ABSTRACT
For centuries, iodine compounds have been used as antiseptics and disinfectants [1]. Iodine preparations are available in aqueous solution, tincture of alcohol, aerosol, ointment, antiseptic gauze pad, foam, and swab sticks [2]. Solubility of iodine is 1 g in about 3000 ml water and 13 ml alcohol [3]. In aqueous solution, iodine is present as seven different species: elemental iodine (I2), hypoiodic acid (HOI), iodine cation ([H2OI]+), triiodine ion (I3-), iodide ion (I-), hypoiodite ion (OI-), and iodate ion (IO3). Elemental iodine, hypoiodic acid, and iodine cation have potent germicidal activity; triiodide and hypoiodite ions are weak oxidants exhibiting mild antibacterial activity, whereas an iodide ion has no antimicrobial activity. Iodate ion has antimicrobial activity only at a pH less than 4, and therefore does not contribute to the germicidal activity of iodine [4]. Povidone-iodine (PVP-I) solution is the most commonly used worldwide because of its potent germicidal activity with relatively low irritancy and toxicity. However, cutaneous irritation has been reported [5-7]. Iodine itself and iodine hydroalcoholic solution are well-known local irritants that can cause iodine burns. To the best of our knowledge, most studies concerning the irritancy of iodine were done either on patients with known iodine-induced contact dermatitis or on normal subjects with PVP-I solution or iodine in ethanol only [6-13]. This study examines the irritant potential and threshold of iodine in three different preparations, namely petrolatum (pet.), 70% isopropyl alcohol (IPA), and PVP-I with different concentrations in normal healthy subjects without iodine allergy, in the hope of refi ning our knowledge of appropriate nonirritant diagnostic patch-test concentrations.
