Survey and comparison of different processes effect, rinsing and baking on remaining amount of heavy metals lead and cadmium in cultivated Tarom rice in Qhaemshahr city paddies in northern Iran

Background & objective:The processes of cooking and also washing reduce the amount of heavy metals in rice. So identify the best method of cooking and washing is essential to reduce heavy metals. The aim of this study is to evaluate the remaining cadmium and lead after cooking and washing processes in Tarom rice in Qaemshahr city. Materials & Methods:Qaemshahr city was divided into five regions and of each region; three rice samples were collected, randomly. The concentration of lead and cadmium were evaluated in 75 raw rice samples, washed by water, cooked, rinsed rice and Kateh. Results were analyzed using software SPSS.18 and t-test student, Analysis of variance (ANOVA) and Duncan's post hoc. Results: According to t-test Student test, amount of lead and cadmium in rice was higher than the international and Iran standards. The minimum amount of cadmium was in the rinsed rice method (0.19 ± 0.08) and lead was in the washed by water method (0.87 ± 0.3). ANOVA showed that there was a significant difference between concentrations of cadmium and lead in samples of rice in different regions (p <0.05).Duncan test also showed that the average of the amounts of cadmium and lead in raw samples had a significant difference with all samples, and residue of these metals in raw rice was more than other samples (p <0.05). Conclusion: The amount of heavy metals in studied rice samples was higher than the standard limit. The minimum amount of metals was observed in the rinsing and washing methods. As regards that contamination in planted ricesnear industrial wastewater was higher than the others, So planting rice in areas closing to the industrial factories should be prevented, and best methods for rice cooking should be trained.