pollution affects human health, the environment, and even some of the Earth's systems, such as the climate and, air and water quality.
Human made pollution has been excessively accumulated since the mid 18th century with the beginning of the industrial revolution. Nowadays, governments, NGO’s and enterprises are trying to find solutions to reduce the effects of pollution (such as GHG emissions, water pollution and air quality deterioration).
The most frequent answer you will find is plastic. This material has been a major part of human life since its creation in 1907. The reason for its excessive use is caused by its “miraculous” properties, it is a cheap to produce, durable, lightweight and easily customizable and malleable material.
In 2020, the global demand of plastic was around 295 million metric tons; 90% (270 million tons) of which were used by the packaging (152 million tons), construction (48 million tons), automobile (12 million tons), textile (12 million tons) and consumer product (46 million tons) industries.
The excessive use of plastic has many harmful effects, such as marine pollution (ocean acidification, water poisoning, poisoning of marine life…), roadside littering, release of microplastics, and over usage of fossil fuel stocks due to a lack of proper recycling (around 5% of all plastic is being properly recycled).
If plastic has such a damaging effect on the planet, can we not use other materials that are less harmful as a substitute?
As expressed previously, plastic has many powerful attributes that make it extremely useful in so many scenarios. For example, the fact that plastic is a material with low weight makes it very useful in the automobile, construction industries, and even in the packaging industry to some degree.
Using plastic in the manufacture of vehicles helps reduce the fuel usage of said vehicle. The more a vehicle weighs, the more fuel it will need to get and keep moving. For example, using HDPE (high density polyethylene) has 90% less GHG emissions than Steel (its closest substitute) when it comes to the construction and use of hybrid fuel tanks in the USA.
The same can be said for the construction Industry, since plastic is used as an insulant, less energy is required to control the room temperature. In the US, approximately 80% of GHG emission can be avoided by using polyurethane rather than fiberglass for insulation.
For the packaging industry, if the packages weigh less, it will require less fuel and energy to transport. Its usage in the food packaging industry is also very beneficial, since it lowers food spoilage rates, therefore it decreases waste.
Since the packaging industry is the biggest purchaser of plastic (with almost 52% of the global plastic demand), it is interesting to study some cases to better understand why it is so predominantly used and why it is hard to find a better substitute to it.
First, let's look at grocery bags. During the early 2010s, the trend of the grocery bag market has switched from mostly plastic to paper and other more “ecological” alternatives. Although most people always point out the fact that paper bags have less GHG emission during manufacture and are able to biodegrade in landfills, it is also important to point out its shortcomings. The first thing to note is a point often overlooked by the consumers is that plastic bags made from HDPE (high density polyethylene) are 6 times lighter than bags made from kraft paper, that sends us back to our previous point that heavier goods require more energy to handle and therefore produce more GHG during transportation. Secondly, the fact that paper bags biodegrade in an anaerobic environment make paper bags release more GHG (such as methane) during their end life cycle than plastic bags. But if not recycled, plastic bags are indeed more nefarious for the environment due to all the effects stated in the first paragraph (roadside littering, marine pollution and creation of microplastics). The third shortcoming of paper bags is its reusability. Paper bags are fragile, tearable, weak to water and humidity. Due to those weaknesses, paper bags are in average reusable 3 times before having to buy a new one, which is 5 time lower than HDPE bags that can be used on average 15 times before needing replacement.
Another case to study is that of airtight liquid/viscous foods, such as pet food and soup, where the two big rivals are plastic pouches and aluminium cans. Both have their advantages and disadvantages in different aspects. For example, aluminium cans are better at preserving said foods on the long term and are more often recycled than pouches, but plastic pouches are cheaper to make, lighter and have less GHG emissions during production. Therefore, the total GHG emission for the life cycle of these products depends on their recycling rates, which are around 50% for aluminium cans and much less for plastic pouches since not all of them are made of Mono materials (using only one type of plastic and not a mix of different plastics which is necessary to be recycled).
There are also several studies on soft drink containers, and they all agree that plastic containers made from HDPE or PET are the most sustainable options regarding their recyclability. Steel, aluminium and glass are all far worse for the environment as they take far more energy, generate far more O2 and also far more waste. Again, the greenest choice is to generally avoid soft drinks and bottled water whenever possible.
Now that we have seen some comparisons between plastic and some of its substitutes by focusing on the GHG impact of those materials. Plastic is a very useful and advantageous material, which makes it hard to be replaced, the usage of plastic in itself isn’t the real problem nor the real cause of the ecological problems that we are facing; but it is the lack of proper recycling and handling of said plastic at the end of its life cycle. All the negative effects that plastic has on the planet and its ecosystems are due to poor diligence and consistency in the recycling methods. From there, it is necessary to work on the infrastructure of recycling methods to advance the circular economy and thus achieve the extension of the product life cycle. Within a circular economy, once a product reaches its useful life, its resources and materials are kept in the economy as much as possible. As such, they are effectively used again and again to continue to generate benefits. The extraction and use of raw materials has a significant impact on the climate and environment. Therefore, reuse and refurbishment of existing products is paramount to create circularity.