On December 6, California’s Carcinogen Identification Committee (CIC) voted in favor of listing PFOS “and its salts and transformation and degradation precursors” as “known to the state” to cause cancer. Formal listing is expected soon and will trigger a one-year grace period, during which companies must determine whether the listing requires changes to warning labels for products that contain the listed substance. The hazard identification document on which the CIC’s evaluation was based identifies a “non-exhaustive list” of 169 precursors. Although that list is lengthy, the greater challenge will be determining what other precursors may be in products.