Which plastic containers should I avoid? Your guide to safer food storage

September 23, 2025 •

4 min read

Scientists have detected microplastics in almost every major human organ, from the heart to the brain. Understanding which plastic containers should I avoid is a critical first step in reducing your exposure to potentially harmful chemicals and minimizing this risk in your kitchen and home.

Quick Summary

You should generally avoid plastic containers with recycling codes 3 (PVC), 6 (PS/Polystyrene), and 7 (Other/Polycarbonate), as they may contain chemicals linked to health issues. Additionally, exercising caution with all plastics, especially when heating food, is a key health consideration for safer food storage practices.

Key Points

Check the Code: Look for the triangular recycling symbol and avoid plastics with codes 3 (PVC), 6 (PS), and 7 (Other, including BPA) for food storage.
Never Heat Plastic: Microwaving and putting hot food in plastic can increase the leaching of chemicals into your food, even in "microwave-safe" containers.
Choose Glass and Stainless Steel: These materials are the safest, most reliable alternatives for storing, reheating, and packing food without chemical concerns.
Discard Damaged Containers: Scratched, discolored, or old plastic containers are more likely to break down and release harmful substances, so they should be thrown out.
Beware of BPA-Free Labels: Some BPA-free products use similar bisphenols that may also pose health risks; opting for non-plastic alternatives is the safest approach.
Avoid Black Plastics: Black plastic containers can be made from recycled e-waste and may contain heavy metals and other toxins, especially when heated.

Understanding the Resin Identification Code

At the bottom of most plastic products, you will find a small triangular symbol with a number inside. This is the Resin Identification Code (RIC), which indicates the type of plastic resin used. While the symbol was originally created for recycling purposes, it has become a useful tool for consumers to identify and avoid potentially harmful plastics used for food storage.

The Most Problematic Plastic Types to Avoid

To make informed choices for your health and safety, it is crucial to recognize and avoid plastic containers labeled with codes 3, 6, and 7.

Recycling Code #3: Polyvinyl Chloride (PVC) Often referred to as the “poison plastic,” PVC is a rigid, durable material that contains softening chemicals known as phthalates. Phthalates are considered endocrine disruptors, meaning they can interfere with the body's hormonal systems. Potential health concerns associated with phthalates include developmental issues, reproductive problems, and increased cancer risks. PVC was once common in food wrap and cooking oil bottles but is less frequently used for these applications today, though it can still be found in various household items.

Recycling Code #6: Polystyrene (PS) Polystyrene is a petroleum-based plastic best known for its foam form, commonly referred to as Styrofoam®. It is often used for disposable cups, plates, and takeout containers. The primary concern with polystyrene is styrene, a chemical component identified by the US Department of Health and Human Services as "reasonably anticipated to be a human carcinogen". When heated, especially in a microwave, styrene can leach from the plastic into food, posing a health risk.

Recycling Code #7: Other (Polycarbonate and Mixed Plastics) This category is a catch-all for any plastic that does not fit into codes 1 through 6. It can include various materials, notably polycarbonate. The primary health concern with polycarbonate is the chemical bisphenol A (BPA). BPA is another endocrine-disrupting chemical that can mimic the hormone estrogen. While the FDA maintains that low-level exposure is safe, ongoing research and the widespread use of BPA in consumer products, including some reusable water bottles, have raised significant health concerns. For this reason, many manufacturers now produce "BPA-free" products, though some use similar bisphenols that may not be much safer.

The Hidden Danger of Black Plastics

Beyond the recycling codes, some experts advise caution with black plastic containers. These containers often contain recycled electronics and other plastic waste, which may carry unregulated levels of toxic chemicals and heavy metals. Since optical sorters in recycling facilities cannot detect the black pigment, the source material can be unknown, potentially exposing you to lead, cadmium, and other dangerous compounds, especially when the plastic is exposed to heat.

The Risks of Heating Plastic Containers

Regardless of the recycling code, one of the most critical safety rules is to avoid heating food in plastic containers. Microwaving, in particular, can cause chemicals to leach from the plastic into your food more readily. Even containers labeled "microwave-safe" simply mean the plastic won't melt or warp, not that it is entirely free from leaching chemicals. Similarly, avoid placing hot or oily foods directly into plastic containers. Frequent use and washing can also cause plastics to break down over time, increasing the risk of chemical migration and microplastic release.

Comparison of Plastic Container Types


Plastic Type	Recycling Code	Primary Concern	When to Avoid	Safer Alternatives
Polyethylene Terephthalate (PETE)	1	Single-use only; can leach when reused or heated.	Reusing, heating, scratching, or prolonged sun exposure.	Glass, stainless steel.
High-Density Polyethylene (HDPE)	2	Generally safe; possible PFAS contamination.	Reusing for food after storing non-food items.	Glass, silicone.
Polyvinyl Chloride (PVC)	3	Phthalates, endocrine disruptors.	All food contact, especially when heated.	Glass, silicone, beeswax wraps.
Low-Density Polyethylene (LDPE)	4	Generally safe; may contain trace phthalates in films.	Using plastic wrap, especially with fatty foods.	Glass, reusable silicone bags.
Polypropylene (PP)	5	Generally safe; can be microwaved but heating can still cause leaching.	Microwaving; use caution when heating.	Glass, ceramic.
Polystyrene (PS)	6	Styrene, a possible carcinogen.	All food contact, especially when heated.	Glass, ceramic, stainless steel.
Other (Polycarbonate, Mixed)	7	BPA, other bisphenols, microplastics.	All food contact, especially when heated or old.	Glass, stainless steel.

Your Safer Kitchen Strategy

To minimize your exposure to potentially harmful plastic chemicals, consider these practical steps:

Prioritize glass and stainless steel: Use glass containers for meal prep, storage, and microwaving. Stainless steel is excellent for water bottles, lunchboxes, and food storage.
Use safer plastics cautiously: For plastics with codes 1, 2, 4, and 5, limit reuse, avoid heating, and discard any that are scratched or discolored.
Ditch single-use plastics: Never reuse single-use water bottles or disposable takeout containers. They are not designed for repeated use and can break down easily.
Cover food carefully: When microwaving, cover your food with a paper towel or a glass plate instead of plastic wrap to prevent chemical transfer.
Wash by hand: Avoid putting plastic containers in the dishwasher, as high temperatures can cause them to break down faster and release chemicals.

For more detailed information on environmental health concerns, you can consult resources from the National Institute of Environmental Health Sciences.

Conclusion

While plastic offers convenience, understanding the risks associated with certain types is vital for protecting your health. By learning which plastic containers should I avoid and adopting safer food storage practices, you can significantly reduce your exposure to potentially harmful chemicals. Prioritizing glass, stainless steel, and carefully managing the plastics you do use are simple yet effective steps toward a healthier kitchen environment. Remember to check the recycling code, avoid heating, and replace old or damaged containers to safeguard your well-being. The small effort of being mindful of your storage containers can have a significant positive impact on your long-term health.

Frequently Asked Questions

Containers with recycling codes 2 (HDPE), 4 (LDPE), and 5 (PP) are generally considered safer for food storage. However, using glass or stainless steel is the best option to completely avoid the risks associated with plastic.

It is best to avoid microwaving food in any plastic container, regardless of the label. The high heat can cause chemicals to leach into your food. Instead, transfer your food to a glass or ceramic dish before microwaving.

BPA, or Bisphenol A, is an industrial chemical used to make certain plastics. It is an endocrine disruptor, meaning it can mimic hormones like estrogen and potentially interfere with the body's normal functions. While the FDA currently considers low-level exposure safe, many health experts advise caution.

Not necessarily. Some manufacturers replace BPA with other bisphenols, such as BPS and BPF, which may have similar endocrine-disrupting effects. The safest choice is to use non-plastic alternatives like glass or stainless steel.

The easiest way to identify the type of plastic is by checking the Resin Identification Code (the number inside the recycling triangle) on the bottom of the container. Look for codes 2, 4, and 5 for safer options, and avoid 3, 6, and 7.

Yes. Microplastics can be released from containers over time, especially when they are scratched, heated, or worn. While the long-term health effects are still being studied, scientists have detected microplastics in human organs, and it's best to minimize your intake.

Excellent alternatives include glass containers with airtight lids for storage and reheating, stainless steel lunchboxes and water bottles, and reusable silicone bags for snacks and freezer storage.