Is peanut butter in plastic jars safe?

December 8, 2025 •

4 min read

According to a 2025 study cited by CNN, more than 3,600 chemicals can leach into consumer food products during manufacturing and packaging, raising concerns about safety. For many, this raises the question: is peanut butter in plastic jars safe to eat?

Quick Summary

The safety of peanut butter in plastic jars is a complex issue involving potential chemical leaching, microplastic contamination, and the type of plastic used. Risks can increase with heat exposure and long-term storage, prompting many to consider glass alternatives for better food quality and personal health.

Key Points

Leaching increases with heat: The oil and fats in peanut butter can accelerate the leaching of chemicals from plastic, a process amplified by heat exposure.
Microplastics are a real concern: Tiny plastic particles called microplastics and nanoplastics can shed from jars and enter food, posing potential health risks.
BPA-free is not a complete solution: While many jars are now BPA-free, other chemicals like phthalates or alternative bisphenols can still migrate from the plastic.
Glass is the safest option: For the most inert and non-leaching storage, glass jars are a superior choice that eliminates plastic-related chemical and microplastic exposure.
Check plastic codes: Plastic recycling codes 1 (PET), 2 (HDPE), 4 (LDPE), and 5 (PP) are generally considered safer for food contact, but codes 3, 6, and 7 should be avoided.
Consider the environment: While plastic is lighter for transport, glass is endlessly recyclable and ultimately better for reducing non-biodegradable waste.
Re-evaluate reusing plastics: Repeated use, especially with heat and oil, can increase the breakdown of plastic and the potential for leaching.

The Hidden Risks of Plastic Packaging

While most consumer-grade plastic jars, including those for peanut butter, are generally considered safe for their intended use, recent scientific reviews have highlighted significant concerns. The potential health risks are not from the peanut butter itself but from the chemical additives and microparticles that can migrate from the plastic packaging into the food. A 2025 review published in ScienceDirect noted that microplastic contamination from food packaging is a critical public health concern, with particles migrating from plastics like polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE).

Chemical Contaminants in Plastic Jars

Several chemicals used in plastic manufacturing can pose health risks. Bisphenol A (BPA) and phthalates are two of the most well-known. Although many manufacturers have moved to BPA-free plastics, some replacements may not be entirely benign, and phthalates are still widely used to increase plastic flexibility.

Phthalates: These endocrine-disrupting chemicals can interfere with the body's hormones and have been linked to reproductive and developmental issues. Studies have found phthalates in consumer goods packaged in plastic, and their migration into food is a key concern.
Bisphenols: While BPA is largely phased out of many food containers, especially for infants, it is sometimes replaced with alternatives like BPS, which also raise health questions. The risk is particularly pronounced when plastics are heated, as heat accelerates the migration of these chemicals into food. The oils and fats in peanut butter can also increase the likelihood of chemical leaching.

Microplastics: A Silent Contamination

Beyond chemical leaching, a more insidious threat is the migration of microplastics and even smaller nanoplastics. These tiny particles shed from plastic packaging through mechanical stress, heat, and wear and tear.

Ingestion Pathway: Microplastics can enter the food chain through various routes, including food processing equipment, water sources, and the packaging itself. Once ingested, studies show that microplastics can cross biological barriers and accumulate in human tissues.
Health Implications: While the full extent of microplastic and nanoplastic ingestion on human health is still under investigation, preliminary research links exposure to oxidative stress, inflammation, and potential organ damage. A March 2024 study even found an increased risk of heart attack or stroke in people with microplastics or nanoplastics in their carotid artery tissue.

Which Plastics are Safest for Food Storage?

For concerned consumers, understanding plastic recycling codes can help identify safer options for food storage, though glass remains the most inert material. The codes are typically found inside a triangle on the bottom of plastic items.

Code 1 (PET/PETE): Commonly used for single-use drink bottles and some peanut butter jars. Generally considered safe for one-time use, but reusing can increase chemical leaching and bacterial growth.
Code 2 (HDPE): Often found in milk jugs and detergent bottles, it is generally considered safe but not recommended for reuse with food.
Code 4 (LDPE): Used for flexible items like squeeze bottles and food bags, it poses minimal leaching risk but is not suitable for high heat.
Code 5 (PP): Often used for tubs and microwave-safe containers, PP has a high heat tolerance and is considered a safer plastic for food contact.
Codes 3, 6, and 7: These plastics, including PVC and those containing BPA, should generally be avoided for food storage.

Comparison: Plastic vs. Glass Jars for Peanut Butter

Choosing the right packaging for your peanut butter involves weighing several factors, from health implications to environmental impact. Here is a side-by-side comparison to help inform your decision.


Feature	Plastic Jars (Typically PET)	Glass Jars
Chemical Leaching	Potential for leaching of chemicals like phthalates and microplastics, especially with heat or damage.	Non-porous and chemically inert, meaning no leaching into food.
Microplastic Contamination	Potential for shedding of microplastics and nanoplastics over time and with use.	Eliminates the risk of microplastic contamination from the packaging.
Environmental Impact	Lighter to transport, reducing shipping fuel consumption, but a major source of non-biodegradable waste.	Heavier to transport, increasing fuel costs and carbon emissions during shipping. However, glass is endlessly recyclable without loss of quality.
Durability	Shatter-resistant, making them safer for households with children or for transport.	Fragile and can break, but durable against wear and tear.
Reusability	Repeated use increases risk of chemical leaching and microbial growth; not ideal for long-term reuse.	Highly reusable for long-term food storage or other purposes.
Cost	Generally cheaper to produce, leading to a lower retail price.	More expensive to manufacture and transport.
Food Quality	May impart a slight plastic taste over time or with heat exposure.	Preserves the original taste and flavor of the food.

Conclusion

While the FDA and other regulatory bodies generally approve the plastic used in commercial peanut butter jars for food contact under specific conditions, ongoing scientific research raises valid concerns about the long-term effects of chemical and microplastic exposure. Heat exposure, such as leaving jars in a hot car or near a stove, can significantly accelerate the migration of potentially harmful substances from plastic into the peanut butter.

For those prioritizing absolute food purity and long-term health, opting for peanut butter packaged in glass jars is the safest and most inert option available. Glass eliminates the risks of chemical leaching and microplastic contamination. Furthermore, glass jars are infinitely recyclable and highly reusable, offering a more sustainable choice for the environmentally conscious consumer. For those who prefer plastic for reasons of durability or convenience, choosing high-quality, BPA-free plastics and storing them away from heat and light can help mitigate some risks. However, the most definitive solution for avoiding plastic-related concerns is to choose a plastic-free alternative.

Additional Safe Food Storage Resources

For more information on safe food storage and sustainable alternatives, consult this resource:

Food Grade Plastic: Which Plastics Are Safe For Food Storage

Frequently Asked Questions

Storing peanut butter in a plastic jar is generally considered safe for short periods at cool temperatures. However, potential health concerns arise from the possibility of chemical and microplastic leaching, especially with long-term storage or exposure to heat.

When a plastic peanut butter jar is exposed to heat, the rate of chemical leaching from the plastic into the food increases significantly. The fats in the peanut butter can also absorb these chemicals more readily.

While BPA-free plastics are an improvement, they are not entirely without risk. Many use alternative bisphenols or other additives that also have potential health concerns, and the risk of microplastic shedding still exists.

Many people find that food, including peanut butter, tastes better when stored in glass. Glass is non-porous and chemically inert, so it does not impart any flavor to the contents, unlike some plastics that can transfer a 'plastic' taste.

Glass is generally considered more environmentally friendly in the long run because it is infinitely recyclable without losing quality. While plastic is lighter to transport, it contributes significantly to non-biodegradable waste and requires fossil fuels for production.

Yes, if you are concerned about potential chemical and microplastic exposure, transferring your peanut butter from its original plastic container to a dedicated glass or stainless steel food storage container is a simple and effective way to reduce risk.

This is the Resin Identification Code (RIC), a recycling symbol with a number from 1 to 7. For food contact, codes 1 (PET), 2 (HDPE), 4 (LDPE), and 5 (PP) are generally considered safer, while 3, 6, and 7 are best avoided for food storage.