Port Blair, Sept. 13: Internationally renowned Padma Shri awardee scientist Dr Ajai Kumar Sonkar said that the production and consumption of plastic products and the amount of plastic debris are constantly increasing. He informed that Plastic fragments smaller than 5 mm are being found in all environments, and their detectable amount is 690,000 particles/kg and 155,000 particles/ liter in soil and freshwater environments, respectively. Common sources of microplastics in soil include plastic waste, polyethylene-based mulching vinyl used in agriculture, and friction of tire tread and shoe soles. This daily friction is generating a considerable amount of plastic particles, which cannot be ignored. Assuming that every person uses one shoe sole within two years, 2 grams of shoe sole fragments are entering the soil ecosystem annually.
Several studies have evaluated the toxicity of tire particles. Research has shown that debris from tires increases human lung cell mortality and damages DNA. Studies have shown that toxicity is caused by zinc and lipophilic organic compounds in the leakage from tire material. It was found that worn tire particles reduce the growth and survival of bloodworms and amphipods. Additionally, tire particles affect soil organisms and their microbiota. Studies have also looked at the toxicity of shoe sole fragments that contain synthetic rubber.
Shoe sole microparticles are generated from the abrasion of soles, which is inevitable. These fragments enter the soil ecosystem. Studies have evaluated their effects on soil and plants. The toxicity of shoe sole fragments on a crop plant, Vigna radiata (mung bean). Shoe sole particles ranging from 57 to 229 micrometers were obtained from four types of shoes (trekking shoes, slippers, sneakers and running shoes) and the toxicity to plants was assessed. Additionally, the fragments were leached for 30 days and potentially toxic leachates were identified. Shoe sole fragments displayed adverse effects depending on the type of shoe. The sneaker sole fragments increased the bulk density of the soil and reduced its water holding capacity.
In addition, microplastic fragments and leachates directly affected plant growth and photosynthetic activities. Slipper and running shoe fragments promoted plant growth but altered flavonoid content and photosynthetic factors. Trekking shoe sole fragments did not exhibit photo inhibition of plants; however, their leachate inhibited photosynthesis. Overall, it was concluded that shoe sole particles are adversely affecting plants and Tires and shoe sole wear have become a major source of unintentional emissions of primary microplastics into the environment.
Tire particles and tire leachate are causing various biological reactions in aquatic and terrestrial organisms. damaging the soil environment. The study findings suggest a need to develop tyre and shoe soles that are not made of petroleum-based plastics that do not have a harmful effect on the environment.
Dr Ajai told that people are not aware of the horrors of microplastics not only in India but also in many developed countries. Just 2 days ago, it was published in a leading newspaper of Singapore that the plastics which cannot be recycled will be used in making roads, which they have named as Greener Road. This is a matter of great concern. This shows that people related to system management across the world are not aware of the results of scientific researches and studies. Its dissemination is very necessary. Dr Ajai told that he has written a letter to the Environment and Foreign Ministry of Singapore, making them aware of the danger of roads made using plastics.
When the friction of vehicle tyres and shoe soles on the road is having such a fatal effect on humans and plants, one can imagine the situation when plastic is used in the construction of roads. The friction of vehicles on the road will increase the production of microplastics in the environment in abundance, and the speed of this process will be many times faster due to the exposure of the road to sunlight.