What You Need To Know About Plastic Milk Bottles: PP, PES & PPSU?

Like most parents, we want our milk bottles to be safe and non-toxic; thus look for labels that say BPA free, PVC free and phthalate free. But that is not enough. We also want a milk bottle that is practical for everyday frequent use. This is where the composition of your baby's bottle plays a part. There are 2 main categories of milk bottles: Glass & Plastic.

Note: Aside from bisphenol A (BPA), a common chemical most of us avoid, plastic is actually made up of a wide variety of chemical compounds such as phthalates, polybrominated diphenyl ethers (PBDE) and tetrabromobisphenol A (TBBPA) — all of which alter hormone production and activity in animals and humans. It would be dangerous to think that a milk bottle with a sticker that says 'BPA free' is good enough.

Glass

Glass milk bottles have been around for many years and should always be the first choice. Even at the highest boiling points, borosilicate glass material does not leach or release toxic chemicals and has excellent transparency. Glass milk bottles can last a lifetime if cleaned and stored properly. The downside of glass milk bottles is its weight. An average glass milk bottle can weight between 140g to 300g. Given that a newborn's average weight is 3kg, one glass bottle makes up 10% of a baby's entire being! Glass also makes cleaning tedious. You have to be careful not to break or crack the glass when washing with soapy water. Always have a good look at the bottle's surface before use.

Glass feeding bottles would be my first choice. Unfortunately, it is not practical. I need a bottle that can withstand the occasional slip from the hand or knock around. It makes for one less thing to fret about when juggling a crying baby in one hand, and literally, everything else in the other.

Plastic

While plastic feeding bottles seem more practical than glass bottles, not all plastics are equal. Have a closer look and you will find 3 kinds of plastic to choose from: PP, PES & PPSU. If the bottle does not indicate the type of plastic, assume it is PP by default.

The biggest problem with plastic bottles is leaching. Given that we sterilize our milk bottles frequently in temperatures that can burn skin off bones, the reality is plastic components do breakdown and harmful chemicals will release into the milk it comes in contact with. Some people even put their bottles and teats in a pot of boiling water. Our parents’ and grandparents’ generation did it. But recent study, published in Toxicology Letters and many others with similar findings, discovered that BPA from common plastic bottles releases 55 faster when placed in boiling water!

The good news is there are bad plastics and not-so-bad plastics.

PP

PP (polypropylene) milk bottles are the most common kind of plastic feeding bottles. They are durable, flexible and economical. Used to manufacture household items, PP milk bottles are available in clear and color-tinted transparency (like those of sports water bottles). Though PP bottles can withstand heat of up to 120°C, they may lose transparency over time with frequent sterilization and exposure to boiling water. This is not a good sign as it indicates a chemical component breakdown of the bottle’s plastic makeup. For this reason, it is recommended to change your PP milk bottles once every 6 months or when you notice a change in the bottle’s texture.

PES

PES (polyethersulphone) is a tougher and safer plastic than PP as it comes from a family of thermoplastic polymers – meaning it can withstand temperatures as high as 180°C without chemically breaking down. Again, if exposed to boiling water, PES plastics will start to disintegrate. PES bottles have a natural cloudy looking appearance or a honey-color tint. Again, it is advisable to change your PES milk bottles every 6 months.

PPSU

PPSU (polyphenylsulfone) is the highest performing thermoplastic that gives better durability and heat tolerance than PP and PES. Not only can it withstand continuous exposure to heat and have extreme capability to absorb impact, PPSU plastic does not absorb odor or color. It is naturally BPA free. Due to its a high melting point of 208°C, PPSU plastics are commonly used in aerospace and medical devices that require repeat sterilization. PPSU milk bottles are significantly more expensive than PP and PES bottles, but if you are willing to spend on milk bottles that your baby uses 5-6 times a day every day, this makes for a worthy investment. Despite its supreme durability, it is advisable to change your PPSU milk bottles yearly.