THE PROBLEM WITH PLASTICS is that they take a long time to decay. These materials do decay when microbes feed on them, breaking big molecules into smaller, simpler ones (such as carbon dioxide and water). Other living things can then feed on these breakdown products to grow.

But traditional plastic hardly decays. That’s because it’s made from petroleum, and few microbes eat them. Biodegradable plastic, in contrast, is made from biological materials, which many microbes prefer. These range from trees, sugarcane and corn stalks to shrimp shells.

There is a problem, however, with such materials. They decay only at very high temperatures — typically 50º Celsius (122º Fahrenheit). Plus, those high temperatures must be maintained for several weeks for microbes to be effective.

Some cities have industrial compost systems that meet those conditions. Many others do not. Instead, biodegradable plastic items can end up in a cold ocean or lake where they can take decades or even centuries to break down, depending on the type of plastic.

Sunlight can speed the breakdown of plastic. But scientists recently showed some biodegradable plastic bags were still strong and intact after three years outdoors. In that regard, they were not much better than regular plastic.

Cleaning (clothes) has become a big source of waterborne plastic. Washing machines tumble and wear down fabrics. This releases lots of little pieces of lint. If the fabric was made from nylon, polyester, polyethylene or polyamide, for instance, those lint particles will be plastic.

One study showed that washing a single 6-kilogram (13-pound) load of clothes made from synthetic fabrics could release some 700,000 plastic lint fibers into the wash water. That explains why some researchers are looking for ways to keep that lint from going down the drain.

The ideal solution would be to not manufacture plastic-based clothing in the first place. Filtering lint out of wash water and then burying it in a landfill would at least keep the pollution out of our waters.

What about the microplastic pollution already polluting rivers, lakes and the ocean?  Researchers reported a potential solution for breaking microplastics into smaller, harmless molecules. They created nanometer-scale coil-shaped tubes. Made from carbon, these tubes are too small to see (even with a compound microscope). But they may produce a very visible change in water pollution by breaking down microplastics. The treatment reduced the amount of microplastics in the water by about a third to one-half.

It’s great to have this option as a tool  to curb microplastic pollution. But researchers caution there still is a lot of work to do. What’s more, such new programs to clean up plastics should not make us forget about what the real problem is — and that’s the release of plastic into places where it is not wanted, just like a weed. By Manny Palomar, PhD (EV Mail October 14-20, 2024 issue)