Reformulation

Reformulation is the process of changing a product’s composition to eliminate or reduce listed chemicals below Proposition 65 safe harbour thresholds, eliminating the need for a warning. Reformulation is one of two primary compliance strategies under Proposition 65 (the other being implementing a compliant warning). Successful reformulation requires: identification of the listed chemical(s) in the product; identification of suitable chemical substitutes that do not trigger other Proposition 65 listing or other regulatory obligations; testing to confirm that the reformulated product does not contain the listed chemical above safe harbour levels; and supply chain implementation to ensure reformulated materials are used consistently.

No official definition available; interpreted based on California Health & Safety Code §25249.6 (warning obligation and its avoidance through elimination of exposure).

Reformulation is often preferable to warnings for consumer-facing products where warnings create stigma or competitive disadvantage. However, reformulation presents its own risks: replacement chemicals must themselves be screened against the Proposition 65 list (e.g., companies replacing BPA with BPS now face BPS listing risk). Reformulation decisions should be supported by toxicological review of substitute chemicals against the Proposition 65 list, RoHS/REACH restrictions, and other applicable regulations. Supplier collaboration is essential for successful reformulation in complex supply chains.