Plastic pollution: A background
- The world has produced over nine billion tons of plastic since the 1950s.
- 165 million tons have reached the oceans, with almost 9 million more tons being added each year.
- According to UN Environmental Programme, UNEP, a staggering 6.5 million tonnes of plastic are being dumped alone in our oceans each year.
- Of all the plastic manufactured in the world, almost 33 % is made for one-time use only.
- According to an estimate only about 9 percent of plastic gets recycled.
- Rest of it pollutes the environment or sits in landfills, where it can take up to 500 years to decompose while leaching toxic chemicals into the ground.
- While traditional plastics are made from petroleum-based raw materials, bioplastics which are made from 20 percent or more of renewable materials.
- Bioplastic is a specific type of plastic derived from renewable biobased resources.
- Bioplastic can be any combination of being non-biobased, partially biobased, fully biobased, non-biodegradable, biodegradable and compostable.
- The global bioplastic market is projected to grow from $17 billion this year to almost $44 billion in 2022.
Types of Bioplastics
There are two main types of bioplastics:
1. PLA (polyactic acid)
- It is typically made from the sugars in corn starch, cassava or sugarcane.
- The starch is comprised of long chains of carbon molecules, similar to the carbon chains in plastic from fossil fuels form a long-chain polymer (a large molecule consisting of repeating smaller units) that is the building block for plastic.
- It is biodegradable, carbon-neutral and edible.
2. PHA (polyhydroxyalkanoate)
- It is made by microorganisms, sometimes genetically engineered, that produce plastic from organic materials.
- The microbes are deprived of nutrients like nitrogen, oxygen and phosphorus, but given high levels of carbon.
- They produce PHA as carbon reserves, which they store in granules until they have more of the other nutrients they need to grow and reproduce. Companies can then harvest the microbe-made PHA, which has a chemical structure similar to that of traditional plastics.
- Because it is biodegradable and will not harm living tissue.
- PHA is often used for medical applications such as sutures, slings, bone plates and skin substitutes; it is also used for single-use food packaging.
Advantages of Bioplastics
- Reduced use of fossil fuel resources.
- Smaller carbon footprint.
- Bioplastics do produce significantly fewer greenhouse gas emissions than traditional plastics over their lifetime.
- Faster decomposition.
- Bioplastic is also less toxic and does not contain bisphenol A (BPA), a hormone disrupter that is often found in traditional plastics.
Potential side effects of Bioplastics
- According to a study done in 2010 University of Pittsburgh bioplastics production resulted in greater amounts of pollutants, due to the fertilizers and pesticides used in growing the crops and the chemical processing needed to turn organic material into plastic.
- The bioplastics also contributed more to ozone depletion than the traditional plastics, and required extensive land use.
- B-PET, the hybrid plastic, was found to have the highest potential for toxic effects on ecosystems and the most carcinogens because it combined the negative impacts of both agriculture and chemical processing.
- Since bioplatics need high temperature industrial composting facilities to break down, lack of infrastructure can lead to bioplastics ending up in landfills.
- In the absence of oxygen in the landfill they may release methane, a greenhouse gas 23 times more potent than carbon dioxide.
- When bioplastics are not discarded properly, they can contaminate batches of recycled plastic and harm recycling infrastructure.
- Separate recycling streams are necessary to be able to properly discard bioplastics.
- Bioplastics are also relatively expensive. PLA can be 20 to 50 percent more costly than comparable materials.