1,2,4-trichlorobenzene

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable documented publication

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Multigeneration study of 1,2,4-trichlorobenzene in rats

Author:

Robinson KS, Kavlock RJ, Chernoff N, and Gray LE

Year:

1981

Bibliographic source:

J Toxicol Environ Health 8: 489 - 500

Reference 2

Reference Type:

secondary source

Title:

European Union Risk Assessment Report - 1,2,4-Trichlorobenzene

Author:

European Commission - European Chemicals Bureau

Year:

2003

Bibliographic source:

Office for Official Publications of the European Communities

Materials and methods

Principles of method if other than guideline:

Rats were continously exposed to 0, 25, 100, or 400 ppm 1,2,4-trichlorobenzene in the drinking water, beginning with birth of the F0 generation and continuing through weaning of the F2 generation. Fertility, growth, viability, locomotor activity, blood chemical analysis, and histopathology analysis were performed

GLP compliance:

no

Remarks:

GLP was not mandatory at the time of the study

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,2,4-trichlorobenzene

EC Number:

204-428-0

EC Name:

1,2,4-trichlorobenzene

Cas Number:

120-82-1

Molecular formula:

C6H3Cl3

IUPAC Name:

1,2,4-trichlorobenzene

Details on test material:

Name of test material (as cited in study report): 1,2,4-trichlorobenzene
- Analytical purity: no data

Test animals

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratory, Wilmington, Mass, USA
- Age at study initiation: (P) 90-d-old; (F0) x 90-d-old; (F1) x 90-d-old
- Fasting period before study: no
- Housing: Upon arrival, 100 time-pregnant animals were housed individually in 43 X 23 X 20 cm plastic cages.
- Diet (e.g. ad libitum): Throughout the study, animals were fed commercial laboratory diet ad libitum.
- Water (e.g. ad libitum): The time-pregnant animals received tap water ad libitum until birth of F0 generation, when they were assigned to one of five treatment groups and given the appropriate water.



ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-26 °C
- Photoperiod (hrs dark / hrs light): 12 h dark/ 12 h light)

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

other: the 1,2, 4-trichlorobenzene solutions contain 0.125% in drinking water.

Details on exposure:

Since 1,2,4-trichlorobenzene is not soluble in water at the concentrations used, the 1,2,4-trichlorobenzene solutions also contained a solubizer, Tween 20 at a concentraion of 0.125%.
Animals were given freshly prepared solutions at least twice weekley and allowed to drink ad libitum.

Details on mating procedure:

- M/F ratio per cage: In F0 and F1 generations 1M/2F.
- Length of cohabitation: 2 weeks
- After successful mating each pregnant female was caged (how): individually

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

Exposure period: from birth of F0 generation through weaning of F2 generation
Premating exposure period (males): F0: 90 days; F1: 90 days
Premating exposure period (females): F0: 90 days; F1: 90 days
Duration of test: until day 32 of F2 generation

Frequency of treatment:

continuously

Details on study schedule:

- Age at mating of the mated animals in the study: 90 days

Doses / concentrations

Remarks:

Doses / Concentrations:
25, 100 or 400 mg/l (see remark)
Basis:
nominal in water

No. of animals per sex per dose:

In all generations, each treatment group consisted in 17-23 litters.

Control animals:

other: yes, concurrent no treatment; yes, concurrent vehicle

Examinations

Statistics:

The significance of treatment-related effects was analyzed by analysis of variance and, when results were significant, by linear regression. Whenever a significant dose response was found by linear regression, Dunn´s procedure was used to determine the significance of pairwise comparisons. The organ weight and blood chemistry data in the F0 and F1 generations at day 95 were analyzed by regression procedure as 2 x 2 x 4 (sex, generation, dose) factorial design.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

not examined

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not examined

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

BODY WEIGHT AND DIETARY INTAKE (PARENTAL ANIMALS)
The postweaning growth of the F0 and F1 animals was not affected by 1,2,4-trichlorobenzene.
A treatment-related increase in food intake was found in the F0 males at day 29 (F [1,59]=4.97, p<0.028). There are also two instances of a treatment related decrease in water intake in the F0 generation, one in the females at day 35 (F [1,80]=5.71, p<0.018) and another in both sexes at day 83 [males, F [1,68]=11.72, p<0.001; females F [1,68]=15.05, p<0.001. In all three of these dietary effects in the F0 generation, Dunn´s procedure found only the high-dose group to be significantly different from controls. No treatment-related differenced in food or water intake was found in the F1 generation during the postweaning period.



ORGAN WEIGHTS (PARENTAL ANIMALS)
The 400 ppm 1,2,4-trichlorobenzene dose produced significantly increase enlarged adrenals in both sexes in the F0 and F1 animals at 95 d of age F [1,154]=7.68, p<0.006.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

ca. 25 mg/L drinking water

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

not examined

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

ca. 25 mg/L drinking water

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

Table 1.Effects of 1, 2, 4-trichlorobenzene

	Females delivering
	Female bred		Litter size,day 1		Percent mortality today 12		Percent mortality from d12 to weaning
Dose (ppm1,2,4-trichlorobenzene)	F0	F1	F1	F2	F1	F2	F1	F2
0 (water)	23/24	18/24	13.3±0.94a	9.8±0.64	15.0±3.42	6.3±2.96	3.3±2.20	1.0±0.70
0 (tween20)	22/24	19/24	12.8 ±0.71	10.3±0.87	14.2±3.46	9.3±5.62	1.2±0.92	3.6±2.74
25	19/24	21/24	14.5± 0.42	10.5±0.98	21.3±5.02	3.7±2.50	2.0±0.97	0.8±0.62
100	18/24	17/24	13.4±0.80	12.8±0.88	21.8±6.77	5.7±2.19	3.2±1.63	1.2±0.60
400	22/24	20/24	14.1±0.36	12.8±0.78	13.1±4.00	5.4±2.33	4.3±2.47	3.0±1.34

^dValuesare means ± SE

 

 

 

Table 2. Representative Dietary Intake data from the F0 Generation with Calculated Dosages

 

Dose (ppm1,2,4-trichlorobenzene	Female food intake (g/d per animal)	Female water intake (g/d per animal)	Calculated female dosage (mg/kg x day 1,2,4-trichlorobenzene)	Male food intake (g/d per animal)	Male water intake (mL/f per animal)	Calculated male dosage (mg/kg x day 1,2,4-trichlorobenzene)
29 days of age
0	13.9±0.4^a	24.4±1.3		17.4±0.5	26.9±1.1
25	14.4±0.6	28.5±2.5	8.3±0.8	15.7±0.8	31.9±2.1	8.5±0.6
100	13.4±0.2	24.8±0.9	28.0±1.2	16.5±0.6	27.2±1.6	27.6±1.6
400	14.1±0.3	27.3±2.2	133.2±13.4	19.3±1.8^b	32.1 ±3.4	133.6±15.6
83 days of age
0	20.0±0.7	31.6±1.6		31.7±0.8	43.9±1.8
25	20.0±0.7	31.6±1.3	3.7±0.1	30.6±1.0	47.0±2.2	2.5±0.1
100	20.0±0.8	30.8±1.7	14.8±1.0	30.9±1.2	42.0±1.3	8.9±0.3
400	19.6±0.8	26.2±0.8^b	53.6±3.9	29.3±0.6	38.6±1.7^b	33.0±1.4

^aValues are means ± SE

^bSignificantly different from control, p<0.05

 

 

 

Table 3. Locomotor Activity of Animals Exposed to 1,2,4-trichlorobenzene

 

			Dose (ppm 1,2,4-trichlorobenzene)
Generation	Age (days)	Sex	0	25	100	400
F0	16	M	227±19.3a	246±19.6	184±30.7	207±16.9
		F	292±44.2	233±36.2	202±35.7	253±34.3
F0	27	M	418±36.8	390±40.0	459±31.5	428±19.6
		F	429±25.4	427±23.5	388±18.1	438±24.0
F0	48	M	620±42.7	744±46.9	633±62.5	633±59.5
		F	701±37.7	778±86.7	772±38.5	811±61.4
F0	90	M	611±70.9	678±44.0	556±69.4	772±70.0
		F	746±65.0	796±58.7	746±42.8	888±65.7
F1	31	M	555±49.3	510±40.7	500±59.3	472±48.7
		F	467±63.2	556±40.7	462±51.3	578±48.7
F1	90	M	611±46.7	590±110.9	596±45.0	586±55.7
		F	728±82.9	802±58.8	712±91.3	784±77.5
F2	26	M	394±30.8	373±28.5	282±14.6	387±41.4
		F	286±44.2	359±88.5	344±58.1	373±70.0

 

Table 4.Effect of 1,2,4-trichlorobenzene in the drinking water on adrenal weights

 

 

 

Dose (ppm1,2,4-trichlorobenzene	Males	Females
F0, 95 days
0 (water)	28.7±1.78^a	34.1±1.87
0 (tween20)	28.6±1.09	36.8±1.14
25	28.8±1.59	35.6±1.70
100	28.2±1.10	36.6±1.08
400	31.8±2.43^b	41.5±1.99^b
F1, 95 days
0 (water)	27.1±1.71	35.8±1.89
0 (tween20)	28.0±1.57	37.0±1.36
25	28.8±1.46	34.8±1.77
100	26.6±0.82	35.3±1.07
400	29.6±1.66^b	38.5±1.89^b

^aValues are means ±SE; weights are in milligrams and for the left adrenal only-

^bSignificantly different from controls, p<0.05

 

Applicant's summary and conclusion

Executive summary:

Robinson (1981):

Rats were continuously exposed to 0, 25, 100, or 400 ppm 1,2,4-trichlorobenzene in the drinking water, beginning with birth of F0 generation and continuing through weaning of the F2 generation. The treatment did not affect fertility, growth, viability, locomotor activity, or blood chemical analyses. Adrenal gland enlargement was observed in both the F0 generation and F1 animals at 95 d of age.