Selenium levels in rice samples from high and low risk areas for esophageal cancer.

OBJECTIVE To assess the relationship between selenium (Se) concentration in rice and the incidence of esophageal cancer (EC) in a high risk area in Northern Iran. METHODS This ecological study was conducted in Golestan province of Iran in 2012. In this area, 45714 acres of land are cultivated by rice. A total of 69 rice samples were taken. We investigated Se concentrations by the voltammetric method. Statistical analysis was performed using the Pearson correlation test and Mann-Whitney U test. RESULTS The mean (+/-SD) Se level in rice samples was 0.229 (+/-0.145) mg/kg. The Se concentration was significantly higher in rice samples from high EC rate areas (0.35 mg/kg) compared with low risk areas (0.16 mg/kg) (p<0.001). There was a significant positive correlation between the levels of Se in rice and the incidence rate of EC (p=0.03). CONCLUSION We found a high rice Se concentration and a significant positive relationship between rice Se levels and EC rates in the Golestan province of Iran. High soil and rice Se levels may play a possible role in the pathogenesis of EC in this area.