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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
July to Aug 1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report date:
1991

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1983
Deviations:
yes
Remarks:
no strains with an AT base pair at the primary reversion site (E. coli WP2 strains or S. typhimurium TA 102) were used to detect cross-linking mutagens
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
454-800-3
EC Name:
-
Cas Number:
70258-18-3
Molecular formula:
C6H5Cl2N
IUPAC Name:
2-Chloro-5-chloromethylpyridine
Test material form:
solid

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 mix from Aroclor 1254 induced rat livers
Test concentrations with justification for top dose:
40, 60, 80, 1000, 1400, 1800 µg/plate (first test);
400, 600, 800, 1000, 1400, 1800 µg/plate (repeat test)
Vehicle / solvent:
Solvents used: ethanol (test substance), DMSO (positive controls)
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: sodium azide, nitrofurantoin and 4-nitro-1,2-phenylene diamine were only used without S9 mix and 2-aminoanthracene was only used with S9 mix
Evaluation criteria:
A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 100 and TA 98 this increase should be about twice the amount of negative controls, whereas for TA 1537, at least a threefold increase should be reached. Otherwise, the result is evaluated as negative. However, these guidelines may be overruled by good scientific judgement. In case of questionable results, investigations should continue, possibly with modifications, until a final evaluation is possible.
Statistics:
not specified

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
weak strain-specific bacteriotoxic effect at 400 µg/plate and above
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
True negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
S. typhimurium, other: TA 98, TA 1535, TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
weak strain-specific bacteriotoxic effect at 400 µg/plate and above
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
True negative controls validity:
not examined
Positive controls validity:
valid

Any other information on results incl. tables

2-Chloro-5-chloromethylpyridine was investigated using the Salmonella/microsome test for point mutagenic effects in doses up to 1800 µg per plate on four Salmonella typhimurium LT2 mutants. These comprised the histidine-auxotrophic strains TA 1535, TA 100, TA 1537 and TA 98.

Doses up to and including 80 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a weak, strain-specific bacteriotoxic effect, so that this range could nevertheless be used for assessment purposes.

Evidence of mutagenic activity of 2-chloro-5-chloromethylpyridine was seen. On Salmonella typhimurium TA 100, a biologically relevant increase was found in the mutant count compared to the corresponding negative control. Both with and without S9 mix, there was a positive response and the effect was comparable. The lowest reproducible effective dose was 1000 µg per plate for Salmonella typhimurium TA 100. The Salmonella/ microsome test thus showed 2-chloro-5-chloromethylpyridine to have a weak but definite mutagenic effect.

The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine and 2-aminoanthracene had a marked mutagenic effect, as was seen by a biologically relevant increase in mutant colonies compared to the corresponding negative controls.

Applicant's summary and conclusion

Conclusions:
positive
Executive summary:

The mutagenic potential of 2-chloro-5-chloromethylpyridine was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 in the presence and absence of S9 mix according to OECD TG 471. Doses up to and including 80 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a weak, strain-specific bacteriotoxic effect. Evidence of mutagenic activity of 2-chloro-5-chloromethylpyridine was seen. On Salmonella typhimurium TA 100, a biologically relevant increase was found in the mutant count compared to the corresponding negative control. Both with and without S9 mix, there was a positive response and the effect was comparable. The lowest reproducible effective dose was 1000 µg per plate for Salmonella typhimurium TA 100. The Salmonella/ microsome test thus showed 2-chloro-5-chloromethylpyridine to have a weak but definite mutagenic effect.

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