Since enactment of the major federal environmental statutes of the 1970s, U.S. toxics policy has departed from a primary goal of controlling pollution to increasingly focus on information transparency. One of the most prominent right-to-know laws, California's Proposition 65, has been in force since 1986, yet there is scant literature on its systemic impacts. We conducted 32 semi-structured interviews with business leaders representing some of the largest actors in their sectors to investigate Proposition 65's impacts. We found that Proposition 65 prompts changes to consumer product ingredients and improves supply chain transparency. Businesses (re)formulated products for national and even international markets based on this state law, highlighting the leverage of environmental regulations in a large state like California. Information-forcing laws can thus protect public health in ways that transcend the immediate impacts of transparency with the public about product ingredients. Where Proposition 65 has prompted reformulation, however, there is no check on the safety of alternatives, aside from the incentive to avoid other Proposition 65-listed chemicals. In this study, semi-structured interviews gave insights into the less visible health benefits of a law that lacks built-in methods for quantifying impact and is often publicly disparaged by the businesses it governs.