With global production of plastics increasing rapidly, numerous plastics are being released in the environment during their life cycle. Introduction of plastics (regardless of sizes, shapes or types) into the environment, is resulting in potential threats to the environment, organisms, or even human health.
When introduced into natural environments, plastics can be transported from land to river, and eventually reach the ocean. During the migration, plastics can lead to detrimental impacts on natural surroundings, wildlife, and even human health. In addition, chemicals, including monomer, oligomer and additives, were observed to be released into the environment from plastics, implying that plastics can also be considered sources of some toxic chemicals.
Types of Plastics
The main types of plastics that are manufactured are resins, i.e. polyethylene, polypropylene, polyvinyl choride, polyethylene terephthalate, polyurethane and polystyrene. Some examples of plastics in common use are give below:
- Polyamides (PA) (including nylon): fibres, bristles for toothbrushes, tubing, fishing line and low-strength components, for example engine parts or gun frames.
- Polycarbonate (PC): compact discs, eyeglasses, riot shields, security windows, traffic lights, ‘plastic’ lenses, smartphone unibody shells.
- Polyester (PES): fibres and textiles.
- Polyethylene (PE): used to make cheap packaging and wrapping materials, along with disposable supermarket shopping bags, and plastic bottles.
- High-density polyethylene (HDPE): detergent bottles, milk jugs and moulded plastic cases, to contain various items.
- Low-density polyethylene (LDPE): garden furniture, floor tiles, shower curtains and clamshell packaging.
- Polyethylene terephthalate (PET): bottles to hold carbonated drinks, food jars, plastic films, and microwavable packaging.
- Polypropylene (PP): bottle caps, drinking straws, yogurt containers, household appliances, tables and chairs, car bumpers (fenders) and pipe systems designed to withstand pressure.
- Polystyrene (PS): loose foam packaging, food containers, plastic tableware, disposable cups, plates and cutlery, boxes for compact discs and cassettes.
- High impact polystyrene (HIPS): refrigerator liners, food packaging and vending cups for drinks.
- Polyurethanes (PU): foams for cushioning, foams to provide thermal insulation, surface coatings, rollers for printing, and is the most common plastic currently used in cars.
- Polyvinyl chloride (PVC): pipes for plumbing and guttering, doors, and frames for doors and windows, flooring material, shower curtains.
- Polyvinylidene chloride (PVDC): food packaging film, such as Saran.
- Polybutadiene: car tyres, to increase the impact resistance (toughness) of plastics such as polystyrene and acrylonitrile butadiene styrene (ABS), and to make golf balls.
- Acrylonitrile butadiene styrene (ABS): computer monitors, printers and keyboards, drainpipes.
- Polycarbonate/acrylonitrile butadiene styrene (PC/ABS) blend: a stronger plastic which is used to make the interior and exterior parts of cars, and the unibody shells of mobile phones.
- Polyethylene/acrylonitrile butadiene styrene (PE/ABS) blend: a low-friction (slippery) material which is used in low-duty, dry bearings.
Types of Plastic Wastes
On the basis of size, plastic pollution can be differentiated as macroplastic, mesoplastic, and microplastic, although the term megaplastic has also been used, and there is speculation as to the likely quantities of nanoplastic that might exist, particularly in marine environments. At present, all plastic items of 5 mm in dimension, or greater, tend to be classed as macro-, and anything smaller than this as micro-. Among the larger-sized (macro) plastic debris are plastic chairs, shoes, parts of vehicles – cars, ships and planes – buoys, footballs, plastic shopping bags, and many other commonly used items.
Threats to Organism and Human Health
Plastic pollution may cause physical damage, chemical harm, and biological threats to organisms. Entanglement and ingestion of plastic debris are two typical ways of physical damage to organisms.
Entanglement could cause lethal damage to mammals by strangulation, sepsis or starvation due to the neck entanglement.
Ingestion of plastic debris can not only cause the death of large animals due to intestinal blockage or gastric impaction but also lead to chronic impacts with the potential accumulation along the food chain.
Recent studies have evaluated tens of thousands of microplastics were consumed by adults each year in America. The primary pathways for plastics to enter humans may be ingestion for daily diets (such as drinking, salts, bivalve, fish etc.), inhalation of plastic-contained air, and the skin (mainly for nanoplastics).
How to deal with the plastic pollution
Since 6% of the current global oil (including natural gas liquids, NGLs) production is used to manufacture plastic commodities – predicted to rise to 20% by 2050 – the current approaches for the manufacture and use of plastics (including their end-use) demand immediate revision. More extensive collection and recycling of plastic items at the end of their life, for re-use in new production, to offset the use of virgin plastic, is a critical aspect both for reducing the amount of plastic waste entering the environment, and in improving the efficiency of fossil resource use.
This is also the central idea underpinning the circular economy, which promotes the redesigning of the manufacturing process to optimize the use of resources in town and city environment, generate less waste and repurpose the waste that is generated.
The food might be produced more on the local than the global scale, with smaller inputs of fuels (including transportation fuels for importing and distributing food), water and fertilizers, and with a marked reduction in the use of plastic packaging. Such an approach, adopted by billions of individuals, could prove of immense significance in ensuring future food security, and in reducing waste and pollution – of all kinds.
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