N-methylaniline

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions Read-across is based on the great structural similarity between aniline and N-methylaniline

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Deviations:

not applicable

Principles of method if other than guideline:

In order to investigate whether the species specific carcinogenicity is reflected in the results of the bone marrow micronucleus tests after oral dosing, aniline hydrochloride was assayed for potential clastogenicity in the mouse micronucleus test after oral administration to male CRH mice. A group of animals dosed i.p. with aniline hydrochloride was included for comparative purposes.

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Aniline hydrochloride

IUPAC Name:

Aniline hydrochloride

Constituent 2

Reference substance name:

Anilinium chloride

EC Number:

205-519-8

EC Name:

Anilinium chloride

Cas Number:

142-04-1

IUPAC Name:

anilinium chloride

Details on test material:

- Name of test material (as cited in study report): Aniline hydrochloride
- Analytical purity: > 99%

Test animals

Species:

mouse

Strain:

other: CRH

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Rodent Breeding Unit, Glaxo Group Research Ltd
- Age at study initiation: 7-8 wks old
- Diet (e.g. ad libitum): no.l Special Diets Services diet
- Water (e.g. ad libitum): ad libitum

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: [sterile water]

Duration of treatment / exposure:

24 or 48 hr

Frequency of treatment:

Single dose

Post exposure period:

None

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
380 mg/kg
Basis:
nominal conc.
i.p. route

Doses / concentrations 2

Remarks:

Doses / Concentrations:
400, 500 and 1000 mg/kg
Basis:
nominal conc.
oral route

No. of animals per sex per dose:

4 to 8 animals/group

Control animals:

yes, concurrent vehicle

Positive control(s):

cyclophosphamide
- Route of administration: oral

Examinations

Tissues and cell types examined:

Polychromatic erythrocytes

Details of tissue and slide preparation:

DETAILS OF SLIDE PREPARATION: Slides were coded prior to analysis and stained using the May-Grunwald/Giemsa technique. Some additional slides were also stained using a Feulgen-Iight green staining technique for DNA

METHOD OF ANALYSIS: For each animal, 2000 polychromatic erythrocytes (PE) were analysed for the presence of micronuclei. Five hundred erythrocytes/animal were scored to determine the percentage of PE among all erythrocytes.

Statistics:

The likelihood ratio test was used to analyse the data from the two i.p. dosing experiments. For the oral dosing experiments statistical analyses of micronucleus frequencies were performed using the non-parametric Dunn's multiple comparison test, with the exception of the repeat test where the Wilcoxon two-sample test was employed due to the use of only one dose group.

Results and discussion

Test results

Sex:

male

Genotoxicity:

positive

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Aniline was positive in the standard (single dose) mouse bone marrow micronucleus test, 24 h after oral dosing, but only at the high dose level of 1000 mg/kg

Any other information on results incl. tables

Table 1. Results of micronucleus test in CRH mice with a single dose of aniline

Treatment	Dose (mg/kg)	Sex	Sample time (h)	No. of animals	MNPE/1000 PE individual animal values	MNPE/1000PE (mean ± SD)	PE(%)(± SD)
Oral dosing (first study)
Water	10 ml/kg	M	24	7	1,0.5,0,0.5,0,0.5,0.5	04 ± 0.3	44 ± 8
Aniline*	4005001000	M	242424	778	2,1.5,0,1,3,0,00.5,2.5,1,2,0,1,218.5,15,4.5,3,2.5,2.5,4,12	1.1 ± 1.21.3 ± 0.96.1 ± 6.b	37 ± 530 ± 849 ± 17
Cyclophosphamide	30	M	24	4	9,11,18,6.5	11.1 ± 4.9c	57 ± 15
Water	10 ml/kg	M	48	7	0,0,1,0.5,2,0,0	0.5 ± 0.8	49 ± 12
Aniline*	4005001000	M	484848	777	1,0,1,0.5,0,0.5,0.50.5,0,0.5,0,0,0,1.51,0,1,1,1,1,2	0.5 ± 0.40.4 ± 0.61.0 ± 0.6	50 ± 849 ± 1039 ± 7
Oral dosing (repeat study)
Water	10 ml/kg	M	24	7	0,1.5,0.5,0,1,0.5,1.5	0.7 ± 0.6	42 ± 6
Aniline*	1000	M	24	7	3,2.5,2,6,10,15,0.5	5 6 ± 5.2b	38 ± 6
Cyclophosphamide	30	M	24	2	8,6.5	7.3c	43
I.p. dosing (first study)
0.9% NaCl	5 ml/kg	M	24	4	0,0.5,0.5,0	0.3 ± 0.3	42 ± 14
Aniline*	380	M	24	4	1,4 5,3.5,3.5	3.1 ± 1.5b	36 ± 8
I.p. dosing (repeat study)
0.9% NaCl	5 ml/kg	M	24	8	0.5,0,0,0.5,1,0,1,0.5	0.4 ± 0.4	37 ± 9
Aniline*	380	M	24	8	2.5,0,1.5,4.5,2.5,3,4.5,2.5	2.6 ± 1.5b	34 ± 12

* Dose levels are expressed as mg/kg free base

b Treatment significantly different from control (P < 0.05).

c Positive control is not included in the statistical analyses.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): positive
The high oral dose of aniline needed for micronucleus induction, the presence of micronuclei with abnormal morphology and the large inter-animal variability found within this group may possibly indicate a more complex mechanism of micronucleus induction than simple clastogenicity.
Given the high resemblance between aniline and N-methylaniline, and their similar physico-chemical properties, the results obtained in this study can be attributed to N-methylaniline.