Antimicrobial properties of iodine based products

Introduction Iodine and iodinated resin have been evaluated for water treatment. Iodine (2.5-7.0 mg/l water) has been used in water treatment since 1900, especially for troops. Iodine’s solubility in water depends on temperature (0.29 g/1 at 20°C, 0.78 g/l at 50°C and 4.45 g/1 at 100°C). Its hydrolysis and hence speciation in water depends on pH and concentration of titrable iodine in solution. Taylor & Butler found iodine most effective against poliovirus at pH 9.0. Karalekas et al found little difference in bactericidal effects of 1.0 mg/1 iodine at pH 5 and 7, but a pronounced reduction in effect at pH 9.0. Elemental iodine (I 2 ) is reported more effective (3-6 times) against spores than hypoiodous acid (HIO), an effective bactericide and virucide. Chang found I 2 more effective (2-3 times) than HIO against cysts of Entamoeba histolytica, whereas HIO to be 40 times more effective against viruses than I 2 . Clark et al studied vulnerability of viruses to HIO. Chang found HIO to be 3-4 times more effective than I 2 against Escherichia coli. Iodine inactivates faecal bacteria in poor quality water at different turbidities. It provides disinfection of water across a wide range of pH due to presence of various iodine moieties. A single serving of many seafoods provide more iodine than daily intake from water. Also, long-term ingestion of iodated water failed to elicit any harmful effects. On the other hand, in goiter prone areas, daily intake of iodized salt (I or IO 3 ) is recommended as follows: adults, 150; pregnant women, 220; and breastfeeding women, 290 μg. Study is available on the amount of I and IO 3 in commercial iodized salt samples. It is of interest to see if IO 3 , present in salt being administered for oral rehydration, would be effective in water disinfection.