Does Plastic Leach Into Dry Food? Understanding the Risks

December 23, 2025 •

5 min read

According to a 2021 review of over 150 scientific papers, contaminants from food packaging, including plastic, regularly transfer to dry foods, sometimes at rates higher than previously assumed by regulatory bodies. This migration raises questions about the cumulative effects of storing staple dry foods in plastic containers over long periods.

Quick Summary

Plastic can leach trace chemicals into dry food, though migration rates are typically lower than with fatty or hot foods. The type of plastic, its age, and storage conditions significantly affect chemical transfer. Prudent consumers can minimize exposure by selecting appropriate food-grade plastics or non-plastic alternatives like glass for storage.

Key Points

Chemical Migration Occurs: Trace chemicals can leach from plastic into dry food, though the rate is lower than with hot or fatty foods.
Storage Duration Matters: The longer dry food is stored in a plastic container, the higher the total potential for chemical migration.
Plastic Type is Key: Safer plastics for dry storage include HDPE (#2), LDPE (#4), and PP (#5). Avoid plastics coded #3, #6, and some #7s.
Older Containers Pose Higher Risk: As plastic ages or becomes scratched, its stability decreases, increasing the risk of chemical leaching.
Consider Alternatives: For completely eliminating leaching risks, opt for inert storage materials like glass or stainless steel.
'BPA-Free' Doesn't Guarantee Safety: Many BPA-free products use similar bisphenol substitutes like BPS or BPF, which are also endocrine disruptors.
Heat is a Major Factor: While dry food is stored at room temp, any exposure to heat, such as microwaving or using the dishwasher, will dramatically increase chemical release.

The Science of Chemical Migration from Plastic

Chemical migration is the process by which substances transfer from a packaging material into the food it contains. Plastics are not perfectly inert; they are made of polymers and various additives like plasticizers, antioxidants, and monomers. These chemicals are not always covalently bound to the plastic matrix, allowing them to potentially move out of the container and into the food over time. While this is a more well-known issue with hot or fatty foods that accelerate the process, studies confirm that a limited, continuous migration can also occur into dry goods.

Factors Influencing Chemical Leaching in Dry Food

Several variables affect the extent to which chemicals can leach into dry food:

Time and Temperature: The duration of contact is a critical factor. The longer a dry food is stored in a plastic container, the greater the potential for chemical migration. Although heat is the primary accelerant, migration happens even at room temperature. Long-term storage, even in cool conditions, can still increase total chemical exposure.
Type of Plastic: Not all plastics are created equal. Some are inherently more stable and less prone to leaching. For example, Polypropylene (PP) is generally heat-resistant and considered safe, while Polyvinyl Chloride (PVC) relies on added plasticizers like phthalates, which can migrate more easily.
Age and Wear of Container: As plastic ages, is repeatedly washed, or develops scratches, its structural integrity can degrade. This deterioration can increase the rate at which chemicals are released from the plastic matrix into the food. Therefore, old, worn, or scratched plastic containers may pose a higher risk.
Food Composition: While dry foods are less reactive than oily or acidic ones, the food's composition can still play a role. However, for dry goods like flour, pasta, and rice, the primary drivers of migration are typically the container's properties and storage conditions, rather than the food itself.

What Chemicals Can Leach into Dry Food?

Chemicals of concern found in plastic packaging include, but are not limited to:

Bisphenols (BPA, BPS, BPF): Bisphenol A (BPA) is an endocrine-disrupting chemical once widely used in hard plastics. While many companies now offer "BPA-free" products, they often replace it with structurally similar chemicals like BPS and BPF, which can also interfere with hormones and may pose similar risks.
Phthalates: Used as plasticizers to make plastic flexible, phthalates are a group of endocrine disruptors found in soft plastics, PVC, and some printing inks. They are not chemically bonded and can easily migrate into food.
Microplastics and Nanoplastics: Small plastic particles can be released from containers, especially when agitated, heated, or stored for long periods. These particles have been found in a wide array of foods and can be ingested by humans.

Understanding Plastic Resin Codes

Resin Identification Codes (RICs), the numbers inside the recycling symbol, can offer guidance on a plastic's potential safety for food contact. The American Academy of Pediatrics recommends avoiding plastics with codes 3, 6, and 7, while those with codes 1, 2, 4, and 5 are generally considered safer for food use.

Resin Identification Codes and Food Safety

#1 (PET or PETE): Single-use plastics like beverage bottles. Safe for one-time use but can degrade with reuse.
#2 (HDPE): High-Density Polyethylene, used for milk jugs and food tubs. Generally safe and non-toxic.
#3 (PVC): Polyvinyl Chloride, often contains phthalates. Should be avoided for food storage.
#4 (LDPE): Low-Density Polyethylene, used in squeeze bottles and bread bags. Considered safe.
#5 (PP): Polypropylene, used for yogurt containers and microwaveable trays. Known for high heat resistance.
#6 (PS): Polystyrene, found in disposable cutlery and styrofoam. Styrene is a potential carcinogen, and leaching is a concern.
#7 (Other): A catch-all category. Avoid unless specifically labeled as safe for food contact.

Safe vs. Unsafe Plastic for Dry Food: A Comparison


Feature	Safer Plastics (HDPE, LDPE, PP)	Less Safe Plastics (PVC, PS, some #7)	Non-Plastic Alternatives (Glass, Stainless Steel)
Chemical Migration	Minimal leaching risk, especially with proper care.	Higher risk of leaching BPA, phthalates, and other additives.	Inert; does not leach chemicals into food.
Heat Resistance	PP is generally microwave-safe; others may soften.	Often melt or degrade with heat, increasing chemical release.	Excellent heat resistance; can be used in microwaves and ovens.
Durability	Good, but can be scratched or become brittle over time.	Can be brittle or degrade with use, especially if single-use.	Very durable and long-lasting, though breakable (glass).
Cost	Generally more affordable and widely available.	Cheaper, especially for single-use or flimsy applications.	Higher initial cost but greater longevity.
Transparency	Varies; HDPE is opaque, PP can be translucent or clear.	Varies, but many are clear (PVC) or opaque (PS).	Transparent (glass), allowing easy content identification.
Storage Suitability	Suitable for short to medium-term dry food storage, adhering to guidelines.	Should be avoided for long-term dry food storage.	Ideal for long-term dry food storage, preventing all chemical contact.

Safer Alternatives for Dry Food Storage

To eliminate the risk of plastic chemical leaching entirely, several alternatives are available:

Glass Containers: Hermetically sealed glass jars are an excellent, inert choice for long-term storage of grains, legumes, flour, and other dry goods. They are non-porous, odor-resistant, and won't leach chemicals.
Stainless Steel Canisters: High-quality, food-grade stainless steel is another inert, durable option. Unlike plastic, it's virtually unbreakable and resistant to odors and staining.
Ceramic Crocks: Glazed ceramic containers are a decorative and safe way to store dry foods like spices or sugar. It is crucial to ensure the glaze is food-safe and lead-free.

Conclusion: The Bottom Line on Dry Food and Plastic

The question of whether plastic leaches into dry food has a clear answer: yes, albeit typically at low levels compared to oily or hot foods. The degree of chemical migration is influenced by the type of plastic, storage duration, and the container's condition. While regulatory bodies often deem approved levels safe, concerns remain about cumulative exposure, especially from endocrine disruptors like BPA and phthalates. Choosing inert materials like glass or stainless steel is the most cautious approach. If using plastic, opt for food-grade, high-quality containers labeled #2, #4, or #5, and avoid using them for long-term storage, especially if they are old or worn. For an official perspective on food contact safety, refer to resources from health authorities such as the FDA's position on BPA.

Frequently Asked Questions

Yes, it is generally considered safe to store dry grains and pasta in food-grade plastic containers for short-term to medium-term periods. However, for long-term storage, especially if concerned about chemical migration, inert materials like glass or stainless steel are safer options.

The safest plastics for food storage are typically High-Density Polyethylene (HDPE, #2), Low-Density Polyethylene (LDPE, #4), and Polypropylene (PP, #5). These are generally stable and less prone to leaching chemicals.

While plastic bags are often used for packaging dry food, they can still contribute to low-level chemical migration, especially with prolonged contact. Over time, these additives can transfer from the bag into the food.

Yes, BPA-free plastic can still leach other chemicals into dry food. Manufacturers often use alternative compounds like BPS or BPF, which can be similar endocrine disruptors.

Yes, exposure to heat (e.g., dishwashers, microwaves, or prolonged direct sunlight) can accelerate the breakdown of plastics and increase the rate of chemical migration into food, even dry food. It is best to store plastic containers in a cool, dry, and dark place.

Yes, older plastic containers that are cracked, scratched, or cloudy from repeated use and washing are more likely to leach chemicals. The degradation of the plastic's surface integrity allows for easier chemical release.

To reduce exposure, use food-grade plastics (#2, #4, #5) for short-term storage, opt for inert materials like glass or stainless steel for long-term storage, avoid microwaving or heating plastic containers, and discard any worn or scratched plastic storage items.