California Just Passed a Diaper Transparency Bill. Here’s What Parents Should Know.
A new bill would force diaper manufacturers to disclose what they intentionally put inside their products — raising a simple question many parents have never thought to ask: what is actually sitting against a toddler’s skin all day?
Most parents can tell you exactly what is in their toddler’s breakfast. They check the ingredients in snacks, read the label on sunscreen and spend ten minutes comparing two bottles of children’s shampoo.
But there is one product many toddlers wear for hours at a time, every single day, where the ingredient list has historically been much harder to find:
That information gap is now getting attention from California lawmakers.
On August 27, California’s Legislature sent Assembly Bill 1901 forward after passing a measure focused on ingredient disclosure for children’s diapers. The enrolled bill would require manufacturers to identify intentionally added ingredients and explain their function, with new disclosure requirements taking effect in 2029.
- Manufacturers would have to disclose intentionally added diaper ingredients.
- The disclosure would include the ingredient name and its purpose in the diaper.
- Ingredient information would be made available online and on outer packaging under the bill’s timetable.
Why would a diaper need an ingredient-transparency law?
Because a disposable diaper is not simply a piece of cotton.
Modern disposables can be built from a mix of absorbent polymers, plastics, adhesives, inks, dyes, elastic materials and other components. Researchers and consumer groups have also scrutinized diapers for substances such as phthalates, PFAS, volatile organic compounds and heavy metals.
Some substances investigated in diapers have names most parents would never associate with something a toddler wears.
The existence and amount of any substance varies by product. The point of the California bill is that parents should be able to see what manufacturers intentionally add rather than having to guess.
Actor and mom of two Hilary Swank, who backed the legislation alongside the Environmental Working Group, told CNN that some ingredients found in diapers have been linked to hormone disruption, nervous-system effects and skin reactions.
And young children are the reason this conversation gets so much attention. Their skin is still developing and is generally more permeable than adult skin — while a diaper can remain in direct contact with that skin for much of the day.
“Look at what’s in constant contact with your baby every single day — diapers, wipes, creams.”Hilary Swank, speaking to CNN about the push for greater product transparency
Which raises an uncomfortable question
If a child is still wearing diapers as a toddler, and parents cannot easily see everything that goes into them, is keeping them in disposables all day still the only practical option?
The obvious alternative is regular cotton underwear.
It is simple. Breathable. Familiar. And it moves a child away from the disposable-diaper routine entirely.
There is just one problem.
Regular underwear is built for children who are already potty trained.
Easy accident protection, but the child remains dependent on the same product parents may now have more questions about.
Simple fabric and a real underwear feel — but one missed potty trip can mean wet pants, floors, couches or car seats.
For a child who is halfway between diapers and underwear, neither option feels quite right.
That is where a third category starts to make sense: underwear designed specifically for the transition out of diapers.
Not a disposable that tries to feel like underwear. And not ordinary underwear that offers no help when an accident happens.
The “middle step” more parents are using
UpAiry training pants were designed for toddlers who are learning to use the potty but are not ready for regular underwear yet.
They look and feel much closer to normal undies, but the construction is designed around the reality of potty training: accidents still happen.
The inner and outer fabric is cotton, so the part your child actually feels resembles real underwear rather than a disposable diaper.
Layers of cotton gauze help catch a normal potty-training accident instead of sending it immediately through to clothing or furniture.
A waterproof TPU layer sits inside the construction to help contain leaks. It is not the fabric sitting directly against the child’s skin.
There is another important difference between training pants and a disposable diaper.
They are not supposed to make an accident disappear.
A disposable is designed to pull moisture away and keep the wearer feeling dry. That makes sense for a baby. But once a toddler is learning the connection between the sensation of needing to pee, having an accident and using the potty, completely hiding that feedback can work against the transition parents are trying to make.
UpAiry pants contain the mess while still allowing the child to notice that an accident happened.
That distinction matters more after the California bill
The new legislation is fundamentally about transparency: parents should be able to know what is in a product that spends so much time against their child’s body.
For babies, diapers are obviously a necessity. But for toddlers who are already at potty-training age, the conversation is slightly different.
Parents are not only choosing which diaper to use. They are also deciding how long their child needs to keep wearing diapers at all.
That is why a washable, underwear-style transition product can be such a practical middle ground: less reliance on disposables without pretending a toddler will suddenly stop having accidents overnight.
UpAiry Training Underwear
Washable training pants for toddlers who still have accidents but are ready to start moving away from disposable diapers.
- Cotton inner and outer fabric
- Absorbent cotton-gauze core
- Internal waterproof TPU barrier
- Made to feel more like real underwear
- Designed for the potty-training transition
Available in multiple prints and sizes. See product page for current options.
The takeaway for parents
The California legislation does not mean every disposable diaper is dangerous. What it does is put a spotlight on something parents have had remarkably little visibility into: the materials and ingredients inside a product their children may wear thousands of times.
And for parents of toddlers, it is a useful reminder that there is another question worth asking alongside “what diaper should I buy?”
Does my child still need to be in one?
If they are old enough to begin potty training, ordinary underwear may be a step too far — but staying fully dependent on disposables is no longer the only option.
Training pants give families a middle step: something that feels like underwear, can handle the accidents that still happen, and is built to help the child move toward toilet independence.
See the training pants mentioned in this article →California AB 1901 is an enrolled 2025–2026 bill concerning disclosure of intentionally added ingredients in children’s diapers. The California Legislature completed passage in late August 2026 and the enrolled version is dated September 1, 2026. This article discusses the proposal and public reporting around it.
Emily Carter
Emily Carter writes about early childhood and family health. This article is sponsored content produced on behalf of UpAiry.