p-tert-butylstyrene

Endpoint summary

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Three fixed doses administered, one to each of three groups on a weight per unit of body weight basis (mg/kg bw). Groups were treated sequentially, Group 1, then Group 2, then Group 3.

GLP compliance:

no

Test type:

other:

Limit test:

no

Species:

dog

Strain:

other: Beagle

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source: Marshall Research Animals, Inc., New York
- Age at study initiation: Groups 1 & 2, 8-12 months; Group 3, 13-14 months
- Weight at study initiation: Males, 9.0-14.7 kg; Females 6.6-9.8 kg
- Housing: Individually, metal-grid cages
- Diet: Wayne Bite Size, standard laboratory diet (400 g/day)
- Water: ad libitum
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

Groups 2 & 3 only; test material: vehicle, 1:1 ratio

Details on oral exposure:

VEHICLE
- Concentration in vehicle: Group 1, undiluted; Groups 2 & 3, 50%
- Amount of vehicle (if gavage): Groups 2 & 3, test material: vehicle, 1:1 ratio
- Justification for choice of vehicle: Not specified
- Lot/batch no. (if required): Not specified
- Purity: Not specified

MAXIMUM DOSE VOLUME APPLIED: High dose: ca 10.0 mL/kg including vehicle (Group 3)

DOSAGE PREPARATION (if unusual): No details specified

CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose: Not specified

Doses:

Group 1: 4 g/kg
Group 2: 4 g/kg, with an equal volume of vehicle
Group 3: 5 g/kg, with an equal volume of vehicle

No. of animals per sex per dose:

2 males & 2 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Twice daily observations for clinical signs and mortality. Body weight determined pre-test, and on Days 1, 2, 4, 7 and 14. Food consumption estimated 4 times weekly, including the week prior to dosing.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other:
Macroscopic necropsy examination performed on animals following exsanguination under sodium pentobarbitone anaesthesia. Gross lesions
preserved in 10% neutral buffered formalin (no microscopic examination).

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no mortalies.

Clinical signs:

other: Group 1: Males and females experienced varying degrees of emesis and salivation within 90 minutes of dosing, which lasted no more than one hour and 45 minutes. All animals also experienced at least one episode of slight to moderate body tremors of varying

Gross pathology:

There were no remarkable macroscopic findings.

Conclusions:

Under the study conditions, the LD50 was considered to be >5000 mg/kg bw.

Executive summary:

A study was conducted to determine the toxicity of the read across substance, vinyl toluene, to dogs. Three groups of 2 male and 2 female Beagle dogs were given a single dose of the test substance by oral gavage at the following doses: Group 1: 4000 mg/kg bw (undiluted), Group 2: 4000 mg/kg bw (with an equal volume of vehicle, corn oil) and Group 3: 5000 mg/kg bw (with an equal volume of vehicle, corn oil). After dosing, the dogs were observed for 14 d. The animals were observed twice daily for clinical signs and mortality. Body weights were determined pre-test and on Days 1, 2, 4, 7 and 14. Food consumption was estimated 4 times weekly, including the week prior to dosing. On completion of the observation period, a macroscopic necropsy examination was performed on all animals following exsanguination under sodium pentobarbitone anaesthesia. Gross lesions were preserved (no microscopic examination). Under the study conditions, there were no mortalities. Group 1 animals experienced varying degrees of emesis and salivation within 90 min of dosing, and at least one episode of slight to moderate body tremors of varying duration 1 h after dosing. Group 2 females vomited within 45 min of dosing. However, emesis was not observed in males until the following day. Slight to extreme body tremors were observed in all animals within 1 h of dosing. Group 3 animals experienced varying degrees of emesis, salivation and tremors within 1 h of dosing. Small body weight losses were noted during the post-dosing period for one male and both females in Group 1, one male and one female in Group 2, and all animals in Group 3 (no effect on food consumption). Macroscopic findings at necropsy were unremarkable. Under the study conditions, the LD50 was considered to be >5000 mg/kg bw (Smart, 1979).

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

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.

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

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

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

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.

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 an 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.

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 read across substance, p-methylstyrene, 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).

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

From August 2, 1979 to August 16, 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No test guideline quoted. Limited study details. Non-GLP; QA signature on report

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Five fixed doses administered concurrently, one to each of five groups on a weight per unit of body weight basis (mg/kg bw).

GLP compliance:

yes

Remarks:

As applicable in the USA, June 1979

Limit test:

no

Species:

mouse

Strain:

CD-1

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Wilmington, USA
- Age at study initiation: 2.5 months
- Weight at study initiation: 26.5 g to 39.3 g
- Fasting period before study: 4 h (water not withheld)
- Housing: Individually, in wire-mesh cages
- Diet (e.g. ad libitum): Purina Certified Rodent Chow, ad libitum
- Water: ad libitum
- Acclimation period: 35 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.0 to 24.4
- Humidity (%): 47 to 72
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

cotton seed oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 21.5, 46.2, 99.3, 213.5 and 459.0 mg/mL
- Dose volume: fixed dose volume of 10 mL/kg, all groups
- Formulation: identified as a suspension, no other details

Doses:

Male and female:
Group 1: 215 mg/kg
Group 2: 462 mg/kg
Group 3: 993 mg/kg
Group 4: 2135 mg/kg
Group 5: 4590 mg/kg

No. of animals per sex per dose:

5 males and 5 females

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, on day 7 and (at termination) on day 14 / day of premature death.
- Necropsy of survivors performed: yes
- Other examinations performed: 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 and slopes of the response curves calculated according to:
Weil, C.S. (1952), Biometrics, Vol.8, 249-263, Tables for Convenient Calculation of Median - Effective Dose (LD50 or ED50) and instructions in their use.
Thompson, W.R. and Weil, C.S. (1952), Biometrics, Vol.8, 51-54, On the Construction of Tables for Moving Average Interpolation.
Eby, R. (1957), Report No. 5711, Miles-Ames Research Laboratory, Elkhart, Indiana, Statistical Tables for Dose Evaluation.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 072.2 mg/kg bw

Based on:

test mat.

95% CL:

> 835 - < 1 376.7

Remarks on result:

other: Slope: 1.0

Mortality:

Group 1: Male, 0/5 : Female, 0/5
Group 2: Male, 0/5 : Female, 0/5
Group 3: Male, 2/5 : Female, 2/5 (1 male and 2 females died day 1; 1 male died day 2)
Group 4: Male, 5/5 : Female, 5/5 (all died day 1)
Group 5: Male, 5/5 : Female, 5/5 (all died day 1)

Clinical signs:

other: Group 1: No signs of toxicity Group 2: No signs of toxicity Group 3: Principal findings included hypoactivity, ataxia, body tremors, ptosis; noted essentially on day 1 only. Group 4: Principal findings included hypoactivity, ataxia, body tremors, ptosis,

Gross pathology:

Macroscopic Pathology Report: Gastro-intestinal hyperaemia was noted for animals in groups 3, 4 and 5 which died. Otherwise, no specific changes were reported for these animals, or for surviving animals in groups 1, 2 and 3.

Conclusions:

Under the study conditions, the LD50 when calculated separately for males and females was, in each case, 1072.2 mg/kg bw, with 95% confidence limits of 736.9 to 1559.9 mg/kg bw. The LD50 when calculated for males and females combined was also 1072.2 mg/kg bw, but with 95% confidence limits of 835.0 to 1376.7 mg/kg bw

Executive summary:

A study was conducted to determine the acute oral toxicity of the read across substance, p-methylstsyrene, to CD-1 mice. Five groups of 5 male and 5 female mice were given a single dose of 215, 462, 993, 2135 or 4590 mg/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 Days 7 and 14. Macroscopic findings were recorded at necropsy of all animals that died or were killed on Day 14. The most frequently observed clinical signs included hypoactivity, ataxia, clear, moist staining around mouth and bradypnea. Under the study conditions, the LD50 when calculated separately for males and females was, in each case, 1072.2 mg/kg bw, with 95% confidence limits of 736.9 to 1559.9 mg/kg bw. The LD50 when calculated for males and females combined was also 1072.2 mg/kg bw, but with 95% confidence limits of 835.0 to 1376.7 mg/kg bw (Mehlan, 1979).

Reference 4

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No test guideline quoted. Limited study details. Non-GLP; QA signature on report

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Two fixed doses were administered concurrently, one to each of two groups on a weight per unit of body weight basis (mg/kg).

GLP compliance:

no

Limit test:

no

Species:

mouse

Strain:

Swiss Webster

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: high dose, 91 mg/mL; Low dose, 85 mg/mL
- Amount of vehicle (if gavage): high dose, approx. 13 mL/kg; Low dose, approx. 9.4 mL/kg

Doses:

Group 1: High dose, 1182 mg/kg
Group 2: Low dose, 800 mg/kg

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 5 days
- Frequency of observations and weighing: clinical signs and mortality daily. Body weight assumed to have been determined on day of dosing (day 0), for dosing according to mg/kg bw.
- Other examinations performed: clinical signs, body weight,organ weights, histopathology

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

>= 800 - ca. 1 182 mg/kg bw

Based on:

test mat.

Mortality:

Group 1: High dose: Male, 3/5 (day 1): Female, 5/5 (day 1)
Group 2: Low dose: Male, 0/5 : Female, 1/5 (day 5)

Clinical signs:

other: Clinical signs noted among the mice treated with poly-test substance: decreased activity, peri-anal discharge, shaking and rough hair.

Conclusions:

Under the study conditions, the LD50 for the test substance was between 800 and 1182 mg/kg bw.

Executive summary:

A study was conducted to determine the acute oral toxicity of the read-across substance, p-methylstyrene, in mice. Fasted Swiss-Webster mice (5 males and 5 females) were treated at the previously determined LD50 of 1182 mg/kg bw and at a lower dose of 800 mg/kg bw. The animals were observed for 5 d and mortality and clinical signs were recorded daily. Surviving animals were killed after 5 d observation without further investigation. Surviving animals treated with the test substance showed signs of shaking, decreased activity, rough hair coat and decreased food consumption. Under the study conditions, the LD50 for the test substance was between 800 and 1182 mg/kg bw (Smart, 1980).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

3 375 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Two groups of 5 male and 5 female rats were exposed (whole body) to the test substance at nominal concentrations of 3300 or 2280 ppm. Mean analysed chamber concentrations were 1960 and 1510 ppm, respectively (equivalent to ca. 7287.53 and 9459.3 mg/m3, respectively). After exposure, the animals were observed for 14 d.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source: Charles River, Wilmington, USA
- Weight at study initiation:
Group 1: Males, 235-294 g; Females, 217-236 g
Group 2: Males, 244-294 g; Females, 238-258 g
- Fasting period before study: Not specified
- Acclimation period: 2-3 weeks

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

Two 6 h inhalation exposures were performed. In each exposure, the test substance was placed in a 1 L nipple bottom bubbler and suspended in awaterbath maintained at 72°C. Nitrogen, at flow rates of 20 and 13 L/minute for Groups 1 and 2, respectively, was passed through a 13 m coil of copper tubing (also immersed in the waterbath) and into the bubbler to create a vapour. The vapour-laden airstream then passed through a kjeldahl trap and through a 1 L round-bottomed trap flask before entering a 760 L glass and stainless steel exposure chamber housing the test animals.

Oxygen was pumped into the chamber at 4 L/minute to maintain the oxygen content of the chamber air at ca 20%. The chamber flow was 125 L/minute.

Additional test substance was delivered into the nipple bottom bubbler from a 1L Erlenmeyer reservoir flask when needed using a pump. A similar pump was used to drain test substance from the 1 L trap flask and deliver it into the Erlenmeyer reservoir flask.

The test substance, 1 L nipple bottom bubbler, three necked round-bottom flask, and Erlenmeyer reservoir flask, clamps, tubing, and stoppers were weighed before and after each exposure period. The difference in weight represented the amount of test substance delivered during each exposure.

The nominal concentration of the test substance was calculated by dividing the amount of substance delivered by the total air flow through the chamber during each exposure period.

Chamber air concentration was monitored continuously during each exposure using an ambient air analyser and recorded once each hour. Waterbath temperature, nitrogen flow rate, oxygen flow rate, and chamber air flow were also recorded hourly.

Nominal and analysed test substance concentrations:

Group 1: During the exposure, a total of 728.98 g of test substance was delivered in a total volume of 45,000 L of air, yielding a nominal exposure concentration of 16.2 mg/L or 3,300 ppm (mol.wt. 118; 1 mg/L = 207 ppm). Mean analysed chamber concentration was 1,960 ppm (range 1840 - 2055 ppm; n=6).

Group 2: During the exposure, a total of 505.20 g of test substance was delivered in a total volume of 45,000 L of air, yielding a nominal exposure concentration of 11.2 mg/L or 2,280 ppm. Mean analysed chamber concentration was 1,510 ppm (range 1480 - 1570 ppm; n=6).

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

6 h

Concentrations:

Group 1 (high dose): 3300 ppm (nominal); 1960 ppm (mean analysed)
Group 2 (low dose): 2280 ppm (nominal); 1510 ppm (mean analysed)

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 d
- Frequency of observations and weighing:
Clinical signs: 15 min intervals during the first hour of exposure, then hourly for the remainder of the exposure; on removal of the animals from the chamber; hourly for 2 h post-exposure; and daily thereafter for 14 d.
Body weights: Day 0 (prior to exposure) and on days 1, 2, 4, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other: any animals dying prematurely were subject to necropsy and macroscopic examination as soon as possible after death. On day 14, all surviving animals were killed (ethyl ether) and a macroscopic examination was performed at necropsy.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1 510 ppm

Based on:

test mat.

Exp. duration:

6 h

Remarks on result:

other: i.e. >9459.3 mg/m3 air

Mortality:

Group 1 (high dose): One male died on day 1.
Group 2 (low dose): There were no mortalities.

Clinical signs:

other: Group 1 (high dose): During exposure, all animals showed excessive lachrymation, reduced activity and closed eyes. Excessive salivation and laboured breathing were observed frequently. Other signs mainly included gasping, ataxia, rapid breathing, shallow

Body weight:

Group 1 (high dose): Small transient weight losses were noted in all animals; body weights recovered by day 7 for most animals.
Group 2 (low dose): Small transient weight losses were noted in all animals; body weights recovered by day 7 for males, and by day 7/14 in females.

Gross pathology:

Groups 1 and 2: There were no remarkable macroscopic findings at necropsy.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Under the study conditions, ocular and nasal irritation and neuromuscular impairment were noted after exposure to both concentrations, but these signs abated within 2 d of exposure at the high concentration, and within one day at the low concentration. One rat exposed to the high concentration died on Day 1. Slight, but transient body weight losses were noted for both sexes at each concentration. Macroscopic findings at necropsy were unremarkable for both groups. The 6 h LC50 was therefore >1510 ppm (i.e. >9459.3 mg/m3 or 9.5 mg/L).

Executive summary:

A study was conducted to determine the acute inhalation toxicity of the read across substance, p-methylstyrene, in Sprague-Dawley rats. Two groups of 5 male and 5 female rats were exposed (whole body) for 6 h at nominal concentrations of 3300 or 2280 ppm. Mean analysed chamber concentrations were 1960 and 1510 ppm, respectively (equivalent to ca. 7287.53 and 9459.3 mg/m3, respectively). After exposure, the animals were observed for 14 d. Mortality and clinical signs were recorded frequently during and immediately after exposure and daily thereafter. Body weights were determined on Day 0 (prior to exposure) and on Days 1, 2, 4, 7 and 14. At necropsy, a macroscopic examination was performed on all animals. Under the study conditions, ocular and nasal irritation and neuromuscular impairment were noted after exposure to both concentrations, but these signs abated within 2 d of exposure at the high concentration, and within one day at the low concentration. One rat exposed to the high concentration died on Day 1. Slight, but transient body weight losses were noted for both sexes at each concentration. Macroscopic findings at necropsy were unremarkable for both groups. The 6 h LC50 was therefore >1510 ppm (i.e. >9459.3 mg/m3 or 9.5 mg/L) ( Biodynamics Inc., 1980).

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

A study was conducted to determine the toxicity of the test substance to Sprague-Dawley rats exposed by inhalation for 6 h. A group of 5 male and 5 female rats were exposed (whole body) to the test substance at a nominal concentration of 3500 ppm (i.e. 16891.62 mg/m3, or 17.8 mg/L) and were then observed for 14 d.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source: Charles River, Wilmington, USA
- Weight at study initiation: Males, 241-258 g; Females, 210-230 g

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

A single 4 h inhalation exposure was performed.
The test substance vapour was generated using a heated-flask flash evaporator. A fluid metering pump was used to draw the test substance from a 250 mL flask containing approximately 75 mL of test substance. The test substance was pumped through a coil of 1/8” teflon tubing which was immersed in a water bath (50-85°C). The heated test substance was then delivered to the flash evaporator through teflon tubing. Dry air, at a flow rate of 15 L/minute, was passed through a coil of 1/4 copper tubing which was immersed in a water bath (90-96°C). The dry air was heated to 30°C through the coil and was delivered to the flash evaporator. The test substance was vaporised by allowing the heated dry air to pass over the tip of the teflon tubing containing the heated test substance. The vaporisation occurred in a 1 L Erlenmeyer flask heated to approximately 65°C using a heating mantle. The test atmosphere was directed, undiluted, into a 26.5 L glass exposure chamber housing the animals. Chamber temperature range was 25-28°C during the 4 h exposure.
The generation flask, connecting tubing, stopper, and clamp were weighed before and after the exposure. The difference in weight represented the total amount of test substance delivered into the chamber; this, divided by the total volume of air delivered yielded the nominal exposure concentration.
Nominal test material concentration:
During the exposure, a total of 61.85 g of test substance was delivered in a total volume of 3,600 L of air, yielding a nominal exposure concentration of 17.18 mg/L, equivalent to approximately 3500 ppm (mol.wt. 118; 1 mg/L = 207 ppm).

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Concentrations:

3500 ppm (nominal)

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 d
- Frequency of observations and weighing:
Clinical signs: 15 min intervals during the first hour of exposure, then hourly for the remainder of the exposure; on removal of the animals from the chamber; hourly for 4 h post-exposure; and daily thereafter for 14 d.
Body weights: Day 0 (prior to exposure) and on Days 1, 2, 4, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: on Day 14, all animals were killed by exsanguination under ethyl ether anaesthesia and a macroscopic examination was performed at necropsy.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 16 891 mg/m³ air (nominal)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

There were no mortalities.

Clinical signs:

other: During exposure, all animals showed respiratory abnormalities and increased ocular, nasal, and oral secretions, commencing after 15 minutes. After removal from the chamber, neuromuscular abnormalities were also noted, including weakness, loss of reflex ac

Body weight:

Small transient weight losses were noted in all animals; body weights recovered by day 7 for most animals.

Gross pathology:

There were no remarkable macroscopic findings at necropsy.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Under the study conditions, ocular, nasal and oral irritation was noted during exposure, decreasing 4 h post-exposure. Neuromuscular impairment was noted after exposure, increasing in severity 4 h post-exposure. All clinical signs had abated by Day 3. Small transient weight losses were noted for all animals. Macroscopic findings at necropsy were unremarkable. The 4 h LC50 was therefore >3500 ppm (i.e. 16891.62 mg/m3, or 17.8 mg/L).

Executive summary:

A study was conducted to determine the toxicity of the read across substance, p-methylstyrene, to Sprague-Dawley rats exposed by inhalation for 6 h. A group of 5 male and 5 female rats were exposed (whole body) to the test substance at a nominal concentration of 3500 ppm (i.e. 16891.62 mg/m3, or 17.8 mg/L) and were then observed for 14 d. Mortality and clinical signs were recorded frequently during and immediately after exposure and daily thereafter. Body weights were determined on Day 0 (prior to exposure) and on Days 1, 2, 4, 7 and 14. At necropsy, a macroscopic examination was performed on all animals. Under the study conditions, ocular, nasal and oral irritation was noted during exposure, decreasing 4 h post-exposure. Neuromuscular impairment was noted after exposure, increasing in severity 4 h post-exposure. All clinical signs had abated by Day 3. Small transient weight losses were noted for all animals. Macroscopic findings at necropsy were unremarkable. The 4 h LC50 was therefore >3500 ppm (i.e. 16891.62 mg/m3 or 17.8 mg/L) ( Biodynamics Inc., 1980).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

16 891 mg/m³ air

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: Federal Hazardous Substances Act, September 27, 1973.

Deviations:

not specified

GLP compliance:

no

Test type:

fixed dose procedure

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test animals:
- Weight at study initiation: 2.10 to 2.50 kg
- Housing: Not specified (each animal was restrained in a harness during the 24 h application period)

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

Removal of the test substance
- Washing: Using a damp towel
- Time after start of exposure: 24 h
- Amount(s) applied: 0.5, 1.0, 2.0, 4.0 or 5.0 mL/kg
- Concentration: Undiluted
- For solids, paste formed: Not applicable

Duration of exposure:

24 hours

Doses:

Group 1: 0.5 mL/kg bw (total volume given: 1.1 mL)
Group 2: 1.0 mL/kg bw (total volume given: 2.2 - 2.3 mL)
Group 3: 2.0 mL/kg bw (total volume given: 4.3 - 4.5 mL)
Group 4: 4.0 mL/kg bw (total volume given: 8.4 - 9.0 mL)
Group 5: 5.0 mL/kg bw (total volume given: 11.0 - 12.5 mL)

No. of animals per sex per dose:

2 males and 2 females

Control animals:

no

Details on study design:

The skin of one male and one female in each group was abraded, while the skin of the remaining male and female was left un-abraded. The test substance was applied to the site and remained in contact with the skin for 24 h, during which time each animal was restrained in a harness. An occlusive wrap was not used (the dental dam routinely used for this purpose was found to be incompatible with the test substance). After the 24 h application period, each animal was removed from its harness and the unabsorbed test substance was removed using a damp towel. All animals were observed for signs of dermal irritation, gross signs of systemic toxicity indicative of percutaneous absorption, and mortality, once daily for the following 14 days. At the end of the observation period, all animals were weighed, killed and a macroscopic examination was performed at necropsy.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 mL/kg bw

Based on:

test mat.

Remarks on result:

other:

Remarks:

based on a relative density of 0.917, this is equivalent to an LD50 of 4585 mg/kg bw

Mortality:

There were no mortalities.

Clinical signs:

other: There were no signs of systemic toxicity or behavioral changes. At the site of test substance application, the following findings were noted: slight to moderate erythema and very slight to slight edema were noted in Groups 1, 2, 3 and 4, with moderate res

Gross pathology:

There were no remarkable macroscopic findings at necropsy.

Conclusions:

Under the study conditions, the dermal LD50 was determined to be >5.0 mL/kg bw. Based on a relative density of 0.917, this is equivalent to an LD50 of 4585 mg/kg bw.

Executive summary:

A study was conducted to determine the acute dermal toxicity of the read-across substance, p-methylstyrene, according to Federal Hazardous Substances Act, September 27, 1973. Five groups of 2 male and 2 female rabbits were given a single non-occluded 24 h application of the test substance at 0.5, 1.0, 2.0, 4.0 or 5.0 mL/kg bw. The skin of two rabbits per group was abraded while the skin of remaining two rabbits was left intact. After 24 h, residual test substance was removed and the animals were observed for a further 14 d. Mortality and clinical signs were recorded daily, including examination for signs of skin irritation and systemic toxicity. Body weights were determined on Day 0 (day of application) and on Day 14, prior to necropsy. At necropsy, a macroscopic examination was performed. No mortality occurred in any of the rabbits during the study and no signs of systemic toxicity or behavioral changes were noted. At the site of test substance application, the following findings were noted: slight to moderate erythema and very slight to slight edema in all groups. These findings returned to normal during the second week of the observation period, except in Group 5. Slight fissuring was noted occasionally in two animals in Group 1 and one animal in Group 2. This finding was classified as being slight to moderate in Group 5. A dose-related incidence of coriaceous skin was noted in most animals, with slight responses in Groups 1, 2, 3 and 4 which returned to normal by the end of the observation period. Moderate responses of coriaceous skin were noted in Group 5. In addition, atonia and desquamation were noted in Group 5. Under the study conditions, the dermal LD50 was determined to be >5.0 mL/kg bw. Based on a relative density of 0.917, this is equivalent to an LD50 of 4585 mg/kg bw ( Adamik, 1997).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

4 585 mg/kg bw

Additional information

Oral

Mouse

A study was conducted to determine the acute oral toxicity of the read across substance, p-methylstyrene, in mice. Fasted Swiss-Webster mice (5 males and 5 females) were treated at the previously determined LD50 of 1182 mg/kg bw and at a lower dose of 800 mg/kg bw. The animals were observed for 5 d and mortality and clinical signs were recorded daily. Surviving animals were killed after 5 d observation without further investigation. Surviving animals treated with the test substance showed signs of shaking, decreased activity, rough hair coat and decreased food consumption. Under the study conditions, the LD50 for the test substance was between 800 and 1182 mg/kg bw (Smart, 1980).

 A study was conducted to determine the acute oral toxicity of the read across substance, p-methylstyrene, to CD-1 mice. Five groups of 5 male and 5 female mice were given a single dose of 215, 462, 993, 2135 or 4590 mg/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 Days 7 and 14. Macroscopic findings were recorded at necropsy of all animals that died or were killed on Day 14. The most frequently observed clinical signs included hypoactivity, ataxia, clear, moist staining around mouth and bradypnea. Under the study conditions, the LD50 when calculated separately for males and females was, in each case, 1072.2 mg/kg bw, with 95% confidence limits of 736.9 to 1559.9 mg/kg bw. The LD50 when calculated for males and females combined was also 1072.2 mg/kg bw, but with 95% confidence limits of 835.0 to 1376.7 mg/kg bw (Mehlan, 1979).

Rat

A study was conducted to determine the toxicity of the read across substance, p-methylstyrene, 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).

Dog

A study was conducted to determine the toxicity of the read across substance, p-methylstyrene, to dogs. Three groups of 2 male and 2 female Beagle dogs were given a single dose of the test substance by oral gavage at the following doses: Group 1: 4000 mg/kg bw (undiluted), Group 2: 4000 mg/kg bw (with an equal volume of vehicle, corn oil) and Group 3: 5000 mg/kg bw (with an equal volume of vehicle, corn oil).After dosing, the dogs were observed for 14 d. The animals were observed twice daily for clinical signs and mortality. Body weights were determined pre-test and on Days 1, 2, 4, 7 and 14. Food consumption was estimated 4 times weekly, including the week prior to dosing. On completion of the observation period, a macroscopic necropsy examination was performed on all animals following exsanguination under sodium pentobarbitone anaesthesia. Gross lesions were preserved (no microscopic examination). Under the study conditions, there were no mortalities. Group 1 animals experienced varying degrees of emesis and salivation within 90 min of dosing, and at least one episode of slight to moderate body tremors of varying duration 1 h after dosing. Group 2 females vomited within 45 min of dosing. However, emesis was not observed in males until the following day. Slight to extreme body tremors were observed in all animals within 1 h of dosing. Group 3 animals experienced varying degrees of emesis, salivation and tremors within 1 h of dosing. Small body weight losses were noted during the post-dosing period for one male and both females in Group 1, one male and one female in Group 2, and all animals in Group 3 (no effect on food consumption). Macroscopic findings at necropsy were unremarkable. Under the study conditions, the LD50 is considered to be <5000 mg/kg bw (Smart, 1979).

Inhalation

Rat

A study was conducted to determine the toxicity of the read across substance, p-methylstyrene, to Sprague-Dawley rats exposed by inhalation for 6 h. A group of 5 male and 5 female rats were exposed (whole body) to the test substance at a nominal concentration of 3500 ppm (i.e. 16891.62 mg/m3, or 17.8 mg/L) and were then observed for 14 d. Mortality and clinical signs were recorded frequently during and immediately after exposure and daily thereafter. Body weights were determined on Day 0 (prior to exposure) and on Days 1, 2, 4, 7 and 14. At necropsy, a macroscopic examination was performed on all animals. Under the study conditions, ocular, nasal and oral irritation was noted during exposure, decreasing 4 h post-exposure. Neuromuscular impairment was noted after exposure, increasing in severity 4 h post-exposure. All clinical signs had abated by Day 3. Small transient weight losses were noted for all animals. Macroscopic findings at necropsy were unremarkable. The 4 h LC50 was therefore >3500 ppm (i.e. >16891.62 mg/m3 or >17.8 mg/L) (Biodynamics Inc., 1980).

A study was conducted to determine the acute inhalation toxicity of the read across substance, p-methylstyrene, in Sprague-Dawley rats. Two groups of 5 male and 5 female rats were exposed (whole body) for 6 h at nominal concentrations of 3300 or 2280 ppm. Mean analysed chamber concentrations were 1960 and 1510 ppm, respectively (equivalent to ca. 7287.53 and 9459.3 mg/m3, respectively). After exposure, the animals were observed for 14 d. Mortality and clinical signs were recorded frequently during and immediately after exposure and daily thereafter. Body weights were determined on Day 0 (prior to exposure) and on Days 1, 2, 4, 7 and 14. At necropsy, a macroscopic examination was performed on all animals. Under the study conditions, ocular and nasal irritation and neuromuscular impairment were noted after exposure to both concentrations, but these signs abated within 2 d of exposure at the high concentration, and within one day at the low concentration. One rat exposed to the high concentration died on Day 1. Slight, but transient body weight losses were noted for both sexes at each concentration. Macroscopic findings at necropsy were unremarkable for both groups. The 6 h LC50 was therefore >1510 ppm (i.e. >9459.3 mg/m3 or >9.5 mg/L) ( Biodynamics Inc., 1980).

Dermal

Rabbit

A study was conducted to determine the acute dermal toxicity of the read across substance, p-methylstyrene, to rabbits according to Federal Hazardous Substances Act, September 27, 1973. Five groups of 2 male and 2 female rabbits were given a single non-occluded 24 h application of the test substance at 0.5, 1.0, 2.0, 4.0 or 5.0 mL/kg bw. The skin of two rabbits per group was abraded while the skin of remaining two rabbits was left intact. After 24 h, residual test substance was removed and the animals were observed for a further 14 d. Mortality and clinical signs were recorded daily, including examination for signs of skin irritation and systemic toxicity. Body weights were determined on Day 0 (day of application) and on Day 14, prior to necropsy. At necropsy, a macroscopic examination was performed. No mortality occurred in any of the rabbits during the study and no signs of systemic toxicity or behavioral changes were noted. At the site of test substance application, the following findings were noted: slight to moderate erythema and very slight to slight edema in all groups. These findings returned to normal during the second week of the observation period, except in Group 5. Slight fissuring was noted occasionally in two animals in Group 1 and one animal in Group 2. This finding was classified as being slight to moderate in Group 5. A dose-related incidence of coriaceous skin was noted in most animals, with slight responses in Groups 1, 2, 3 and 4 which returned to normal by the end of the observation period. Moderate responses of coriaceous skin were noted in Group 5. In addition, atonia and desquamation were noted in Group 5. Under the study conditions, the dermal LD50 was determined to be >5.0 mL/kg bw. Based on a relative density of 0.917, this is equivalent to an LD50 of 4585 mg/kg bw (Adamik, 1997).

Justification for classification or non-classification

Oral

Based on results for the read across substance, p-methylstyrene, the test substance is assessed to be of overall low acute oral toxicity. The mouse is the most sensitive species, being almost a factor of 10 more sensitive than the rat following oral administration. However, the rat is the preferred test species for evaluation of acute oral toxicity according to CLP (EC 1272/2008) criteria and the result in the rat is supported by a result in second species (dog) in the same range. The oral LD50 in the rat is 3375 mg/kg bw, suggesting that the substance does not require classification for this endpoint under the CLP.

Inhalation

The available data from two acute inhalation studies in rat suggest that the LC50 via this route is >16.9 mg/L. Assuming 16.9 mg/L as a conservative value, classification as Acute Tox. 4 – H332 (Harmful if inhaled)is warranted according to CLP (EC 1272/2008) criteria.

Dermal

Acute dermal toxicity testing in rabbit yielded an LD50 value >4585 mg/kg bw, suggesting that the substance does not require classification for this endpoint according to CLP (EC 1272/2008) criteria.