California mandates ingredient disclosure on children's diaper packaging from 2029

California has signed AB 1901 into law, requiring manufacturers of children's diapers to disclose intentionally added ingredients both online and on packaging, with on-pack requirements phased in from January 2029 and extended to all diapers sold in the state from July 2029. The law follows similar measures in New York and Illinois and adds another state-specific compliance burden for US hygiene packaging.

Why this mattersA third US state now requires chemical-level diaper disclosure, forcing manufacturers to choose between state-specific packaging artwork or a single national transparency standard.

• Governor Gavin Newsom signed AB 1901 on 28 September 2026.
• From 1 January 2029, outermost diaper packaging distributed or manufactured in California must list intentionally added ingredients and a disclosure webpage address.
• From 1 July 2029, the same on-pack disclosure applies to all children's diapers sold in California.
• Manufacturers must publish ingredient name, CAS number and function for each ingredient online, ordered by weight.
• First violations carry penalties up to USD 5,000, rising to USD 10,000 for subsequent violations, enforced by the California Department of Toxic Substances Control.
• New York's diaper-labeling law took effect December 2024 and Illinois's takes effect 1 January 2027, both requiring printed ingredient lists by predominance.

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