Rice is one of the most highly consumed foodstuffs in the world. In keeping with this, produced rice of many regions of the world contains high lead content. The present research was done to study the effects of the pre-cooking process of rice with acetic acid and citric acid on the concentration of lead. Rice samples were divided into 5 different pre-cooking treatment groups of soaking in acetic acid 1% and soaking in citric acid 1% (2 hrs), boiling with acetic acid 1% and boiling with citric acid 1% (20 min) and finally 6 times rinsing with deionized water. Then, measurement of lead remains was done using an atomic absorption optical spectrometer equipped with a detector of graphite furnace with deuterium lamp. The mean concentration of lead in primary rice samples without any processing operation was 87±4.8 ppb. The mean concentration of lead in rice samples processed with soaking in acetic acid, soaking in citric acid, boiling with citric acid, boiling in acetic acid and finally 6 times rinsing with deionized water were 55±3.8, 14±1.6, 32±2.4, 14±1.1 and 30±0.5 ppb, respectively. The highest reeducation percent of lead in rice samples was obtained in both soaking with citric acid and boiling with citric acid (84%). In keeping with the high concentrations of lead in studied rice samples, obtained concentrations were lower than the allowed limit of lead announced with the international standard organization of Iran (150 ppb). Boiling and soaking of rice samples with citric acid 1% can be a convenient and fast way to reduce the concentration of lead in rice samples.

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Arrival of heavy metals into environment is along with development and industrialization and is one of the subjects of present age. The sources of spreading heavy metals are completely different. Besides the natural sources, the arrival of these metals into environment is starting to grow through artificial factors, i.e., utilizing phosphate fertilizers, fossil fuels, industrial waste-waters and traffic. Recently, the general pollution caused by heavy metals is rising that it is led to create a risky situation following the accumulation of these metals in plants and animals. Besides their serious damage to the health of these creatures, the use of their end product is detrimental for human (1,2). Encountering some of them through water and food substances can cause acute, chronic and dangerous poisonings (3). Among heavy metals, elements such as lead, cadmium and