Once upon a time, plastic was announced as a miracle material. Cheap, lightweight, infinitely customizable yet virtually indestructible, plastic has quickly replaced natural materials in a myriad of products, especially bags. Today, plastic bags are ubiquitous for shopping and groceries, and even inside other types of packaging. Plastic bags are found on roadsides, in waterways and at the bottom of the oceanwhere they break down into microplastics that end up in our food.
Biodegradable is better
We need to move towards a post-plastic world. Unlike other non-biodegradable materials like metals, plastic is not infinitely recyclable. In fact, it is often not recyclable at all. What we need is a biodegradable alternative. But creating a bio-based material that functions like plastic is a technological challenge; creating a workable production model for bioplastics is another challenge. Switching to biodegradable products can also be as complicated for consumers as making bioplastics is for manufacturers.
Plastic as we know it is made from natural gas and represents between 4% and 8% of world oil consumption. But functionally similar materials can be made from polylactic acid (PLA), which is usually made from vegetable starch. The other main type of bioplastic is made from polyhydroxyalkanoates (PHA). PHAs are long chain polyesters produced by microorganisms and plants. Both types of materials are called bioplastics. You will also see them referred to as biodegradable plastics and compostable plastics. Despite their name, not all bioplastic products biodegrade naturally or break down in a compost bin. In a studyonly one plant-based plastic bag (out of four bioplastics tested) quickly decomposed in water, and even this type survived more than a year buried in the ground.
Many desirable qualities of plastic – such as toughness and waterproofness – work against biodegradability. Many bioplastics can only decompose in a high temperature commercial composting facility. Those that are readily biodegradable are not strong enough for most products. Easily compostable bags are available, but they should be stored with care. They may break down in hot or humid environments before use.
Most biodegradable plastic bags still require a commercial composting facility. If your local composting facility accepts biodegradable bags, look for ones with a “BPI Certified Compostable” label. If you don’t have access to a commercial composting facility that specifically accepts bioplastics, landfill is usually the best option for disposal.
Bioplastics cannot be placed with recycling, even if your community recycles other plastics. Products like compostable plastic bags are a contaminant in recycling because they are chemically different from petroleum-based plastics. There have been some attempts to develop consistent labels that will inform consumers on how best to dispose of bioplastic products.
Bioplastics have mainly been used as an alternative to PET, especially in food packaging like beverage bottles and compostable cutlery. Durable goods might be a better option for these products. One product category where biodegradability makes the most sense is plastic bags. Even when made of a recyclable polymer, plastic bags cannot go through regular recycling in most communities. A few curbside recycling programs accept bagged plastic bags, but most often they must be delivered in special collection bins – which are not available everywhere.
Unfortunately, biodegradable bags are not necessarily more ecological. As a replacement for shopping bags, biodegradable bags might not eliminate the waste problem, as many of them don’t break down in the environment. They are also not a very good substitute for garbage bags; they do not break down in landfills. But they could break before they reach the landfill, creating waste. Biodegradable collection bags for pet waste are only better for the environment if your municipal composting facility specifically states that it accepts pet waste.
The best use of biodegradable bags is to contain food waste in communities that have a three-bin recycling program that accepts both food and yard waste for industrial-scale composting. Even then, you should confirm that your local composting facility accepts biodegradable plastics before disposing of them in the trash.
BioBag is BPI certified and even OK Compost Home for home composters. EcoSafe the bags are also BPI certified. Besides food waste bags, they also make compostable grocery bags and a compostable alternative to latex gloves for food prep. Good Housekeeping reviewed BPI and OK Compost Home certified bags from BIOOK as the best choice for home composters. Full Circle’s biodegradable compost bag can give you with lemon flavor compost collection. They also offer a Kraft paper compost bag with a vegetable-based plastic liner that looks a bit nicer than standard green bioplastic and can hold up better in storage.
This article was originally published on September 6, 2022.