Image Source: builtconstructions, shabra
Recently, a post in The Logical Indian celebrated the use of waste plastic for road laying as a possible solution to the mounting crisis of plastics contamination.
This is an effort to explain why I think this intervention is not a solution.
First, something about the details of the “success story.” Innovated by Dr. A. Vasudevan, a chemist from Thiagarajar College of Engineering (TCE), Madurai, the plastic-bitumen road-laying technique is a patented idea. Dr. Vasudevan does not intend to profit from it. Rather, he is making it available to municipalities to tackle the mounting waste plastic piles. The intent is good.
The technology is simple and is described in a dedicated TCE website. It involves a) collecting waste plastics, including plastic carry bags, cups, soft and hard foams and laminated plastics; b) cleaning it by washing; c) shredding it to a uniform size; d) melting the waste plastics at 165 degree celsius at temperatures of 166 degree celsius, and blending it with hot aggregates and bitumen and using this mixture to lay the road.
To understand the efficacy of a solution, it is important to understand what is seen as the problem.
According to the Worldwatch Insitute, “From 1950 to 2012, plastics growth averaged 8.7 percent per year, booming from 1.7 million tons to the nearly 300 million tons of today.” [Source: Worldwatch Institute. “Vital Signs, Volume 22: Trends that are shaping our future.” 2015.] The recent rains in Chennai left us with haunting images of plastic trashed beaches.
Every year, about 8 million tonnes of plastic waste is dumped into our oceans. Floating bags of plastic are mistaken for jelly fish and consumed by whales and turtles. Brightly coloured plastic items attract sea birds and mammals that ingest them and die. Midway Atoll is 2000 miles from the nearest human settlement in the Pacific. But its beaches are littered with plastic trash. See this video to understand my cynicism with people who say recycling is the answer to plastic pollution.
Plastics dumped on land too break down into tiny pieces and are washed down water courses into rivers, lakes and seas. These microplastics are hugely problematic. http://www.greenfacts.org/…/marine…/l-2/3-micro-plastics.htm They absorb other pollutants like legacy pesticides and carcinogenic hydrocarbons from the ocean or aquatic environment. These microscopic toxic bombs tend to be mistaken for food and ingested by zooplankton. Planktons are the foundations of any aquatic food chain, and plastics has found a way to contaminate that.
Despite all the talk about “Reduce, Reuse and Recycle” — a mantra that ironically was promoted by the plastics manufacturers themselves – plastics production continues to grow at a steady rate of 9 percent.
Plastics are virtually indestructible, and any attempts to destroy them give rise to new problems and new pollutants.
So what’s my problem with plastic roads? a) End-of-pipe interventions contribute to the perpetuation of the problem – By making it seem as if there is a safe, sustainable and efficient way of disposing plastics, interventions such as this tend to take the focus off the steadily mounting plastics crisis — increasing plastic production, the inherent unsustainability of the industry and the toxic pollution associated with production, use and disposal of plastics. The sooner we admit that we need to phase out plastics, the sooner we will begin the earnest quest for alternatives.
b) Far from being a solution to plastic pollution, plastic road-making itself is a source of pollution. Dr. Vasudevan specifies that only polypropylene (PP), polystyrene (PS) and polyethylene (PE) polymers should be used, and that PVC (polyvinyl chloride or flex) should not be allowed to contaminate the feedstock of waste plastics used in road laying. Thermal degradation of PVC, he says, will result in the emissions of harmful gases like hydrochloride acid. Dr. Vasudevan is right about PVC. But this caveat conveys the wrong impression that heating PP, PS or PE plastics will be safe. These plastics too release toxic gases when heated.
Plastics are not merely molecules of carbon and hydrogen. To convert them into daily-use products, chemical additives are added to give them flexibility (softeners and plasticisers), to delay degradation due to heat or sunlight (stabilisers and anti-oxidants), to give them colour, to make them fire proof (flame retardants), to give them body (fillers). The toxicity of most of these chemicals is not known. But the few chemicals that have been studied – like phthalates – a category of chemicals used as softeners, or brominated flame retardants are highly toxic. They can cause birth defects and cancer, and hormonal problems particularly for women. Because they persist in the environment and can build up in the food chain, even seemingly insignificant amounts in the environment can grow to deadly levels in our bodies or in the food we eat.
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