The toxicity of dietary E 171, a food grade titanium dioxide was evaluated. A recent
study reported rats receiving E 171 in water developed inflammation and aberrant crypt
foci (ACF) in the gastrointestinal tract, here, rats received food containing E 171
(7 or 100 days). The 100-day study included feeding E 171 after dimethylhydrazine
(DMH) or vehicle only pretreatment. Food consumption was similar between treatment
groups with maximum total cumulative E 171 exposure being 2617 mg/kg in 7 days and
29,400 mg/kg in 100 days. No differences were observed due to E 171 in the percentage
of dendritic, CD4 + T or T reg cells within Peyer’s patches or the periphery, or
in cytokine production in plasma, sections of jejunum, and colon in 7- or 100-day
E 171 alone fed rats. Differences were observed for IL-17A in colon (400 ppm E 171+DMH)
and IL-12p70 in plasma (40 ppm E 171+DMH). E 171 had no effect on histopathologic
evaluations of small and large intestines, liver, spleen, lungs, or testes, and no
effects on ACF, goblet cell numbers, or colonic gland length. Dietary E 171 administration
(7- or 100-day), even at high doses, produced no effect on the immune parameters or
tissue morphology.