Stability of Iodine in Iodized Salt Against Heat, Light and Humidity

Background: Iodine has undeniable effects on human in all stages of life and its deficiency during fetal stages causes mental retardation, which incurs huge costs for treatment and care. Objectives: The aim of this study was to evaluate the effect of heat, humidity and light on the iodine content in iodized salt. Methods: In this analytical-descriptive study, five brands of refined iodized salts were randomly selected from supermarkets in Babol City. All tests were performed in the Chemistry Laboratory of Paramedical School in Babol University of Medical Sciences. In the current study, the samples were kept for three months under different conditions of humidity, without humidity, light, darkness, and temperatures of 37°C, refrigerator and ambient. The iodine amount of samples was tested every 15 days using titration method based on Britain Pharmacopoeia. Data were analyzed with ANOVA in SPSS. Results: The results showed that iodine was reduced in all samples of refined salts: 9.69 ± 1.3 for refrigerator temperature with humidity, 8.34 ± 1.4 for refrigerator temperature without humidity, 8.85 ± 1.2 for 37°C with humidity, 7.80 ± 1.4 for 37°C without humidity, 13.96 ± 1.3 for ambient temperature with light and humidity, 9.61 ± 1.5 for ambient temperature with light and without humidity, 8.64 ± 1.1 for ambient temperature with humidity in darkness, and 5.41 ± 1.2 mg/L for ambient temperature without humidity in darkness. Conclusions: The results indicated that ambient temperature, darkness and non-humidity were the best conditions for keeping iodized salt.