Can You Microwave Ziploc Bags? TESTED

We often use ziploc bags to store food in the cupboard, fridge or freezer. For me I use ziploc bags to store my spaghetti sauce.

Usually I pull the spaghetti sauce out of the ziploc bag and put it in a bowl to rehead. But the other day I was wondering “can you microwave ziploc bags?”

Can I just throw my frozen food in the microwave in the ziploc bag to defrost it, or to cook it? Will the bag break, melt or will it leach harmful chemicals into my food?

I did my own experiment microwaving ziploc bags as well as researched the health risks and here's what I found:

You can microwave ziploc bags but it's advised to keep temperatures below 170ºF (75ºC) as higher temperatures seem to deform and nearly melt the bags. Ziploc bags are safe to microwave and I found no research evidence of chemical leaching or negative health outcomes from the plastic used in ziploc bags.

So let's have a great look into the details and what exactly happens when you microwave ziploc bags and what sort of precautions you should take.

What Happens When You Microwave Ziploc Bags?

There were no videos or experiments I could find where people actually microwaved ziploc bags to see what would happen.

So I decided to do an experiment myself and to see what would happen if I put a ziploc bag in the microwave.

I tried it by itself laying flat just to see if it would melt or catch fire and then I put some water in a ziploc bag and microwaved it until the water was boiling to see what would happen.

You can see my experiment in the video below. The results were pretty interesting.

NOTE: I didn't use “Ziploc” branded bags, but used a different brand of a similar bag.

Personally, I fully expected the boiling water to melt a hole in the ziploc bag and to completely destroy it. This didn't happen.

This didn't happen but the heat from the boiling water and the steam permanently deformed the ziploc bag.

Is It Safe To Microwave Ziploc Bags? Are There Health Risks?

Recently there has been a lot of concerns around the use of plastics for food and drink given that some plastics can leach harmful chemicals.

After researching if you can microwave styrofoam (spoiler: don't) and discovering high temperatures leach the probably carcinogen styrene into your drinks I wanted to look at the research behind ziploc bags and the plastic they are made from.

From my research it appears it IS safe to microwave ziploc bags up to 170ºF (76ºC). I couldn't find any research linking the plastic in ziploc bags to chemical leaching into food or drinks or links to negative health outcomes.

Ziploc bags are made from low-density polyethylene plastic (LDPE) as well as linear low density polyethylene plastic (LLDPE) – according to SCJohnson.

So I did some research into LDPE and LLDPE to see if there was any link to leaching of chemicals and/or cancer or other negative health outcomes.

With other plastics you can find multiple research reports and reputable publications talking about the health threats of the plastics and the leaching of chemicals. I searched high and low for research about negative health outcomes associated with LDPE and LLDPE and I couldn't find anything.

From what I can gather it seems that ziploc bags and the plastic they are made out of are relatively safe plastics and are fine to put in the microwave and reheat food in, up to a certain temperature.

You likely know about BPA in plastics which can disrupt the body's endocrine system and wreak all sort of havic. From causing reproductive issues, to neurological problems as well as asthma, cancer and other diseases.

However, BPA is used in a plastic type called “polycarbonate” and not in LDPE. So Ziploc bags do not contain BPA as they are made from a plastic that doesn't have BPA.

What Does Ziploc Say About Microwaving Their Bags?

Ziploc have a safety section on this page of their website where they talk about their plastics and microwaving their bags.

They state that Ziploc bags are BPA free as well as being dioxin free. They state:

When label directions are followed, Ziploc® brand products can be used with confidence. All Ziploc® brand Containers and microwavable Ziploc® brand Bags meet the safety requirements of the U.S. Food and Drug Administration (FDA) for temperatures associated with defrosting and reheating food in microwave ovens, as well as room, refrigerator and freezer temperatures.

I was also able to find this user manual about their vacuum seal bags. It said this:

When ready to use, simply cut the corner of the bag and place with the cut corner up in either a microwave dish or drop into water at a low simmer, below 170ºF (77ºC).

Would I Personally Microwave Ziploc Bags?

I personally prefer paper coffee cups over plastic

The company and the research points to the fact that it's fine to microwave ziploc bags up to a certain temperature. But would I personally microwave ziploc bags?

Given the experiments and the research I have done my answer to this is:

Yes, I would personally feel comfortable microwaving ziploc bags but in very specific circumstances.

I would only microwave them for short periods of time and I would only microwave them to do a partial defrost of frozen food (so I can then remove it and put it in a glass or ceramic bowl) or to slightly reheat something lightweight like a sandwich.

I personally would NOT cook an item in a ziploc bag. My experiment showed how much the bag can deform under high heats and while there is no current research to link LDPE and LLDPE to cancer or other negative health outcomes who knows what they may discover in the future.

It's not difficult to take the food out of a ziploc bag and put it into a glass or ceramic container before micowaving. So personally I would do that unless I was really stuck and a ziploc bag was my only choice.

I definitely won't be microwaving ziploc bags on a regular basis.