Ames test
1. Look at whether the acceptance criteria is fulfilled
a. Positive control(s) should show two-fold increase (TA98, TA102 or TA100) or three-
fold increase (TA1535 and TA1537) of revertants in comparison to concurrent vehicle
control.
b. Use max recommended conc of 5000 µg/ml / or show toxicity
2. Check outcome of the test
a. Negative (non-mutagenic)
i. The test item does not produce:
1. Two-fold increase (mean number) of revertants in one of the strains
TA98, TA102 or TA100 or three-fold increase (mean number) of
revertants in one of the strains TA1535 and TA1537 at one or more
concentration levels in comparison to the mean concurrent vehicle
control.
ii. No concentration-related effect is observed.
b. Positive (mutagenic)
i. The test item produces:
1. Two-fold increase (mean number) of revertants in one of the strains
TA98, TA102 or TA100 or three-fold increase (mean number) of
revertants in one of the strains TA1535 and TA1537 at one or more
concentration levels in comparison to the mean concurrent vehicle
control.
ii. A concentration-related effect is observed.
c. Additionally can check difference between with S9 or without S9 to see if it is a pro-
mutagen
Example
Figure 1: Figure 2:
- Validity test: 7x3=21 → ≠20→ not valid - Test results test 2: decreasing fold change→ toxicity, HOWEVER not
genotoxic because fold change too low
- Conclusion: negative
1. Look at whether the acceptance criteria is fulfilled
a. Positive control(s) should show two-fold increase (TA98, TA102 or TA100) or three-
fold increase (TA1535 and TA1537) of revertants in comparison to concurrent vehicle
control.
b. Use max recommended conc of 5000 µg/ml / or show toxicity
2. Check outcome of the test
a. Negative (non-mutagenic)
i. The test item does not produce:
1. Two-fold increase (mean number) of revertants in one of the strains
TA98, TA102 or TA100 or three-fold increase (mean number) of
revertants in one of the strains TA1535 and TA1537 at one or more
concentration levels in comparison to the mean concurrent vehicle
control.
ii. No concentration-related effect is observed.
b. Positive (mutagenic)
i. The test item produces:
1. Two-fold increase (mean number) of revertants in one of the strains
TA98, TA102 or TA100 or three-fold increase (mean number) of
revertants in one of the strains TA1535 and TA1537 at one or more
concentration levels in comparison to the mean concurrent vehicle
control.
ii. A concentration-related effect is observed.
c. Additionally can check difference between with S9 or without S9 to see if it is a pro-
mutagen
Example
Figure 1: Figure 2:
- Validity test: 7x3=21 → ≠20→ not valid - Test results test 2: decreasing fold change→ toxicity, HOWEVER not
genotoxic because fold change too low
- Conclusion: negative
