Information disclosure programs play a vital role in informing the public about risks, yet accurate assessment of the value of information provision requires understanding how individuals respond to risk information. Previous research suggests subtle changes in information presentation can affect both risk perceptions and response to risk. This paper examines how risk perceptions are affected by variations in risk communication about environmental health risks. We conduct an experiment about the health risks posed by arsenic in drinking water and introduce four manipulations in communication with experimental subjects: (1) the level of arsenic in drinking water, (2) framing of risk in terms of health gains or losses, (3) variations in the “bright line” for safety based on federal and state standards for arsenic in drinking water, and (4) variations in relative risk comparing respondents’ arsenic to arsenic of their neighbors. We find that participants do respond to information about the level of risk posed by their drinking water; those with higher levels of arsenic are more concerned. We do not find an effect of information framing. We find that information about “bright lines” standards and relative risk information influences perceptions for participants with intermediate levels of arsenic only. These results support a rational choice model, as these participants at high and low levels of risk were able to understand the risk they faced and additional information did not unnecessarily heighten their perceptions of risk. This suggests the existence of sensitive levels of risk where people can be influenced by additional information.