A year or so ago, I decided to start using less plastic. I bought a bottle of water with insulation for my morning coffee, as well as beeswax wrappers to replace the cellophane, and I largely stopped putting my groceries in plastic bags. Instead, I switched to cotton bags.
I felt very good about myself, until I saw a report published earlier this year by the Danish Ministry of Environment and Food which said that plastic bags are better for the environment than organic cotton bags. In fact, of all the shopping bags that the study analyzed – from paper to recycled plastic – the cotton bags were the worst: they need to be reused thousands times to have the same environmental footprint as a lightweight plastic bag, according to the report. A study published in 2011 by the Environment Agency of the United Kingdom reached similar conclusions. So, was it my decision to get rid of environmental plastic bags?
The answer is not so easy. First, these studies, called "life cycle assessments," should be taken with a grain of salt. The research analyzes different types of shopping bags throughout their life cycles: from the extraction of the raw material needed to make the bag to the way it is used and then discarded. Next, determine how "environmentally friendly" each bag is based on several categories of impact, such as climate change, toxicity and water use.
Here's the problem: it's basically impossible for one stock to outperform all other stock markets in each impact category, says David Tyler, a professor in the Department of Chemistry and Biochemistry at the University of Oregon. "So you have to decide, when you talk about the impact on the environment, what environmental impacts are I most interested in mitigating?" Says Tyler.
I decided to leave the plastic bags because I wanted to do something about the scourge of plastic pollution in our oceans. Scientists estimate that around 8 million metric tons of plastic waste enter the oceans every year. That plastic does not degrade and poses a threat to wildlife, including corals. Sea turtles that eat plastic bags thinking they are food can drown. Last month, it was discovered that a dead whale in Spain had more than 60 pounds of plastic debris in its stomach, including bags. Several cities in the USA US, like Austin, Los Angeles and Seattle, banned single-use plastic bags to solve the garbage problem. Last month, the governor of New York, Andrew Cuomo, proposed a bill for nix plastic bags in the state of New York for the same reason.
The Danish study did not include marine litter as an impact factor. (Researchers followed EU guidelines on what categories to include, such as climate change and ozone depletion, says study author Anders Damgaard of the Technical University of Denmark). That's not right or wrong, says Travis Wagner, a professor in the Department of Environmental Sciences. And Politics at the University of Southern Maine. All of these life evaluation studies are done differently and evaluate the stock exchanges that can be found in a specific country, but not in others. The studies also need to make many assumptions about how people use these bags, says Wagner. Do you line up your trash can with a plastic bag? How many items do you place in your handbag in front of a paper bag when you go shopping?
"You must be careful when drawing important conclusions," says Wagner.
Even so, in all these life cycle evaluation studies, plastic bags appear to be "greener" than cotton bags. That's because cotton requires a lot of soil, water and fertilizers to grow; Then, it must be harvested, processed and brought to the market. "Cotton is a very thirsty crop," says Tyler. A study conducted by the Australian government in 2007 found that plastic bags also have a lower carbon footprint than paper bags. Making paper from trees sends a lot of waste to the landfill, says Tyler. In comparison, "oil is generally considered so valuable that there is very little waste," he says. In addition, transporting 1,000 paper bags across the country with a truck consumes much more fuel than transporting 1,000 thin plastic bags, says Wagner. "A lot of carbon production is a function of the weight of the bag," he says. "That's why it's complicated when you start comparing them."
At the end of the day, it's all about what matters most to you. If marine litter is your biggest concern, paper bags are better because paper degrades and does not stick for years. In New York City, the Sanitation Department spends more than $ 12 million a year to dispose of more than 10 billion single-use plastic bags, which is why the city has tried (unsuccessfully) to impose a rate of 5 cents. In Africa, the concern is that discarded plastic bags also accumulate water that can breed mosquitoes that cause disease.
So, what should you do if you want to limit your environmental footprint? Many of the experts I spoke with affirm that using reusable plastic bags, whether recycled plastic, nylon or woven polypropylene, is the best. "You can use them hundreds of times, the ones I'm using show some wear and tear, but I've had them for a couple of years and they're in good shape," says Tyler. "When you can use a bag so many times, you finally reach a point of equilibrium." These bags are durable and can be easily cleaned if, for example, meat juices are spilled.
Whatever supermarket bag you choose, try to reuse it as many times as possible, even if it's a single-use plastic bag . You can line up your trash can with it, use it to take your lunch or take it with you the next time you go shopping. "All these bags pay off if you use them a significant number of times," says Wagner. "That's the goal: how many times can you reuse them?" However, when it comes to mitigating climate change, which grocery bags you use have a relatively small impact, says Jonna Meyhoff Fry, senior life cycle management consultant who led the UK study in 2011. It matters more what You put them inside those bags (do you eat a lot of meat? Do you buy local food?) and how do you get to the supermarket? (Do you drive your car or do you walk?)
As for me, my apartment is flooded with travel bags. I have more than 20 of my favorite bookstores and stores, so it makes sense for me to continue using as much as you do. May l. I will not buy new ones anymore and I will only say that next time they will not offer me one for free.
