Babies feeding from sterilised plastic bottles are drinking millions of microplastic particles a day, a scientific study published in Nature¹ has found. It’s a very worrying finding for parents, but also important to remember that it’s currently not known if microplastics are harmful.


“We don’t know yet if there are any adverse health effects from exposure to microplastics,” explains Professor John Boland of Trinity College, Dublin, one of the lead authors of the report. “There haven’t been any definitive studies in terms of health implications,” Professor Boland told BBC Radio 4’s Today programme. “We didn’t want to unduly alarm parents but were rather concerned when we saw these numbers.”

Why are baby bottles a particular problem?

The issue with baby bottles is that the advised method of making a sterilised bottle of milk increases the quantity of microplastics released. It’s a combination of two factors:

  • High temperatures required for sterilisation
  • Shaking bottles to mix the formula in

It’s the level of microplastics released by baby bottles that’s the particular concern.

We all consume microplastics on a daily basis from our food and drink. A 2019 World Health Organisation (WHO) report showed that microplastics are in our drinking water and that adults are consuming around 300-600 microplastics a day. But the researchers found that baby bottles could shed millions of microplastics a day.

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Therefore, they suggest a method of preparing baby bottles that will reduce the risk of microplastic release.

What can I do to reduce microplastic exposure when using baby bottles?

This involves some additional steps into the normal bottle-making process, which Professor Boland states will dramatically reduce the level of microplastics released. Please note, sterilisation is still a crucial part of the process and shouldn’t be avoided.

  1. Follow WHO advice to sterilise your baby bottles as usual
  2. NEW If using baby formula, use a sterilised NON-PLASTIC container to prepare it rather than a plastic bottle. Important - still use water heated to at least 70°C to make sure you kill any bugs in the powder
  3. NEW If using baby formula, shake the powder mixture gently to mix it into the water. If your non-plastic container doesn't have a lid, stir gently with a sterilised metal spoon
  4. NEW Prepare some additional sterilised water using a NON-PLASTIC container to heat it. Let it cool
  5. NEW Gently rinse 3 times the sterilised bottle with this additional cool sterilised water before pouring in the prepared fomula or expressed milk. This will help to remove the loose microplastics

Non-plastic containers can include stainless steel, glass bottles or a ceramic container. Remember - when using non-plastic containers, these can be very hot after sterilisation. For containers that have not been in contact with milk or milk powder, you can sterilise these by washing them thoroughly at a high temperature and immersing them in boiling water.

What are microplastics?

Microplastics are very small pieces of plastic less than 5mm in length. They’re created when plastic degrades. Research has found microplastics all over the world, including within our food and drinking water. However, it’s thought most microplastics are excreted from our bodies and scientists are calling for more research to investigate whether microplastics can be absorbed into our bloodstream.

The WHO stated in its 2019 report about microplastics in drinking water: “Although there is insufficient information to draw firm conclusions on the toxicity of nanoparticles, no reliable information suggests it is a concern.” We’ll report as soon as further research results are available.

Does this affect all baby bottles?

No, but it is most. The study found that bottles made from polypropylene are the ones that shed microplastics. However, polypropylene is one of the most common types of plastic and used in 82% of baby bottles. Glass bottles don’t contain polypropylene and so do not release microplastics.

Should I change to glass bottles?

In the UK, we don’t have high usage of glass bottles, although they are available to buy. In other countries, such as China, glass bottles are frequently used. There are pros and cons to using glass bottles. Obviously, there isn’t the risk of microplastic particles being released. On the downside, they’re heavy, less available and can potentially break when dropped.

What about silicone or stainless steel bottles?

There’s limited research on silicone and stainless steel bottles, particularly around potential leaching when using high temperature liquids, such as near boiling water. We’ll be looking into this further.

Should I stop bottlefeeding?

If you're able to breastfeed or part-breastfeed, then your baby won't be exposed to microplastics from bottles (remember, if you're expressing, you need to gently rinse out your sterilised bottles - Step 5 above). This is an additional upside to other benefits of breastfeeding.

What if I’m using expressed milk rather than formula milk?

This issue concerns polypropylene bottles rather than formula milk. Using your own milk means you don’t have to shake it, but you do still need to sterilise your bottles, so the new method will still reduce the microplastics level.

What about using plastic containers for solid baby food?

The study showed that microplastics are released at a much higher level when plastic is exposed to a high temperature, so if you’re heating food in a microwave, it’s always best to use non-plastic containers.



¹Li, D., Shi, Y., Yang, L. et al. Microplastic release from the degradation of polypropylene feeding bottles during infant formula preparation. Nat Food (2020)


Susie Boone, Editorial Director MadeForMums
Susie BooneEditorial Director, MadeForMums