Groups of 50 male and 50 female of F344 rats (Charles River Japan, Inc.), six weeks old, received drinking water containing 0, 200, 1000 or 5000 ppm 1,4-dioxane (>99.0% Wako Pure Chemical Co., Tokyo) for 104 weeks. And groups of 50 male and 50 female of BDF1 mice (Charles River Japan, Inc.), six weeks old, received drinking water containing 0, 500, 2000 or 5000 ppm 1,4-dioxane for 104 weeks.
