Microwaving plastics 101
 Do
the recycle numbers assigned to plastic containers indicate if they are safe to
use for heating food in a microwave oven?
April Holladay
Published on Monday, Feb. 08,
2010 12:01 PM MST
This seemed a simple
question when I first read it and it actually is. But it took time to
spot a recycle myth and realize the answer is just: NO.
I can easily say what plastics are microwave safe — any
that the label says is safe — but the recycle numbers don't help.
Do the recycle numbers assigned to plastic containers indicate if they are
safe to use for heating food in a microwave oven?
Lanney, Sandia Park, New Mexico, USA
At first, I tried to make a connection between the recycling numbers and
microwave safety. The Internet was all too happy to
help. I found charts merrily connecting recycling numbers (those raised
numbers we find on the bottom of plastic containers) with food safety.
"It ain't necessarily so," as the character Sportin' Life (a drug
dealer) sung in Porgy and Bess.
As I constructed a similar table of my own, I ran into
big problems. For example, I found frozen-food manufacturers routinely
package their TV dinners in plastic trays they label as "microwavable."
The plastic trays are made out of a plastic called PET, which has a recycle code
of #1. So far, so good.
But manufacturers of cold-storage jars and 2-liter soft-drink bottles also
use PET plastic with, of course, the same recycle number, #1. These
cold-storage bottles could warp if placed in the microwave and used for reheating
something. A warped or melted plastic is not safe. I scratched my
head. How to resolve this?
The American Chemistry Council (representing hundreds of companies in the
business of chemistry, such as, Dupont) set me straight: "[The recycling
symbol] is not intended to provide guidance on safe or recommended uses."
Well, no wonder, I thought.
Health Canada and the US Food and Drug Administration (FDA) go to much trouble
determining what plastics are safe to use in a microwave oven. If a
manufacturer labels its plastic product as "microwavable," or
"microwave safe" then it is. If
the product isn't so labeled, it likely is not safe. Don't put it in the
microwave! That's the bottom line.
I redid the table to summarize my findings. See
below.
By the way, "...we have read the article and agreed with the 'Comments,'"
says Christelle Legault of Health Canada.
Information from publications written by Health Canada
and FDA:
| Label |
Container |
Comments |
| No label |
Most restaurant takeout Styrofoam
containers, water and two-liter soft-drink bottles, and plastic tubs or jars containing margarine,
yogurt, whipped topping, and foods such as cream cheese, mayonnaise, and
mustard. Also plastic bags (such as flimsy produce bags from grocery stores) |
These containers are not microwave safe.
The heated food may melt them. |
| "Microwave Directions" or
similar wording. |
Plastic storage bags (such as Ziploc bags) |
These bags are not microwave safe.
Hot food may melt them. |
| 'One-time use only' |
Any plastic container with the 'one-time
use only' label, for example, frozen TV dinner trays. |
The FDA approves them only for one time
use. |
| Microwave safe |
Plastic cling wrap |
OK to microwave, but don't allow the wrap
to touch the food during micro-waving because the hot food may melt the
plastic wrap |
| Microwave safe |
Any plastic with the microwave-safe label
(except be careful with plastic cling wrap, see above). |
These plastic containers are safe to heat
food in the microwave oven. |
More exploring
How
the FDA tests plastic chemicals for safety, WonderQuest.com
Further Reading:
Microwave Ovens and Food Safety, Health Canada, July 2005
Microwaving food in plastic: Dangerous or not? Health Harvard newsletter,
July 2006
PLASTICS AND THE MICROWAVE, FDA Consumer magazine, Nov-Dec 2002
Cooking Safely in the Microwave Oven, FDA Fact sheet, 3 April 2006
FAQs: Using Plastics in the Microwave, Plastics Info, American Chemistry
Council, 2007
Leslie Beck (Globe and Mail columnist) nukes the microwave myths, CTV global
media, 10 Sep. 2008
April Holladay lives in Albuquerque,
New Mexico. Her column, WonderQuest, appears every second Monday of the month
on WonderQuest.com. To read April's past columns, please visit her
website . If you have a question for
April, visit this
information page .
(Answered Feb. 08, 2010)
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