Polyethylene terephthalate (PET) is one of the most widely produced plastics globally, recognized for its strength, lightness, and clarity. It is the material of choice for nearly all single-use plastic beverage containers, such as water and soda bottles, and many types of food packaging. Given its widespread use with consumables, questions regarding PET’s safety are common. This article examines the chemical makeup of PET and reviews the facts around potential leaching and safe usage.
What PET Plastic Is and How It Is Identified
Polyethylene terephthalate is a thermoplastic polymer belonging to the polyester family. Its chemical structure is composed of repeating units derived from two primary monomers: terephthalic acid and ethylene glycol. The resulting material is a clear or semi-crystalline plastic that is lightweight, durable, and highly resistant to moisture and gases, making it an excellent packaging barrier.
Consumers can identify PET packaging by looking for the Resin Identification Code (RIC). This symbol is a triangle containing the number “1,” typically molded into the bottom of the container. While PET is widely used for single-use bottles, its strength and flexibility also make it suitable for food jars, clothing fibers (sold as polyester), and other thermoformed packaging.
Chemical Safety and Leaching Concerns
PET plastic is considered chemically inert and safe for food and beverage contact by major regulatory bodies, including the U.S. Food and Drug Administration (FDA). PET plastic does not contain Bisphenol A (BPA), which is a common concern in other polycarbonate plastics. Also, PET does not require the use of common plasticizers like DEHP or DBP, which are phthalates often associated with flexible plastics.
The main chemical concern associated with PET production is Antimony trioxide, which is used as a catalyst to manufacture the polymer. Trace amounts of this metal can migrate into the contents of the bottle, and this migration increases over time and with higher temperatures. However, the levels detected in bottled water and beverages under normal storage conditions are consistently far below the safety thresholds set by international health organizations. For instance, antimony concentrations measured in commercial bottled water are typically well below the U.S. Environmental Protection Agency’s maximum contaminant level of 6 parts per billion.
Safe Handling and Common Misconceptions
High heat exposure is the primary factor that accelerates the migration of trace chemicals from PET plastic. Placing PET containers in a hot car or storing them in direct sunlight can increase the leaching rate of antimony and other substances like acetaldehyde, which can affect the taste of the contents. Experts advise against heating PET bottles and recommend storing them in cool, dark environments to minimize potential migration.
A common misconception is that reusing single-use PET bottles causes a significant chemical risk. While repeated use might slightly increase chemical migration due to wear and tear, the far greater risk is microbial contamination. PET bottles are not designed for repeated cleaning. The narrow openings and difficulty of thorough scrubbing allow bacteria and fungi from hands and the mouth to rapidly multiply. Physical damage, such as scratches and cracks from reuse, creates surfaces where these pathogens can easily harbor and form biofilms, posing a health risk that outweighs the low concern of chemical leaching.