1H-Pyrazole, 1,4-dimethyl-

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP compliant, similar to guideline study, available as unpublished report, adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,4-Dimethyl-1H-pyrazole

EC Number:

600-813-6

Cas Number:

1072-68-0

Molecular formula:

C5H8N2

IUPAC Name:

1,4-Dimethyl-1H-pyrazole

Details on test material:

- Name of test material (as cited in study report): DP
- Lot No.: DP9001
- Purity: 99.3%
- Storage condition: cold and dark room
- Physical state: liquid
- Stability: no hydrolyzable effect

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Japan SLC. Inc., 3371-8, Koto-cho, Hamamatsu-shi, Shizuoka-ken 431-11, Japan
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: males 163 – 195 g, females 121 – 138 g
- Fasting period before study: 16 hours
- Housing: five rats per cage, in wire mesh cages (21.5 x 27.5 x 19.5 cm) suspended from stainless steel and aluminium racks (745 x 50 x 182 cm) made by Tokyo Giken service Co., Ltd. (Wakamatsu-cho 2-8-16, Fuchu-shi, Tokyo, Japan).
- Diet: ad libitum, a commercial rat and mouse diet MF (Oriental Yeast Co., Ltd., Kodenma-cho 10-11, Nihonbashi, Chuo-ku, Tokyo)
- Water: ad libitum, tap water
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 - 24
- Humidity (%): 50 - 60
- Air changes (per hr): 20
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

distilled

Details on oral exposure:

VEHICLE
- Amount of vehicle (if gavage): 1 mL/100 g bw

Doses:

518, 622, 746, 896, 1075 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Following administration, each animal was observed at every hour during the first 8 hours and at least twice daily and as often as practicable thereafter. The body weight of each animal was determined shortly before the administration, and 7 and 14 days after dosing. All of the dead animals were weighed and then necropsied.
- Necropsy of survivors performed: yes

Statistics:

The LD50 values were calculated by the method of Litchfield and Wilcoxon (1949).

Results and discussion

Effect levels

Effect levels 1

Sex:

male

Dose descriptor:

LD50

Effect level:

969 mg/kg bw

Based on:

test mat.

95% CL:

777 - 1 210

Effect levels 2

Sex:

female

Dose descriptor:

LD50

Effect level:

859 mg/kg bw

Based on:

test mat.

95% CL:

742 - 993

Mortality:

- No mortality was observed in animals exposed to 518 or 622 mg/kg bw.
- 1 male and 1 female rat died exposed to 746 mg/kg bw, at 2 and 3 days after dosing, respectively.
- 2 male and 3 female rats died exposed to 896 mg/kg bw, within 2 and 3 days after dosing, respectively.
- All animals died exposed to 1075 mg/kg bw, the males within 3 days and the females within 2 days after dosing.

Clinical signs:

- Decrease in spontaneous motor activity, prone position, miosis, lacrimation and ptosis were observed in both sexes exposed to 518 mg/kg bw. In the male group chromodacryorrhea was additionally observed. The surviving male and female rats recovered from these toxic signs within 8 to 24 hours after dosing.
- Decrease in spontaneous motor activity, prone position, miosis, lacrimation and ptosis were observed in both sexes exposed to 622 mg/kg bw. Additionally lateral position and chromodacryorrhea in female group were observed. The surviving male and female rats recovered from these toxic signs till 8 to 24 hours after dosing.
- Decrease in spontaneous motor activity, lateral position, prone position, subnormal temperature, miosis, lacrimation, chromodacryorrhea and ptosis were observed in both sexes exposed to 746 mg/kg bw. Nasal discharge was additionally observed in the female group. The surviving male and female rats recovered from these toxic signs within 8 to 24 hours and 4 days after dosing, respectively.
- Decrease in spontaneous motor activity, lateral position, prone position, subnormal temperature, miosis, salivation, lacrimation, chromodacryorrhea and ptosis were observed in both sexes exposed to 896 mg/kg bw. Further, the toxic signs of nasal discharge in male group and of tarry stool in female group were observed. The surviving male and female rats recovered from these toxic signs within 3 days and 6 days after dosing, respectively.
- Decrease in spontaneous motor activity, prone position, subnormal temperature, miosis, salivation and ptosis were observed in both sexes exposed to 1075 mg/kg bw. Further, the toxic signs of edema in male group and of lateral position and nasal discharge in female group were observed.

Body weight:

All of the surviving animals showed an increase in body weight both 1 and 2 weeks after dosing.

Mean body weight (g) males:
- 518 mg/kg bw: 178, 242 and 308 at day 0, 7 and 14, respectively.
- 622 mg/kg bw: 176, 236 and 294 at day 0, 7 and 14, respectively.
- 746 mg/kg bw: 175, 236 and 294 at day 0, 7 and 14, respectively.
- 896 mg/kg bw: 173, 231 and 302 at day 0, 7 and 14, respectively.
- 1075 mg/kg bw: 176 at day 0.

Mean body weight (g) females:
- 518 mg/kg bw: 129, 162 and 186 at day 0, 7 and 14, respectively.
- 622 mg/kg bw: 129, 163 and 190 at day 0, 7 and 14, respectively.
- 746 mg/kg bw: 130, 157 and 187 at day 0, 7 and 14, respectively.
- 896 mg/kg bw: 130, 148 and 193 at day 0, 7 and 14, respectively.
- 1075 mg/kg bw: 129 at day 0.

Gross pathology:

- Necropsy of animals that died: Expansion of stomach, existence of black-brownish content in the gastric lumen, black zone in the glandular stomach, existence of black-brownish content in the small intestine, enlargement (bilateral) of the kidney, retention of dark-red urine in the urinary bladder and the existence of black-brownish content in the cecum were observed in both sexes. Moreover, the change to red in color of the small intestine and the red zone in the cecum in male rats and of dilated lumen in the small intestine in female rats were observed and only two male rats in 1075 mg/kg bw were observed edema in cervical subcutaneous tissue.
- Necropsy of surviving animals: No abnormalities observed.