By Carol P. Chamberland, Central New Mexico Zero Waste
Recently a friend sent me a disturbing chart on the decomposition rates of various types of garbage. I looked further into the matter and found it’s worse than I thought. Way worse.
America is a wasteful country. Daily, we generate four pounds of waste per person. Annually, that’s more than 220 million tons of trash, three times the global average.
We use 1.6 million barrels of oil per year just to produce plastic water bottles that can take up to 1,000 years to decompose. Plastic bags can take up to 500 years.
But how do we know how long it takes to decompose? Plastic hasn’t been around that long, so there’s no firsthand evidence of its decomposition rate. To make long-term estimates, scientists place a solid waste sample — like a newspaper, banana peel, or plastic bag — into a vessel containing microbe-rich compost, then aerate the mixture. Over the course of several days, microorganisms assimilate the sample bit by bit and produce carbon dioxide; the resultant CO2 level serves as an indicator of degradation.
These tests work perfectly for newspapers and banana peels. But when scientists test generic plastic bags, they find no decomposition; microorganisms don’t recognize polyethylene as food any more than we do.
Although plastic doesn’t biodegrade, it does photodegrade when exposed to ultraviolet radiation from sunlight. This suggests that plastic will eventually fragment into microscopic granules. But scientists still aren’t sure how many centuries it will take for the sun to work its magic. That’s why some news sources cite a 500-year estimate for plastic bags, while others prefer a more conservative 1,000-year lifespan. They all agree it’s a really, really long time.
I looked into some other common trash materials.
- Aluminum can be recycled over and over again. It is considered the most sustainable beverage container. The average aluminum can is made from 70% recycled metal. Nevertheless, many aluminum cans make it into landfills where they take 80 to 200 years to completely decompose.
- Cigarette butts are the most littered item worldwide. In America, 176 million pounds of cigarette butts are discarded annually.
- Disposable diapers: An estimated 90-95% of American babies use disposable diapers, creating 7.6 billion pounds of nonbiodegradable garbage each year. This is enough diapers to stretch to the moon and back nine times — every year.
- Food waste: an estimated one third of the world’s food produced for human consumption gets lost or wasted annually. Over 97% of food waste ends up in a landfill, producing methane, a greenhouse gas 21 times more potent than CO2. Landfills account for over 34% of all the methane released into the environment, making them the largest source of methane. Composting would alleviate much of this methane production.
- Glass is 100% recyclable and can be recycled over and over again without loss of quality. Despite this, glass still makes its way into landfills. The most shocking aspect of this is that glass takes a MILLION years to decompose. Some sources say it may never break down at all.
- Paper is by volume the largest element of American landfills. On average, paper products take two to six weeks to fully decompose. If we recycle paper, we save room in landfills and use far less water and energy. Like food waste, decomposing paper creates methane.