The credibility of a human health risk assessment depends, in the first instance, on what it actually says. The facts need to be accurate, the analysis needs to be rigorous, and the conclusions need to flow rationally from the underlying facts and analysis. The credibility of a risk assessment may also depend, however, on what it does not say. If the risk assessment omits certain facts that might otherwise alter the analysis or interpretation of the scientific data on which the risk assessment is based, confidence in the risk assessment can be diminished when the omitted facts are disclosed or discovered. Information quality as a principle in risk assessment helps to ensure that any information omitted from a risk assessment does not reduce confidence in the conclusions of the risk assessment. This article examines the link between information quality and credibility with reference to a recent “residual risk” assessment completed by the U.S. Environmental Protection Agency (EPA) for the ferroalloy source category under §112(f) of the Clean Air Act (CAA).1 This article concludes that the most credible risk assessments are risk assessments that comply with EPA’s guidelines for ensuring the quality, objectivity, utility, and integrity of information developed pursuant to the Information Quality Act (IQA).2 The article also concludes that EPA’s failure to comply with IQA requirements should be subject to judicial review under §307(d) of the CAA.