Question

"Biodegradable Plastic Bags, Not So Biodegradable"
by Vicky Stein

The average person uses a typical plastic bag for as short a time as 12 minutes before throwing it away, never thinking of where it may end up.

Yet once consigned to a landfill, that standard grocery store tote takes hundreds or thousands of years to break down — much more than a human lifetime. Bags make up an alarming amount of the plastic found in whale stomachs or bird nests, and it’s no wonder — globally, we use between 1 and 5 trillion plastic bags each year.

Biodegradable plastic bags are marketed as more eco-friendly solutions, able to break down into harmless material more quickly than traditional plastics. One company claims their shopping bag “will degrade and biodegrade in a continuous, irreversible and unstoppable process” if it ends up as litter in the environment.

In a study published this week in Environmental Science and Technology, researchers put supposedly eco-friendly bags made from various organic and plastic materials and sourced from U.K. stores to the test. After three years buried in garden soil, submerged in ocean water, exposed to open light and air or stashed in a laboratory, none of the bags broke down completely in all the environments.

In fact, the biodegradable bags that had been left underwater in a marina could still hold a full load of groceries.

“What is the role of some of these really innovative and novel polymers?” asked Richard Thompson, a marine biologist from the University of Plymouth and the study’s senior author. A polymer is a repeating chain of chemicals that makes up a plastic’s structure, whether biodegradable or synthetic.

Use the article to answer the question.

In 3–5 sentences, explain one example of valid reasoning and explain how that example strengthens the overall argument.

(4 points)
6 grader

Answer 1

One example of valid reasoning is the study where researchers put different “biodegradable” bags in several real environments (garden soil, ocean water, open air, and a lab) and then checked whether they broke down. Because the bags did not completely decompose in any of those places — and some underwater bags could still carry groceries — the study shows the claim that these bags quickly biodegrade is not true in real-world conditions. This strengthens the article’s argument by giving real evidence that the marketing claims are misleading, so readers have a good reason to doubt that these bags solve the plastic pollution problem.