(Z)-3,7-dimethylocta-2,6-dienal

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: Sufficient documentation; comparable to guideline study with acceptable restrictions

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2003

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1995

Reference 3

Reference Type:

other: abstract

Title:

TR-505 Toxicology and Carcinogenesis Studies of Citral (Microencapsulated) (CAS No. 5392-40-5) in F344/N Rats and B6C3F1 Mice (Feed Studies) - Draft Abstract

Author:

National Toxicology Program NTP

Year:

2003

Bibliographic source:

http://ntp-server.niehs .nih .gov/htdocs/LT-studies/tr505 .html

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

(No positive control included; other exposure subchronic feeding)

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Citral

EC Number:

226-394-6

EC Name:

Citral

Cas Number:

5392-40-5

IUPAC Name:

3,7-dimethylocta-2,6-dienal

Constituent 2

Reference substance name:

(Z)-3,7-dimethylocta-2,6-dienal

EC Number:

203-379-2

EC Name:

(Z)-3,7-dimethylocta-2,6-dienal

Cas Number:

106-26-3

Molecular formula:

C10H16O

IUPAC Name:

(2Z)-3,7-dimethylocta-2,6-dienal

Details on test material:

- Name of test material (as cited in study report): Citral
- Physical state: colourless liquid
- Analytical purity: ca. 97.6%
- Impurities (identity and concentrations): seven substances corresponding to 2.4 % in total
- Isomers composition: ratio geranial:neral = 2:1
- Lot/batch No.: 06930PG
- Expiration date of the lot/batch: no data
- Stability under test conditions: no degradation of the neat chemical after storage for 2 weeks at temperatures up to 60°C when protected from light; no loss of citral from the microcapsules during 14 weeks

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, N.Y.
- Age at study initiation: 6 weeks
- Weight at study initiation: males ca. 20 g, females ca. 16.5 g
- Fasting period before study: no
- Housing: males inidividually, females 5 per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 13 to 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C (calculated from 72° +- 3° F)
- Humidity (%): 50% +- 15%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: June 7 or 8, 1995 To: September 7 or 8, 1995

Administration / exposure

Route of administration:

oral: feed

Vehicle:

VEHICLE
- Justification for use and choice of vehicle: microcapsules prepared from food-grade sugar and starch were loaded with citral to prevent loss of test substance
- Concentration in vehicle: 31.3 % citral (analytical method GC)
- Lot/batch no.: 20295

Details on exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): every 2 to 4 weeks
- Mixing appropriate amounts with nonirradiated NTP-2000 feed: final concentrations of 3,900, 7,800, 15,600, or 31,300 ppm citral were achieved by adding loaded and/or placebo microcapsules at a total concentration of 10% microcapsules
- Storage temperature of food: room temperature

Duration of treatment / exposure:

13 w

Frequency of treatment:

continuously

Post exposure period:

No

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
3900, 7800, 15600, or 31300 ppm
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
745, 1840, 3915, and 8110 mg/kg bw/d
Basis:
other: actual ingested by male mice

Doses / concentrations 3

Remarks:

Doses / Concentrations:
790, 1820, 3870, and 7550 mg/kg bw/d
Basis:
other: actual ingested by female mice

No. of animals per sex per dose:

10

Control animals:

yes, concurrent no treatment

yes, concurrent vehicle

Positive control(s):

none

Examinations

Tissues and cell types examined:

peripheral blood

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION:
based on pre-study of Dieter et al., 1993 (see Section 7.5.1)

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
after 13 weeks of continuous feeding

DETAILS OF SLIDE PREPARATION:
Smears were immediately prepared and fixed in absolute methanol. The fixed slides were stained with acridine orange.

METHOD OF ANALYSIS:
1000 mature erythrocytes (normochromatic erythrocytes or NCEs) are scored per animal for presence of micronuclei. In addition, the percentage of PCEs among the total erythrocyte population in the periphral blood was scored for each exposure group as a measure of chemical-induced toxicity to the bone marrow. All data were analyzed separately for male and female mice.

Evaluation criteria:

Test positive if
the trend test P value is < or = 0.025
or if the P value for any single dosed group is < or = 0.025 divided by the number of dosed groups; for this study the relevant P value is < or = 0.006
Final call of positive for micronucleus induction based on reproducibly positive trials

Statistics:

Test for increasing trend over dose groups with a one-tailed Cochran-Armitage trend test
Pairwise comparisons between each dosed group and the control group

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

not specified

Additional information on results:

Toxicity: For details see Section 7.5.1, 14 week repeated dose toxicity study

Any other information on results incl. tables

Table 1: Frequency of micronuclei in peripheral blood erythrocytes of mice following administration of citral in Feed for 13 Weeks

Sex	Dose group (mg/kg bw/d)	Number of test animals evaluated	Micronucleated NCEs/1,000 NCEs		P value	PCEs (%)
			Mean	SE
Male	Untreated control	10	1.30	0.32		2.2
	Vehicle control	10	1.90	0.22		2.1
	745	10	1.50	0.32	0.5818	2.2
	1,840	10	1.70	0.28	0.4199	1.9
	3,915	10	2.50	0.25	0.0458	1.8
	8,110	6	1.83	0.28	0.3482	1.8
			Trend: P=0.145
Female	Untreated control	10	1.00	0.35		2.3
	Vehicle control	10	1.50	0.32		2.6
	790	10	1.00	0.24	0.7251	2.4
	1,820	10	1.10	0.36	0.6382	2.4
	3,870	10	0.90	0.22	0.8022	2.3
	7,550	10	1.60	0.29	0.2196	2.2
			Trend: P=0.217

NCE normochromatic erythrocyte; PCE polychromatic erythrocyte

Tables with a compilation of data from the individual test animals are available from Appendix 2