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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:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study. Limitation: only 4 strains tested, not tested in TA102 or E. coli

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1994

Materials and methods

Principles of method if other than guideline:
OECD Guide-line 471 (1983)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
IUCLID4 Test substance: other TS: n-butyl isocyanate, purity: 99.4 %

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S-9 mix
Test concentrations with justification for top dose:
up to 5000 ug/plate
Vehicle / solvent:
ethylene glycole dimethylether (EGDE) for butyl isocyanante
dimethyl sulfoxide for positive controls
Details on test system and experimental conditions:
IUCLID4 Type: Ames test

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
plate incorporation assay: up to 40 µg/plate not bacteriotoxic, doses up to 1000 µg/plate could still be used for assessment; preincubation method: up to 16 µg/plate not bacteriotoxic, doses up to 500/plate were at least partially interpretable
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'. Remarks: S. typhimurium TA 98, TA 100, TA 1535, TA 1537

Any other information on results incl. tables

GENOTOXIC EFFECTS:
None of the four test strains showed a dose-related and
biologically relevant increase of revertant colony numbers
after exposure to the test substance over negative control
levels.
Thic applied to the test with and without S9 mix and was
confirmed by the results of the repeat tests which were
performed as preincubation tests.

CYTOTOXIC CONCENTRATION: 
There was no indication of a bacteriotoxic effect of
n-butyl isocyanate at doses of up to and including 40 ug per
plate when the plate incorporation method (= 1. experiment)
was used: Total bacteria counts remained unchanged and
no growth inhibition was observed. The substance revealed
strong, strain-specific bacteriotoxic effects at higher
doses, yet doses up to 1000 ug per plate could still be used
for assessment purposes. When the preincubation was used (2.
and 3. experiments) bacteriotoxic effects were detected for
doses of 16 ug per plate and above. In this case, plates
containing doses up to 500 ug were at least partially
interpretable.

Applicant's summary and conclusion

Executive summary:

Method: Ames test according OECD Guideline 471 (1983)

Result: negative (None of the four test strains showed a dose-related and
biologically relevant increase of revertant colony number after exposure to the test substance over negative control levels (with and without S-9 mix)

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