Abstract
Rice bran is a common feed/food stuff for animals and humans; however, it usually contains a substantial amount of arsenic that is a class-I, non-threshold carcinogen to humans. This study was to investigate the fecal arsenic excretion pattern from the pigs fed an arsenic-containing rice bran. Twenty growing gilts (26.3 kg) were randomly assigned to 3 dietary treatments (n = 6 or 7) with Diets I, II, and III containing 0, 36.7, and 73.5% rice bran, and 0, 306, and 612 ppb arsenic, respectively. The feeding trial lasted 6 weeks, and fresh fecal samples were collected on Days 0, 14, 28, and 42 post-treatments. Fecal arsenic concentrations were analyzed using an ICP-MS protocol standardized by the U.S. Environmental Protection Agency. Tobit statistical model was employed for data analysis because some censored values were obtained from the laboratory sample analysis. Results (Table 1) showed that there were no differences in fecal arsenic concentrations from Day 0 through 42 post-treatment in pigs fed Diet I (a control diet). Nevertheless, the fecal arsenic concentration was increased significantly (P < 0.05) on Days 14 and 28 when compared to Day 0 post-treatment with Diet II (a moderate level of rice bran inclusion), and it was further increased (P < 0.05) on Day 42 post-treatment. The fecal arsenic excretion pattern in pigs fed Diet III (a high level of rice bran inclusion) was the same as that in pigs fed Diet II. The dietary treatment effects on fecal arsenic excretion were already reported previously. In short, the results of this study suggest that the fecal arsenic excretion is increased in the first 4 weeks and then further increased around the 6th week since the start of feeding arsenic-containing rice bran. This further increase may be due to the saturation of arsenic retention in pig body.
Measured versus modeled dietary arsenic and relation to urinary arsenic excretion and total exposure
