They are up to 20% to 100% more expensive than petrochemical plastics, and although they are marketed as more eco-friendly solutions able to break down into harmless material more quickly than traditional plastics, in reality they do not.
In a recent study published 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 being buried for three years 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 environments. In fact, the biodegradable bags that had been left underwater in a marina could still hold a full load of groceries. Read more here.