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Toxicological information

Genetic toxicity: in vivo

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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
Study period:
2006/08/31-2007/10/04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study under GLP condition

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
Qualifier:
according to
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: slightly brown crystalline powder
- Analytical purity: 99.9%
- Lot/batch No.: LTQ5219 (Wako Pure Chemical Industries, Ltd.)
- Storage condition of test material: in the cool and dark space(3 - 7℃)
:

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan, Inc.
- Age at study initiation: 8 weeks old
- Weight at study initiation: Males: 32.3 - 35.9 g
- Housing: Animals were individually housed in plastic cage.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 8days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 25 ℃
- Humidity (%): 42 - 59%
- Air changes (per hr): 10 - 15 times/hr
- Photoperiod (hrs dark / hrs light): 12 hrs dark /12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: 0.5 %CMC (carboxymethyl cellulose)-Na
Duration of treatment / exposure:
1 day
Frequency of treatment:
once
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 125, 250, 500 mg/kg
Basis:
actual ingested
Remarks:
Doses / Concentrations:

Basis:

No. of animals per sex per dose:
6 males/dose
Control animals:
yes, concurrent vehicle
Positive control(s):
Mitomycin C
- Route of administration: i.p.
- Doses / concentrations: 1 mg/kg bw (0.1 mg/ml)

Examinations

Statistics:
Statistical analyses were conducted by Kastenbaum & Bowman's statistical table, Cochran-Amitage test, student's t-test

Results and discussion

Test results
Sex:
male
Genotoxicity:
positive
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
RESULTS OF RANGE-FINDING STUDY
- Dose range: 0, 250, 500, 1000, 2000 mg/kg
- Toxicological findings in test animals:
Mortality: 1000 mg/kg (Male:8/9, Female:7/9), 2000 mg/kg (Male:8/9, Female:7/9)
Clinical sign: Orange brown urine(male/female: >=250 mg/kg), Cyanosis(male: 1000 mg/kg, female: 500, 1000, 2000 mg/kg)
Body weight changes: Decreased body weight or inhibition of body weight gain (male: 250, 500 mg/kg, female: 250, 500, 1000, 2000mg/kg)
- Induction of micronuclei:
Examination periods: at a 24, 48 and 72 h after administration.
The frequency of micronucleated polychromatic erythrocytes was significantly increased in males and females at a 24 h after administration.
- Ratio of PCE/NCE:
Inhibition of bone marrow cell proliferation was observed at a dose of 500 mg/kg at a 24 and 48h after administration.


RESULTS OF DEFINITIVE STUDY (See Table1)
- Induction of micronuclei:
The frequency of micronucleated polychromatic erythrocytes was significantly increased in males at a dose of 125 mg/kg and above.
- Ratio of PCE/NCE:
Examination periods: at a 24h after administration.
Inhibition of bone marrow cell proliferation was observed at a dose of 125 mg/kg and above under the test conditions.

Any other information on results incl. tables

Table 1. Observation of bone marrow smears (about 24 hours after administration)

Group Animal No. MNPCE/PCE (%) PCE/ERY (%)
Vehicle control 1001 1 (0.05) 89 (44.5)
1002 3 (0.15) 112 (56.0)
1003 1 (0.05) 112 (56.0)
1004 3 (0.15) 143 (71.5)
1005 2 (0.10) 110 (55.0)
1006 2 (0.10) 120 (60.0)
Mean ± S.D.(%) 2 ± 1 114 ± 17
%(Mean ± S.D.)  0.10 ± 0.04 57.2 ± 8.7
125 mg/kg 2001 24 (1.20) 71 (35.5)
2002 23 (1.15) 109 (54.5)
2003 25 (1.25) 62 (31.0)
2004 14 (0.70) 109 (54.5)
2005 23 (1.15) 96 (48.0)
2006 21 (1.05) 80 (40.0)
Mean ± S.D.(%) 22 ± 4 88 ± 20
%(Mean ± S.D.) 1.08 ± 0.20a),b) 43.9 ± 9.9*c)
250 mg/kg 3001 19 (0.95) 79 (39.5)
3002 21 (1.05) 89 (44.5)
3003 29 (1.45) 79 (39.5)
3004 34 (1.70) 106 (53.0)
3005 22 (1.10) 59 (29.5)
3006 12 (0.60) 52 (26.0)
Mean ± S.D.(%) 23 ± 8 77 ± 20
%(Mean ± S.D.) 1.140 ± .39a),b) 38.7 ± 9.9**c)
500 mg/kg 4001 25 (1.25) 79 (39.5)
4002 20 (1.00) 65 (32.5)
4003 24 (1.20) 61 (30.5)
4004 24 (1.20) 75 (37.5)
4005 18 (0.90) 66 (33.0)
4006 21 (1.05) 59 (29.5)
Mean ± S.D.(%) 22 ± 3 68 ± 8
%(Mean ± S.D.) 1.10 ± 0.14a),b) 33.8 ± 3.9**c)
Positive control
 (Mytomycin C: 1mg/kg)
5001 52 (2.60) 84 (42.0)
5002 52 (2.60) 100 (50.0)
5003 17 (0.85) 100 (50.0)
5004 55 (2.75) 102 (51.0)
5005 37 (1.85) 114 (57.0)
5006 16 (0.80) 84 (42.0)
Mean ± S.D.(%) 38 ± 18 97 ± 12
%(Mean ± S.D.) 1.91 ± 0.90a) 48.7 ± 5.8

MNPCE: Micronucleated polychromatic erythrocytes

PCE: Polychromatic erythrocytes

ERY: Erythrocytes

a): Statistically significant increase from the vehicle control value (Kastenbaum & Bowman's statistical table, P<0.05)

b): Dose-dependency by Cochran-Amitage test, P<0.01

c): Statisyically significant difference from the vehicle control value (student's t-test, *: P<0.05; **: P<0.01)

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): positive
Executive summary:

4-aminophenol was administeed orall at doses of 125, 250 and 500 mg/kg and at 24 hours after the administration, bone marrow smear specimens were prepared. Sodium CMC aqueous solution of 0.5% w/v% and 1 mg/kg of mitomycin C were used for a negative convrol and a positive control, respectively.

The occurrence frequency of immature erthrocyes having a micronucleus increased was statistically significant in the groups administered with the test compound compared to the negative control group and was also dose-dependent. Additionally, the percentage of immature erythrocytes per 200 erythrocytes was significnatly decreased in the test article groups compared to the negative control group which was considered to be caused by the test article causing suppressive effects at these doses on bone marrow cell growth. The occurrence frequency of immature erythrocytes having a micronucleus in the negtive and positive controls was within the range of the the historical background of the laboratory, indicating the validity of the test result.

Based on these data, 4 -aminophenol was judged capable of inducing chromosomal aberrations in vivo in bone marrow cells of Crlj:CD1(ICR)(SPF) strain mice under the conditions in this study.