Abstract |
Background: Radioiodine(131I), a major component of
nuclear fallout and a valuable therapeutic agent for
thyrotoxicosis and thyroid cancer, has been regarded as
a mutagen or a carcinogen without any convincing
evidence. To evaluate the genotoxicity of
radioiodine(131I) we performed a micronuclei test mice
bone marrow. Materials and methods: Mice (ICR strain,
25∼30 g) were divided to 4 groups: control, group 1
(0.17 mCi/kg, usual therapeutic dose for
thyrotoxicosis), group 2 (1.67 mCi/kg, usual
therapeutic dose for thyroid cancer), and group 3
(16.67 mCi/kg, usual accumulated dose causing bone
marrow suppression). 131I was administered
intraperitoneally. Ten mice of each group were
sacrificed at days 1 and 3. Bone marrow were smeared
and stained with May-Grunwald Giemsa method. One
thousand polychromatic erythrocytes (PCE) and
normochromatic erythrocytes (NCE) were counted under
the light microscope, and the number of micronucleated
PCEs were recorded. Results: The frequency of
micronuclei in PCE (and NCE in parenthesis) in the
control group was 0.25±0.07 (0.23±0.07)% in day 1 and
0.24±0.07 (0.21±0.07)% in day 3. Those in group 1 was
0.27±0.1 (0.23±0.09)% in day 1 and. 0.28±0.07
(0.25±0.06)% in day 3. Micronuclei was noted in
0.29±0.08 (0.26±0.09)% in day 1 and 0.31±0.05
(0.29±0.06)% in day 3 in group 2, and in 0.32±0.06
(0.25±0.09)% in day 1 and 0.33±0.08 (0.3±0.06)% in
day 3 in group 3. There was no difference in the
frequency of micronuclei between each groups (p〉0.05)
Conclusion: Radioiodine (131I) did not cause any
genotoxicity in mice bone marrow even at the large dose
(16.67 mCi/kg). |