Nitrobenzene

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

Remarks:

Type of genotoxicity: DNA damage and/or repair

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions (limited documentation)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1982

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 486 (Unscheduled DNA Synthesis (UDS) Test with Mammalian Liver Cells in vivo)

Deviations:

yes

Remarks:

only one sampling time (12 h) and only 50 cells/animal evaluated

GLP compliance:

not specified

Type of assay:

unscheduled DNA synthesis

Test material

Test material information

Constituent 1

Reference substance name:

Nitrobenzene

EC Number:

202-716-0

EC Name:

Nitrobenzene

Cas Number:

98-95-3

Molecular formula:

C6H5NO2

IUPAC Name:

nitrobenzene

Details on test material:

- Name of test material (as cited in study report): nitrobenzene; Eastman Kodak
- Analytical purity: no data

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Labs, Kingston, NY
- Weight at study initiation: 175 - 275 g
- Diet (e.g. ad libitum): NIH-07 feed (Ziegler Brothers, Gardner, PA), ad libitum
- Water (e.g. ad libitum): untreated tap water, ad libitum

Sera from the animals were tested and did not contain antibodies against pneumonia virus of mice, revirus 3, GD VII, Kilham rat virus, H-1, Sendai, mouse adenovirus, mouse hepatitis virus, lymphocytic chorioimeningitis virus or rat corona virus.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil
- Amount of vehicle (if gavage or dermal): 0.1 - 0.4 mL/100g body weight

Details on exposure:

The highest dose was generally selected to be at or near the LD50 when such information is available.

Duration of treatment / exposure:

single dose

Post exposure period:

Hepatocytes were isolated 12 h after treatment.

Doses / concentrations

Remarks:

Doses / Concentrations:
200 and 500 mg/kg in corn oil
Basis:
actual ingested

No. of animals per sex per dose:

3

Control animals:

yes, concurrent vehicle

Positive control(s):

2-acetylaminofluorene; methylmethanesulfonate, benzidine (genotoxic hepatocarcinogens)
- Route of administration: oral, gavage
- Doses / concentrations: 2-AAF: 50 mg/kg; MMS: 100 mg/kg; benzidine: 200 mg/kg

Examinations

Tissues and cell types examined:

freshly isolated hepatocytes

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: The highest dose was generally selected to be at or near the LD50 when such information is available.


DETAILS OF SLIDE PREPARATION: Cultures were washed twice with Williams Medium E (WE), fixed followed by six washes with deionized water. When dry, coverslips were mounted with permount and dipped in Kodak NTB-2 emulsion diluted 1.1 with water. Slides were exposed for 12 - 14 days at -20°C and developed for quantitative autoradiography.


METHOD OF ANALYSIS: An area of the slide was randomly selected and 50 morphologically unaltered cells were counted (ARKTEK Model 880 colony counter interfaced to a microscope). All counts were made on the "OBJ AREA" mode. The highest of three nuclear-sized areas over the cytoplasm and adjacent to the nucleus was subtracted from the nuclear count to give net grains/nucleus. The percentage of cells in repair, which is a useful indicator of the extent of damage throughout the liver, is defined as those exhibiting five or more net grains.


OTHER: Cells were incubated in WE medium containing 10% fetal calf serum for ca. 90 min at 37 °C to allow attachment of the cells to the coverslips. Cultures were washed and incubated in WE containing 10 µCi/mL 3H-thymidine for 4 hours. Cultures were again washed and incubated overnight (14 - 16 h) in 0.25 mM thymidine.

Evaluation criteria:

Five or more net grains/nucleus was considered positive.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Any other information on results incl. tables

Chemical	Dose [mg/kg]	Time [h]	Net grains ± SE	Cells in repair [%] ± SE
Corn oil		2	-5.1 ± 0.5	1 ± 0
		12	-4.4 ± 0.5	3 ± 1
Nitrobenzene	200	12	-4.4 ± 1.2	5 ± 2
	500	12	-5.6 ± 1.3	6 ± 3
2-AAF	50	2	13.2 ± 2.7	71 ± 7
		12	45.0 ± 11.3	96 ± 3