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What is Plastic Number 4 (LDPE) and Is it Safe for Babies?

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Plastic is everywhere and you aren’t likely to be able to avoid it completely anytime soon. With this in mind, you might be wondering about which plastics are safe and which ones can cause problems for you and your baby. As the fourth installment of my plastics mini-series, I’m going to check out plastic number 4 (LDPE) to see what it is and if it’s safe for babies!

Plastic number 4 (Low-density polyethylene or LDPE) is considered one of the safest plastics that you can use today and it has no known health concerns. It doesn’t leach chemicals into food or beverage and can be recycled. It’s used to make items such as plastic bags, milk cartons, mats, and playground equipment.

Luckily, some plastics are actually quite safe to use with your baby and this is one of them! Let’s dive into what exactly number 4 plastic is, where you can find it, and its overall safety profile.

What does plastic number 4 mean?

When looking at a plastic food container, you’ve probably seen numbers and a triangular arrow symbol stamped on the bottom. If you don’t know what they mean – don’t worry! That’s why we’re here. That’s a recycling symbol and the number is called a resin identification code (RIC). They are there to help recyclers know what sort of plastic they are dealing with so they can handle it correctly during processing. As an added bonus, consumers can learn what kind of plastic is being used in their products.

Plastic items with a number 4 on the bottom are made from low-density polyethylene, or LDPE, which is a petroleum-based thermoplastic. It’s very tough and light-weight plastic, but it is especially prized for its softness and flexibility. It can be translucent or opaque and has excellent resistance to acids. Although recyclable, acceptance has been limited until recent years leading to less than 6 percent being reused each year.

Of the seven different ways to categorize plastics, according to the standards maintained by the American Society for Testing and Materials (ASTM International), LDPE fits into the fourth group. Importantly, these classifications are in reality only in place to help manufacturers and recyclers. They aren’t regulated by a federal body and it’s essentially voluntary to put the labels on consumer products. As a result, you will usually only find them on food or drink containers.

Examples of plastic number 4

LDPE has been around for a long time. In fact, it was first produced in 1933 and it’s used to produce all sorts of everyday items that need to be lightweight and flexible. Since it’s also food-safe and resistant to extreme temperatures, you’ll also find it on many grocery store shelves as well.

In general, you’ll find this plastic in:

  • Compost bins and trash cans
  • Artificial wood
  • Furniture
  • Tubing
  • Trays and general-purpose containers like tubs and flower pots
  • Foam packaging material

Despite the fact that plastic number 4 is very safe for humans, it currently poses an environmental risk for the planet because it isn’t frequently recycled. This means that most of the LDPE produced each year finds its way into landfills. Unfortunately, it’s also not biodegradable so it will sit in these places for hundreds or thousands of years. Plastic bags also frequently find their way into waterways where they can be eaten by wildlife.

Food containers made from LDPE

An excellent example of where to find number 4 plastic at the grocery store is in the plastic bags you use at checkout. You’ll also find it in the plastic bags used to hold bread.

In addition to bags, LDPE is frequently used as:

  • Waterproof liners in food and beverage containers
  • Food cling wrap
  • Six-pack rings
  • Squeezable condiment bottles
  • Lids for various containers

Is plastic number 4 reusable?

Unlike many other plastics, LDPE is completely reusable because it won’t leach chemicals into its contents over time. This means lots of products around the house could get a second life as something else down the road!

Baby products made from LDPE

Other than everyday items, plastic number 4 is also used in many products that you would consider for your baby. Here are a few examples:

  • Disposable liners for baby bottles
  • Playground equipment like slides and swing seats
  • Playmats
  • Bibs
  • Lunchboxes
  • Plastic ‘ball pit’ balls

The biggest benefit to using LDPE in baby products is that it is safe for them to use and won’t cause issues with chemical contamination over time. This plastic is also easy to clean, impact-resistant, and generally holds up to the rough play of babies and toddlers without having to worry about it falling apart too quickly!

Also, don’t underestimate its waterproofing capability. With playmats and bibs, this quality is essential! This playmat (check out the latest reviews on Amazon), for example, uses an LDPE coating on top to make it completely impervious to spills, drool, and other baby messes. Instead of pulling out the carpet cleaner, you’ll just need a few paper towels!

Is plastic number 4 (LDPE) safe for babies?

Like I mentioned earlier, LDPE is very safe for babies because it is chemically stable and won’t leach chemicals into food or beverage, the air, or through contact.

I would personally not be concerned at all when using food containers, toys, or other things that were made from LDPE.

For an added peace of mind, you won’t have to worry about finding any BPA or phthalates inside of number 4 plastic because they aren’t using during the manufacturing process. In the world of plastics, these two chemicals are always the biggest concerns because they have been shown to cause dangerous harm to children and adults alike. Since it’s not an issue, don’t fret if your LDPE baby product doesn’t say ‘BPA free’ on the package.

Can you microwave LDPE?

In general, you probably shouldn’t microwave plastics.

Many plastics, even those that don’t leach chemicals under normal circumstances, could do so when they are heated up to a high temperature. Additionally, getting the plastic too hot could actually cause it to melt or catch fire – not a good thing!

For LDPE specifically, it will usually say that the product is ‘microwave-safe’ on the bottom, but that really just means that it isn’t likely to melt. Personally, I don’t ever heat food or beverages up in the microwave if they are in a plastic container.

Can you recycle LDPE?

Mostly, yes!

While plastic number 4 isn’t recycled at high rates right now, that mostly comes down to a lack of acceptance at many curbside recycling pickups. In recent years, however, this has begun to change!

Be sure to check with your local facility to ask about putting LDPE in the bin for pickup or dropping it off. If you aren’t able to send it that way, check with your local grocery store to see if they will at least let you return your plastic bags after use!

Finding alternatives to plastic for your baby

While it’s generally safe to use LDPE for a wide range of applications, there are still many downsides to using plastic other than immediate health concerns. Since these products are made from petroleum in most cases, you have to consider all of the various by-products and side-effects of the oil and gas industry as well. There’s also the fact that the vast majority of plastics produced in the world today end up in landfills and waterways, leading to environmental pollution and posing a danger to wildlife.

If you want to avoid plastic completely, it’s going to be tough. Reducing it, however, really just comes down to finding long-lasting alternatives that you can invest in now so that you can stop using disposable items.

Stainless steel cups and utensils

This is a big one here because your baby will be using bottles, sippy cups, plates, forks, and spoons constantly during their first few years. In many cases, these items are made from plastic so that your baby won’t break a plate or something that could be dangerous. If there’s one thing for sure, steel won’t break on the floor. Surprisingly, it won’t break the bank either!

Here are a few options:

  • Stainless steel divided trays – It might look like your baby is joining the army, but don’t worry! These plates have 5 sections to keep food separate and they will last a lifetime! stainless steel plateware
  • Stainless steel utensils – Safe, simple, and cute! This set includes 4 each of the spoons, forks, and knives (rounded with no sharp points!) that your baby will need to learn how to feed herself.
  • Pura Kiki Stainless steel infant bottle/sippy cups – I’ve recommended these before with good reason. This is a nice starter set that gets you two each of stainless steel bottles, low flow nipples, medium flow nipples, sippy cup spouts, and travel lids. These extras allow you to start your baby on the bottle and have room to grow for years!

Learn more about the other plastic numbers

There are six other categories of plastic to think about when it comes to keeping your baby safe from harmful chemicals. Check out my article on plastic number 5 (polypropylene) to see the next installment of my series on plastic numbers!

Joshua Bartlett
Joshua Bartlett

My name is Joshua Bartlett I run this blog with my wife Jarah. We have more than 11 years of parenting experience including three girls and one boy. I started this blog in late 2018 when I realized that I was dealing with baby-related issues on a constant basis…please read more about me here!

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