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EC number: 215-481-4
CAS number: 1327-53-3
NaAsO2 induces sparse benign and malignant tumors among treated rats
(not statistically significant).
2-year (104-week) carcinogenicity dose–response study was
conducted with sodium arsenite (NaAsO2) administered via drinking
water to Sprague-Dawley rats (50/sex/group, 8 weeks old at the
start of the study) at concentration of 0, 50, 100 and 200 mg/L ad
libitum. Mean daily drinking water and feed consumption were
measured once weekly per cage for the first 13 weeks, then every 2
weeks until 111 weeks of age. Body weight was measured
individually once weekly for the first 13 weeks, then every 2
weeks until 111 weeks of age (however, dose levels expressed in
mg/kg bw/day are not provided in the publication). The rats were
maintained until spontaneous death, at which time each animal
underwent complete necropsy. Histopathological evaluation of all
pathological lesions and of all organs and tissues collected was
dose-related lower intake of water was observed in both male and
female rats. In females, water consumption became similar between
the group treated at 50 mg/L and the control after 88 weeks of
age. A dose-related lower intake of feed was also noted in both
male and female rats. This difference was less marked between the
group treated at 50 mg/L and the control. A dose-related
difference in mean body weight was observed in males. The
difference was more evident at 200 mg/L (circa 15% when compared
with controls). Mean body weight in females was about 20% less at
200 mg/L compared with control and about 10% less at 100 mg/L. No
treatment-related differences in body weight were observed in
females at 50 mg/L. A slight decrease in the survival rate was
observed in males at 200 and 100 mg/L, particularly from 40 to 88
weeks of age, whereas in females, a decrease in survival rate was
observed from 104 weeks of age until the end of the experiment.
males treated at 100 mg/L, a slightly increased incidence of
animals bearing malignant tumors and a statistically significant
increase in number of total malignant tumors (p<0.05) were
observed when compared to controls. One adenocarcinoma of the lung
was seen at 200 mg/L, one carcinoma of the kidney and one
papilloma of the pelvis at 100 mg/L and two papillomas of the
renal pelvis in another rat at the same dose. Renal pelvis
papillomas were also observed in two males at 50 mg/L.
females treated at 100 mg/L, a slightly increased incidence of
animals bearing malignant tumors and an increased number of total
malignant tumors were observed when compared to controls. Three
animals were found bearing kidney adenomas, one bearing a kidney
carcinoma and one bearing a renal pelvis papilloma. One animal
with a bladder carcinoma was also noted in this group. At 200
mg/L, one adenocarcinoma of the lung was observed. The same group
also included two animals bearing kidney adenomas, two bearing
kidney carcinomas and one bearing a renal pelvis carcinoma.
authors concluded that, under the conditions of their study,
sodium arsenite induced sparse benign and malignant tumours
amongst treated rats. They noted that the types of tumours
observed were infrequent in the strain of Sprague-Dawley rats of
the colony used in their laboratory (Soffritti et al., 2006).
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