pomeroy said.

"But if you're going to ask me, 'Could we do this with anything?' I'm pretty sure we could do this with most anything," he said.

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