Nitrobenzene

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Meets generally accepted scientific standards, well documented and acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

A 28-day repeated dose toxicity study of nitrobenzene in F344 rats.

Author:

Shimo, T. et al.

Year:

1994

Bibliographic source:

Eisei Shikensho Hokoku 112, 71-81

Materials and methods

Principles of method if other than guideline:

28-day repeated dose toxicity study in rats. Additional two groups of animals exposed to 0 and 125 mg/kg/d were used for examinations of subsequent recovery for two weeks.

GLP compliance:

not specified

Limit test:

no

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
- Analytical purity: no data

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 - 25
- Humidity (%): 50 - 60
- Air changes (per hr): 18
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

not specified

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
5, 25 and 125 mg/kg bw
Basis:
other: nominal

No. of animals per sex per dose:

12 for control and 125 mg/kg bw; 6 for 25 mg/kg bw

Control animals:

yes

Details on study design:

Post-exposure period: 14 days (control and high dose group)

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: no data

DETAILED CLINICAL OBSERVATIONS: No data


BODY WEIGHT: Yes
- Time schedule for examinations: weekly


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: No data
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: all animals
- Parameters examined: red blood cells, hemoglobin, hematocrit, MCV, white blood cells


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:
- Animals fasted: No data
- How many animals: all animals
- Parameters examined: AST, ALT, ALP, ChE, TP, total cholesterol, BUN, CRN, albumin, A/G ratio, Na, K, Cl, Ca, P


URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: No data
HISTOPATHOLOGY: Yes: brain, pituitary gland, salivary gland, thymus, lung, heart, spleen, liver, adrenal gland, kidneys, testis

Statistics:

Statitic tests acc. Bartlett, Kruskal-Wallis, Dunnett

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
- Clinical signs: Decreased movement, pale skin, gait abnormality were seen in the 125 mg/kg groups
- Mortality: One female in the 125 mg/kg group died on day 27

BODY WEIGHT AND WEIGHT GAIN
- Decreases of body weights or their gains were seen in the 125 mg/kg groups

HAEMATOLOGY
125 mg/kg bw:
- males: Significant decrease of red blood cells (-46%), which was normal again after the 14 day recovery period. Significant decreases of hemoglobin (-16%), hematocrit (-16%) changed to a significant increase of +6% and +20% after the 14 day recover period, respectively.The significant increase of MCV (+54%) remains, while the significant decrease of white blood cells (+3141%) recovered within the recovery period.
- females: The significant decreases of red blood cells (-35%) and of hemoglobin (-17%) was normal again after the 14 day recovery period. The hematocrit was not changed compared to control. The significant increase of MCV (+43%) remains, while the significant decrease withe blood cells (+4875%) recoverd within the 14 day recovery period.

25 mkg/kg bw:
- males: Significant decreases of red blood cells (-31%), hemoglobin (-14%) and hematocrit (-22%); significant increase of MCV (+12%) and white blood cells (+177%)
- females: Significant decreases of hemoglobin (-11%) and a significant increase of MCV (+11%) was noted. Levels of red blood cells, hematocrit and white blood cells were not significantly changed.

5 mg/kg bw: no significant differences found in males and females


CLINICAL CHEMISTRY
125 mg/kg bw:
- males: significant increases of total cholesterol (+26%), albumin (+9%) and A/G ratio (36%) and the significant decrease of the BUN level (-29%) disapeared within the 14 day recovery period. After the recovery period a significant decrease of the ALP level was noted (-11%). No other significant changes were noted.
- females: the significant increase of ALT (+36%) turned to an significant decrease (-21%) within the 14 day recover period. The significant increases of ALP (+57%), TP (+11%), albumin (+18%) and A/G ratio (+15%) were normalized throughout the recovery period. This was also true for the significant decrease of BUN (-30%). Wheras the level of K was normal directly after the 28-day study, it was significantly decreased by 2% after the recovery period. No other significant changes were noted.

25 mg/kg bw:
- males: significant increases of total cholesterol (+15%), albumin (+6%); significant decreases of the BUN level (-21%), ALP (-12%) and AST (-23%). No other significant changes were noted.
- females: significant decreases of AST (-11%) and BUN (-27%); significant increase of total cholesterol (+26%). No other significant changes were noted.

5 mg/kg bw:
- males: significant decreases of the BUN level (-10%) and AST (-27%). No other significant changes were noted.
- females: significant increases of total cholesterol (+22%) and chloride content (+2%); significant decreases of AST (-18%), ALP (-10%), BUN (-19%) andphosphor content (-18%). No other significant changes were noted.

ORGAN WEIGHTS
125 mg/kg bw:
- males: significant increases of the relative weights of the brain (+12%), pituitary gland (+16%), liver (+40%) and kidney (+16%); the significant increases of relative weights of heart (+8%) and spleen (+350%) were still apparent after the 14 day recovery period (+9% and +46%, respectively). The significant decrease of relative testis weight was -64% and then -44% after the recovery period. No other significant changes were noted.
- females: significant increases of the relative weights of brain (+8%), heart (+11%), spleen (+259%), liver (+87%) and kidney (+16%); significant decreases of the relative weights of the thymus (-28%). All effects were normalized after the 14 day recovery period.after the 14 day observation period. No other significant changes were noted.

25 mg/kg bw:
- males: significant increases of the relative weights of the spleen (+109%) and the liver (+30%). No other significant changes were noted.
- females: significant increases of the relative weights of the spleen (+56%) and the liver (+24%). No other significant changes were noted.

5 mg/kg bw: significant decrease of the relative weight of the adreanal gland (-24%) in males. No other significant changes were noted.

HISTOPATHOLOGY: NON-NEOPLASTIC
125 mg/kg bw:
- Brain: spongiotic changes (moderate in 1/6 males and 2/5 females; severe in 5/6 males and 3/5 females) and brown pigmentation in perivascular region of the cerebellum (moderate in 4/6 males and 2/5 females; severe in 1/6 males and 1/5 females).
After the 14 day recovery period: spongiotic changes (moderate in 3/6 males and 3/6 females; severe in 2/6 males and 1/6 females), and brown pigmentation in perivascular region of the cerebellum (moderate in 3/6 males and 2/5 females).
- Liver: increased extramedullary hematopoiesis (moderate in 5/6 males and 2/5 females) and brown pigmentation in Kupffer's cells (moderate in 5/6 males and 4/5 females; severe in 1/6 males and 1/5 females).
After the 14 day recovery period: brown pigmentation in Kupffer's cells (moderate in 6/6 males and 3/6 females
- Kidney: brown pigmentation of renal tubular epithelium (moderate in 5/6 males and 5/5 females; severe in 1/6 male)
After the 14 day recovery period: brown pigmentation of renal tubular epithelium (moderate in 5/6 males and 6/6 females; severe in 1/6 male)
- Spleen: congestion (severe in all males and females), increased brown pigmentation in red pulp (moderate in 3/5 females; severe in 6/6 males and 2/5 females) and severe increased extramedullary hematopoiesis in all males and females.
After the 14 day recovery period: increased brown pigmentation in red pulp (moderate in 2/6 males and 3/6 females; severe in 4/6 males) and moderate increased extramedullary hematopoiesis in 1/6 male
- Bone marrow: severe increased hematopoiesis in all males and females.
After the 14 day recovery period: moderate increased hematopoiesis in 3/6 females
- Testis: degeneration of seminiferous tubular epithelium and atrophy of seminiferous tubule, as well as reduction of spermatozoa in all males
After the 14 day recovery period: degeneration of seminiferous tubular epithelium and atrophy of seminiferous tubule (moderate in 5 and sever in 1/6 males), as well as reduction of spermatozoa in all males

25 mg/kg bw:
- Spleen: congestion (moderate in 4/6 males and 4/6 females), increased brown pigmentation in red pulp (moderate in 5/6 males and in 6/6 females) and moderate increased extramedullary hematopoiesis in all males and females
- Bone marrow: increased hematopoiesis in 3/6 females

5 mg/kg bw:
- Spleen: moderate congestion in 1/6 females, increased brown pigmentation in red pulp in 1/6 females and increased extramedullary hematopoiesis (moderate in 3/6 males and 3/6 females)
- Bone marrow: moderate increased hematopoiesis in 1/6 females
OTHER FINDINGS
In general, the findings disappeared or tended to be decreased during or at the end of the recovery period.

Effect levels

Dose descriptor:

LOAEL

Effect level:

5 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: relative liver weight, increased extramedullary hematopoiesis and overall splenic effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Body weights (g):

	28-day dosing study					14-day recovery study
	Control	5 mg/kg bw	25 mg/kg bw	125 mg/kg bw		Control	125 mg/kg bw
Males	231 ± 10	226 ± 13	233 ± 8	192 ± 17		259 ± 12	246 ± 14
Females	148 ± 6	154 ± 4	151 ± 6	144 ± 5		169 ± 2	172 ± 9

Changes in relative organ weights (compared to control values):

		28-day dosing study				14-day recovery study
		5 mg/kg bw	25 mg/kg bw	125 mg/kg bw		125 mg/kg bw
Males	Brain	-	-	+12%		-
	Pituitary gland	-	-	+16%		-
	Salivary gland	-	-	-		-
	Thymus	-	-	-		-
	Lung	-	-	-		+18%
	Heart	-	-	+18%		+9%
	Spleen	-	+109%	+350%		+46%
	Liver	+8%	+30%	+40%		-
	Adrenal gland	-	-	-		-
	Kidney	-	-	+16%		-
	Testis	-	-	-64%		-44%
Females	Brain	-	-	+8%		-
	Pituitary gland	-	-	-		-
	Salivary gland	-	-	-		-
	Thymus	-	-	-28%		-
	Lung	-	-	-		-
	Heart	-	-	+4%		-
	Spleen	-	+56%	+259%		-
	Liver	-	+24%	+87%		-
	Adrenal gland	-24%	-	-		-
	Kidney	-	-	+16%		-
	Ovary	-	-	-		-