These bags presumably break down in the environment or in landfills, but many of the tests on them have been done in labs rather than the real world, which isn’t necessarily a good indicator of what could happen. Moreover, there’s a lack of standards when it comes to what can be considered a biodegradable bag; must it degrade in a matter of weeks, months or years to qualify? After all, almost everything is technically biodegradable if you give it enough time. In the meantime, of course, it’s having the same impact on the environment that traditional plastic bags do, breaking down into microplastics that marine life can ingest.
Writing in the Royal Society Open Science journal, the University of Edinburgh‘s Jesse Harrison says that we simply don’t know enough about these bags to assume they are better for the environment.
He wrote: "Current standards and test methods are insufficient in their ability to realistically predict the biodegradability of filmic carrier bags in these environments, due to several shortcomings in experimental procedures and a paucity of information in the scientific literature."
Another serious problem is that there aren’t any standards related to the chemicals that are left behind when the bag does degrade; testing was generally focused solely on whether or not the bag actually broke down in the first place. What kind of damage could these toxins that come from plastic breakdown cause over time?
The study’s authors reached their conclusions after studying available papers that examine the manufacture and life cycle of plastic bags that claim to be biodegradable.
More testing needed
The researchers would like to see a lot more testing carried out on these bags, and they emphasize that it needs to be done under real-world conditions. In addition, standards need to be put in place governing the definition of the term “biodegradable” and the potential of the broken-down chemicals to cause environmental damage.
Another issue is that many of these biodegradable plastic bags end up in landfills, where they won’t biodegrade. If they do manage to break down, it will be an extremely slow process that releases methane gas into the atmosphere. Landfills block out moisture, air and sunlight, and these bags are designed to break down in the presence of sunlight and oxygen. Moreover, they can’t be recycled with other types of plastic.
Even if they’re left out in the open air, the speed at which biodegradable plastic bags break down will depend largely on the local conditions; cold weather and high humidity can slow the process down significantly, if not stop it altogether.
Right now, a trillion plastic bags are produced annually around the world, and they are considered a top contributor to the growing problem of marine plastic pollution. There are currently an estimated five trillion pieces of plastic in the ocean that tip the scale at 250,000 tons collectively.
Making an effort not to harm the environment is always commendable, but you can’t truly make a difference unless you ensure that your choices are truly as “green” as they appear to be. When it comes to plastic bags, it’s best to avoid all types and stick to reusable options like those made of organic cotton or canvas.
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