Is Silicone Really Safe? Will It Ever Leach Chemicals?


Studies have found that even after 6 hours of contact, silicone doesn’t leach any chemicals into milk. Parents can rest easy when giving baby a bottle; however, cooks might want to think twice about silicone bake ware since the material becomes less stable at temperatures above 300°F.

We often get asked by our customers what our baby bottle nipples are made of. The answer is silicone.

Really the only other option for baby bottle nipples is Latex, but this rubber sometimes provokes allergies.

Silicone is more flexible, and therefore more “breast-like,” so for Mason Bottle, the choice to use silicone was clear.

(We also use silicone for our Mason Bottle sleeves. The material is durable and stretches easily over the jars. And even though mason jars are pretty tough to break, adding a silicone sleeve can also add peace of mind for parents.)

Ok, now back to the question at hand: “Is silicone really safe?” One of our favorite authors, Alexandra Zissu, wrote a great article answering this question for Healthy Child Healthy World. We are just linking to her post and reproducing it below, because frankly we can’t say it any better than she did:


From Bottle Nipples to Baked Goods: Is Silicone Safe?

By Alexandra Zissu, February 25, 2014

Silicone has emerged as the new essential material, and it’s easy to see why. It goes from oven to freezer without blinking, and offers non-stick, quick-cooling, easy-cleaning performance in any shape under the sun from baking molds and cookie sheets to bottle nipples and pacifiers.

Before you jump on the bandwagon, it’s good to ask a few questions. As in: what exactly is this stuff and how safe is it to use?

Silicone is made from silicon, the second most abundant element on earth and a chief component of sand. Combine silicon with oxygen, add ingredients like hydrogen, carbon, and methyl chloride, and you get silicones. The FDA says that silicone won’t react with other materials or release hazardous compounds when heated and is safe for food contact. Several studies, however, suggest that such pronouncements are premature.

The concern revolves around compounds found in silicone called siloxanes. Let’s dig a little deeper. There are siloxanes designated as D4, D5, and D6. Research finds that D4 and D5 are persistent in the environment, meaning they don’t break down or decompose and therefore can accumulate in the bodies of people or wildlife. Animal tests link D4 to reproductive impairment, liver changes, and benign uterine tumors, and show it may be an endocrine disruptor. D5 is associated with uterine cancers and adverse reproductive, neurological, and immune effects. D6 is persistent but doesn’t appear to accumulate in animal tissues. It’s linked to liver and thyroid enlargement, and reproductive issues.

They can also get into our bodies when we use silicone products. Studies have found that small amounts of siloxanes migrate into foods baked in silicone. The amounts involved were dependent on fat content—the more fat a food had, the more siloxanes were transferred. For the most part, these amounts were well within regulatory limits (60 milligrams per kilogram of food). However, tests on meatloaf found its siloxane contamination exceeded this standard. Another study observed that silicone molds remained stable at temperatures up to 300°, but lost siloxane above this temperature. Most baking is done above 300°. Some molds lost over 0.5% of their total weight after 4 hours of heating.

Good news for parents of young babies: The situation appears to be much different where nipples and pacifiers are concerned. A 2012 study examining potential siloxane migration into milk and infant formula from silicone nipples detected no contamination after six hours of direct contact with silicone.

Here are some silicone coping strategies:

  • Until more is known about the effects of siloxane exposures in people, it may be a wise precautionary step to bake in something other than silicone.
  • That said, when it comes to your cookie sheets, silicone cookware is likely safer than traditional non-stick varieties using perfluorochemical coatings. If it’s a choice between the two, use silicone. Glass, ceramic, and stainless steel bakeware are best.
  • Given the negligible time they come into contact food, silicone items like spatulas, splatter guards, pot holders, etc. appear safe. Just don’t melt them!
  • The evidence indicates that clear bottle nipples and pacifiers can likely be used without worry. (Siloxane migration concerns appear to be linked to a combination of heat exposure and food fat content). To be safe, keep yours out of the dishwasher and discard any that are excessively cloudy or worn. Nipples should replaced every 6 to 8 weeks regardless of appearance.
  • Always test all silicone before buying by pinching and twisting a flat surface on the product. Pure silicon won’t change color. If the product contains fillers, a potential source of contamination, white will show through.

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@faustisland just bought a pack of Mason Bottle Silicone Nipples, and then combined one with a classic blue mason jar she had at home. Extra adorable! uses Mason Bottle Silicone Sleeves to make toddler training cups for her big girls.

@headygrimm gets a Mason Bottle + Silicone Sleeve ready for her little one. She got the whole bottle including the jar as part of the Essential Mason Bottle Gift Set, but you can also make your own with jars from home using the Mason Bottle DIY Kit.

@loveandcovenant uses the 8 oz DIY Kit in combination with their mason jars from home.

@eyecreate_ gave her little lade The Original Mason Bottle. The width of mason jars makes them easy to hold for little hands.

@headygrimm got the Essential Mason Bottle Gift Set for her little one. It comes with both size bottles, both sleeves, and set of extra set of Medium Flow Nipples.

Paola used Mason Bottle with her son Max from the day they brought him home from the NICU. Though he didn't take to the preemie nipples in the hospital, he latched onto his Mason Bottle immediately!

Checkout the 4-in-1 design of the Toddler Tumbler.

@MasonBottle we like to use our 4 oz. sleeves with baby food portions.

Why Moms Love Us


Made in the USA

"I wish I knew about these before I had my shower, and avoiding all the plastic bottles I ended up with. They will also make great glasses after bottle use is over. Also happy to see the Made in the USA mark on the product as well." -Cathryn


Easy to Clean

"The next best thing to breastfeeding and the world's best shower gift! I love that I will never again have to buy a baby bottle because I already have tons of mason jars and they are so easy to clean. Our little guy loves his bottle!" -Susan


Breast Like Shape

"The nipples are very wide, like on an actual breast, and our daughter really liked them. Early on, she would suck really hard on the other nipples and make a very strange noise. As soon as we changed over to these her feeding became effortless." -Denielle

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