SACRAMENTO, California, 2 October 2026 - California has enacted new ingredient-disclosure requirements for children’s diapers that will require manufacturers to identify intentionally added ingredients on packaging and publish product-specific information online, including Chemical Abstract Service (CAS) numbers and ingredient functions.
Governor Gavin Newsom signed Assembly Bill 1901 (AB 1901) on 28 September 2026. The first requirements take effect 1 January 2029, followed by a 1 July 2029 packaging deadline for diapers sold in California.
The law does not prohibit particular chemicals or require reformulation. Instead, it requires manufacturers to disclose intentionally added ingredients in covered diaper products.
What manufacturers must disclose
AB 1901 covers children’s absorbent products including disposable briefs, protective underwear, liners, boosters, inserts and underpads. Covered components include wetness indicators, absorbent linings and fillings, outer shells, adhesive tabs, dyes and fragrances.
The law applies to chemicals intentionally added for a functional or technical effect. It can also cover components or intentional breakdown products of an added chemical when they themselves have a functional or technical effect in the diaper.
By 1 January 2029, manufacturers must maintain a dedicated webpage for each specific diaper product identifying covered ingredients by:
chemical or raw-material name;
CAS number; and
specific function or purpose in the diaper.
Ingredients must be listed by chemical or raw-material weight.
Also beginning 1 January 2029, diapers manufactured or distributed in California must carry an ingredient list and the manufacturer’s disclosure webpage address on the outermost package. Diapers sold in California must meet the packaging requirement beginning 1 July 2029.
Manufacturers will therefore need product-level ingredient inventories and sufficient information from suppliers to identify covered ingredients, CAS numbers and their functions.
Industry raises concerns over confidential information
The disclosure provisions drew industry concerns about confidential business information (CBI).
During legislative consideration, industry representatives sought protections for proprietary formulations and ingredient information, pointing to other California ingredient-disclosure laws that contain mechanisms for protecting qualifying confidential information.
The final AB 1901, however, does not establish a specific CBI or trade-secret exemption from its diaper disclosure requirements. Manufacturers cannot rely on AB 1901 itself to withhold an otherwise covered ingredient simply because its identity is considered confidential.
That could be particularly important where manufacturers depend on suppliers for proprietary ingredient or formulation information. Manufacturers will need enough information to satisfy AB 1901’s disclosure requirements even when components are supplied by third parties.
The California Department of Toxic Substances Control (DTSC) is authorized to adopt regulations to implement, enforce, interpret or make the requirements more specific.
Violations can block California sales
DTSC may impose penalties of up to $5,000 for a first violation and $10,000 for subsequent violations, with penalties possible for each day a continuing violation occurs.
Children’s diapers that do not comply with the law may not be sold, distributed or manufactured in California.
California joins other state disclosure laws
California follows New York and Illinois, which have also enacted diaper ingredient-labeling requirements. New York’s requirements took effect in 2025, while Illinois enacted its Diaper Labeling Act in 2026.
California goes further by requiring product-specific online disclosures that include CAS numbers and the function or purpose of covered ingredients, in addition to package disclosure.
The Environmental Working Group (EWG), which co-sponsored AB 1901 with Consumer Reports, Children Now, and the Center for Environmental Health, has highlighted the additional ingredient information required under California’s approach.
Manufacturers should now determine which diaper products fall within AB 1901, identify covered ingredients and any information gaps with suppliers, and prepare product-specific disclosure systems ahead of the first requirements on 1 January 2029.