Are Your Plastic Water Bottles and Meal Prep Containers Safe to Use?

If you've ever glanced at the bottom of your water bottle or meal prep container, you may have seen a number printed on the plastic.

That's the Resin Identification Code — or recycling number that identifies the type of plastic. These numbers are crucial for indicating and understanding the type of plastic you're using.

If your soda bottle or peanut butter jar has the number 1 printed on the bottom, it's a PET container, according to the Sea Studios Foundation. These containers are lightweight, clear and smooth in texture — and intended for single use only.

One of the most easily recycled plastic varieties, PET is commonly used for water or soda bottles, detergent containers and peanut butter jars. Currently, there are no known health issues or concerns associated with this plastic and it is commonly recycled into new bottles or polyester fabric.

Like PET, HDPE is a frequently used, safe plastic container. It's denoted by a number 2 on plastic containers. HDPE products are safe and are not known to transmit any chemicals into foods or drinks, making this plastic a low health risk variety, according to Chemical Safety Facts.

This plastic is most often used for milk or water jugs, laundry detergents and shampoo bottles. Like PET, HDPE is a single-use container and should be properly recycled after use. Typically, these containers are either recycled back into new containers or converted into plastic lumber, pipes, rope or toys, according to the Sea Studios Foundation.

While PET and HDPE don't have any associated health risks, PVC (which is denoted by a number 3 on plastic) has been shown to produce harmful chemicals like lead, DEHA and dioxins in manufacturing, disposal or destruction, according to the Sea Studios Foundation.

PVC is often found in clear food packaging or cling wrap, some plastic squeeze bottles, vinyl pipes and shower curtains. This type of plastic is one of the least recyclable varieties due to the chemical additives.

Low-density polyethelene is a generally safe plastic variety that has no known health risks associated with use. However, the manufacturing of LDPE does produce organic pollutants, causing potential harm to the environment, according to the Sea Studios Foundation.

Not usually recycled, LDPE (denoted by the number 4) is most commonly used to package bread or frozen food. Most plastic wraps are also made of LDPE and are intended for single use only.

Polypropelene containers do not leach harmful chemicals into foods or liquids and are not associated with any known health issues. Typically, this plastic is transluscent or opaque in color and has a high melting point, which typically makes these containers microwave- or dishwasher-safe, according to Chemical Safety Facts.

Type 5 plastic is used to make yogurt containers, cream cheese containers, maple syrup bottles or prescription bottles. Unlike other safe plastics, PP is not easily recycled, according to the Sea Studios Foundation.

Polystyrene can be either rigid or formed (aka styrofoam) and is denoted by the number 6. While recycling this plastic is possible, it's not generally economically beneficial.

Rigid forms of PS plastic are typically found in CD cases or disposable cutlery, whereas styrofoam is used for egg cartons or building insulation.

The number 7 indicates that your container is constructed with a mixed variety of other plastics. Typically, mixed plastics are practically impossible to recycle, according to the Sea Studios Foundation.

Mixed plastics are typically used to construct lids, medical storage containers, sports drink bottles and large water jugs, among other items.

While certain plastics can be risky, this doesn't mean you have to go and toss all your meal prep containers and water bottles. Here are some steps you can take to safely handle your plastic:

• Avoid heating food in plastic containers
• Wash plastic with a mild detergent
• Opt for glass containers when you can

‌Correction: An earlier version of this story incorrectly identified the number on polystyrene. We appreciate readers who bring errors like these to our attention! If you spot something in one of our articles, please reach out: editorial@livestrong.com.‌