Accumulation and Transport of Roxarsone, Arsenobetaine, and Inorganic Arsenic Using the Human Immortalized Caco-2 Cell Line.

Roxarsone (Rox), an organoarsenic compound, served as a feed additive in the poultry industry for more than 60 years. Residual amounts of Rox present in chicken meat could give rise to potential human exposure to Rox. However, studies on the bioavailability of Rox in humans are scarce. We report here the accumulation and transepithelial transport of Rox using the human colon-derived adenocarcinoma cell line (Caco-2) model. The cellular accumulation and transepithelial passage of Rox in Caco-2 cells were evaluated and compared to those of arsenobetaine (AsB), arsenite (As), and arsenate (As). When Caco-2 cells were exposed to 3 μM Rox, AsB, and As separately for 24 h, the maximum accumulation was reached at 12 h. After 24-h exposure, the accumulated Rox was 6-20 times less than AsB and As. The permeability of Rox from the apical to basolateral side of Caco-2 monolayers was similar to As but less than As and AsB. The results of lower bioavailability of Rox are consistent with previous observations of relatively lower amounts of Rox retained in the breast meat of Rox-fed chickens. These data provide useful information for assessing human exposure to and intestinal bioavailability of Roxarsone.