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Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
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

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Toxicity studies of 1,3-dichlorobenzene in Sprague-Dawley rats
Author:
McCauley PT, Robinson M, Daniel FB, and Olson GR.
Year:
1995
Bibliographic source:
Drug & Chem. Toxicol. 18, 201-221
Reference Type:
review article or handbook
Title:
1,3-dichlorobenzene, Supplement 2008
Author:
The MAK Collection for Occupational Health and Safety
Year:
2013
Bibliographic source:
The MAK-Collection Part I, MAK Value Documentations 2013 DFG, Deutsche Forschungsgemeinschaft © 2013 Wiley-VCH Verlag GmbH & Co. KGaA

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
Mortality was recorded once a day instead of twice; ophthalmological examination not performed; platelet count not performed; some organ not examined; individual weight not reported.
Principles of method if other than guideline:
Male and female Sprague-Dawley rats received 1,3-dichlorobenzene daily doses of 0, 9, 37, 147 or 588 mg/kg bw/day by corn oil gavage for 90 consecutive daily. All rats were observed daily for physiological and behavioral responses and for mortality. Body weights and food and water consumption were recorded weekly throughout the study. Blood samples were collected at necropsy for hematologic and serum chemistry measurements prior to necropsy. A gross and histopathological examination was performed on all major organs.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
Name of test material (as cited in study report): 1,3-dichlorobenzene
- Analytical purity: 99.99%

Specific details on test material used for the study:
Purity > 99.99% (by GC/MS)

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Portage, MI, USA
- Age of the animals when received in the testing laboratory: 70 days
- Weight at study initiation: 300-325 g (males); 225-250 g (females)
- Housing: Animals were used 2 per cage by sex in polycarbonate hardwood chip bedding (Absorb-Dri, Maywood, NY, USA)
- Diet (e.g. ad libitum): Purina Certified Rodent Chow 5002 (Ralston-Purina Co., St. Louis, MO, USA) ad libitum
- Water (e.g. ad libitum): ad libitum
- Quarantine period: 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Animals were held in a temperature controlled room
- Humidity (%): Animals were held in a humidity controlled room
- Photoperiod (hrs dark / hrs light): 12 hrs dark: 12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
One hundred animals were divided into five experimental groups consisting of 10 males and 10 females per group. There were four treatment Ieveis of 1 ,3-DCB [9, 37,
14 7, 588 mg/kg] and a vehicle control of corn oil. Individual animal dosages were determined weekly from individual body weights. Each rat received a dosing volume of 0.1 ml per 100 g of body weight. Animals were gavaged daily for 90 consecutive days.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
90 days
Frequency of treatment:
daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 9, 37, 147 or 588 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
10 male and 10 female animals/dose
Control animals:
yes

Examinations

Sacrifice and pathology:
GROSS PATHOLOGY: yes
HISTOPATHOLOGY: Yes : brain, liver, spleen. lungs with the lower half of the trachea, thymus, kidneys, adrenal glands, heat and gonads, skin, mandibular and mesenteric lymph modes, mammary gland, thigh muscle, sciatic nerve, sternebrae, thymus, esophagus, stomach, duodenu, jejunum, tongue, salivary gland, ileum, colon, cecum, rectum, pancreas, urinary bladder, seminal vescicles, prostate, uterus, nasal cavity and turbinated, pituitary, preputial or clitoral gland, Zymbal´s gland, aorta, thyroid, parathyroids.
Statistics:
Males and females were considered separately in all statistical analyses. One-factor (dose) analysis of variance (ANOVA) was used to analyze normally distributed measures: body weights, organ weights, organ weight ratios, food and water consumption, haematology and clinical chemistry. When a treatment effect was noted (p= 0.05, F-test) the difference between the control and treatment groups was probed using Tukey´ Multiple Comparison Procedure. For those haematological and clinical chemistry measures which were not normally distributed (extreme values, high variability), a nonparametric procedure, the Kruskal-Wallis test, was used to determine differences among the dose groups. If a significant difference was reached (p= 0.05), a Wilcoxon Rank Sum method was applied for multiple comparison of treatment groups. Incidence of histopathological lesions was analyzed by Fisher Exact test, with a criterion of (p= 0.05).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
There were no compound-related deaths or other clinical signs of toxicity at any dose level.

BODY WEIGHT AND WEIGHT GAIN
Both sexes administered 588 mg/kg showed a significantly decreased final body weight. This weight loss was progressive through the period of exposure.

FOOD EFFICIENCY
Average daily food consumption in treatment groups was not significantly different from controls but when food usage was normalized by the final body weight, both sexes at 588 mg/kg significantly increased by 18%.

HAEMATOLOGY
Statistical significance was achieved at the high dose level (599 mg/kg), with females having an increased white blood count and males having an increased red blood count. The white blood count of males was significantly increased at 147 mg/kg. There were no other significant hematologic findings in either sex at the other dose levels.

CLINICAL CHEMISTRY
In females, BUN levels were depressed but cholesterol and calcium levels were elevated in the 588 mg/kg group whole males at this level had decreased lactate dehydrogenase (LDH) and blood urea nitrogen (BUN) levels and increased calcium and aspartate aminotransferase (AST) levels.
In the 147 mg/kg group, males and females had significantly increased cholesterol and calcium levels with males having a significantly decreased LDH and increased AST.
In the 37 mg/kg group, increased cholesterol and calcium levels in both sexes, increased alkaline phosphatise levels in females and decreased LDH in males were noted.
The lowest dose group (9 mg/kg) produced decreased LDH levels and increased AST and cholesterol levels in males. No alteration in clinical chemistries in the females were evident at this dose levels

ORGAN WEIGHTS
Females had significantly increased kidney and liver weight ratios in the high dose group while males at this dose level had significantly increased brain, testes, kidney, and liver weight ratios.
Decreased brain weight ratio and increased liver weight ratio in females, and increased liver and kidney weight ratios in males were noted at 147 mg/kg. Organ weight ratios were not altered at the 9 or 37 mg/kg dose levels.



HISTOPATHOLOGY: NON-NEOPLASTIC
In the thyroid, a depletion of colloidal density within thyroid follicles exceeding variability was observed in both sexes in > 80% of the animals in the 37, 147, and 588 mg/kg dose groups. Depletion of colloid density was characterized in the thyroid gland by decreased follicular size with scant colloid and follicles lined by cells which were cuboidal to columnar.
Hepatic inflammation, characterized by spherical, brightly eosinophilic homogeneous inclusions, were evident in only one of the ten control males, but no control females, but was noted in 26 of 78 male and female rats receiving the test compound. A dose-related increase in the severity of the change was present in males. Hepatocellular necrosis, characterized by loss or pyknosis and disruption of cytoplasmic integrity was observed as scattered single necrotic hepatocytes or by foci of multiple necrotic hepatocytes. The 588 mg/kg dose groups. These vacuoles were variably sized, irregularly shaped and often poorly defined. A compound related increase in the severity, based on the number of cells containing vacuoles, was observed. The females displayed no anterior pituitary changes.
Spontaneous inflammatory and degenerative changes were encountered in both control and treated groups, in the pancreas, lung, preputial and clitoral glands, kidneys, and prostate. These changes were not considered treatment related.



Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
37 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: increased incidence of thyroid changes in the form of a decreased colloid density in the thyroid follicles are not regarded as relevant for humans.
Dose descriptor:
LOAEL
Effect level:
147 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: increased relative liver and kidney weights occurred and in male rats and a vacuolization in cells of the pars distalis in the pituitary glands were observed

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1. Body weights and relative organ weights (X± SD) of rats exposed by gavage for 90 days to 1,3-dichlorobenzene

 

Parameters

Corn oil

0

9

37

147

588

Females

Body weight (g)

277± 22

279 ± 18

286 ± 15

283 ± 21

249 ± 13*

Brain

0.74 ± 0.07

0.73 ± 0.05

0.68 ± 0.06

0.67 ± 0.03*

0.77 ± 0.06

Ovaries

0.07 ± 0.01

0.08 ± 0.02

0.07 ± 0.02

0.06 ± 0.01

0.07 ± 0.03

Heart

0.37 ± 0.04

0.34 ±0.03

0.34 ± 0.03

0.32 ± 0.09

0.36 ± 0.07

Kidneys

0.72 ± 0.07

0.75 ± 0.06

0.72 ± 0.07

0.80 ± 0.09

0.87 ± 0.10*

Adrenals

0.04 ± 0.01

0.04 ± 0.01

0.03±0.01

0.04 ± 0.01

0.05 ± 0.03

Liver

2.93 ± 0.33

2.79 ± 0.28

3.05 ± 0.32

3.86 ± 0.28 *

5.11 ± 0.35*

Lung

0.57 ± 0.06

0.53 ± 0.05

0.49 ± 0.05

0.48 ± 0.06

0.53 ± 0.12

Spleen

0.21 ± 0.03

0.19 ± 0.02

0.19 ± 0.02

0.19 ±0.03

0.18 ±0.03

Thymus

0.14 ± 0.04

0.12 ± 0.03

0.12 ± 0.03

0.12 ± 0.03

0.12 ± 0.04

Males

Body weight (g)

517 ± 47

551 ± 57

536 ± 38

501 ± 41

392 ± 47 *

Brain

0.41 ± 0.04

0.40 ± 0.04

0.40 ± 0.05

0.43 ± 0.04

0.50 ± 0.07*

Testes

0.68 ± 0.08

0.67 ± 0.06

0.65 ± 0.08

0.69 ± 0.11

0.85 ± 0.14*

Heart

0.30 ± 0.03

0.29 ± 0.03

0.30 ± 0.04

0.28 ± 0.06

0.34 ± 0.08

Kidneys

0.71 ± 0.06

0.70 ± 0.08

0.74 ± 0.06

0.99 ± 0.08*

0.96 ± 0.14 *

Adrenals

0.02 ± 0.01

0.02 ± 0.01

0.02 ± 0.01

0.02 ± 0.01

0.02 ± 0.01

Liver

2.81 ± 0.27

3.00 ± 0.26

3.21 ± 0.22

4.24 ± 0.25*

5.20 ± 0.78*

Lung

0.41 ± 0.03

0.37 ± 0.04

0.40 ± 0.05

0.40 ± 0.05

0.46 ± 0.07

Spleen

0.15 ± 0.03

0.16 ± 0.02

0.15 ± 0.03

0.17 ± 0.04

0.14 ± 0.02

Thymus

0.09 ± 0.02

0.09 ± 0.02

0.08 ± 0.03

0.07 ± 0.02

0.07 ± 0.03

*Significantly different from controlgroup ;p =0.05,Tukey´sMultiple Comparison.

 

Table 2.Hematology values (X± SD) in rats treated with 1,3-dichlorobenzene for 90 days

 

Parameters

Corn oil

0

9

37

147

588

Females

RBC X 106

6.4 ± 0.4

6.5 ± 0.4

6.7 ± 0.4

6.1 ± 0.7

6.7 ± 0.3

WBC X 103

4.1 ± 1.0

3.4 ± 1.0

4.9 ± 1.7

4.7 ± 1.0

6.4 ± 1.0*

Hgb (g/dL)

14.5. ± 0.8

14.2 ± 0.9

14.4 ± 0.7

13.5 ± 1.0

14.1 ± 0.5

Hct (%)

36.4 ± 2.6

36.0 ± 2.5

37.0 ± 2.2

34.4 ± 1.8

36.1 ± 1.6

MCV (u3)

55.2 ± 1.2

53.9 ± 1.4

54.1 ± 1.4

56.0 ± 5.4

52.9 ± 1.3

Males

RBC X 106

7.4 ± 0.3

7.5 ± 0.3

7.4 ± 0.2

7.3 ± 0.4

7.9 ± 0.3*

WBC X 103

5.6 ± 0.9

5.9 ± 1.5

6.1 ± 1.3

8.7 ± 2.1*

7.6 ± 2.2

Hgb (g/dL)

14.9 ± 0.5

14.9 ± 0.7

15.1 ± 0.5

15.0 ± 0.5

15.2 ± 0.4

Hct (%)

39.9 ± 1.6

40.5 ± 2.4

39.5± 1.1

38.9 ± 1.5

42.2 ± 1.9

MCV (u3)

52.9 ± 0.7

53.0 ±1.4

52.2 ± 1.5

52.2 ± 1.3

52.0 ± 1.1

 RBC= red blood cell

WBC =white blood cell

Hgb=hemoglobin

Hct=Hematocrit

MCV= mean corpuscular volume

 

Table 3.Clinical Chemistry Values (X± SD) in rats exposed to 1,3-dichlorobenzene for 90 days

Parameters

Corn oil

0

9

37

147

588

Females

Glu (mg/dL)

107.3 ± 3.0

107. 5 ± 17.5

128.4 ± 18.1

109.1 ± 18.9

82.4 ± 30.4

BUN (mg/dL)

19.4 ± 3.5

18.0 ± 2.4

19.5 ± 1.7

16.8 ± 2.2

13.1 ± 2.0*

Creat (mg/dL)

0.07 ± 0.03

0.06 ± 0.01

0.06 ± 0.02

0.06 ± 0.01

0.06 ± 0.01

Phos (U/L)

6.9 ± 1.0

7.4 ± 1.1

8.0 ±0.7*

7.8 ±0.3

7.3 ±0.4

AST (U/L)

115.9 ± 41.6

119.1 ± 32.8

105.4 ± 27.9

188.7 ±113.0

108.0 ± 25.4

ALT (U/L)

42.2 ± 23.2

49.2 ± 34.4

35.5 ± 9.3

63.7 ± 51.1

52.9 ± 10.8

Chol (mg/dL)

68.2 ±23.2

85.0 ± 3.0

108.4 ± 2.2 *

158.9 ± 1.8*

152.6 ± 2.6*

LDH (U/L)

932 ± 262.3

964.8 ± 313.5

762.8 ± 467.6

1029.8 ± 229.8

904.7 ± 447.1

Ca (mg/dL)

10.8 ± 0.3

11.0 ± 0.4

11.5 ± 0.6*

12.0 ± 0.5*

12.1 ± 0.5*

Males

Glu (mg/dL)

123.3 ± 34.7

147 ± 16.2

129.1 ± 9.6

121.3 ± 20.3

106.9 ± 30.6

BUN (mg/dL)

20.0 ± 3.0

18.2 ± 3.3

20.2 ± 2.6

20.4 ± 2.0

15.8 ±2.3*

Creat (mg/dL)

0.06 ± 0.01

0.05 ± 0.01

0.07 ± 0.02

0.06 ± 0.01

0.06 ± 0.01

Phos (U/L)

9.7 ± 1.0

8.7 ±0.9

10.2 ± 1.3

9.3 ± 1.2

8.8 ± 1.0

AST (U/L)

43.7 ± 37.7

87.6 ± 24.7 *

109.8 ±9.5

88 ± 23.3 *

82.8 ± 13.8*

ALT (U/L)

46.8 ± 7.7

40.8 ±9.7

43.3 ± 4.5

38.5 ± 8.2

59.3 ± 11.0

Chol (mg/dL)

73.5 ± 1.4

96.6 ± 1.7*

111.1 ± 1.6*

157.9 ± 2.5 *

89.5 ± 1.5 *

LDH (U/L)

1762.0 ± 765.2

623.0 ± 466.3*

797.8 ± 237.6*

777.8 ± 529.9*

735.0 ± 287.7*

Ca (mg/dL)

11.3 ± 0.7

11.9 ± 0.5

12.0 ± 0.5*

11.9 ± 0.3*

12.0 ± 0.5*

*Significantly different from controlgroup ;p =0.05,Tukey´sMultiple Comparison.

Glu= glucose

BUN= blood urea nitrogen (BUN)

Creat= creatinine

Phos= alkaline phosphatase

  AST= aspartate aminotransferase (AST)

ALT= alanine aminotransferase (ALT)

Chol= cholosterol

LDH= lactate dehydrogenase (LDH)

Ca= calcium (Ca)

Applicant's summary and conclusion

Executive summary:

Male and female Sprague-Dawley rats received 1,3-dichlorobenzene ( 0, 9, 37, 147 and 588 mg/kg bw) daily by corn oil gavage for 90 days (method similar to OECD guideline 408 with deviations: mortality was recorded once a day instead of twice; ophthalmological examination not performed; platelet count not performed; some organ not examined; individual weight not reported.

Body weights were significantly depressed in both sexes at 588 mg/kg.

Normalization of food and water consumption by final body weight indicated that at 588 mg/kg both sexes had increased food and water consumption in comparison to controls. Absolute and relative liver weights were significantly increased in both sexes at 147 and 588 mg/kg. Relative kidney weights were significantly higher in both sexes at 588 mg/kg and in males at 147 mg/kg. Serum cholesterol and calcium levels were significantly elevated over controls in females at 37, 147, and 588 mg/kg, and in males at all dose levels. Histopathological evaluation at 147 and/or 588 mg/kg demonstrated liver and thyroid lesions in both sexes, and pituitary and kidney lesions in males.