4-nitrotoluene

Toxicity to reproduction

Administrative data

Endpoint:

fertility, other

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

NTP study (standard protocol comparable to OECD 408 with acceptable restrictions (no post exposure period, slight deviations from guideline recommended housing conditions, limited chemical chemistry, not all recommended organs were weighed). Study indicative of reproduction toxicity.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: 408

Deviations:

yes

Remarks:

(no post exposure period, slight deviations from guideline recommended housing conditions, limited chemical chemistry, not all recommended organs were weighed)

Principles of method if other than guideline:

NTP standard protocol for determination of subchronic toxicity after 90 days repeated dose application. Groups of rats animals were fed diets containing p-nitrotoluene for 13 weeks.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-nitrotoluene

EC Number:

202-808-0

EC Name:

4-nitrotoluene

Cas Number:

99-99-0

Molecular formula:

C7H7NO2

IUPAC Name:

1-methyl-4-nitrobenzene

Details on test material:

- Source: Aldrich Chemical Co. (Milwaukee, WI),
- Analytical purity: >96%
- Impurities: < 1% (mostly m- and o-nitrotoluene)
- Storage: RT
- Stability: reanalysis performed at approx. 4 months intervals indicated that the test
substance was stable under the storage conditions chosen

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Inc. (Germantown, NY)
- Age at study initiation: 6 weeks
- Mean weight range at study initiation: 133 - 145g (male), 106 - 110g (female)
- Housing: 5/cage
- Diet: ad libitum, NIH-07 feed (Zeigler Brothers, Gardners, PA)
- Water ad libitum
- Acclimation period: 10-15 days
- Other: 5 viral screens performed at the study start and termination indicated no positive antibody titer

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.9 - 26.1
- Humidity (%): 32-90%
- Air changes (per hr): 16-29
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

daily

Details on study schedule:

Groups of rats animals were fed diets containing o-nitrotoluene for 13 weeks. Reproductive system evaluation were then performed in male and female animals

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 625, 1250, 2500, 5000, or 10000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

10

Control animals:

yes, plain diet

Results and discussion

Results: P0 (first parental generation)

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

5 000 ppm (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: see 'Remark'

Results: F1 generation

Effect levels (F1)

Dose descriptor:

other: not measured/tested

Generation:

other: not measured/tested

Based on:

other: not measured/tested

Remarks on result:

not measured/tested

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

 

GROSS PATHOLOGY AND TESTES WEIGHTS AND HISTOPATHOLOGY Relative testis weights were unchanged in dosed animals. Potential treatment-related gross lesions were limited to 2 males from the 10000 ppm exposure group which had small testes. Microscopically, treatment-related lesions were found in the kidney, spleen, and testis of rats

 

REPRODUCTIVE ORGANS MALES Degeneration of the testis (minimal to mild) was seen in high-dose male rats; this was characterized by the absence of spermatogenesis, decreased number of germinal epithelial cells, and the presence of syncytial giant cells (degenerate spermatids) in a few seminiferous tubules, usually at the periphery of the testis. Epididymal sperm concentration and testicular spermatid head count were reduced in high dose males.

 

FEMALES Among females, 9/10 in the 10000 ppm group did not have a discernible estrous cycle. There were no gross or histopathologic changes in the uterus or ovaries at the end of this 13-week study

Table1:Summary of Reproductive Tissue Evaluations in Male Rats in the 13-Week Feed Study of p-Nitrotoluene (n=10 animals/dose)

Study Parameter		0 ppm	2500 ppm	5000 ppm	10000 ppm
Weights (g)	Necropsy weight	353 ± 6	344 ± 11	320 ± 6**	251 ± 6**
	Left testicle	1.51 ± 0.025	1.47 ± 0.045	1.42 ± 0.028	1.09 ± 0.079 **
	Left epididymis	0.46 ± 0.011	0.45 ± 0.020	0.44 ± 0.012	0.13 ± 0.027 **
	Left epididymal tail	0.18 ± 0.007	0.18 ± 0.009	0.20 ± 0.0018	0.13 ± 0.016 *
Spermatid measurements	Spermatid heads 10^7/ g testis	10.13 ±0.42	9.81 ±0.41	9.73 ± 0.49	8.71 ± 0.82
	Spermatid heads 10^7/ testis	15.29 ±0.71	14.31 ±0.55	13.78  ± 0.64	10.03± 1.34 **
	Spermatid count (mean/10^4/ml suspension)	76.43 ± 3.55	71. 55 ±2.74	68.90 ± 3.22	50. 15 ±6.70 **
Spermatozoal Measurements	Motility (%)	79 ±2	77 ±3	81 ±2	59 ± 11
	Concentration (10^6/g cet)^1	501 ± 45	604 ± 112^3	451 ± 40	325 ± 60^*3

¹g cet = grams of caudal epididymal tissue.

* Significantly different (P<= 0.05) from the control group by Dunn's or Shirley's test.

** Significantly different (P<= 0.01) from the control group by Dunn's or Shirley's test.

 

Table 2:Summary of Estrous Cycle Characterization in Female Rats in the 13-Week Feed Study of p-Nitrotoluene (n= 10 animals/dose except where indicated)

		0 ppm	2500 ppm	5000 ppm	10000 ppm
Necropsy body weight	-	202 ±3	196 ±3	185 ±3**	174 ±3 **
Estrous cycle length	-	5. 15 ±0.13	5. 15 ±0.08	6.05 ± 0.51	5.00^2
Estrous stages as % of cycle	Diestrus	45.8	45.0	55.0	78.3
	Proestrus	15.0	14.2	12.5	4.2
	Estrus	24.2	25.8	20.0	11.7
	Metestrus	15.0	15.0	12.5	5.8

²n=4, estrous cycle length longer than 12 days or unclear in 6 of 10 animals

³Evidence by multivariate analysis of variance (MANOVA) suggests that females in all dose groups differ from controls in the relative frequency of time spent in the estrous stages; P=0.06 for the 2,500 ppm group, P=0.04 for the 5,000 ppm group, and P = 0.01 for the 10,000 ppm group

** Significantly different (P<=0.01) from the control group by Dunn's or Shirley's test

Applicant's summary and conclusion

Executive summary:

NTP, 1992

The study was comparable to OECD guideline 408 with acceptable deviations (no post exposure period, slight deviations from guideline recommended housing conditions, limited chemical chemistry, not all recommended organs were weighed).10 animals/sex/dose (F344/N rats) were fed diets containing p-nitrotoluene at nominal concentrations of 0, 625, 1250, 2500, 5000, or 10000 ppm. Only animals in the 3 highest dose groups were subjected to reproductive system evaluations. Gross and histopathological examinations of the reproductive systems indicated that p-nitrotoluene might be a reproduction toxicant. Relative testis weights were unchanged in dosed animals. Potential treatment-related gross lesions were limited to 2 males from the 10000 ppm exposure group which had small testes. Microscopically, treatment-related lesions were found in the kidney, spleen, and testis of rats. Degeneration of the testis (minimal to mild) was seen in high-dose male rats; this was characterized by the absence of spermatogenesis, decreased number of germinal epithelial cells, and the presence of syncytial giant cells (degenerate spermatids) in a few seminiferous tubules, usually at the periphery of the testis. Epididymal sperm concentration and testicular spermatid head count were reduced in high dose males. Among females, 9/10 in the 10000 ppm group did not have a discernible estrous cycle. There were no gross or histopathologic changes in the uterus or ovaries at the end of this 13-week study