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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in mammalian cells
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: Comparable to guideline study with acceptable restrictions
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Assessment of the genotoxic effects of methyl chloride in human lymphoblasts
Author:
Fostel, J. et al.
Year:
1985
Bibliographic source:
Mutation research 155:75-81
Reference Type:
secondary source
Title:
Chloromethane CAS: 74-87-3
Author:
OECD SIDS
Year:
2004
Bibliographic source:
SIDS Initial Assessment Report for SIAM 15 ; www.iccahpv.com
Reference Type:
secondary source
Title:
Methyl Chloride
Author:
Löf, A. et al.
Year:
2000
Bibliographic source:
Concise International Chemical Assessment Document 28
Reference Type:
secondary source
Title:
Toxicological review of methyl chloride (CAS No. 74-87-3)
Author:
Greenberg, M. and Riddle, J.
Year:
2001
Bibliographic source:
U.S. Environmental Protection Agency, EPA/635/R01/003

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
yes
Remarks:
no test with metabolic activation was performed
GLP compliance:
not specified
Type of assay:
mammalian cell gene mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Chloromethane
EC Number:
200-817-4
EC Name:
Chloromethane
Cas Number:
74-87-3
Molecular formula:
CH3Cl
IUPAC Name:
chloromethane
Details on test material:
- Name of test material (as cited in study report): methyl chloride
- Analytical purity: no data

Method

Target gene:
thymidine kinase
Species / strain
Species / strain / cell type:
human lymphoblastoid cells (TK6)
Details on mammalian cell type (if applicable):
- Type and identity of media: RPMI 1640 medium supplemented with 20% heat-inactivated horse serum and penicillin
Additional strain / cell type characteristics:
not specified
Metabolic activation:
without
Metabolic activation system:
no
Test concentrations with justification for top dose:
1, 2, 3, 4 or 5% chloromethane (1% chloromethane is equivalent to 0.73 mM (38.37 mg/L).)
Vehicle / solvent:
none
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
no
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: ethylmethanesulphonate (0.2 and 0.4 mM) and methylmethanesulphonate (0.025 and 0.05 mM)
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium
Between 2 and 2.5 x 10^7 TK6 cells were added to each of three 50 mL aliquots of complete medium in 75 cm2 flasks with lids that had been punctered with a 16-gauge needle. The flasks were sealed into 1.9 L Gas Pak chambers and 9 changes of an atmosphere containing a known concentration of chloromethane were pumped through each chamber. To correlate the percent of atmospheric chloromethane with chloromethane concentration in the culture medium, a small volume of [14C]chloromethane was added to pure chloromethane to generate a mixture of chloromethane with a known specific activity.

DURATION
- Exposure duration: 3 h
- Expression time (cells in growth medium): 3 d from the point where growth rate was normal again
- Selection time (if incubation with a selection agent): 12-14 d

SELECTION AGENT (mutation assays): 1 µg trifluorothymidine/ mL

NUMBER OF REPLICATIONS: 2 (4 experiments per replication)

NUMBER OF CELLS EVALUATED: 4 x 10^4 each experiment

DETERMINATION OF CYTOTOXICITY: extrapolation of the exponential portion of the growth curve back to the treatment time
Evaluation criteria:
The mutant fraction was calculated by dividing the efficiency of colony formation in the mutant dishes by the efficiency of colony formation on the dishes without selection.

Results and discussion

Test results
Species / strain:
human lymphoblastoid cells (TK6)
Metabolic activation:
without
Genotoxicity:
positive
Remarks:
dose-dependent increase
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at all concentrations there was a lag in the growth of the cultures
Vehicle controls validity:
not applicable
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Water solubility: according to measurements a linear relationship between atmospheric concentration of chloromethane and concentration in the medium was observed. 1% chloromethane is equivalent to 0.73 mM (38.37 mg/L).
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive without metabolic activation