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EC number: 200-073-0
CAS number: 50-97-5
Table 2. Comet Assay - Summary of Group Data on Glandular stomach
Group Mean % Hedgehogs
Group Mean % Tail Intensity
Group Mean of Median % Tail Intensity
Group Mean Standard Deviation of % Tail Intensity
Table 2b. Comet Assay - Summary of Group Data on Jejunum
Table 2c. Comet Assay - Summary of Group Data on Liver
MNU = N-nitroso-N-methylurea
*** = P<0.001
In comet assay assessment OECD 489 - 2019: Five males from each dose
group (Groups 1 to 4) were dosed once daily with the test item at
concentration of 0, 100, 350 & 750 mg/kg bw/day for 45 consecutive days
and killed approximately 3 hours after the last dose. Another set of
three males were dosed with N-nitroso-N-methylurea (NMU) on Days 44 and
45 only (approximately 27 and 3 hours before euthanasia) and used as
Samples of liver, glandular stomach and jejunum were taken at necropsy
from these males and transferred to the Cell and Molecular Sciences
Department and processed to provide slides for the comet assay.
The vehicle control group induced percentage tail intensities which were
consistent with the current laboratory historical control data ranges.
The positive control item (MNU) produced a statistically significant
increase in the percentage tail intensity and median percentage tail
intensity in the liver, glandular stomach and jejunum indicating that
the test method itself was operating as expected and was considered to
be valid under the conditions of the test.
The glandular stomach did not demonstrate any marked increases in the
percentage tail intensity or the median percentage tail intensity over
the vehicle control. One individual slide, the ‘B’ replicate slide for
animal 56 in the intermediate dose group had a percentage tail
intensity which was much greater than the remaining slides in the group
and it exceeded the upper limit of the laboratory historical control
range for a vehicle. The reason for this is unclear since the ‘A’
replicate of the same animal and tissue had percentage tail intensities
which were consistent with the rest of the group. However, since the
group as a whole had no statistically significant increases in
percentage tail intensity, the increase observed in one slide is
considered to be artefactual and of no significance in the overall
result. Therefore, it is considered that the test item did not induce
DNA damage in the glandular stomach tissue investigated under the
conditions of the test. There were no dose-related increases in the
percentage hedgehog frequencies in the dose groups of the glandular
stomach. There were no significant increases in the percentage mean
tail intensity or median tail intensity in the jejunum or liver for any
of the test item dose groups when compared to the vehicle control. The
incidence of hedgehog cells in both tissues, however, in the jejunum was
lower than minimum of the historical control range for a vehicle but
this was seen in both the vehicle and the test item dose groups and was
therefore considered to be of no consequence.
Under the condition of the study, the test item did not demonstrate any
significant increases in the percentage tail intensity or median
percentage tail intensity of the jejunum, glandular stomach and liver
and was considered to not induce DNA damage in these tissues. The item
does not meet the criteria for classification for mutagenicity in
accordance with the Regulation (EC) 1272/2008.
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