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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Method similar to OECD 471 except certain E. coli strains missing.
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
E. col wpA2 strains not included
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
2,4-dichlorophenol
EC Number:
204-429-6
EC Name:
2,4-dichlorophenol
Cas Number:
120-83-2
Molecular formula:
C6H4Cl2O
IUPAC Name:
2,4-dichlorophenol
Details on test material:
Received as coded aliquots from Radian Corporation, Texas, USA

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
S9 fraction from Syrian hamster or Sprague Dawley rat Aroclor 1254 induced liver
Test concentrations with justification for top dose:
0, 3.3, 10, 33, 100, 333 µg/plate
Controls
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Remarks:
2-aminoanthracene, 4-nitro-o-phenylediamine, sodium azide
Details on test system and experimental conditions:
2,4-DCP in addition to the solvent and positive controls were tested in the presence or absence of S-9 mix. 3 replicates were used. The experiment was repeated no less than 1 week after completion of the initial test. Liver S9 fraction were prepared from male Sprague Dawley rats and Syrian hamster that were induced with Aroclor 1254 5 days before sacrifice.
Evaluation criteria:
A positive repsonse was defined as a reproducible, dose related increase in histidine-independent (revertant) colonies in any one strain/activation combination. An equivocal response was defined as an increase in revertants which was not dose related, not reproducible, or of insufficient magnitude to support a determination of mutagenicity. A reponse was considered negative when no increase in revertant colonies was observed after chemical treatment.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with
Genotoxicity:
ambiguous
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Slight toxicity seen at highest dose tested (333 µg/plate)
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at highest dose tested 333 µg/plate
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium, other: TA 1537, TA98 and TA 100
Metabolic activation:
with
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at highest dose tested (333 µg/plate)
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
The equivocal or ambiguous result see with metabolic activation in TA 1535 was seen in the presence of Hamster derived S9 only and NOT with rat derived S9.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
ambiguous with metabolic activation Strain 1535 gave equivocal results in the presence of hamster derived S9 only (and not rat derived S9)).

2,4 dichlorophenol gave an ambiguous result in strain TA 1535 in the presence of Hamster derived S9 only. Results obtained in all other scenarios examined were negative.
Executive summary:

In a reverse gene mutation assay in bacteria, strains TA 98, TA 100, TA 1535, TA1537 of S. typhimurium were exposed to 2,4-dichlorophenol, at concentrations of 0, 3.3, 10, 33, 100, 333 µg/plate (co-incubation) in the presence and absence of mammalian metabolic activation derived from both Aroclor 1254 induced Sprague Dawley rat and Syrian hamster liver.

2,4-dichlorophenol was tested up to cytotoxic concentrations (300 µg/plate). The positive controls induced the appropriate responses in the corresponding strains.  There was some evidence of induced mutant colonies over background (2 fold) for strain TA 1535 at the top dose (i.e. in the presence of cytotoxity) in the presence of Syrian hamster S9 but not rat S9.

This study is classified as acceptable and satisfies the requirement of Test Guideline OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data with the exception that certain E. coli strains were missing.