Plastic have been existing for not more than a century, yet in such a span of time has become a global phenomenon and is present all over the world. Plastics came from Greek word ‘plastikos’ which means to form or fit for molding, therefore, it is beneficial for engineering processes. Plastics are kinds of macromolecules derived from monomers, also called polymer where poly means many and mer means designating the nature of the repeat unit. In order for a compound to be a polymer, it should have at least 100 mers (Lokensgard, 2017). Polymers are from synthetic materials which can be modified for the processing procedures and are made from carbon atoms in combination with other elements or it can be formed from petrochemical products which are rich source of ethylene, methane, and aromatics. Plastic have become ubiquitous to the world for it produces diverse products, and is a light, hygienic, functional, and an economical material as it promotes low costs and possibility of total recycling. As cited by Subramanian (2011), as the years passed by, the processing of plastics increased and has reached an annual consumption around 5 million metric tons in 1950s to nearly 10 million metric tons in 2011 with the assumption that the numbers will continue to rise in the succeeding years.
Classifying plastics may vary based on their recyclability namely, thermoplastics and thermosets. Subramanian (2011) stated that both thermoplastics and thermosets can be molded to achieve a finish product. The difference between the two is that thermoset plastics stay in its state due to irreversible chemical bond resulting to non-recyclable products that cannot be either reprocessed or softened. Examples of these are phenol formaldehyde and urea formaldehyde which are used for adhesives and coatings. In contrast to thermoset, thermoplastics have the ability to melt back into a liquid state and are reversible as no chemical bonding takes place. This characteristic of thermoplastics enables them to be reprocessed without affecting the physical properties of the materials negatively. According to Lokensgard (2017), the classification of plastics in the standard resin code are examples of thermoplastics like High and Low-density Polyethylene (HDPE & LDPE), Polypropylene (PP), Polyvinylchloride (PVC), Polyethylene Terephthalate (PET), etc.
In connection to the Resin code stated by Subramanian (2011), Polyethylene is the most used polymer in plastic industry because of its inexpensive nature. Though it has several advantageous characteristics like water, chemical, and electrical resistance, it is subjected to environmental stress cracking leading to brittle failure. Lokensgard (2017) stressed that HDPE, LDPE, PET and PP are the safest plastics for human consumption. HDPE is a stiffer polyethylene than LDPE and is used in the bigger materials like water and juice jugs, and shampoo bottles. On the other hand, LDPE is a soft and flexible material commonly used in dispensing bottles or wash bottles. Furthermore, PP are used in the processing of straws and baby bottle containers while PET plastics are widely used in the creation of glass-reinforced plastics, and soft drinks containers.
Plastic water bottles which are abundantly consumed by the people are also made of PET. Lokensgard (2017) indicated the numbers of consumption of plastic water bottles has become phenomenal with global sales around liters in 2004. In USA, as of 2007, the consumption of bottled water is set to exceed 8.5 billion gallons. Conlan, Demzsky, Hiltner, & Zemplini, (2014) noted that PET bottles take an estimated 700 years for to be completely decomposed. Due to the increasing statistics of plastics and its long-term decomposition characteristic, proper waste management became difficult. Most of the plastics debris had gone to the coastal entangling marine life or is mistaken for food (Attrill, Clark, & Frid, 1997). In United States alone, there are around 50 billion water bottles are used annually contributing to the Global waste and to world’s pollution.
Despite knowing the effects of plastic bottles as an addition to the world’s total waste, people still buy these products for these are known for its safe water quality. Gray (2008) stressed that bottled waters are based on specific and general legislation, and so should be of excellent quality. The production of Bottled water must follow to the drinking water Directive Quality Standards which limit the values for a range of potentially toxic elements. Limits had been set to a range of ions that do not harm public health. The Directive also emphasized that bottled waters or its source must be free from any pathogenic parasites, microorganisms, and bacterial content to prevent the incidence of waterborne diseases. Also, the fear of using the public drinking water facilities pushes them to buy water bottles. Public drinking water facilities are subjected to intensive inspections and must exhibit thorough filtration-distillation processes. Gray (2008) also highlighted that drinking water supply must be palatable, safe, clear, odorless, non-corrosive, and low in organic content to not encourage unwanted biological growth in pipes or storage tanks, which can affect the quality of the water supplied. It was also pointed out that hesitations rose up due to the uncertainty of the source and the water pipes which must not be made from specific elements that are potential diseases carriers. However, everyone must also instill in their minds that not all plastics are recommended for human consumption. Lokensgard (2017) said that although PET which is the foundation of plastic water bottles is considered a safe plastic, it is appropriately made for a single-application only since using this plastic regularly may introduce carcinogenic diseases.