The life story of your plastic bag

April 10, 2021

Photo credit: Emmet

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Picture this: you come home from the grocery store. You put your groceries away. What do you do with your plastic bags? Do you ball them up and shove them under the sink? Maybe you've been inspired by Pinterest to fold, roll, or even iron the bags; maybe they sit disorganized and damp between the dishwasher detergent and water heater. Sure, we could just throw them in the trash, but maybe someday we'll need them.

Does this sound familiar? If so, you aren't alone: in 2018, the U.S. produced about 14.5 million tons of plastic containers and packaging. This includes drink containers, food trays and lids, and -- of course -- the ubiquitous plastic bag. Put another way, that's the weight of about 12,000 Ford F-150s worth of plastic produced every day.

Why do we have so many plastic bags?

How did we get here? In some ways it began in the late 19th century: America's Gilded Age. With it came the meteoritic rise in two pastimes: piano and billiards. Driven by growing wealth and important innovations in piano design, the United States began producing pianos domestically, with Chickering and Steinway pianos earning a new role as "the altar of home."

Billiards Room

Separately, the game of billiards achieved immense success in this period. Led in part by popular figures such as Michael Phelan, as well as the growth of popular annual billiard tournaments, this era ushered in the standardization of rules, improvements in pool table designs, and the invention of a series of new billiard games.

Piano and billiards featured one important commonality: the use of ivory. The white (or 'natural') keys of the piano were historically covered in a thin layer of bleached ivory; similarly, billiard halls were stocked with ivory balls. Ivory production exploded, with entire towns dedicated to the import and processing of ivory products from elephant tusks (propped up by an ugly slave trade in Africa and the decimation of its elephants).

Concerned with the decline in elephant populations, in 1863 the billiard ball manufacturer Phelan and Collender issued a public challenge: it would pay $10,000 (about $136,000 in today's dollars) to anyone who could produce a non-ivory billiard ball. The eventual answer came from inventor John Wesley Hyatt, who developed the first commercially successful plastic (although, despite going on to launch a company producing plastic piano keys and sometimes explosive billiards balls, he never received the prize). The Age of Plastics had dawned.

Plastics have since proliferated across the globe and come to dominate all facets of our lives. We've come a long way from the piano and pool hall: a series of innovations in chemistry and marketing have brought us plastic tapes and cling wrap (1930s), airtight plastic food containers and spray bottles (1940s), garbage bags and zip-seal bags (1950s), bubble wrap (1960s), and microwaveable dinner trays (1980s).

Annual plastic production in million metric tons, 1950-2015

Source: Geyer, Jambeck, and Law. Production, use, and fate of all plastics ever made. Science Advances. 19 Jul 2017: Vol. 3, no. 7, e1700782. Plastics include all polymer resin and fiber production.

What about the plastic bag? Polythene, the polymer used to create plastic bags, was discovered by a team of British chemists in 1933. In 1959, Swedish engineer Sten Gustaf Thulin created the first plastic bag with the intention of reducing the environmental impact of paper bags -- since the bags were reusable and didn't require logging wood. Early plastic bags were initially unpopular in the United States, yet due to an intense lobbying effort by manufacturing companies, supermarket chains Safeway and Kroger adopted plastic bags in 1982, and plastic bags soon exploded across the country.

You've used your bag. What next?

Back to you. You've driven home from the grocery store, plastic bags in hand. Those bags may live a while in your home, get reused a few times, but eventually they will reach the end of their usable life. In general, plastic packaging takes about six months to travel from its initial creation to being discarded to its final resting place.

Where do old bags go? Let's say you're interested in recycling. If you look on the bottom of your plastic bags, you'll usually see a recycling logo, typically a #2 (for high-density polyethylene plastics) or #4 (for low-density polyethylene plastics). Like any other plastic, these plastics can technically be melted down into resins that can be re-used in new products, and manufacturers are keen to promote their plastic products as environmentally friendly. The truth is plastics aren't great candidates for recycling: unlike glass and metal, which can be recycled infinitely, plastics can only be recycled two or three times (usually with virgin plastic mixed in to maintain durability).

But where can you recycle that bag? Legally, a product can be labeled recyclable if 60% of communities have an established recycling program that can collect and reuse the plastic. Some municipal waste programs and many private retailers, like grocery stores, do accept returned bags. Although this means that most Americans can access plastic bag recycling, not all recyclers are the same. Some recycling programs accept plastic bags, but ultimately send them to landfills. Others export plastic waste to other countries. According to a report from Greenpeace, only 2% of Americans have access to a city recycling program that accepts plastic bags and is likely to actually recycle them.

We do have an approximate understanding of where plastics end up. According to a 2017 analysis, a total of 8,300 million metric tons of plastic was produced between 1950 and 2015. Across that entire time period, 600 million tons (or about 7% of all plastics ever produced) have been recycled. Some of those recycled plastics ended up back in use for a time, some were even recycled again, but eventually about two-thirds of recycled plastics ended up being discarded or incinerated. In the end (excluding the plastics that are currently still in use or in the recycling stream), 86% of all plastics have ended their useful lives by being discarded in landfills and 14% have been incinerated.

Fate of all plastics produced, 1950-2015

Source: Geyer, Jambeck, and Law. Production, use, and fate of all plastics ever made. Science Advances. 19 Jul 2017: Vol. 3, no. 7, e1700782. Plastics include all polymer resin and fiber production. Plastics in oceans are estimated from Jambeck et al (2015).

Swimming with the fishes (and the plastic bags)

Unfortunately, not all plastic waste will make it to a recycling center or a landfill. Some of it, either due to littering, illegal dumping, or waste mismanagement, will end up in rivers and eventually will flow out into the ocean. By one 2015 analysis, somewhere between 4.8 and 12.7 million metric tons of plastic enter the oceans every year.

Once in the ocean, plastic particles spread throughout the ocean. Data from the National Oceanic & Atmospheric Administration (NOAA) show how particles released from North America (in this case, buoys with GPS tracking) can travel all the way across the Atlantic and Pacific oceans within a year. Plastics collect into trash vortexes, or garbage patches, as well as sinking into the deep ocean, washing up on beaches, and settling into coral reefs and estuaries.

One-year trajectory of buoys released from coastal areas

Source: The National Oceanic & Atmospheric Administration's Global Drifter Program Global Drifter Program. Only buoys released within 5° latitude and longitude of a coast were included in the visual.

As plastics float through waterways and oceans, they are eaten up by marine animals. Plastic bags may resemble jellyfish to predators like sea turtles (52% of which have eaten plastic waste) and many birds and fish eat plastic since it smells like food. Nearly 700 species have encountered marine debris, primarily plastics, ranging from whales with hundreds of pounds of plastics in their digestive tracts to albatrosses found with dozens of pieces of plastic in a single bird.
Albatross body filled with plastic waste. Source: Forest and Kim Starr

Eventually, plastics degrade and break into smaller pieces until becoming microplastics. Today, about 90% of all ocean plastics are microplastics. These tiny plastics are difficult to filter during wastewater treatment and accumulate in marine organisms; by one estimate, humans eat or drink around 74,000 microplastic particles every year (or five grams per week).

Recycling, after China

Of course, rates of recycling have increased dramatically in the past 70 years: in 1960, less than 10% of all municipal solid waste was recycled; today, that number is over 35%. What about plastic waste? According to the U.S. Environmental Protection Agency, the percent of plastics that are recycled in the United States has grown from less than 1% in 1980 to nearly 9% in 2018. (In the European Union, by contrast, 30% of plastics are recycled.)

However, while plastic recycling has grown steadily in past decades, recent international political changes have thrown a major wrench in plastic recycling. In past decades, many American cities did not actually do their own recycling: China was importing nearly half of the planet's plastic waste. This trade, worth $24 billion per year, was initially beneficial to both American cities (which paid for their recyclable materials) and China (which received raw materials for domestic use).

In 2018, however, China cracked down on imports of recyclable materials, citing growing environmental concerns and a desire to shift toward higher profit industries. Other South-East Asian countries have followed suit, banning and sending back waste from Europe and North America.

These bans have fundamentally changed the recycling trade, with many waste programs having no options but to dump plastics recycling in landfills. Recent reports find that American industries are shifting toward sending plastic waste to Africa instead or ignoring international bans entirely.

Source: Susan White/USFWS

What can you do?

The truth is it's almost impossible to know if your plastic bag will be recycled. You can call up your local municipal waste management and ask them where their plastic ends up, and where they're sending it. Following the plastics to their final destination is tricky, though, and would require some serious investigation to find if the materials end up re-used or in a landfill somewhere across the planet.

There are lots of ways to reduce plastic use. If you're finding more and more of your produce is wrapped in plastic, call up your grocery store (there's a whole movement toward zero waste grocery). Re-use the plastics you already have, and transport your groceries home in something that can be reused many times.

You may also choose to support, or advocate for, local bans or taxes on plastic bags. Since 2007, when San Francisco banned plastic shopping bags, more than one hundred American cities and counties have instituted plastic bag bans. These bans have dramatically reduced plastic bag litter. Charging for bags, rather than outright banning them, can also have important benefits (and may actually be better for the environment).

Want to see for yourself? All our data are on GitHub.

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