Arsenic Tracking in Iranian Rice: Analysis of Agricultural Soil and Water, Unpolished Rice and White Rice

Abstract

Since rice is a staple food most consumed world-wide, there have been increasing health concerns regarding exposure to arsenic through rice consumption. Several studies have reported the accumulation of arsenic in rice grains cultivated in regions with elevated levels of arsenic in groundwater or contaminated soil. Therefore the principal aim of this study was determining the amount of arsenic in Iranian rice cultivated in the same farms in two consecutive years and arsenic tracking through agricultural water and soil. Therefore different provinces (Mazandaran, Gilan, Fars, Ghazvin, Lorestan and Khozestan) with high harvested area and various weather conditions were selected. Since the arsenic levels in water and soil that were used for rice cultivation are effective on adsorbed arsenic by the rice, therefore to specify the origin of the contamination, sampling from soil, water and unpolished rice of each selected farms were carried. Total arsenic content was determined from the digests by hydride generation atomic absorption spectrophotometer. The results indicated that accumulation and the increase in arsenic content of agricultural soil causes an increase in the arsenic content of white rice. The results have also shown that arsenic contents in all the investigated white rice samples are less than the maximum limit specified by the national standard (0.15 mg/kg), and no significant difference was observed in the arsenic content in two consecutive years of rice cultivation. Therefore the control of arsenic content in water used for irrigation, limited the usage of chemical fertilizers and pesticides that might affect the concentration of arsenic in the soil and maintain the aerobic conditions during either the vegetative or the reproductive stages of the rice growth that might reduce the concentration of arsenic in the soil and consequently in the rice.