The public controversy surrounding bisphenol A (BPA) revolves around competing claims about what scientific evidence shows regarding the effects of the chemical on human health. This study uses an experiment embedded within a public opinion survey to test the effects of exposure to such claims on public support for banning the use of BPA in products. Exposure to the claim that "there is not enough scientific evidence that BPA harms human health" reduced support, whereas exposure to the claim that there "is enough scientific evidence" failed to increase support. No effect emerged among those simultaneously exposed to both claims. The "not enough evidence" claim influenced less educated respondents and women but not college-educated respondents or men. Aspects of the underlying structure of opinion also differed depending on which claim(s) respondents received. The results illuminate how members of the public respond to competing scientific claims regarding controversial issues.