Safe to Microwave Medela Breast Pump Parts to Sterilize?

Updated on February 12, 2008
L.L. asks from Minneapolis, MN
6 answers

I sterilize my breast pump parts in this special plastic bag made by Medela that you put a tiny bit of water in and then put it in the microwave for 3 minutes. Last night the local 5pm news reported a new study about a toxin (bisphenol-A or BPA) that leaches from some plastic baby bottles when they're heated or washed in hot water (including Avent, Evenflo, Dr. Brown's and Disney/First Years). At first, I freaked out but then I read the report and discovered that Medela breast pump bottles are BPA-free. (The report is at

(BPA is bad b/c it mimics hormones, which also act at very low levels. Exposure to BPA has been linked to diabetes, thyroid disease, breast cancer, and prostate cancer. I've switched to glass bottles which they sell at BabiesRUs.)

Anyway, now I'm wondering if I should stop sterilizing my plastic breast pump parts in this microwavable bag. Maybe there are other nasty things in the plastic that leach out when heated? I did a little web research but didn't find anything. Does anyone know?

I know I could worry til the cows come home about the toxic soup I swim in just by living in the modern world every day, but if I can make even a little dent by simply changing the way I wash my breast pump parts, why not.

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So What Happened?

I decided to stop using the microwave to sterilize my breast pump parts and just use good ol' soap and water. Thanks for all the great advice everyone.

More Answers



answers from Minneapolis on

I've raised three kids and I always usued the sanitizing setting on the dishwaser and they were just fine. I always kept a crockpot plugged in with water in it to heat the bottles. I always boiled the parts of my Medela pump in a pan then took them out with a tongs and put them on a fresh cloth to airdry. My kids are 20,11 and 7yrs old. and perfectly healthy, smart and beautiful. Good luck with everything. R. G.

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answers from Minneapolis on

My husband works for 3M and works with plastics. He said any time you expose plastic to extreme temperature changes(microwave/dishwasher) it can change it's chemical makup.
We don't dishwash or microwave any plastics anymore. The softer plastic the medela stuff is made of is the most safe(polypropelene). The harder plastic like Nalgene bottles or Avent(polycarbonate)is the most unsafe and leeches out the most stuff and into our bodies if we use them. Hope that's helpful.

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answers from Minneapolis on

Chemicals tend to leach out of plastics when there is food in them (particularly high-fat food) that is then heated. The BPA leaches into the fat. This is so alarming when you realize just how many baby bottles are filled with fatty formula or milk and then heated. Almost all of the commonly used bottles are made from the problematic plastics, or are unlabeled. Medela bottles and parts are one of the few brands that are safe to use.

In "Boys Adrift" by Dr. Leonard Sax he outlines research about BPA and other endocrine disruptors from plastic bottles that may also be contributing to problems with testosterone levels in boys, and affecting their success in school and in life.

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answers from Minneapolis on

Hi L.,
I'm a nurse-midwife and breastfeeding instructor (and a mom who uses the same product). I relate to your worries - so much is unknown about the effects of plastic compounds on our bodies. But my thinking is that since there isn't any food in the plastic pump parts at the time of the sterilization, it should be ok. I worry more about microwaving food in plastic containers (I transfer to glass or ceramic). I'd also wait until everything is completely cooled before putting milk in the bottles.

I also hear that once plastic products are old enough to become cloudy or scratched it's time to replace them. The Consumer Products Safety Commission has a good site at
I hope that helps...
Amma Maternity

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answers from Minneapolis on

Hi L. -

I have the same breast pump and my instinct has been to wash the pieces in soap and water, and then I boil them on the stove. The combination of the plastic and the microwave seem to me, two not so good ingredients when it comes to our babies.

I have a five month old.


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answers from Minneapolis on

I have heard the same results. The report I saw said to look at the bottom of the bottles and see what recycling number to look for. I believe it was #1, 2, 5 where the best.. I used the same bags from Madela and I believe you can trust that it is more safe than having dirty bottles and pump parts. On a side note How do the glass bottles hold up and are they worth the $10.99 a bottle. How many do you have in stock? Sorry we are expecting our second and I am throwing away all of our Avent bottles!

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