4-methylstyrene

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: No test guideline quoted. Limited study details. Non-GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1977

Report date:

1977

Materials and methods

Principles of method if other than guideline:

Four fixed doses administered concurrently, one to each of four groups on a volume per unit of body weight basis (mL/kg bw).

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-methylstyrene

EC Number:

210-762-8

EC Name:

4-methylstyrene

Cas Number:

622-97-9

Molecular formula:

C9H10

IUPAC Name:

1-ethenyl-4-methylbenzene

Test material form:

liquid

Details on test material:

- Name as cited in study report: MCTR-243-77

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

- Weight at study initiation: 225.8 g to 261.0 g at randomisation

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

- Concentration in vehicle: Test substance administered undiluted
- High dose: 5.0 mL/kg (test substance administered on a volume per unit of body weight basis)

Doses:

Group 1: 0.6 mL/kg
Group 2: 1.3 mL/kg
Group 3: 2.5 mL/kg
Group 4: 5.0 mL/kg

No. of animals per sex per dose:

10 males

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Daily observations for clinical signs and mortality. Body weight determined on day of dosing and at termination / day of premature death.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: Clinical signs, body weights, and macroscopic necropsy examination performed on animals that died / surviving animals on day 14.

Statistics:

Calculation of LD50 with 95% confidence limits.
Weil, C.S., Biometrics, Vol.8, No.3, 249-263, Tables for Convenient Calculation of Median - Effective Dose (LD50 or ED50) and Instructions in their Use, 1952.

Results and discussion

Effect levels

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

3.68 mL/kg bw

Based on:

test mat.

95% CL:

> 2.07 - < 6.52

Remarks on result:

other:

Remarks:

Based on a relative density of 0.917, this is equivalent to and LD50 of 3375 mg/kg bw

Mortality:

Group 1: 1/10 (day of dosing, day 0; attributed to mis-dosing)
Group 2: 0/10
Group 3: 3/10 (2 on day 1 of observation; 1 on day 14)
Group 4: 7/10 (7 on day 1 of observation)

Clinical signs:

other: Group 1: No signs of toxicity Group 2: No signs of toxicity Group 3: On the day of dosing (day 0), 10/10 animals showed an increase in respiration, slight trembling and slight listlessness; these clinical signs generally persisted until day 2/3 of observa

Gross pathology:

Principal macroscopic findings noted for animals in groups 3 and 4 which died included haemorrhagic lungs and small intestsine, clear colourless fluid in the urinary bladder and red oral/nasal/ocular discharge. No significant macroscopic findings noted for animals in Groups 1 and 2.

Applicant's summary and conclusion

Conclusions:

Under the study conditions, the calculated oral LD50 was 3.68 mL/kg/bw, with 95% confidence limits of 2.07 to 6.52 mL/kg/bw. Based on a relative density of 0.917, this is equivalent to and LD50 of 3375 mg/kg bw.

Executive summary:

A study was conducted to determine the toxicity of the test substance in Sprague-Dawley rats. Four groups of 10 male rats were given a single dose of 0.6, 1.3, 2.5 or 5.0 mL/kg bw. The animals were observed for 14 d and mortality and clinical signs were recorded daily. Body weights were determined on Day 0 (day of dosing) and on Day 14. Macroscopic findings were recorded at necropsy of all animals that died or were killed on Day 14. On the day of dosing, all rats at 2.5 mL/kg and 7/10 rats at 5.0 mL/kg had an increase in respiration rate, slight trembling throughout the body and were slightly listless while the other 3 rats were also lying on their side very listlessly. On Days 1 and 2, the rats that survived in the two highest groups were slightly listless and had a slight increase in respiration, with the exception of one rat at the highest dose which was still very listless on Days 1 and 2, and slightly listless on Day 3. All surviving rats were normal thereafter until Day 14 when one rat at 2.5 mL/kg died. Gross necropsy revealed and enlarged lobe of the lung which contained a reddish-yellow, foamy fluid. All other rats were normal on Day 14. Under the study conditions, the calculated oral LD50 was 3.68 mL/kg bw, with 95% confidence limits of 2.07 to 6.52 mL/kg bw. Based on a relative density of 0.917, this is equivalent to an LD50 of 3375 mg/kg bw (Adamik, 1977).