Storing food safely in plastic containers

There are certain rules of thumb when it comes to storing, freezing and heating food in plastic containers. Read on to find out how to use plastics safely

We have been enslaved to plastic for the last few decades, and indeed it is an amazing material with many important uses. But food storage, reheating, and serving are not among them. To reduce the risk that plastic chemicals will leach into food during heating, avoid cooking in plastic containers, even if the label says 'microwave safe,' or 'oven safe'.

If you are stuck and you absolutely must microwave in plastic, follow the manufacturer's directions carefully. For example, some brands of plastic wrap advise to avoid letting the plastic wrap touch the food during microwaving.

Pyrex glass containers with lids are good alternatives to plastic food storage containers. They are widely available in stores and are ideal for food storage because they can move from freezer or refrigerator to microwave and table with ease.

When it comes to plastic food containers, some are safer than others. You can tell what kind of plastic you have by looking at the 'resin identification number' located in a triangle on the product. Note that the triangle by itself does not mean that the plastic is recyclable. You need to look at the number in the triangle and check with your local recycling company to see what types of plastic they accept. Some plastics are safer than others.


#1 Polyethylene terephthalate (PET or PETE) (water, juice, and soda bottles, peanut butter jars): PET is usually accepted by municipal recyclers. PET bottles can be reused if cleaned with hot soapy water and dried thoroughly between uses. However, environmental groups advise against washing the bottles repeatedly due to concerns that toxic chemicals can migrate from the plastic into the water. Recycle them when they become cloudy or cracked.

#2 High-density polyethylene (HDPE) (miscellaneous food containers, milk jugs, water jugs, cereal box liners): Containers made with HDPE do not leach chemicals into food and are sometimes accepted by municipal recyclers.

#4 Low-density polyethylene (LDPE) (sealable sandwich bags, plastic cling wrap, squeezable condiment bottles): These plastics do not leach toxic chemicals into food, but some municipal recyclers do not accept them.

#5 Polypropylene (PP) (yogurt containers, reusable plastic snack containers): These containers do not leach toxic chemicals into food. Many municipalities do not accept them for recycling, but you can find a list of recycling spots here. (In the UK the technology does not yet exist to recycle this kind of plastic efficiently.)

#7 Bio-plastics (picnic plates, cups, utensils): #7 is an 'other' category that sometimes is used on bio-based plastics such as polylactic acid (PLA). Bio-plastics are made from renewable resources such as corn, potatoes, sugarcane, and other materials with a high starch content. Although they are compostable, few facilities exist that can compost large amounts of them.


#3 Polyvinyl chloride (PVC) (miscellaneous containers, cling wrap for meat and cheese): PVC is manufactured using processes that release dioxins, which the EPA classifies as likely human carcinogens. PVC also contains plastic softeners called phthalates that some studies have shown to harm hormonal systems. Cut away the part of the meat or cheese that came in contact with the cling wrap and store in a safe type of plastic.

#6 Polystyrene (PS) (cups, take-out containers, egg cartons, picnic utensils): The iconic white foam cup is made of polystyrene, as are many clear or solid plastic picnic utensils and cups. (It is not made of Styrofoam, which is actually a registered trade name for polystyerene foam used in construction.) Polystyrene manufacture involves the formation of toxic chemicals, and these products should be avoided in favour of reusable picnic items or safer plastics. Many alternatives now exist, including compostable, plant-based plastics.

#7 Polycarbonate (PC) (baby bottles, hard plastic cups, five-gallon water cooler bottles): #7 is an 'other' category but it often refers to polycarbonate, a plastic that is made with bisphenol A (BPA), a suspected hormone-disrupting chemical. Polycarbonate may also be labelled 'PC'. Some BPA-free PC plastics are available.

Should you wash plastics in the dishwasher?

Many plastic containers now contain a symbol that indicates they are safe to be washed in the dishwasher. However, you'll get more use out of your plastics and be assured that the hot water and abrasive detergents aren't degrading the plastics and releasing chemicals if you wash them by hand.

Green Guide FamiliesThis is an edited extract from the book Green Guide Families: The Complete Reference for Eco-friendly Parents (£12.99, National Geographic Books) Copyright ©2010 National Geographic Society. Available wherever books are sold.



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