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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: Non-GLP, near guideline study, published in peer reviewed literature, limitations in design and/or reporting but otherwise adequate for assessment.

Data source

Reference
Reference Type:
publication
Title:
A method for studying the mutagenicity of some gaseous compounds in salmonella typhimurium
Author:
Victorin K and Stahlberg M
Year:
1988
Bibliographic source:
Environmental and Molecular Mutagenesis 11: 65-77

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
only a single bacterial strain was used.
Principles of method if other than guideline:
Modified Ames assay reported.
GLP compliance:
not specified
Type of assay:
other: Modified Ames test

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethylene
EC Number:
200-815-3
EC Name:
Ethylene
Cas Number:
74-85-1
Molecular formula:
C2H4
IUPAC Name:
ethylene
Details on test material:
- Name of test material (as cited in study report): Ethene
- Physical state: gas
- Source: AGA Specialgas, Stockholm
- Analytical purity: 99.5%

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 100
Metabolic activation:
with and without
Metabolic activation system:
Aroclor-induced rat liver S9
Test concentrations with justification for top dose:
0.5-20% (up to 200,000 ppm)
Controls
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
other: 1 µg benzo(a)pyrene and 1 µg 2-nitrofluorene
Remarks:
with and without metabolic activation
Details on test system and experimental conditions:
EXPOSURE SYSTEM
- Dynamic flow-through exposure system
- Ethene (ethylene): diluted with air in a mixing chamber to 0.5-20% concentration. The gas was passed into an exposure chamber containing 3 bacterial plates and out to the ventilation system through a carbon filter. The internal air of the exposure chamber was kept at 34°C.
- The air and gases are dry, but the atmosphere in the exposure chamber becomes saturated with water (~85% humidity) due to the humidity of the agar plates.
- IR-detection was used to analytically measure the concentration of ethylene within each cylinder.
- Measurements of the gas concentrations were calculated from the gas concentration in the cylinder and from the dilution factors.
- No actual measurement of the gas concentrations during mutagenicity experiments was performed.

METHOD OF APPLICATION: in agar (plate incorporation)
- 0.1 mL of a 14 hr (overnight) bacterial culture was mixed with 0.5 mL phosphate buffer or a metabolic activation system (0.5 mL S9-mix, containing 20 µL S9) in 2 mL soft agar containing traces of biotine and histidine. This was poured onto minimal glucose agar plates. When the agar was solid, three plates (without lids) were placed in the exposure chamber, and three control plates (with lids) were placed in the 37°C incubator. Three flow rates were used, 250, 500, and 1000 mL/min.
- After 6 or 7 hours exposure to the gas stream, the bacteria plates were removed from the exposure chamber and placed in the incubator. Some experiments were performed with longer exposure times.
- The number of revertant colonies was counted after 48-60 hr.
- Control experiments: bacteria plates exposed to pure air in the exposure chamber for 6-7 hr prior to incubation.
Evaluation criteria:
Toxicity was assessed by examination of the background lawn of bacteria: sparse background growth on the plate was classed as slightly toxic and a very sparse background growth indicated toxicity.
Statistics:
As the number of spontaneous revertants can vary from day to day variation and only one dose was tested per day, the increase in the number of revertants on exposed plates compared to non-exposed plates was computed for each dose.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Vehicle controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
1 µg benzo(a)pyrene and 1 µg 2-nitrofluorene gave approximately 740 and 500 revertants per plate with and without S9, respectively.
Remarks on result:
other: other:
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

The mean increment of revertants from control experiments (n=8) was ~37%±17% due to mutagenic contaminants in the compressed air or to enhanced growth that would also result in the production of more spontaneous mutants. No mutagenic effect was demonstrated with ethylene concentrations up to 20% in air when tested with flow rates of 250, 500, and 1000 mL/min for 7 hours with or without metabolic activation.

Applicant's summary and conclusion

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

Ethylene is not mutagenic when tested at concentrations of 0.5 to 20% in air for 7 hours in Salmonella typhimurium strain TA100.
Executive summary:

A dynamic flow-through exposure system was designed for mutagenicity studies of gaseous substances, including ethylene. Salmonella typhimurium strain TA100 was used to test ethylene concentrations from 0.5 to 20% in air with flow rates of 250, 500, and 1000 mL/min. Exposure was 7 hours with and without metabolic activation.

No mutagenic effects were demonstrated with or without metabolic activation.