Is PET Material in Storage Boxes Safe — Even for Repeated Food Storage?

However, some consumers have expressed concern about whether PET might release harmful substances over time — especially when a PET container is used repeatedly for storing food. Let's examine what the science says.

1. PET's Chemical Stability and Safety Profile

Polyethylene terephthalate (PET) is a polyester polymer formed by reacting terephthalic acid (or dimethyl terephthalate) with ethylene glycol. Its chemical bonds are strong and highly resistant to breakdown under normal use conditions.

In terms of thermal stability, PET softens around 70–80 °C and melts above 250 °C. Depolymerization in laboratory studies typically requires temperatures of ≥200 °C along with a catalyst (Kumar et al., Polymer Degradation and Stability, 2020). Common household use—including cold storage, room-temperature storage, and warm washing—remains far below these thresholds.

Authoritative agencies confirm PET’s safety for food contact. The U.S. Food and Drug Administration (FDA) affirms that PET meets the requirements of 21 CFR 177.1630, authorizing its use for food contact, including repeated-use articles. Similarly, the European Food Safety Authority (EFSA) notes that PET, when manufactured according to Regulation (EU) No 10/2011, has a “very low migration potential” under intended use conditions.

2. What Happens if PET Breaks Down?

Even in rare cases of minor hydrolysis, the by-products of PET are considered low-risk at realistic exposure levels.

Terephthalic Acid is solid at room temperature and only undergoes a phase change near 300 °C. Its negligible volatility makes inhalation exposure highly unlikely.

Ethylene Glycol is a liquid at room temperature, with a boiling point of 197 °C. Its vapor pressure at 20 °C is just 6.5 Pa, far lower than water’s 2,338.8 Pa, meaning it evaporates extremely slowly under normal conditions. According to the World Health Organization (WHO) International Programme on Chemical Safety (IPCS), ethylene glycol toxicity occurs only at high ingestion levels—far above any trace amounts that could migrate from PET containers.

3. Catalyst Residues — Antimony

Most PET is produced using antimony trioxide as a catalyst, which has raised questions about whether antimony could migrate into food or beverages.

Peer-reviewed evidence shows that this risk is minimal. A 2009 study published in Science of the Total Environment (407: 4731–4735) found that PET water bottles stored at room temperature for three years released less than 1 ppb of antimony.

For context, regulatory limits are much higher: China’s GB 5749-2022 standard sets a maximum of 5 ppb for drinking water, and the WHO Guidelines for Drinking-water Quality (2022) establish a health-based guideline value of 20 ppb. Across all tested conditions, antimony migration from PET remained well below safety thresholds, confirming that PET containers are safe for long-term food and beverage storage.

4. Safe Practices for Repeated Food Contact Use

PET can be safely reused for food storage as long as a few basic precautions are followed. It is suitable for cold and room-temperature foods, but it should not be exposed to boiling water, microwaves, or high-temperature dishwasher cycles above 70 °C. The FDA specifically notes that PET is not designed for high-temperature cooking or sterilization, and using it under such conditions may compromise its integrity.

When cleaning PET containers, mild detergent and warm water are recommended. Abrasive tools like steel wool or harsh scrubbers should be avoided, as they can scratch the surface and create areas where bacteria might accumulate. Containers that become cracked, cloudy, or warped should be replaced promptly. The EFSA advises discarding any plastic container that shows significant surface damage to maintain hygiene and ensure safe performance.

Consumers should also look for the “PET” or “#1” recycling code and a food-contact symbol (a cup and fork) when selecting containers, and confirm that the products comply with FDA, EU, or equivalent national food-contact standards.

5. Regulatory Consensus

Regulatory agencies worldwide are in agreement about the safety of PET for food use. The FDA authorizes PET for repeated food-contact use under 21 CFR 177.1630, while EFSA has concluded that migration of substances from PET under intended use is negligible and well within strict limits. Health Canada also confirms that PET does not pose a health risk when used as intended, and the WHO reports no evidence of significant health risks from trace substances at normal migration levels.

6. Importance of Raw Material Compliance and Recommendation of WK-781

Ensuring that PET raw materials comply with food-contact regulations is a critical factor for the safety of reusable containers. Even when the polymer itself is chemically stable, non-compliant additives or impurities in the resin can pose health risks or affect product performance. Using certified, food-grade PET not only guarantees safety for repeated food contact but also improves processability, product consistency, and long-term durability.

In this context, WK-781 is a highly reliable food-grade PET resin suitable for direct injection molding. It is widely used in transparent containers such as wine bottles, cosmetic packaging, file boxes, and storage boxes. Beyond these applications, WK-781 can also be applied to highly permeable water bottles and sterile-filled beverage packaging. The product is fully compliant with China GB 9685 and GB 4806.6, EU No 10/2011, and US FDA 21 CFR 177.1630, ensuring adherence to the strictest international food-contact standards.

Key Features of WK-781:

• Food-grade PET resin with low acetaldehyde content
• Good color quality with slightly low molecular weight and stable molecular distribution
• Excellent processing performance and compatibility with diverse injection molding equipment
• High injection molding fluidity and production stability

By selecting compliant and high-quality PET resins like WK-781, manufacturers can ensure that reusable food containers, storage boxes, and beverage packaging not only meet regulatory requirements but also deliver consistent performance, transparency, and durability in daily use.

7. Conclusion

Multiple independent studies and global regulatory evaluations consistently show that food-grade PET is safe for both single-use and repeated-use storage when used properly. Its chemical structure is highly stable at normal temperatures, its degradation products are of low concern at realistic exposure levels, and antimony migration remains minimal, far below established safety thresholds. 

Using compliant PET plastic raw materials, such as WK-781, further guarantees safety and performance, providing manufacturers and consumers with a reliable, long-lasting option for food storage and packaging applications.