Is #4 Plastic Food-Safe? A Comprehensive Guide to LDPE

December 23, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA), #4 plastic, or Low-Density Polyethylene (LDPE), is approved as a food-safe material for contact with edibles. This makes it a popular choice for everything from bread bags to squeeze bottles. Understanding the specific properties of LDPE is crucial for its proper use and to ensure food remains safe from contamination.

Quick Summary

LDPE (#4 plastic) is a food-safe and inert material used in many food packaging applications. Its chemical stability makes it safe for normal food contact, but its low heat resistance means it should not be microwaved. It excels in cold applications, such as freezer bags, due to its flexibility.

Key Points

LDPE is Food-Safe: LDPE (#4 plastic) is approved by the FDA and is considered safe for food contact under proper use.
Avoid Microwaving: It has a low melting point and is not heat-resistant, so you should never use it in a microwave.
Excellent for Freezing: LDPE's flexibility and durability at low temperatures make it a great material for freezer bags.
Does Not Contain BPA: Unlike plastics like polycarbonate (#7), LDPE is BPA-free and doesn't leach hormone-disrupting chemicals.
Recycling Varies: While technically recyclable, flexible #4 plastic is not accepted in all curbside recycling programs and often requires special drop-off locations.
Intended Use is Key: To ensure safety, always use LDPE products as intended by the manufacturer and inspect them for damage.
Common Uses: LDPE is commonly found in flexible items like bread bags, squeeze bottles, and plastic wraps.

What is #4 Plastic (LDPE)?

To determine if #4 plastic is food-safe, it's essential to first understand what it is. The recycling code #4 identifies Low-Density Polyethylene, or LDPE. This thermoplastic polymer is created from the monomer ethylene through a high-pressure process. Unlike its rigid cousin, High-Density Polyethylene (HDPE, #2), LDPE has a highly branched molecular structure, resulting in a flexible, soft, and translucent material with a lower density.

This unique combination of properties makes it a versatile choice for packaging and other consumer products. In food packaging, you will commonly find LDPE used for:

Plastic grocery bags
Bread bags and other food wraps
Squeezable bottles for honey or mustard
Flexible lids on margarine tubs and other containers
Frozen food bags

Safety and Food Contact

For most applications, LDPE is considered a very safe plastic for food contact, largely due to its chemical inertness and stability. It does not contain Bisphenol A (BPA) or phthalates, which are chemicals of concern in other plastic types. This inert nature means that LDPE is unlikely to leach harmful substances into food or beverages under standard conditions of use.

The FDA approves many grades of LDPE for direct food contact. This means that manufacturers using it for food packaging must comply with strict regulations to ensure the material contains no harmful additives or colorants. The integrity of this safety profile, however, is highly dependent on using the plastic as intended by the manufacturer, particularly concerning temperature.

Temperature Considerations: Microwave and Freezer Safety

The most significant safety caveat for LDPE involves temperature exposure. Its low melting point, between 105°C and 115°C (221°F and 239°F), means it is not suitable for high-heat applications like microwaving. Heating LDPE can cause the plastic to melt, deform, and potentially leach chemicals into the food, compromising its safety. Therefore, you should never place #4 plastic in the microwave.

In contrast, LDPE excels in low-temperature environments. It maintains its flexibility and impact resistance even in freezing temperatures, making it a perfect material for frozen food bags. Its durability prevents it from becoming brittle and cracking when cold, which is a key requirement for freezer-grade plastics.

How Does #4 Plastic Compare to Other Food-Safe Plastics?

Understanding how LDPE stacks up against other common food-safe plastics can help consumers make informed decisions. Here is a comparison of LDPE (#4), HDPE (#2), and PP (#5).


Feature	LDPE (#4)	HDPE (#2)	PP (#5)
Flexibility	High. Soft and pliable.	Medium. More rigid than LDPE.	High. Flexible but more heat-resistant.
Heat Resistance	Low. Not microwave safe; can melt at high temperatures.	Medium. Better than LDPE but still not recommended for microwaving.	High. Best for microwaving; heat-resistant.
Freezer Safe	Yes, excellent impact resistance at low temps.	Yes, very durable at low temperatures.	Yes, good crack resistance at low temperatures.
Common Uses	Bags (bread, frozen food), plastic wrap, squeeze bottles.	Milk jugs, juice bottles, butter tubs.	Yogurt containers, medicine bottles, bottle caps.
BPA Content	No.	No.	No.

The Importance of Proper Use

Even with food-safe plastics, proper handling is key to maintaining safety. Following these guidelines will ensure you are using #4 plastic appropriately:

Avoid Heat: Never microwave, cook in, or store hot food in LDPE containers. Transfer contents to a microwave-safe container (such as glass or PP #5) for heating.
Inspect for Damage: Discard any LDPE plastic that shows signs of cracking, wear, or damage. These imperfections can create surfaces where bacteria can accumulate.
Wash Appropriately: While some LDPE products like flexible lids might be top-rack dishwasher safe, check the manufacturer's instructions to prevent warping or damage from high heat.
Consider Alternatives: For those who want to minimize plastic use entirely, alternatives like glass, stainless steel, and silicone offer durable and long-lasting food storage options.

The Environmental Factor: Recycling #4 Plastic

While LDPE is recyclable, its flimsy and flexible nature often complicates the process. Unlike rigid plastics, soft films like grocery bags and plastic wraps can clog sorting machinery at recycling facilities. Consequently, many municipal curbside programs do not accept flexible LDPE.

Check Local Guidelines: To recycle your LDPE, you must check with your local waste management services or look for dedicated collection points, such as those often found at grocery stores.
Recycled Products: When successfully recycled, LDPE can be repurposed into useful new products, including plastic lumber, floor tiles, and garbage cans.

Conclusion: The Bottom Line on #4 Plastic Food Safety

In summary, is #4 plastic food-safe? Yes, LDPE is considered safe for food packaging and storage under most normal conditions and is approved by the FDA for this purpose. It is a reliable material for applications that require flexibility, moisture resistance, and chemical stability. However, its low heat tolerance means it should never be used for heating food, especially in a microwave, to prevent melting and potential chemical leaching. By understanding its specific uses, limitations, and recycling challenges, consumers can utilize #4 plastic safely and responsibly.

Outbound Link

For more in-depth information on LDPE properties, consult the guide available from Xometry: What is Low-Density Polyethylene (LDPE)?

Frequently Asked Questions

The #4 recycling symbol stands for Low-Density Polyethylene, or LDPE. This is a soft, flexible, and translucent plastic commonly used for films and squeeze bottles.

No, you should not microwave food in #4 plastic. LDPE has a low melting point and can deform or leach chemicals into food when exposed to high heat.

Yes, LDPE is freezer-safe. It maintains its flexibility and does not become brittle in cold temperatures, making it a good choice for freezer bags and other frozen food packaging.

No, LDPE (#4 plastic) is naturally BPA-free. It is chemically inert and does not contain the hormone-disrupting chemical bisphenol A found in some other plastics.

Common examples of #4 plastic include plastic grocery bags, bread bags, produce bags, food wraps, and squeezable bottles for condiments.

For general long-term food storage, more rigid plastics like High-Density Polyethylene (#2) are often preferred for their durability. However, LDPE is safe for standard food contact as approved by the FDA.

To identify food-safe plastics, look for the cup and fork symbol or a clear label that says "food-safe" or "FDA compliant." Generally, plastics with recycling codes #1, #2, #4, and #5 are considered safe for food contact.

While LDPE is known for its flexibility and used for many flexible items, other polymers, like LLDPE (Linear Low-Density Polyethylene), are also used to create flexible films and bags with different properties.