Reusing plastic bottles balances environmental consciousness with health concerns. While repurposing containers reduces waste, not all plastics are chemically suitable for repeated contact with food and drink. The primary concern is chemical leaching, where compounds migrate into the liquid, and the accelerated growth of bacteria on compromised surfaces. Understanding the material composition of a bottle is the most reliable way to determine its safety for long-term reuse.
Identifying Plastics Safe for Repeated Use
To identify a plastic bottle’s material, look for the Resin Identification Code (RIC), a number typically found inside a small triangle on the bottom of the container. This number indicates the type of polymer used. Plastics with codes 2 and 5 are generally considered the most stable and safest choices for repeated use.
Code 2 is High-Density Polyethylene (HDPE), a robust polymer commonly used for opaque milk jugs. HDPE is chemically stable, resistant to breakdown, and does not pose a known leaching risk. Code 5 is Polypropylene (PP), known for its high heat resistance and chemical stability. This material is frequently used for yogurt containers and some microwave-safe food containers, making it an ideal choice for durable, long-term reuse.
Code 1, Polyethylene Terephthalate (PET or PETE), is the plastic used for most single-use water and soda bottles. Although chemically stable for its intended single-use purpose, PET is less durable than HDPE or PP and is more susceptible to physical degradation from repeated washing and handling. While it is chemically safe for limited reuse if cleaned properly, codes 2 and 5 are superior for durability and prolonged contact with liquids.
Plastics to Avoid and Why They Pose Risks
Certain plastic types should be avoided for refilling, as their chemical composition makes them unsuitable for repeated use with food or beverages. These materials are prone to breaking down and releasing component chemicals, especially when exposed to stress or heat. It is best to avoid plastics marked with codes 3, 6, and 7.
Code 3, Polyvinyl Chloride (PVC), contains plasticizers like phthalates to make it flexible. These plasticizers are not chemically bonded to the polymer and can easily leach out, posing a health risk as they are known endocrine-disrupting chemicals. PVC is rarely used for primary food packaging but can be found in some films and non-food containers.
Code 6, Polystyrene (PS), is used in disposable foam cups and take-out containers. Polystyrene can leach styrene, a compound classified as a probable human carcinogen, into food or liquids. This migration is accelerated when the plastic is exposed to heat, such as when hot beverages are poured into the container.
Code 7, labeled as “Other,” is the most concerning category because it is a catch-all for plastics not covered by the first six codes, frequently including polycarbonate (PC). Polycarbonate is historically known to contain Bisphenol A (BPA), a synthetic compound that acts as an endocrine disruptor. While many manufacturers now use “BPA-free” alternatives like Bisphenol S (BPS) or Bisphenol F (BPF), these substitutes are also bisphenols and can still exhibit similar endocrine-disrupting properties. Due to the unknown exact composition and the high risk associated with bisphenol compounds, these bottles should not be reused for drinking.
Proper Care and Handling for Long-Term Reuse
The continued safety of a reusable plastic bottle depends heavily on proper maintenance, regardless of the material. Thorough hygiene is necessary because plastic surfaces can harbor bacteria, especially in small cracks or crevices that develop over time. Bottles should be cleaned daily with warm water and soap; abrasive cleaners or scouring pads should be avoided as they can scratch the surface.
Allowing the bottle to air-dry completely after washing is essential to prevent the growth of mold and bacterial biofilms. Bacteria thrive in moist environments, and residual moisture can quickly lead to an unhealthy layer of microorganisms inside the container. This significantly reduces the risk of illness from bacterial exposure.
Heat Sensitivity
Temperature sensitivity is a factor to consider, as heat accelerates the chemical leaching process in all plastics. Never expose a plastic bottle to high temperatures, such as by placing it in a dishwasher, microwave, or leaving it in a hot car. Temperatures exceeding 45°C can cause the polymer structure to loosen, increasing the migration rate of chemicals like antimony into the liquid.
Physical Degradation
A bottle should be discarded immediately if it shows signs of physical degradation, such as cloudiness, deep scratches, or cracks. These damaged areas create perfect breeding grounds for bacteria and further compromise the structural integrity, making chemical leaching more likely.