California has enacted legislation requiring manufacturers of children’s diapers to disclose intentionally added ingredients online and on product packaging, introducing new transparency and labeling requirements for the US diaper market beginning in 2029.
Governor Gavin Newsom signed Assembly Bill 1901 (AB 1901) into law on September 28, 2026. The measure applies to children’s diapers sold, distributed or manufactured in California and establishes requirements for both online ingredient disclosures and information displayed on product packaging.
WHAT MANUFACTURERS WILL HAVE TO DISCLOSE
Starting January 1, 2029, manufacturers will be required to publish a list of all intentionally added ingredients used in children’s diapers on a dedicated webpage on their websites. The legislation also allows manufacturers to provide the information through the product-details page of a website where the diapers are sold.
For each intentionally added ingredient, manufacturers must identify the chemical or raw-material name, the Chemical Abstracts Service (CAS) number and all specific functions or purposes for which the ingredient is used in the diaper.
The information must be listed according to the weight of each chemical or raw material, with the ingredient name, CAS number and function or purpose presented together.
The legislation establishes a broad definition of children’s diapers. The products covered include disposable briefs, protective underwear, liners, boosters, inserts and underpads designed for children.
PACKAGING REQUIREMENTS
AB 1901 establishes packaging requirements in two stages.
Beginning January 1, 2029, children’s diapers distributed or manufactured in California must include, on the outermost package, a publicly identifiable list of intentionally added ingredients along with the internet address of the manufacturer’s dedicated disclosure webpage.
From July 1, 2029, the same information must appear on the outermost package of children’s diapers sold in California.
The two deadlines mean manufacturers will need to consider the January 2029 requirements when producing or distributing products in the state, rather than treating July 2029 as the only packaging compliance date.
ENFORCEMENT AND PENALTIES
The California Department of Toxic Substances Control (DTSC) will be responsible for enforcing the requirements and may adopt regulations to implement and interpret the legislation.
Manufacturers that fail to comply may face administrative penalties of up to $5,000 for a first violation and $10,000 for each subsequent violation. Penalties may also apply for each day that a continuing violation remains in effect.
The legislation prohibits the sale, distribution or manufacture in California of children’s diapers that do not meet the established requirements.
INDUSTRY AND CONFIDENTIALITY CONSIDERATIONS
The new requirements are expected to create additional demands for diaper manufacturers in areas such as ingredient mapping and supply-chain data management. The work may be particularly relevant to products containing multiple polymers, adhesives, fragrances, additives and other intentionally added substances.
The disclosure rules also introduce considerations related to commercially sensitive formulation information. Rather than allowing manufacturers to identify ingredients only through broad categories, the legislation requires individual chemical or raw-material identities, CAS numbers and specific functions or purposes to be disclosed.
Supporters of the legislation have presented the measure as a way to give parents greater visibility into the materials used in products worn by children. Assemblymember Marc Berman, who introduced AB 1901, has said the legislation is intended to provide consumers with information about ingredients used in products worn by children.
PART OF A WIDER US LABELING TREND
California is the latest US state to establish requirements for the disclosure of ingredients in children’s diapers, following measures adopted in other states.
New York enacted its diaper-labeling law in December 2024. The legislation requires packages or boxes containing diapers sold in the state to include a printed list of ingredients in order of predominance and applies to both disposable and reusable diapers.
Illinois subsequently enacted its Diaper Labeling Act, which takes effect on January 1, 2027. The law requires packages or boxes of diapers sold in the state to carry a printed ingredient list in order of predominance. Ingredients present at concentrations of 1% or less may be listed in any order. The legislation also allows manufacturers to use a common or functional name instead of a specific chemical identity when an ingredient qualifies as confidential or a trade secret under applicable law.
California’s requirements differ by combining on-package disclosure with a dedicated online ingredient disclosure system. The state also requires manufacturers to provide the CAS number and specific function or purpose associated with each intentionally added ingredient.
IMPLICATIONS FOR DIAPER MANUFACTURERS
Manufacturers supplying the California market will need to prepare for the new requirements well ahead of the 2029 compliance deadlines. Companies will need systems capable of identifying intentionally added ingredients across products and suppliers, maintaining CAS-number and function information, updating online disclosures when formulations change and incorporating the required information into packaging artwork.
Differences between state-level requirements could also increase the complexity of managing diaper labeling for companies supplying multiple US markets. Manufacturers may need to assess whether to maintain state-specific packaging and disclosure systems or implement broader ingredient-transparency processes across their product portfolios.
AB 1901 adds another regulatory requirement for the US hygiene products sector, as California joins a growing number of states seeking greater disclosure of ingredients used in children’s diapers.
