Propionaldehyde

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key 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:

1993

Report date:

1993

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

only 1000 instead of 2000 immature erythrocytes per animal were scored

GLP compliance:

yes

Remarks:

Bushy Run Research Center

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Specific details on test material used for the study:

- Name of test material (as cited in study report): propionaldehyde
- Physical state: water white liquid
- Analytical purity: approximately 98%
- Storage condition of test material: room temperature under nitrogen

Test animals

Species:

mouse

Strain:

Swiss Webster

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, (Portage, MI, USA)
- Age at study initiation: approximately 5 weeks
- Weight at study initiation: 23.3 to 27.3 g for males and 18.4 to 22.0 g for females
- Assigned to test groups randomly: yes, under following basis: nonstratified randomization procedure based on body weight
- Housing: group housed
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 40-70
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 1992-03-30 To: 1992-04-09

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle(s)/solvent(s) used:sterile, distilled, deionized water
- Concentration of test material in vehicle: no data
- Positive control was diluted first in ethanol then in sterile, distilled, deionized water

Details on exposure:

Animals were given 240, 480 or 768 mg/kg of propionaldehyde as a single intraperitoneal injection. Injection volumes for all animals were based on
individual body weights determined the day before dosing. Bone marrow was collected 12, 24, and 48 hours after treatment with the test substance.
Vehicle control and positive control were given as a single intraperitoneal injection. Bone marrow was collected 24 hours later.

Duration of treatment / exposure:

12, 24, 48 hours

Frequency of treatment:

single injection

Post exposure period:

none

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

240 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

480 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

768 mg/kg bw/day (nominal)

No. of animals per sex per dose:

5/sex for control groups
15/sex for propionaldehyde groups (5/sex for each time point of bone marrow preparation)

Control animals:

yes, concurrent vehicle

Positive control(s):

triethylenemelamine
- Route of administration: intraperitoneal
- Doses / concentrations: 3 mg/kg

Examinations

Tissues and cell types examined:

bone marrow, polychromatic erythrocytes (PCE), normochromatic erythrocytes (NCE)

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: 25%, 50%, and 80% of LD50

DETAILS OF SLIDE PREPARATION: a drop of the bone marrow cell suspension was smeared on a microscopic slide. Slides were stained with Gurr's R-66 Giemsa diluted in phosphate buffer.

METHOD OF ANALYSIS: Slides were coded with the randomly-assigned animal numbers and read without knowledge of treatment group to prevent bias. The PCE:NCE ratio for a total of 1000 celle for each animal was calculated to provide an estimate of propionaldehyde cytotoxicity. A minimum of 1000 PCE for each animal was scored for the presence of micronuclei unless the cytotoxicity of the test substance prevented this.

Evaluation criteria:

The PCE:NCE ratio for approximately 1000 total cells will be calculated, recorded, and shown in the final report to provide an estimate of the cytotoxicity of the test agent. Excessive cytotoxicity in this test system will be defined by a PCE:NCE ratio of 0.10 or lower. Animals with an excessive reduction in the PCE:NCE ratio will be identified in the raw data and final report but micronuclei will not be scored. A minimum of 1000 PCE per animal will be scored for the presence of micronuclei unless the cytotoxicity of the test substance prevents this.

Statistics:

Data were statistically evaluated using the Mann-Whitney U test. All statistical analyses were performed using BMDP Statistical Software (Dixon, 1990). For all statistical tests, the probability value of < 0.05 (two-tailed) was used as the critical level of significance.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

at 768 mg/kg bw.

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
LD50 = 961 mg/kg bw. (95% confidence interval, 836 to 1104 mg/kg) for the combined sexes. At 667 mg/kg, the highest dose with 3 or more survivors of each sex, the proportion of PCE was 67% of the vehicle control value for the male mice and 92% for the female mice. Based upon the results of the range-finding study, the dose levels for the definitive study were set at 25%, 50% and 80% of the LD50 or 240, 480, and 768 mg/kg propionaldehyde.

RESULTS OF DEFINITIVE STUDY
There was a statistically significant decrease (57.9% of control, p < 0.01) in the PCE to NCE ratio at the 48 hour sampling time among female mice treated with 768 mg/kg propionaldehyde. There was also a decrease (79.3% of control) in the PCE to NCE ratio among male mice treated with propionaldehyde, but it was not statistically significant. Statistically significant increases in the PCE to NCE ratios were also observed in propionaldehyde-treated mice of both sexes. However, those increased ratios were within normal ranges and were not considered biologically significant.
Results micronucleated PCE: see table 1.

Clinical observations for the micronucleus assay:
There were no signs of toxicity in male or female mice in the 240 mg/kg group or in females in the 480 mg/kg group. Among the males in the 480 mg/kg group, lethargy, rapid breathing and unkempt appearance were observed after dosing, but no signs of toxicity except unkempt appearance persisted beyond the postdosing period. Toxic signs including gasping, prostration, and rapid breathing were observed in males and females in the 768 mg/kg group immediately after dosing, but did not persist. In the 768 mg/kg group, toxic signs during Days 2 and 3 were limited to unkempt appearance, except that 1 female was also prostrate and 1 male died on Day 3.

Any other information on results incl. tables

Table 1:

		# PCE observed	# PCE with MN	% PCE with MN
Dose (mg/kg)	Sex	12-hour sample
240	M	5000	3	0.06
	F	5000	4	0.08
480	M	5000	1	0.02
	F	5000	7	0.14
768	M	5000	2	0.04
	F	5000	2	0.04
		24-hour sample
water	M	5000	2	0.04
	F	5000	7	0.14
240	M	5000	3	0.06
	F	5000	4	0.08
480	M	5000	9	0.18
	F	5000	2	0.04
768	M	5000	9	0.18*
	F	5000	2	0.04
TEM (positive control)	M	5000	92	1.84***
	F	5000	56	1.12***
		48-hours sample
240	M	5000	6	0.12
	F	5000	1	0.02
480	M	5000	4	0.08
	F	5000	6	0.12
768	M	4000	9	0.22*
	F	5000	4	0.08

*: p< 0.05; *** p< 0.01

Although the incidence of micronucleated PCE was statistically significant among high dose males at both the 24 and 48 hour sacrifices, propionaldehyde was not considered to be an inducer of micronuclei in male mice for the following reasons. First, the incidence of micronucleated PCE was low in the vehicle control males as compared to the vehicle control females. Although the frequency of micronucleated PCE in the vehicle control males is within a normal range, it is at the low end of the range. The high dose male mice had a high incidence of micronucleated PCE as compared to the male vehicle control, but both the overall incidences of micronucleated PCE and the distribution of micronucleated PCE in each animal were within normal ranges. Furthermore, there was no consistent relationship between increasing propionaldehyde dose and increasing incidence of micronucleated PCE among either male or female mice.

Applicant's summary and conclusion

Conclusions:

Propionaldehyde did not produce biologically significant or dose-related increases in the frequency of micronucleated polychromatic erythrocytes in the bone marrow of male or female Swiss-Webster mice assessed at 12, 24, or 48 hours after treatment with a single dose by intraperitoneal injection. Therefore, propionaldehyde was not considered to be an inducer of micronuclei under the conditions of this in vivo assay.