Awareness of Alcohol and Cancer Risk and the California Proposition 65 Warning Sign Updates: A Natural Experiment

In 1986, California enacted Proposition 65 (P65), requiring businesses to display warning signs informing consumers that specific chemicals and alcohol exposure increase the risk of cancer and reproductive harm. In 2018, the P65 alcohol warning signs were updated to include an informational P65 website link, and the update was associated with media coverage and increased enforcement of warning requirements. This study examines knowledge of the association between alcohol use and cancer risk in California compared to the rest of the US before and after the 2018 P65 update. We analyzed state-level data on alcohol and cancer knowledge from the Health Information National Trends Survey from 2017 (n = 3285), 2019 (n = 5438), and 2020 (n = 3865). We performed multinomial logistic regressions to examine knowledge levels by survey year and location (California vs. all other states) and reported the predicted marginals of knowledge by survey year and location. The adjusted prevalence of respondents who reported an association between alcohol and cancer risk was higher in California (41.6%) than the remaining states (34.1%) (p = 0.04). However, knowledge levels decreased significantly over survey years, and there was no evidence for an effect of the P65 update on knowledge in California compared to other states based on the testing of an interaction between state and year (p = 0.32). The 1986 warning signs may have had an enduring effect on awareness, though the update, so far, has not. Further efforts are needed to determine how to increase alcohol and cancer knowledge to address the burden of alcohol-attributable cancers.