Do PET Bottles Leach Chemicals?

I. Basic Introduction Of PET Bottles

What is a PET bottle

PET bottles are bottles made of polyethylene terephthalate which is a common plastic bottle named after the transliteration of the English word “PET”, which stands for polyethylene terephthalate. PET bottles were used as beverage containers in 1977, developed by Nathaniel Wyeth at DuPont and patented by DuPont in 1973. It quickly became popular worldwide after being sold in the US market in 1978 due to its lightweight, safety, energy saving, and suitability for household use, becoming the main packaging material for beverages, alcoholic beverages, and hygiene products. After the introduction of PET bottles in 1980, PET bottles quickly replaced glass containers as the main packaging material for beverages and soy sauce products, especially for mineral water. Up to now, PET bottles have become one of the most common plastic bottles worldwide.

PET bottles have many characteristics, and their plastic raw materials are in a highly crystalline state of milky white or light yellow. PET has excellent optical properties and weather resistance, it is non-toxic and stable, but is not resistant to hot water immersion or alkali. PET bottle packaging is suitable for packaging products in the food, pharmaceutical, cosmetics, and other industries. PET plastic has the characteristics of light weight, high transparency, impact resistance, and not easy to break. It can also prevent carbon dioxide gas and keep soda water “gas”.

PET bottles have a wide range of applications, not only for packaging carbonated beverages, drinking water, fruit juice, enzymes, and tea drinks, but also widely used in various fields such as food, chemical, and pharmaceutical packaging. They are currently the most widely used in beverage packaging. In addition, PET bottles can also be used as non-woven fibers, zippers, filling materials, and other applications. For example, after the PET bottle is crushed into pieces, it can be made into “environmentally friendly cloth” through drawing and weaving processes, which has excellent wear resistance, moisture absorption, and permeability.

It can be used as shoe lining, shoe upper, hiking shoes, travel bags, etc. In addition, at home or school, recycled PET bottles can be used to unleash creativity and design various works, such as piggy banks, flower pots, pen holders, candle holders, kettles, water rockets, photo frames, children’s toys, cup holders, observation boxes, letter stands, watering plants, eco-friendly trees, seismometers, aquariums, lanterns, musical instruments, cookie models, wind chimes, filters, etc.

Distinguishing PET bottles is very simple. Use a lighter to light the bottle body. If it emits a comfortable smell, it is a PET bottle. If it emits a pungent smell, it is not a pure PET bottle. The preparation of PET bottles is made of polyethylene terephthalate, commonly known as PET. PET bottles have the characteristics of transparency and toughness, and have barrier properties against carbon dioxide. They are often used for packaging carbonated beverages. The simplest way to identify PET bottles is colorless and transparent. After coloring, they can become light green, light blue, or brown. The circular PET bottle has a dot at the bottom and no seams on the bottle body.

II. The Concept And Classification Of Chemical Substances

A. Definition of Chemical Substances

Chemical substances refer to substances composed of different atoms or molecules that undergo changes through chemical reactions. Chemical substances are the fundamental units that make up the material world and the core object of chemical research. Chemical substances are composed of atoms or molecules. Atoms are the basic units that make up chemical substances, consisting of protons, neutrons, and electrons. Molecules are formed by the covalent bonding of two or more atoms, which combine in a certain proportion and manner to form various substances. The composition of chemical substances determines the differences in their properties and uses.

B. Classification of Chemical Substances

Chemical substances can be classified based on their composition and properties. According to the continuous and discontinuous forms of matter, it can be divided into continuous macroscopic forms of matter, such as various elements and compounds. And discontinuous microscopic substances, such as various chemical particles and other two categories of substances.

The hierarchical classification of chemical substances is as follows:

Mixture: air, liquid, alloy.
Pure substance;

Elemental substances: metal, non-metal.

Compounds: oxides, acids, bases, salts.

Cross classification is the process of classifying the same substance according to different criteria. For example, NaSO4 can be classified as sodium salt from a cationic perspective and sulfate salt from an anionic perspective.

There are six other forms of chemical substances: solid, liquid, gas, plasma, Bose Einstein condensate, and fermion condensate. Solid substances have shape and volume, with tightly bound molecules. Liquid substances have volume but no shape, and their molecules are loosely bound. Gases have neither volume nor shape, and molecules move freely. Plasma state is composed of equal amounts of negatively charged electrons and positively charged ions. Bose Einstein condensate is the condensation of atoms from different states into the same state. Gaseous substances are abundant in our living space. Early philosophers believed in the existence of the element “air”. In the 17th century, Torricelli proved that air has weight, and in the 18th century, chemists proved that air is a mixture of multiple gases and discovered many gases in chemical reactions.

III. Will PET Bottles Leak Chemicals

A. Exploration Of The Possibility Of Chemical Substances Seeping Out Of PET Bottles

Although PET bottles are generally considered relatively safe packaging materials, there is still a risk of chemical leakage. For example, under specific conditions, antimony in PET bottles may seep out. Antimony, as a plastic processing aid, is widely used in the production of PET. If there is no antimony removal process in the manufacturing process, antimony may remain in the final PET product. When PET plastic bottles are heated, stored, exposed to light, or used to package acidic beverages, more antimony will seep into food and beverages. In addition, long-term repeated use or high temperature may cause PET bottles to precipitate chemicals such as phthalates.

B. Factors Affecting The Leakage Of Chemicals From PET Bottles

Temperature is one of the important factors affecting the leakage of chemicals from PET bottles. The heat-resistant temperature of PET material is around 65 ℃, and its physical and chemical properties are unstable beyond 70 ℃. When the temperature of the hot water added exceeds the heat-resistant temperature of PET material, harmful substance antimony may precipitate. Moreover, high temperatures can cause deformation and even rupture of the bottle body. If the bottle is not tightly sealed, hot water may overflow, leading to accidents such as burns.

In addition to temperature, storage time and substances in contact can also affect the leakage of chemicals from PET bottles. The storage time is positively correlated with the migration of harmful substances from plastic bottles to water. Unreasonable storage methods can lead to harmful substances in bottled water exceeding the water quality shelf life. When PET bottles come into contact with acidic or alkaline substances, such as vinegar or soy sauce, harmful chemicals in plastic materials are more easily dissolved. For example, when the contents of a PET bottle are replaced with 4% acetic acid and 20% ethanol, the migration amount of antimony in the plastic bottle filled with acetic acid is twice that of the other bottle. Meanwhile, the time required to precipitate antimony of the same mass is only half that of another bottle.

IV. What Chemicals May Seep Out Of PET Bottles

A. List Of Common Exudative Chemicals

The chemicals that may seep out of PET bottles mainly include antimony and phthalates. Antimony is a plastic processing aid widely used in the production of PET. Antimony is insoluble in water at room temperature and pressure, but it may react with water at high temperature and pressure. When PET plastic bottles are heated, stored, exposed to light, or used to package acidic beverages, more antimony will seep into food and beverages. Phthalates, such as di (2-ethylhexyl) phthalate (DEHP), may precipitate from PET bottles under long-term repeated use or high temperature. DEHP, as a plasticizer, long-term exposure and ingestion may interfere with the human endocrine system and be associated with various health problems, including reproductive system diseases and the occurrence of certain types of cancer.

B. Potential Impact On Human Health

These leaked chemicals may have many adverse effects on human health. Excessive intake of antimony can cause liver disease and may increase the risk of cancer, heart disease, and other organ toxicity. Antimony can enter organs such as the kidneys and liver through the digestive tract, disrupting tissue metabolism and damaging the heart, liver, and nervous system. Moreover, the characteristic of antimony is that it accumulates for a long time and causes irreversible physical damage. Phthalates may interfere with the human endocrine system, and long-term exposure may lead to the occurrence of reproductive system diseases and certain types of cancer.

In addition, placing plastic bottles containing seasonings in high-temperature environments such as by the stove can cause faster precipitation of the biologically toxic element “antimony”, which can cause damage to the liver and kidneys if ingested for a long time. For children, the risk is greater. Infants and young children sucking on soft and cute toys, blankets, clothes, and other polyester products may also come into contact with unsafe antimony. In the United States, children are exposed to almost three times more antimony per kilogram of body weight than adults. At the same time, children may have already been exposed to a lot of potential antimony in their daily lives. If they come into contact with antimony from PET plastics and polyester, it will increase the health risks that may have already overflowed, exacerbating the overall harm.

V. Safety Assessment Of PET Bottles

A. Current Research Status On The Safety Of PET Bottles

At present, there are abundant research results on the safety of PET bottles, and there are also some differences in viewpoints. On the one hand, health and regulatory agencies around the world, such as the US Food and Drug Administration, Health Canada, and the EU Food Safety Agency, have recognized the safety of PET for food and beverages. PET bottles and food cans can be found everywhere in grocery stores or markets, commonly used for packaging soda water, water, juice, salad dressings, cooking oil, peanut butter, and seasonings. Special grade PET can also be used to carry household food containers and prepared food trays, and can even be heated in ovens or microwaves. The global confidence in the hygiene and chemical safety of PET stems from the fact that PET polymers are highly stable and inert. They are sturdy, resistant to microbial attacks, non reactive with food, non biodegradable, lightweight, easy to transport, and not easily broken.

On the other hand, some studies have also pointed out that if plastic bottles are repeatedly used to drink hot water (above 70 ℃) for a long time, or if microwave heating is directly applied, it will break the chemical bonds in plastic bottles and other plastics, and may migrate plasticizers, antioxidants, oligomers and other substances into the beverage. Once these substances migrate excessively, they can have an impact on the health of drinkers. In addition, researches show that plastic water bottles exposed to sunlight can release harmful volatile organic compounds, including highly toxic volatile organic compounds such as n-hexadecane, which can lead to a series of health problems if exposed for a long time.

B. How To Ensure The Safe Use Of PET Bottles

To ensure the safe use of PET bottles, the following suggestions and measures can be taken:

Firstly, when using PET bottles, attention should be paid to the characteristics and uses of different types of PET plastic bottles to avoid exceeding the heat-resistant temperature. The high temperature resistance range of PET bottles is generally around 65 ℃ to 70 ℃. Beyond this temperature, their physical and chemical properties are unstable and harmful substances may precipitate. Therefore, for health and safety reasons, it is best not to use PET bottles for hot water exceeding 70 ℃. Meanwhile, it is advisable to avoid exposing PET bottles to sunlight for extended periods of time or using them for packaging acidic beverages, as PET bottles may release chemicals such as antimony and phthalates.

Secondly, when choosing a water cup, one should consider the material, thickness, and workmanship to ensure safety and practicality. For example, it is best to choose high borosilicate glass for glass cups because of its heat resistance, wear resistance and other characteristics. The bottom of plastic cups usually has markings, with different markings representing different materials and uses, such as PET markings indicating heat resistance up to 65 ℃. The inner wall of the ceramic cup should be colorless and have a fine and dense texture, which can be judged by gently tapping. When purchasing ceramic cups, it is also important to ensure that the lid is tightly closed to avoid any usage issues.

Again, any refilling and reuse of the bottle should be carefully cleaned with soap and hot water, thoroughly dried to ensure it is hygienic and free of bacteria. It is particularly important to completely dry the bottle before refilling and reusing, as bacteria can thrive in damp environments and it is difficult to dry all areas inside the narrow necked bottle. Any bottle scratched on the inner surface should be discarded in the recycling bin rather than reused, as bacteria may remain in the scratches and multiply.

Finally, consumers should try to avoid exposing plastic water bottles to sunlight for extended periods of time, especially in high-temperature environments, when choosing and using them. In addition, consumers can also choose to use safer water containers, such as stainless steel or glass water bottles, to reduce exposure to harmful compounds. Manufacturers should actively explore safer and more environmentally friendly water container materials and production methods to reduce the release of volatile organic compounds. At the same time, the government and enterprises should strengthen cooperation and develop stricter industry standards and regulations to ensure that plastic water bottles sold in the market meet safety standards. We also need to strengthen our scientific research efforts, conduct in-depth studies on the chemical stability and safety of plastic water bottles in different environments, provide scientific basis for formulating more effective preventive measures, and provide theoretical support for the development of new water container materials and technologies.

VI. Conclusion

PET bottles, as a common packaging material, are closely related to the leakage of chemical substances. Under specific conditions, PET bottles may release chemicals such as antimony and phthalates, potentially affecting human health and the environment.

From a safety perspective, although health and regulatory agencies around the world consider PET safe for food and beverages, there are also studies indicating that long-term repeated or improper use of PET bottles may lead to the migration of chemicals and have adverse effects on human health. For example, PET bottles may precipitate chemicals such as antimony and phthalates under high temperature, long-term storage, and contact with acidic or alkaline substances. Excessive intake of antimony can cause liver disease and may increase the risk of cancer, heart disease, and other organ toxicity. Phthalates may interfere with the human endocrine system, and long-term exposure may lead to the occurrence of reproductive system diseases and certain types of cancer.

To ensure the safe use of PET bottles, both consumers and manufacturers need to take a series of measures. Consumers should be careful not to exceed the heat-resistant temperature, avoid prolonged exposure to sunlight, and avoid using PET bottles for packaging acidic beverages. When choosing a water cup, material, thickness, and workmanship should be considered to ensure safety and practicality. At the same time, any refilling and reuse of bottles should be carefully cleaned with soap and hot water and thoroughly dried. Manufacturers should actively explore safer and more environmentally friendly water container materials and production methods to reduce the release of volatile organic compounds. The government and enterprises should also strengthen cooperation and develop stricter industry standards and regulations to ensure that plastic water bottles sold in the market meet safety standards. We also need to strengthen our scientific research efforts, conduct in-depth studies on the chemical stability and safety of plastic water bottles in different environments, provide scientific basis for formulating more effective preventive measures, and provide theoretical support for the development of new water container materials and technologies.

In short, the relationship between PET bottles and chemical leakage needs to be highly valued. Only through the joint efforts of consumers, manufacturers, and governments, can the safe use of PET bottles be ensured.