Tumorigenesis and body weight in CPC;Apc mice.

A, Tumorigenesis in 40-week-old CPC;Apc mice. Left, mouse administered chlorinated water (10.0 mg/L chlorine). Right, mouse administered tap water (0.7 mg/L chlorine). Tumors were mainly detected in the colon and at the end of the ileum in the chlorinated and tap water groups, respectively. st, stomach; je, jejunum; ce, cecum; co, colon; an, anus. Bar, 10 mm. B, Tumor histology in CPC;Apc mice. H&E staining of a colonic tumor from a chlorinated water-treated mouse (left) and a small intestinal tumor from a tap water-treated mouse (right). Bar, 500 μm. C, Body weight gain in the chlorinated water group (black box) was the same as in wild-type C57B/6 mice, while the tap water group (white box) had significantly lower weight gain. *P < 0.05 (ANOVA).