Bioplastics are being heralded as a panacea to the plastics problem. What are bioplastics, and are they safer alternatives to plastics? India according to a report in the journal Nature is the largest polluter of plastic waste. Will bioplastics solve our problem with plastics?

The term “bioplastics” is often used to describe very different materials, and the terms “biobased”, “biodegradable” and “compostable” may be misleading. Bioplastics are polymers that are either sourced from biobased resources or if they are derived from fossil fuels but are biodegradable. Bioplastics have been in existence for a long time. Producing plastic from fossil fuels remains cheaper than producing bioplastics.

Several products are classified as bioplastics. The term "biobased" refers to materials partially or fully sourced from biomass, including polylactic acid (PLA), polybutylene succinate (PBS), thermoplastic starches (TPS), and polybutylene adipate terephthalate (PBAT). Drop-in plastics, such as Bio-PET from ethanol, which have a similar chemical structure to traditional plastics, are also considered bioplastics. Another category includes oxo-biodegradable plastics, which are conventional plastics with additives that promote biodegradability. This article focuses on biobased plastics marketed as biodegradable and/or compostable. It is important to note that not all biobased plastics are biodegradable, and even fewer are compostable.

Biodegradability refers to the physical or chemical breakdown of a material by biological activity, where microorganisms convert the polymer into carbon dioxide, water, methane, biomass, and residue. This degradation depends on whether the process is aerobic or anaerobic, as well as on the material’s molecular structure and environmental conditions. It is not dependent on whether the plastic is biobased or fossil-fuel-based.

There is a lot of confusion regarding the end of life of these bioplastics. Bioplastics companies claim that their products are easily biodegradable, and/or compostable. The distinction should be made between biodegradable and compostable. Bioplastics are compostable under certain conditions but not biodegradable in nature. Biodegradation is a process that occurs without human intervention, while composting is with human intervention. Composting is a controlled aerobic decomposition of organic waste to release CO2, water and biomass in the presence of microorganisms. The composting is being used for food remains, agriculture waste, wood and grass from home yards. The compost is then used for agricultural uses especially in organic farms.

Bioplastics cannot be composted in the home yard or municipal composting; they need industrial composting. The composting in industrial units can happen from 60 to 120 days under stipulated pressure and temperature criteria. Industrial composting units are not available widely in India. Even in the US there are only a few composting units that accept compostable bioplastics. With the heightened awareness of plastic pollution, consumer and business attitudes are shifting towards using these bioplastics even if they are at a higher cost. The average consumer does not understand the intricacies involved with biodegradability and compostability. The consumers are being greenwashed in believing bioplastics are the solution to plastic problems.

There is no central authority to regulate bioplastics production or its end of life. However, there is an effort to push bioplastics to be an alternative to plastics making them look identical and for the same functions.

The bioplastics that are not accepted in the compostable units end up in our landfills. Under the anaerobic conditions in landfills, they emit methane which is 30% more potent as a greenhouse gas than CO2. Also, there is a cross-contamination risk to the recyclable conventional plastics if they end up in recycling channels and could damage the equipment.

Bioplastics can clog our waterways and can cause damage to our oceans if they are littered assuming they are eco-friendly. They do not degrade on their own. The marine environment presents a unique challenge for biodegradability because of the cold temperature and different microorganism profile. Bioplastics would not biodegrade in oceans left to the elements.

Bioplastics such as PLA, PBS, TPS, PBAT are produced from feedstocks such as cornstarch, potato starch etc. These feedstocks are first generation. The technology for bio-based plastics production from second generation feedstock such agro waste, algae is still evolving. There is an ethical question of using food crops diverting the land, resources to the production of bioplastics that is mostly for packaging and single use when global food insecurity is a problem. Further growing these crops for bio-based plastics may lead to using more GMOs, pesticides, fertilizers indiscriminately leading to biodiversity loss, genetic pollution, erosion, nutrient loss and pesticide resistance that may affect agriculture landscape. These practices can introduce pesticide residues and heavy metals into bioplastic products and compost, which can harm both the environment and human health, and in organic farming settings. The fertilizers in the runoff may cause algal bloom in aquatic environments causing harm to agriculture.

Plastics, both conventional and biobased, use similar additives that include stabilizers, plasticizers, flame retardants, antioxidants. A typical plastic product can contain over 20 additives as per a study, overall, there are about 4,000 additives used. Many are known to be toxic. Information on additives is rarely disclosed. The manufacturers use the existing machinery to make the end products using the same additives as conventional plastics. There could be differences in additives from product to product and from one manufacturer to another, creating further confusion.

Most additives do not chemically bind to the polymers and can leach out. Also, they undergo bioaccumulation and biomagnification and climb up the food chain. Several additives include PFAS (per- and polyfluoroalkyl substances) and BPA (Bisphenol- A) are known toxins causing a risk to humans and marine organisms even at a low concentration. PFAS are ‘forever’ chemicals that remain in the environment without biodegrading. They are used in plastics to repel moisture and water and used in bowls and packing for food. In the US Chipotle and Sweetgreen chains had to phase out compostable bowls since they contained PFAS. PFAS are known carcinogens that are also found in soils, rainwater and in the marine environment. There is a risk of chemicals penetrating through bioplastics via agriculture. BPA is used as a flame retardant and is an endocrine disrupter posing a risk to humans and wildlife.

While bioplastics are often promoted as environmentally friendly, it is essential to consider the full environmental impact, including the carbon footprint of producing feedstocks, the energy required for industrial composting, and the emissions from transportation of produce and fertilizer use.

The recycling of bioplastics remains a challenge, and more research is needed through Life Cycle Assessment to understand the upstream and downstream impacts of bioplastics. A study by the UK's University of Plymouth pointed out that compostable bioplastic bags have remained in the soil even after 27 months with some deterioration. Bioplastics can also produce microplastics with toxins that may accumulate in the soil, impacting the soil health and into livestock and marine organisms.

Consumers need clear, easily understandable information about the use and end-of-life disposal of bioplastics. Biodegradable and compostable bioplastics should be properly labeled in local languages, and governments should regulate them, including additives, including a unique color coding to distinguish them from conventional plastics. Currently several Indian companies import the bioplastic PLA/PBAT pellets and additives to produce the final product. We need to assess the toxicity of these materials. Bioplastics are significantly more expensive than conventional plastics and not safe as they are claimed.

Another risk to the environment that is often overlooked is with the nurdles- tiny plastic resin pellets used as an input in manufacturing the products. They pollute the environment causing immense harm to our lakes, rivers, oceans. Marine organisms, including fish may mistake them for eggs and ingest them leading to harmful consequences. Bioplastic nurdles are also at risk of spilling into the environment during transportation and production compounding the issue.

More research is needed on eco-friendly additives, second-generation feed stocks such as agro waste, industrial composting, microorganisms and enzymes that break down bioplastics. The newly announced BioE3 (Biotechnology for Economy, Environment and Employment) initiative should drive this research.

Ultimately, bioplastics are not necessarily safer than conventional plastics. As consumers we must focus on reducing plastic consumption overall—by recycling, upcycling, and reusing. We need to use plastics sustainably in our retail sector.

We need to find solutions to reduce single use plastics, packaging waste generated by our food delivery and e-commerce sectors, which is rapidly contributing to the plastic problem. Currently, conventional plastic recycling rates are low, at 9%. To address this, we need to advance recycling technologies, raise more awareness and expand recycling infrastructure.

We must be cautious in embracing bioplastics until further research is conducted to avoid creating bigger environmental challenges. Responsible plastic use is essential for protecting our planet’s future.

(Dr. K. Nagaiah is Chief Scientist, CSIR- Indian Institute of Chemical Technology, Hyderabad and Phaniraj G is IT Professional based in Boston, US. Views expressed in the article are personal views of the authors.)