The Institute for Safe Medication Practices (ISMP), which operates the National Medication Errors Reporting Program, is warning healthcare providers about repeated incidents of accidental application of “glacial” acetic acid (= 99.5%) to skin or mucous membranes instead of a much more diluted form. Glacial acetic acid is the most concentrated form of acetic acid available. Inadvertent application of this corrosive chemical has led to severe burns, scarring, and other permanent damage to skin or mucous membranes. For more information.