Butyraldehyde

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Secondary literature source

Data source

Reference

Reference Type:

publication

Title:

Micronucleated erythrocyte frequency in peripheral blood of B6C3F(1) mice from short-term, prechronic, and chronic studies of the NTP carcinogenesis bioassay program.

Author:

Witt, K.L., Knapton, A., Wehr, C.M., Hook, G.J., Mirsalis J., Shelby M.D., MacGregor J.T.

Year:

2000

Bibliographic source:

Environ Mol Mutagen. 2000;36(3):163-94.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Mouse peripheral blood micronucleus test was performed on samples collected from a 90 day subchronic toxicity study.

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Butyraldehyde

EC Number:

204-646-6

EC Name:

Butyraldehyde

Cas Number:

123-72-8

Molecular formula:

C4H8O

IUPAC Name:

butanal

Details on test material:

No information provided

Test animals

Species:

mouse

Strain:

B6C3F1

Details on species / strain selection:

Mice provide a convenient model for the study because unlike rats, mice do not selectively remove micronucleated cells from the peripheral circulation. Therefore, the frequency of micronucleated cells in the circulating blood of mice would be expected to closely reflect the frequency in bone marrow, and unlike bone marrow sampling, repeated peripheral blood measurements can be made, without disturbing the physiology of the animals, by sampling a few microliters of blood at a time.

Sex:

male/female

Details on test animals or test system and environmental conditions:

No information provided

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

Corn oil

Details on exposure:

No information provided

Duration of treatment / exposure:

90 days

Frequency of treatment:

No information provided

Post exposure period:

No information provided

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0.075 other: g/kg

Doses / concentrations 2

Dose / conc.:

0.15 other: g/kg

Doses / concentrations 3

Dose / conc.:

0.3 other: g/kg

Doses / concentrations 4

Dose / conc.:

0.6 other: g/kg

Doses / concentrations 5

Dose / conc.:

1.2 other: g/kg

No. of animals per sex per dose:

Number o animals that were analysed in the end of the study:

Males
Control: 10
0.075 g/kg: 9
0.15 g/kg: 10
0.3 g/kg: 10
0.6 g/kg: 10
1.2 g/kg: 5

Females
Control: 10
0.075 g/kg: 9
0.15 g/kg: 7
0.3 g/kg: 9
0.6 g/kg: 10
1.2 g/kg: 4

Control animals:

yes, concurrent vehicle

Positive control(s):

Positive control group was not included in the test. This is because the toxicity bioassay from which the test animals were obtained did not include a positive control group. However, positive control slides were included in the experiment to control for staining and scoring procedures.

Examinations

Tissues and cell types examined:

Erythrocytes

Details of tissue and slide preparation:

Blood was obtained immediately before or at the time of sacrifice (90 days).

Drops of blood were spread on precleaned standard glass microscope slides, air dried, and fixed in absolute methanol for 5 min. All slides were coded prior to scoring by a person not involved in reading the slides.

Evaluation criteria:

Identification of micronucleus (MN) was based on fluorescence emission characteristic of the fluorescent stain used (blue with UV excitation and orange with green [540nm] excitation with Hoechst/pyronin stain, or yellow to greenish yellow with acridine orange stain).

Polychromatic erythrocytes (PCE) were scored by direct manual counting. Normochromatic erythrocytes (NCE) were scored using a semiautomated method, in which cell counts were determined by counting a subfield of approximately 1/16th of the full microscope field. Routine micronucleus frequency scores were based on approximately 10,000 NCE or 1000 PCE per sample, and the percentage of PCE among the total erythrocyte population was based on the number of PCE among approximately 10,000 or 5,000 erythrocytes.

Statistics:

The micronucleus results were tabulated as the mean frequency of micronucleated erythrocytes per 1000 cells per animal, plus or minus the standard error of the mean among animals within a treatment group.

The frequency of micronucleated cells among normochromatic erythrocytes or polychromatic erythrocytes was analyzed by a statistical software package that tested for increasing trend over exposure groups using a one-tailed Cochran-Armitage trend test, followed by pairwise comparisons between each exposure group and the control group.

The percentage of polychromatic erythrocytes (%PCE) data were analyzed by a standard ANOVA to determine if significant PCE suppression or stimulation occurred.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

not specified

Negative controls validity:

not specified

Positive controls validity:

not specified

Additional information on results:

Results indicate that the test has low sensitivity for prediction of carcinogenicity, a convincingly positive result in this assay appears to be highly predictive of rodent carcinogenicity.

The authors highlight that the chemicals that produced equivocal or negative results in the mouse peripheral blood MN test, predictivity for noncarcinogenic activity in rodents was poor.

Any other information on results incl. tables

Table 1: Micronucleated Erythrocyte Frequencies in Peripheral Blood of B6C3F1 Mice from NTP Subchronic Toxicity Study, males

Dose (g/kg)	N	MN-NCE/1000 NCE	P value	% PCE
Control	10	1.85 ± 0.18	0	3.17 ± 0.21
0.075	9	1.94 ± 0.18	0.2360	3.44 ± 0.25
0.15	10	1.57 ± 0.10	0.9342	3.42 ± 0.31
0.3	10	1.77 ± 0.10	0.6537	3.17 ± 0.21
0.6	10	1.50 ± 0.13	0.9725	3.29 ± 0.18
1.2	5	2.05 ± 0.07	0.1601	3.49 ± 0.45
Trend test		p=0.424
ANOVA				p=0.873

 

Table 2: Micronucleated Erythrocyte Frequencies in Peripheral Blood of B6C3F1 Mice from NTP Subchronic Toxicity Study, females

Dose (g/kg)	N	MN-NCE/1000 NCE	P value	% PCE
Control	10	1.35 ± 0.13	0	3.09 ± 0.23
0.075	9	1.20 ± 0.14	0.7667	3.26 ± 0.30
0.15	7	1.38 ± 0.21	0.4372	3.14 ± 0.40
0.3	9	1.23 ± 0.19	0.7053	3.54 ± 0.21
0.6	10	1.27 ± 0.05	0.6102	3.27 ± 0.26
1.2	4	1.48 ± 0.19	0.2586	4.18 ± 0.16
Trend test		p=0.236
ANOVA				p=0.195

 

 

 

Applicant's summary and conclusion

Conclusions:

In this assay the test substance showed a negative result after 90 days exposure via oral gavage.

Executive summary:

In a study conducted by Witt et al (2000) the mouse peripheral blood micronucleus (MN) test was performed on samples collected from a sub-chronic toxicity study conducted by the National Toxicology Program (NTP). The incidence on polychromatic erythrocytes (PCE) provided an index of damage induced within 72 hours of sampling whereas the incidence of MN in the normocromatic erythrocytes (NCE) population at steady state provided an index of the average damage during the 30 -day period preceding sampling.

 

In a B6C3F1 mouse peripheral blood micronucleus assay, mice were treated by oral gavage with Butyraldehyde at doses of 0, 0.075, 0.15, 0.3, 0.6 and 1.2  g/kg bw. The vehicle was corn oil. Blood samples were taken at the day of termination.  

 

There was not a significant increase in the frequency of micronucleated NCE and PCE in the mouse peripheral blood micronucleus test.