Isobutyraldehyde

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo insect germ cell study: gene mutation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Reference 2

Reference Type:

publication

Title:

Chemical mutagenesis testing in Drosophilia. V. Results of 53 coded compounds tested for the National Toxicology Program.

Author:

Woodruff R.C., et al.

Year:

1985

Bibliographic source:

Environ. Mutagen. 7: 677-702

Materials and methods

Principles of method if other than guideline:

The test substance was assayed in the SLRL test by feeding for 3 days to adult Canton-S wild-type males no more than 24 hours old at the beginning of treatment. Because the response was negative, isobutyraldehyde was retested by injection into adult males.

GLP compliance:

not specified

Type of assay:

Drosophila SLRL assay

Test material

Test material information

Constituent 1

Reference substance name:

Isobutyraldehyde

EC Number:

201-149-6

EC Name:

Isobutyraldehyde

Cas Number:

78-84-2

Molecular formula:

C4H8O

IUPAC Name:

2-methylpropanal

Details on test material:

- Name of test material (as cited in study report): Isobutyraldehyde
- Purity: 98%

Test animals

Species:

Drosophila melanogaster

Strain:

other: Canton-S

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 24- to 72-hour old

Administration / exposure

Route of administration:

other: feed and injection

Vehicle:

An aqueous solution of isobutyraldehyde dissolved in saline was used.

Details on exposure:

Injection was performed either manually, by attaching a rubber bulb to the other end of the pipette and forcing through sufficient solution (0.2 to 0.3 μL) to slightly distend the abdomen of the fly, or by attaching the pipette to a micro injector that automatically delivered a calibrated volume. Flies were anesthetized with ether and immobilized on a strip of tape. Injection into the thorax, under the wing, was performed with the aid of a dissecting microscope.

Oral exposure was achieved by allowing Canton-S males to feed for 72 hours on a solution of isobutyraldehyde in 5% sucrose .

Duration of treatment / exposure:

single dose

Post exposure period:

24 hr

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
50,000 ppm
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
80,000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

6100 - 7700

Control animals:

yes, concurrent vehicle

Examinations

Tissues and cell types examined:

Treated males were mated to three Basc females for 3 days and given fresh females at 2-day intervals to produce three matings of 3, 2, and 2 days (in each case, sample sperm from successive matings were treated at successively earlier post-meiotic stages). F1 heterozygous females were mated with their siblings and then placed in individual vials. F1 daughters from the same parental male were kept together to identify clusters. (A cluster occurs when a number of mutants from a given male result from a single spontaneous premeiotic mutation event, and is identified when the number of mutants from that male exceeds the number predicted by a Poisson distribution.) If a cluster was identified, all data from the male in question were discarded. Presumptive lethal mutations were identified as vials containing fewer than 5% of the expected number of wild-type males after 17 days; these were retested to confirm the response.

Evaluation criteria:

A test result was considered positive if the P value was less than or equal to 0.01 and the mutation frequency in the tested group was greater than 0.10 % or if the P value was less than or equal to 0.05 and the frequency in the treatment group was greater than 0.15%. A test was considered to be inconclusive if the P value was between 0.05 and 0.01 but the frequency in the treatment group was between 0.10 % and 0.15 % or the P value was between 0.10 and 0.05 but the frequency in the treatment group was greater than 0.10 %. A test was considered negative if P was less than or equal to 0.10 or if the frequency in the treatment group was less than 0.10 %.

Statistics:

SLRL data were analyzed by simultaneous comparison with the concurrent and historical controls, using a normal approximation to the binomial test.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

not examined

Additional information on results:

Injection: The percentage lethals was 0.13 (8/6165) in the treatment group compared to 0.08 (5/6145) in the control group.
Feed: The percentage lethals was 0.06 (4/6250) in the treatment group compared to 0.12 (9/7666) in the control group.