4-methylstyrene

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Limited investigations for clinical pathology and pathology; old study design; poor quality report

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

No FOB, limited clin path and histopathology

GLP compliance:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats were obtained form Harlan Industries Inc, acclimatised for 7 days and housed singly. Diet (ground Purina Rat Chow, Ralsten Purina Company) and water (tap water mixed with distilled water) available freely. Fluorescent lighting was on a 12 hours/day cycle. Temperature and humidity not specified.

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Oral administration according to most recently recorded body weight, via a 1.0 cc syringe with a 13 gauge probang.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

daily for 13 weeks

Frequency of treatment:

5 days/week for 13 weeks (total 64 administrations)

Dose / conc.:

0.1 other: mL/kg

Dose / conc.:

0.3 other: mL/kg

Dose / conc.:

0.6 other: mL/kg

No. of animals per sex per dose:

15 males and 15 females

Control animals:

other: given water, dose volume not specified

Observations and examinations performed and frequency:

Clinical signs: daily
Body weights: weekly

Clinical pathology:
Haematology: orbital sinus: days 0, 30, 60 and 90: PCV, haemoglobin, RBD, WBC (total and differential), reticulocyte count. Clinical pathology: termination only: calcium, phosphorus, glucose, BUN, total protein, SGOT, SGPT, alkaline phosphatase, total cholesterol and uric acid. Urinalysis: days 0, 30, 60 and 90: pH, specific gravity, protein, glucose, colour and appearance.

Sacrifice and pathology:

Necropsy: exsanguinations under anaesthesia; all animals subject to full necropsy.
Organ weights: (not early decedents) ovaries, testis, kidneys, liver, lungs.
The following tissues were examined: adrenal, bone and marrow, brain, heart, large intestine (colon), small intestine (duodenum, jejunum, ileum), kidney, liver, lung, ovary, pancreas, spleen, stomach, testis, thyroid gland, and all gross lesions.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All test animals exhibited increased motor activity and/or salivation immediately after dosing; sometimes followed by a decrease in motor activity with fine body tremors.

Mortality:

mortality observed, treatment-related

Description (incidence):

All mortalities were related to aspiration pneumonia.

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The only lesions were considered to be related to administration of the test substance were aspiration pneumonia and peri-oral dermatitis, both resulting from direct contact irritation during dosing.

Other effects:

not specified

Details on results:

Necropsy: all test groups had an area of excoriation near the side of the mouth where the dosing tube was inserted.

Key result

Dose descriptor:

NOAEL

Basis for effect level:

other: Clinical signs and histopathology associated with irritation observed at lowest dose level

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Key result

Dose descriptor:

LOAEL

Effect level:

0.1 other: mL/kg bw/day

Mean bodyweights (BWT), survival and selected histopathology

	Control	the test substance (ml/kg)
MALES
Survival wk 13	15	15	15	13
BWT wk 12 (a)	435	95	93	90
Aspiration pneumonia	0	0	0	2
FEMALES
Survival wk 13	15	13	13	15
BWT wk 12 (a)	276	100	102	96
Aspiration pneumonia	0	2	2	0

(a) control value (g) treated value % of control, wk 12 used because wk 13 were fasted weights

Conclusions:

Under the study conditions, clinical signs (increased motor activity and or salivation were apparent in all treated groups. Body weight was lower in treated males only. There were no organ weights or clinical pathology findings of note. Histopathological findings were restricted to aspiration pneumonia and peri-oral dermatitis, both resulting from direct contact irritation during dosing. The NOAEL was not identified in this study. Based on a density of 0.917, this is equivalent to 91.7 mg/kg bw/day.

Executive summary:

A study was conducted to determine the repeated dose toxicity of the test substance when administered to rats daily for 13 weeks. The substance was administered to groups of 15 male and 15 female Sprague Dawley rats at dose volumes of 0.1, 0.3 and 0.6 mL/kg bw daily; controls received distilled water. Animals were observed daily, body weight and food consumption was recorded weekly. Clinical pathology investigations were conducted prior to termination and limited histopathological investigations were conducted on all animals. Under the study conditions, clinical signs (increased motor activity and/or salivation) were apparent in all treated groups. Body weight was lower in treated males only. There were no organ weights or clinical pathology findings of note. Histopathological findings were restricted to aspiration pneumonia and peri-oral dermatitis, both resulting from direct contact irritation during dosing. The NOAEL was not identified in this study. The LOAEL was considered to be 0.1 mL/kg bw/day, the lowest dose tested. Based on a density of 0.917, this is equivalent to 91.7 mg/kg bw/day (Springborn, 1980).

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 1979 to January 1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Principles of method if other than guideline:

Male and female Fisher rats (15/sex/group) received the substance by oral gavage at dose levels of 0, 50, 100, 300, 700 and 1500 mg/kg bw, in olive oil. One group of 15/sex served as the control and received only the vehicle, in volumes comparable to those received by treated groups. Animals were observed daily, body weight and food consumption was measured weekly. Clinical pathology investigations (haematology, clinical chemistry and urinalysis) were conducted prior to termination in Week 13. All animals were subject to a full necropsy and histopathological examination of a comprehensive range of tissues.

GLP compliance:

yes

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

F344 Fisher rats were obtained from Charles River Breeding Laboratories, Wilmington, MA. Age at initiation was approx. 6 weeks. Initial body weights were: males 109.0 – 156.8 g and females 81.1 – 124.2 g. Housed singly and commercial rodent ration (Purina Laboratory Chow) and tap water (automated system) freely available.

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

All animals received 1 mL/kg olive oil. These solutions were made weekly. Dose volumes were then adjusted to take account of test substance. Those dose volumes (mL/kg) were 1.0, 1.06, 1.12, 1.34, 1.79 and 2.69 and were adjusted according to the most recently recorded mean body weight for each group/sex.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

Daily

Frequency of treatment:

13 weeks

Dose / conc.:

0 mg/kg bw/day (actual dose received)

Dose / conc.:

50 mg/kg bw/day (actual dose received)

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Dose / conc.:

700 mg/kg bw/day (actual dose received)

Dose / conc.:

1 500 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

15 males and 15 females

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

Mortality: twice daily
Clinical signs: weekly
Body weight: weekly
Food consumption: weekly

Clinical pathology: at termination
Blood samples form the orbital sinus, urine samples overnight in metabolism cages.
Haematology samples were examined for haematocrit, haemoglobin, erythrocyte, platelet count and leukocyte count and differentials.

Clinical chemistry samples were examined for blood urea nitrogen, glucose, Serum glutamic oxaloacetic transaminase (aspartate amino transaminase) creatinine, total protein, albumin, alanine aminotransferase, and alkaline phosphatase.

Urine samples were examined for appearance, pH, specific gravity, ketones, protein, urobilinogen and volume.

Sacrifice and pathology:

At termination animals were killed by exanguination under sodium pentobarbital. The weight of the brain, heart, kidney, liver, lungs, testis with epididymis and ovaries were recorded.
Tissues were fixed in 10 % neutral buffered formalin. The following tissues were examined: brain, pituitary, spinal cord, eyes, mandibular salivary gland, thyroid, thymus, trachea, oesophagus, lungs, heart, liver, spleen, kidneys, adrenals, stomach, pancreas, duodenum, jejunum, ileum, colon, cecum, mesenteric lymph nodes, urinary bladder, testes with epididymides, prostate, ovaries, uterus, femur, bone marrow and any unusual lesions. The following tissues were examined microscopically: lungs, liver, kidneys, testes, ovaries, prostate and uterus.

Statistics:

For body weight, food consumption clinical pathology and organ weight data the test groups were compared to the control group using Bartlett’s test for homogeneity of variance followed by one-way ANOVA if the variance was homogenous. Non-homogenous data was log transformed. If ANOVA was significant Scheffe’s multiple pair-wise comparisons of Games and Howell’s multiple pair-wise comparisons were used. All analysis conducted at the 5% probability level.

Clinical signs:

effects observed, non-treatment-related

Mortality:

mortality observed, treatment-related

Description (incidence):

1500 mg/kg/day exceeded the MTD and were associated with notable mortality. Deaths were also observed at 300 (1/30) and 700 (3/30) mg/kg/day.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Male body weight was lower than control in all treated groups; there was no similar effect in females.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

In males, some statistically significant differences in organ weights were considered to reflect the reduced body weight, and not a direct effect of treatment. However, liver weight was increased at 300 mg/kg/day and greater and kidney weight at 700 mg/kg/day and greater.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

In animals given 700 or 1500 mg/kg/bw per day there were some changes that were considered to reflect dehydration rather than a direct toxicological change. These included increased packed cell volume and erythrocyte count and increases in total protein and albumin values. There were no urinalysis findings of note. The only change considered to be related to treatment was an increase in blood urea nitrogen values but this was not dose related and the increase above control level was small.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Lungs: Severe irritation of the bronchial and bronchiolar epithelium with focal sloughing of the respiratory epithelium with histiocytic filling of the eroded foci; peribronchial and peri bronchiolar fibrosis; focal bronchietasis; hyper-secretion of mucous with-in airways often accompanied by mucous lake formation within alveoli; and occasional perivascular and peribronchial aggregates of eosinophils at 700 and 1500 mg/kg. There was no NOEL for the exacerbation of multifocal chronic pneumonitis and focal hyperplasia of bronchial and bronchiolar epithelium. Control animals usually had focal areas of minimal to slight pneumonitis, whereas treated animals more frequently had lesions of moderate severity.

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Key result

Dose descriptor:

LOAEL

Effect level:

50 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Lung pathology: exacerbation of multifocal chronic pneumonitis and focal hyperplasia of bronchial and bronchiolar epithelium apparent in all treated groups

Key result

Critical effects observed:

not specified

Conclusions:

Under the study conditions, the LOAEL was considered to be 50 mg/kg bw/day, the lowest dose tested.

Executive summary:

A study was conducted to determine the repeated dose oral toxicity of the test substance when administered to rats daily for 13 weeks. Male and female Fisher rats (15/sex/group) received the substance by oral gavage at dose levels of 0, 50, 100, 300, 700 and 1500 mg/kg bw/day, in olive oil. One group of 15/sex served as the control and received only the vehicle, in volumes comparable to those received by treated groups. Animals were observed daily, body weight and food consumption were measured weekly. Clinical pathology investigations (haematology, clinical chemistry and urinalysis) were conducted prior to termination in Week 13. All animals were subject to a full necropsy and histopathological examination of a comprehensive range of tissues. Following mortalities were recorded during the course of the study: one male in dose group 300 mg/kg bw/day, one male in dose group 700 mg/kg bw/day, two females in dose group 700 mg/kg bw/day, nine females in dose group 1500 mg/kg bw/day. The survival rate of the 1500 mg/kg bw/day dose group males and females was significantly lower than that of the respective control group. Gross pathology findings of lung (hypersecretion of mucous) and stomach alterations were the most notable observations in this dose group. The lung was identified as a target organ and there was no NOEL for the exacerbation of multifocal chronic pneumonitis and focal hyperplasia of bronchial and bronchiolar epithelium, which as observed in all treated groups at a greater severity than in the controls. Comparison of the hematology data between the control and treated groups revealed significantly higher than control value in the mean hematocrit value in the highest dose group males and females and in the mean erythrocyte count in the highest dose group in females. Male body weight was lower than control in all treated groups, there was no similar effect in females. Liver weight was increased at 300 mg/kg bw/day and greater and kidney weight at 700 mg/kg bw/day and greater. No treatment–related effects were noted in comparison of the urinalysis. Under the study conditions, no NOAEL was identified. The LOAEL was considered to be 50 mg/kg bw/day, the lowest dose tested (Wolfe, 1980).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEL

50 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

March - June 1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Deviations:

yes

Remarks:

No functional observation battery, no histopathology data

GLP compliance:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats were obtained from Charles River Breeding Laboratories (Wilmigton MA) and acclimatised in the facility for 13 d prior to the start of the study, approximately 48 days old at first exposure (males 234 – 267 g; females 142 – 179 g). Housed singly, but paried in the exposure chamber. Tap water (automatic system) and diet (Purina Laboratory Rodent Chow 5001) available ad libitum, except during exposure period. Fluorescent lighting was on a 12 h/day cycle. Temperature and humidity not specified.

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

Exposure concentrations generated by flash evaporation of the test substance. The test substance was pumped into a round bottom, three-necked flask. The flask temperature was maintained at or near 70°C. The flask was connected by glass tubing to the horizontal intake portal of a 760 L steel and glass exposure chamber. This portal was set to draw room air at 190 L/minute. This flow rate provided one complete air change every 5.3 min and a 99 % equilibrium time of 24.2 min. Chamber concentrations were achieved by adjusting the rate of delivery of the test substance to the flask, via a syringe pump.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Atmospheric monitoring: Daily during the 1st, 3rd and 5th h of exposure, sample drawn from each exposure chamber. Analysed against calibration curve using a Miran Long Pathlength Infrared analyser, Model IA (Wilks Instrument Company).

Cumulative mean analysed concentrations were 101 and 505 ppm for the target concentration of 100 and 500 ppm respectively. The dose for the 1600 ppm group was dropped to 1300 ppm on Day 28 and the analysed concentrations were 1538 and 1313 ppm, respectively.

Duration of treatment / exposure:

6 h

Frequency of treatment:

Daily, 5 d/week for 13 weeks (total 64 exposures)

Dose / conc.:

100 ppm

Remarks:

nominal

Dose / conc.:

500 ppm

Remarks:

nominal

Dose / conc.:

1 300 ppm

Remarks:

nominal

Dose / conc.:

1 600 ppm

Remarks:

nominal

No. of animals per sex per dose:

15 males and 15 females

Control animals:

yes, sham-exposed

Observations and examinations performed and frequency:

Clinical observations: twice daily, detailed examination weekly
Body weights: weekly
Ophthalmic examination: all animals pre test and at termination
Clinical pathology: 5/sex/group at week 5. All animals at termination. Overnight fast and orbital sinus collection
Haematology: haemoglobin, PCV, RBC, WBC count (total and differential), clotting time
Clinical chemistry: blood urea nitrogen, serum glutamate pyruvic transaminase, alkaline phosphatase, glucose
Urinalysis: appearance, specific gravity, occult blood, pH, protein, bilirubin, ketones, glucose

Sacrifice and pathology:

Organ weights: (not early decedents) ovaries, testis, kidneys, liver, lungs.
Tissues were fixed in 10 % neutral buffered formalin. The following tissues were examined: abdominal aorta, adrenal gland, bone and marrow, brain, esophagus, eyes, heart, large intestine (caecum, colon), small intestine (duodenum, jejunum, ileum), kidney, liver, lung, lymph nodes (peribronchial and mesenteric), mammary gland, nasal turbinates, ovary, pancreas, parathyroid gland, pituitary, prostate gland, salivary gland, sciatic nerve with muscle, skin, spinal cord, spleen, stomach, testis (with epididymidis and seminal vesicles), thymus, thyroid gland, trachea, urinary bladder uterus, vagina and all gross lesions. Tissues form controls and high dose animals plus early decedents examined.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

At 1600 ppm there were notable signs of toxicity including general body tremors, loss of balance, prostration, hunched appearance, matted fur, increased activity and incoordination. When this dose was reduced to 1300 ppm these signs decreased with the exception of matted fur. At 500 ppm and greater there was excessive lacrimation, chcomodacryorrhea, yellow ano-genital staining and swollen eyes/eyelids.

Mortality:

mortality observed, treatment-related

Description (incidence):

In the first week of treatment 2 females given 1600 ppm died and were replaced. Subsequently a further 3 females and one male in this group died.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There was no effect on bodyweight at 500 ppm or lower.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Description (incidence and severity):

WBC was increased for high dose females. There were no other findings of note.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Alkaline phosphatase was increased at 1600/1300 ppm; serum glutamate pyruvate transaminase was raised at Week 5 only.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Liver weights were increased as 1600/1300 ppm but this was not accompanied by any pathological changes (stated in report text, data not present).

Gross pathological findings:

no effects observed

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Key result

Dose descriptor:

NOAEC

Effect level:

100 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Clinical signs at 500 ppm. Report states no histopathology findings but data not available for review

Remarks on result:

other:

Remarks:

Based on a molecular weight of 118.19, this is equivalent to 483.4 mg/m3

Mean body weights (BWT), survival and ALK PHOS levels

	Control	test substance (ppm)
		100	500	1600/1300
MALES
Survival wk 13	15	15	15	15(b)
BWT wk 5 (a)	447	100	96	90**
BWT wk 13 (a)	536	99	95	90*
ALK PHOS IU wk 13	105	110	101	113
FEMALES
Survival wk 13	15	15	15	12
BWT wk 5 (a)	255	97	97	95
BWT wk 13 (a)	283	96	96	95
ALK PHOS IU wk 13	43	53	55	67**

(a) control value (g) treated value % of control

(b) according to text this should be 14, not possible to verify from individual data

*  Significantly different (p <0.05) from the control, Dunnett’s test

**  Significantly different (p <0.01) from the control, Dunnett’s test

Conclusions:

Under the study conditions, the 90 d inhalation NOAEL was determined to be 100 ppm. Based on a molecular weight of 118.19, this is equivalent to 483.4 mg/m3.

Executive summary:

A study was conducted to determine toxicity of the test substance in Sprague Dawley rats exposed by inhalation for 90 d.  The substance was administered to groups of 15 male and 15 female rats at target concentrations of 0, 100, 500 and 1600/1300 ppm daily for a 6 h exposure period (total 64 exposures). Animals were observed daily, body weight was measured on Days 1, 4, 7, 11 and 15. All animals were subject to a full necropsy. Cumulative mean analysed concentrations were 101 and 505 ppm for the target concentration of 100 and 500 ppm respectively. The dose for the 1600 ppm group was dropped to 1300 ppm on Day 28 and the analysed concentrations were 1538 and 1313 ppm, respectively. There were notable clinical signs at 1300 and 1600 ppm including ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors and hypoactivity. At 500 ppm and above clinical signs were restricted to increased secretions and respiratory abnormalities. Body weight remained comparable to the controls. Liver weight was increased at 500 and 1600 ppm, and alkaline phosphatase levels were increased at 1600 ppm but there were no pathological changes. No histopathological changes and treatment-related findings at necropsy were noted. Under the study conditions, the 90 d inhalation NOAEC was determined to be 100 ppm. Based on a molecular weight of 118.19, this is equivalent to 483.4 mg/m3 (Ben Dyke, 1980).

Reference 2

Endpoint:

repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From January 14, 1980 to January 25, 1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

The toxicity of the test substance was determined in Sprague-Dawley rats exposed by inhalation for 14 d. The substance was administered to groups of 10 male and 10 female rats at target concentrations of 0, 125, 250, 500, 1000 and 1600 ppm daily for 6 h (total 10 exposures). Animals were observed daily and bodyweight was recorded on Days 1, 4, 7, 11 and 15. All animals were subject to a full necropsy.

GLP compliance:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test animals: 60 rats (30/sex)
Strain: Sprague-Dawley
Supplier: Charles River Breading Laboratories Wilmingron, Massachusetts 01887
Age upon receipt: 35 days
Age at initial exposure: 58 days
Last mean weight prior to exposure: 287 g (males), 175 g (females)
Housing: individual in hung, stainless steel wire mesh cages
Food: standard laboratory pellet diet (Purina laboratory) ad libitum
Water: tap, city water ad libitum

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

For the group two (low level) exposure, the test substance was placed in a 100 mL round glass syringe mounted on a sage syringe pump. The test substance was metered into a three-neck round bottom flask that was heated to approximately 70°C by a heating mantel and a variable transformer. The test material was flash evaporated and the vapors were drawn into a horizontal intake portal of a one cubic meter glass and stainless steel exposure chamber housing the test animals.
For the group three exposure, the test substance was placed in an Erlenmyer flask reservoir and metered into a three-neck round bottom flask using an FMI lab pump. The three-neck round bottom flask that was heated to approximately 70 °C by a heating mantel and a variable transformer and the test substance was flash evaporated. The vapors were drawn into a horizontal intake portal of a one cubic meter glass and stainless steel exposure chamber housing the test animals.
For the groups four, five and six exposures the same exposure procedure as fro group three was implemented. The concentrations were achieved by varying the pump settings and in the group six by also using a larger piston.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chambers concentrations were monitored approximately every 12 minutes using a Miran IA Ambient air analyser and a multi-point sampling system. Three absorbance readings per day (at a, 3 and 5 h into the exposure) were recorded for each exposure chamber. The concentrations were recorded by comparing the measured absorbance to a calibration curve prepared using the same instrument with the same instrumental settings.
The rats received exposure to mean measured cumulative concentrations of: 107, 251, 498, 1057 and 1612 ppm.

Duration of treatment / exposure:

6 h

Frequency of treatment:

Daily for 5/days a week for 2 weeks

Dose / conc.:

0 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks

Dose / conc.:

125 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks (nominal)

Dose / conc.:

250 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks (nominal)

Dose / conc.:

500 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks (nominal)

Dose / conc.:

1 000 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks (nominal)

Dose / conc.:

1 600 ppm

Remarks:

6 hf/day, 5 day/wk for 2 weeks (nominal)

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes, sham-exposed

Details on study design:

Chamber operation: the glass and stainless steel exposure chambers housing the test animals had a total volume of one cubic meter and an effective volume of 760 L. They were operated dynamically at a flow rate of 190 L per minute providing one air change every 5.3 min and a 99% equilibrium time of 24.4 min.

Observations and examinations performed and frequency:

The test animals were observed twice daily for mortality. In chamber and individual post-exposure observations were recorded daily for each group. Individual body weights were recorded before the first exposure and twice weekly thereafter.

Sacrifice and pathology:

Necropsy:
Organs weighted: liver, lungs, pituitary, spleen, brain, gonads, kidneys, heart.
Tissues fixed: adrenals, bone marrow, brain, esophagus, eyes, gonads, ovaries, testes, pancreas, pituitary, prostate, salivary gland, seminal vesicle, skeletal muscle, skin.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

There were notable clinical signs at 1000 and 1600 ppm including: ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors, hypoactivity. At 250 ppm and above clinical signs were restricted to increased secretions and respiratory abnormalities.

Mortality:

not specified

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Liver weight was increased at 1000 and 1600 ppm.

Gross pathological findings:

effects observed, non-treatment-related

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Details on results:

No treatment-related findings at necropsy.

Key result

Dose descriptor:

NOAEC

Effect level:

125 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 250 ppm associated with clinical signs

Remarks on result:

other: (Based on a molecular weight of 118019, this is equivalent to 604.25 mg/m3)

Conclusions:

There were notable clinical signs at 1000 and 1600 ppm including ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors and hypoactivity. At 250 ppm and above, clinical signs were restricted to increased secretions and respiratory abnormalities. Bodyweight remained comparable to the controls. Liver weight was increased at 1000 and 1600 ppm. No treatment-related findings at necropsy were noted. The doses for the main 90 d study were selected to be 0, 100, 500 and 1600 ppm.

Executive summary:

A dose range-finding study was conducted to determine the toxicity of the test substance in Sprague-Dawley rats exposed by inhalation for 14 d. The substance was administered to groups of 10 male and 10 female rats at target concentrations of 0, 125, 250, 500, 1000 and 1600 ppm daily for 6 h (total 10 exposures). Animals were observed daily and bodyweight was recorded on Days 1, 4, 7, 11 and 15. All animals were subject to a full necropsy. Analytical dose verification confirmed mean measured cumulative exposure concentrations of 107, 251, 498, 1057 and 1612 ppm. There were notable clinical signs at 1000 and 1600 ppm including ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors and hypoactivity. At 250 ppm and above, clinical signs were restricted to increased secretions and respiratory abnormalities. Bodyweight remained comparable to the controls. Liver weight was increased at 1000 and 1600 ppm. No treatment-related findings at necropsy were noted. The doses for the main 90 d study were selected to be 0, 100, 500 and 1600 ppm (Ben-Dyke, 1980).

Reference 3

Endpoint:

chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

From January 1981 to April 1981

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:

Design similar to OECD 413, but did not include clinical pathology investigations.

GLP compliance:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats were obtained from Charles River Breeding Laboratories (Kingston, NY) and acclimatised in the facility for 20 days prior to the start of the study, approximately 7-8 weeks old at first exposure. Housed singly. Tap water (glass bottles) and diet (NIH-07 Rat and Mouse Ration, Zeigler Bros, PA) available ad libitum, except during exposure period.
Chamber environment: Temperature was maintained between 69-810 °F and relative humidity 30 to 51 %. Fluorescent lighting was on a 12 hours/day cycle and room air changes were 10-18 hour.

Route of administration:

inhalation: gas

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

The test substance was metered from a reservoir via a precision pump into a J-tube containing 1/4 inch glass beads. Compressed air, heated to 60 °C-70 °C, was passed through the system. The test substance vapor then entered the airstream at the top of the chamber (Hazleton 2000@, Lab Products, Inc.) and was mixed in the chamber plenum before entering the exposure area of the chamber and delivered at 30 – 50 litres/minute.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

6 hours

Frequency of treatment:

daily, 5 days/week for 13 weeks (64 days)

Dose / conc.:

25 ppm

Remarks:

nominal

Dose / conc.:

60 ppm

Remarks:

nominal

Dose / conc.:

160 ppm

Remarks:

nominal

Dose / conc.:

400 ppm

Remarks:

nominal

Dose / conc.:

1 000 ppm

Remarks:

nominal

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes, sham-exposed

Observations and examinations performed and frequency:

Clinical observations: daily
Bodyweight: weekly

Sacrifice and pathology:

Necropsy performed on all animals.
Histopathology: all control and high dose animals. Tissues examined include: adrenal glands, bone, brain, cecum, colon, duodenum, epididymid seminal vesicle, prostate/testes or oviduct /ovaries/uterus, esophagus heart, ileum, jejunum, kidneys, larynx, liver, lungs, mammary gland, mandibular and mesenteric lymph nodes, mesentery, nasal passage, pancreas, parathyroid glands, pituitary gland, preputial or clitoral gland, rectum, salivary glands, skin, spinal cord, spleen, stomach, thymus, thyroid gland, trachea, and urinary bladder.

Statistics:

Lesion incidence was assessed using the Fisher exact test. Normally distributed data (organ and body weights) were analysed using Dunnett and Williams test.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Excessive lacrimation, palpebral closure, and rough hair coats were seen in rats exposed to 1000 ppm.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The final mean body weights of rats exposed to 160, 400, or 1000 ppm were 6%, 8%, or 19% lower than that of controls for males and 5%, 6%, or 12% lower for females.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Relative liver weights, but not absolute weights, for rats exposed to 1000 ppm were significantly greater than those for controls.

Gross pathological findings:

no effects observed

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

A mild nephropathy characterized by increased tubular casts was found in male rats exposed to 160,400, or 1000 ppm. No compound-related lesions were observed in female rats.

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Key result

Dose descriptor:

NOAEC

Effect level:

60 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reduced bodyweight gain at 160 ppm

Remarks on result:

other: (equivalent to 290.04 mg/m3 based on a molecular weight of 118.19)

Key result

Critical effects observed:

no

Mean bodyweight (BWT) and liver weight (mg/g):

	Untreated	test substance ppm
		25	60	160	400	1000
MALES
Survival	10/10	10/10	10/10	10/10	10/10	10/10
Week 13 BWT (% of controls)	NA	100	99	94	92	81
Liver wt /body wt (mg/g)+SD	39.5+1.66	43.6+1.37	43.0+1.29	43.8+1.27	43.9+1.51	52.9+0.1.55**
FEMALES
Survival	10/10	10/10	10/10	10/10	10/10	10/10
Week 13 BWT (% of controls)	NA	99	98	95	94	88
Liver wt /body wt (mg/g)+SD	38.0+2.41	38.8+1.55	41.0+1.30	40.4+1.54	41.7+2.37	48.3+1.51**

*  Significantly different (p <0.05) from the control, Dunnett’s test

** Significantly different (p <0.01) from the control, Dunnett’s test

 

Conclusions:

Under the study conditions, clinical signs of excessive lacrimation, palpebral closure, and rough coats were observed at 1000 ppm only. Bodyweight gain was reduced at 160 ppm and greater. Liver weight was increased at 1000 ppm only, but not associated with any histopathological changes. Histology was restricted to male animals where a mild nephropathy characterized by increased tubular casts was found in male rats exposed to 160 ppm or greater. The study report did not cite a NOAEC but this can be considered to be 60 ppm, equivalent to 290.04 mg/m3 based on a molecular weight of 118.19 .

Executive summary:

A study was conducted to determine the repeated dose toxicity of the read across substance, vinyl toluene, by inhalation in F344 rats. Groups of 10 male and 10 female rats were exposed to the substance at concentrations of 0, 25, 60, 160, 400 and 1000 ppm, daily for 6 h, 5 d a week for 13 weeks (total of 64 exposures). Clinical observations were recorded daily and body weight was monitored weekly. At the end of the study, all animals were subject to necropsy.  Histopathology was conducted on the control group and all rats in high dose group. Clinical signs of excessive lacrimation, palpebral closure, and rough coats were observed at 1000 ppm only. Bodyweight gain was reduced at 160 ppm and greater. Liver weight was increased at 1000 ppm only, but not associated with any histopathological changes. Histology was restricted to male animals where a mild nephropathy characterized by increased tubular casts was found in male rats exposed to 160 ppm or greater. The study report did not cite a NOAEC but this can be considered to be 60 ppm, equivalent to 290.04 mg/m3 based on a molecular weight of 118.19 (NTP, 1990).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

290.04 mg/m³

Study duration:

subchronic

Species:

rat

System:

respiratory system: upper respiratory tract

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

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

Principles of method if other than guideline:

Two dose levels applied for 21 days.

GLP compliance:

no

Specific details on test material used for the study:

Lot Nr.: 145070177-2

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

New Zealand White rabbits: weight 2.05 to 2.55 Kg acclimatised for 7 days and housed individually in a laminar flow room. Diet (Purina Rabbit Chow) and water ad libitum.

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Details on exposure:

Application site of approximately 25 % of total body surface was clipped free of hair prior to study and once weekly. One rabbit per group/sex abraded at the test site with a clipper head before each application.
The test substance was delivered from a glass syringe and spread evenly over the test site and left for 6 hours before the area was rinsed with water and dried. Rabbits were maintained in a harness during the exposure period to prevent oral ingestion.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

6 hours

Frequency of treatment:

daily for 21 days

Dose / conc.:

0.5 other: mL/kg

Remarks:

nominal per unit body weight

Dose / conc.:

0.2 other: mL/kg

Remarks:

nominal per unit body weight

No. of animals per sex per dose:

3 males and 3 females

Control animals:

other: 2.0 mL/kg distilled water

Details on study design:

Eighteen New Zeeland rabbits (nine males and nine females) weighing from 2.05 kg to 2.55 kg were randomized by weight into three groups of three males and three females each. Animals were dosed daily, for 21 days at dose volumes of 0.5 or 2.0 mL/kg of the test substance and 2.0 mL/kg distilled water (controls).

Observations and examinations performed and frequency:

Observations: daily
Skin irritation scores: twice daily, before and after application
Clinical pathology: prior to treatment and at the end of treatment. Blood collected from the ear artery.
Haematology: PCV, Haemoglobin, MCV, RBC, WBC (total and differential)
Clinical chemistry: glucose, BUN, alkaline phosphatase, SGOT, SGPT, bilirubin, total protein, calcium and phosphorus

Sacrifice and pathology:

At the end of the 21-day period, all rabbits were weighed, anesthetized with sodium pentobarbital and exsanguinated. A necropsy to observe gross lesions was performed and the following tissues were fixed in 10% buffered formalin and evaluated histomorphologically: skin, heart, lung, adrenals, brain, gonads, liver, kidney, spleen, stomach, du odenum, bone marrow, bladder, pancreas, pituitary, unusual lesions, mesentery lumph node.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All rabbits experienced pain when the test substance was applied.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

The test substance was a skin irritant at both dose levels. Observation at skin site included thickening of the epidermins, congestion, edema, inflammatory cellular infiltration, serum exudates and necrotic cellular debris on the surface.

After the first application there was very slight erythema and edema, by day 4 the severity was slight and coriaceious skin and atonia were apparent. After the 5th application moderate to marked fissuring of the skin was noted eventually leading to slight bleeding from the fissures. By day nine the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There was a dose related decrease in body weight, considered to be a consequence of the pain and irritation at the skin application site.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Effects on WBC due to irritation: elevated WBC and increase in segmented and non-segmented neutrophils.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Elevated SGOT and considered to be related to skin cell damage.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

No evidence of systemic pathology. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) olor rather than a normal red colour.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Sex:

male/female

Basis for effect level:

other: Skin irritation at both dose levels

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Conclusions:

Under the study conditions, there were no results to suggest systemic toxicity. However, the test substance caused moderate to severe skin irritation. Further, the irritation resulted in pain, reduced body weight, elevated WBC and increase in segmented and non-segmented neutrophils. By day nine the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups. The only effect on the clinical chemistry parameters was an elevation in the serum glutamic oxaloacetic transaminase(SGOT) ezyme which probably is related to the skin cell damage at the application site. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) colour rather than a normal red colour. No NOAEL was established for the study (Adamik, 1977).

Executive summary:

A study was conducted to determine the toxicity of the test substance when applied to the skin of albino rabbits during a period of 21 consecutive days. The test substance was applied dermally to groups of 3 male and 3 female New Zealand rabbits, daily, at dose volumes of 0.5 or 2.0 mL/kg bw/day. Controls received 2.0 mL/kg bw/day of distilled water. The test substance was in contact with the skin, non-occluded, for 6 h each day. Clinical signs were recorded daily and body weight weekly. Blood samples for haematology and clinical chemistry were taken prior to treatment and at termination. All rabbits were subject to necropsy and limited histopathology. Under the study conditions, there were no results to suggest systemic toxicity. However, the test substance caused moderate to severe skin irritation. Further, the irritation resulted in pain, reduced body weight, elevated white blood cells and increase in segmented and non-segmented neutrophils. By Day 9, the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups. The only effect on the clinical chemistry parameters was an elevation in the serum glutamic oxaloacetic transaminase (SGOT) enzyme which was probably related to the skin cell damage at the application site. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) colour rather than a normal red colour. No NOAEL was established for the study (Adamik, 1977).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

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

Principles of method if other than guideline:

Two dose levels applied for 21 days.

GLP compliance:

no

Specific details on test material used for the study:

Lot Nr.: 145070177-2

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

New Zealand White rabbits: weight 2.05 to 2.55 Kg acclimatised for 7 days and housed individually in a laminar flow room. Diet (Purina Rabbit Chow) and water ad libitum.

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Details on exposure:

Application site of approximately 25 % of total body surface was clipped free of hair prior to study and once weekly. One rabbit per group/sex abraded at the test site with a clipper head before each application.
The test substance was delivered from a glass syringe and spread evenly over the test site and left for 6 hours before the area was rinsed with water and dried. Rabbits were maintained in a harness during the exposure period to prevent oral ingestion.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

6 hours

Frequency of treatment:

daily for 21 days

Dose / conc.:

0.5 other: mL/kg

Remarks:

nominal per unit body weight

Dose / conc.:

0.2 other: mL/kg

Remarks:

nominal per unit body weight

No. of animals per sex per dose:

3 males and 3 females

Control animals:

other: 2.0 mL/kg distilled water

Details on study design:

Eighteen New Zeeland rabbits (nine males and nine females) weighing from 2.05 kg to 2.55 kg were randomized by weight into three groups of three males and three females each. Animals were dosed daily, for 21 days at dose volumes of 0.5 or 2.0 mL/kg of the test substance and 2.0 mL/kg distilled water (controls).

Observations and examinations performed and frequency:

Observations: daily
Skin irritation scores: twice daily, before and after application
Clinical pathology: prior to treatment and at the end of treatment. Blood collected from the ear artery.
Haematology: PCV, Haemoglobin, MCV, RBC, WBC (total and differential)
Clinical chemistry: glucose, BUN, alkaline phosphatase, SGOT, SGPT, bilirubin, total protein, calcium and phosphorus

Sacrifice and pathology:

At the end of the 21-day period, all rabbits were weighed, anesthetized with sodium pentobarbital and exsanguinated. A necropsy to observe gross lesions was performed and the following tissues were fixed in 10% buffered formalin and evaluated histomorphologically: skin, heart, lung, adrenals, brain, gonads, liver, kidney, spleen, stomach, du odenum, bone marrow, bladder, pancreas, pituitary, unusual lesions, mesentery lumph node.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All rabbits experienced pain when the test substance was applied.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

The test substance was a skin irritant at both dose levels. Observation at skin site included thickening of the epidermins, congestion, edema, inflammatory cellular infiltration, serum exudates and necrotic cellular debris on the surface.

After the first application there was very slight erythema and edema, by day 4 the severity was slight and coriaceious skin and atonia were apparent. After the 5th application moderate to marked fissuring of the skin was noted eventually leading to slight bleeding from the fissures. By day nine the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There was a dose related decrease in body weight, considered to be a consequence of the pain and irritation at the skin application site.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Effects on WBC due to irritation: elevated WBC and increase in segmented and non-segmented neutrophils.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Elevated SGOT and considered to be related to skin cell damage.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

No evidence of systemic pathology. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) olor rather than a normal red colour.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Sex:

male/female

Basis for effect level:

other: Skin irritation at both dose levels

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Conclusions:

Under the study conditions, there were no results to suggest systemic toxicity. However, the test substance caused moderate to severe skin irritation. Further, the irritation resulted in pain, reduced body weight, elevated WBC and increase in segmented and non-segmented neutrophils. By day nine the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups. The only effect on the clinical chemistry parameters was an elevation in the serum glutamic oxaloacetic transaminase(SGOT) ezyme which probably is related to the skin cell damage at the application site. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) colour rather than a normal red colour. No NOAEL was established for the study (Adamik, 1977).

Executive summary:

A study was conducted to determine the toxicity of the test substance when applied to the skin of albino rabbits during a period of 21 consecutive days. The test substance was applied dermally to groups of 3 male and 3 female New Zealand rabbits, daily, at dose volumes of 0.5 or 2.0 mL/kg bw/day. Controls received 2.0 mL/kg bw/day of distilled water. The test substance was in contact with the skin, non-occluded, for 6 h each day. Clinical signs were recorded daily and body weight weekly. Blood samples for haematology and clinical chemistry were taken prior to treatment and at termination. All rabbits were subject to necropsy and limited histopathology. Under the study conditions, there were no results to suggest systemic toxicity. However, the test substance caused moderate to severe skin irritation. Further, the irritation resulted in pain, reduced body weight, elevated white blood cells and increase in segmented and non-segmented neutrophils. By Day 9, the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups. The only effect on the clinical chemistry parameters was an elevation in the serum glutamic oxaloacetic transaminase (SGOT) enzyme which was probably related to the skin cell damage at the application site. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) colour rather than a normal red colour. No NOAEL was established for the study (Adamik, 1977).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Additional information

Oral

A study was conducted to determine the repeated dose oral toxicity of the test substance when administered to rats daily for 13 weeks. Male and female Fisher rats (15/sex/group) received the substance by oral gavage at dose levels of 0, 50, 100, 300, 700 and 1500 mg/kg bw/day, in olive oil. One group of 15/sex served as the control and received only the vehicle, in volumes comparable to those received by treated groups. Animals were observed daily, body weight and food consumption were measured weekly. Clinical pathology investigations (haematology, clinical chemistry and urinalysis) were conducted prior to termination in Week 13. All animals were subject to a full necropsy and histopathological examination of a comprehensive range of tissues. Following mortalities were recorded during the course of the study: one male in dose group 300 mg/kg bw/day, one male in dose group 700 mg/kg bw/day, two females in dose group 700 mg/kg bw/day, nine females in dose group 1500 mg/kg bw/day. The survival rate of the 1500 mg/kg bw/day dose group males and females was significantly lower than that of the respective control group. Gross pathology findings of lung (hypersecretion of mucous) and stomach alterations were the most notable observations in this dose group. The lung was identified as a target organ and there was no NOEL for the exacerbation of multifocal chronic pneumonitis and focal hyperplasia of bronchial and bronchiolar epithelium, which as observed in all treated groups at a greater severity than in the controls. Comparison of the hematology data between the control and treated groups revealed significantly higher than control value in the mean hematocrit value in the highest dose group males and females and in the mean erythrocyte count in the highest dose group in females. Male body weight was lower than control in all treated groups, there was no similar effect in females. Liver weight was increased at 300 mg/kg bw/day and greater and kidney weight at 700 mg/kg bw/day and greater. No treatment–related effects were noted in comparison of the urinalysis. Under the study conditions, no NOAEL was identified. Following a conservative approach, the LOAEL is considered to be 50 mg/kg bw/day, the lowest dose tested (Wolfe, 1980).

A study was conducted to determine the repeated dose toxicity of the test substance when administered to rats daily for 13 weeks. The substance was administered to groups of 15 male and 15 female Sprague Dawley rats at dose volumes of 0.1, 0.3 and 0.6 mL/kg bw daily; controls received distilled water. Animals were observed daily, body weight and food consumption was recorded weekly. Clinical pathology investigations were conducted prior to termination and limited histopathological investigations were conducted on all animals. Under the study conditions, clinical signs (increased motor activity and/or salivation) were apparent in all treated groups. Body weight was lower in treated males only. There were no organ weights or clinical pathology findings of note. Histopathological findings were restricted to aspiration pneumonia and peri-oral dermatitis, both resulting from direct contact irritation during dosing. The NOAEL was not identified in this study. The LOAEL was considered to be 0.1 mL/kg bw/day, the lowest dose tested. Based on a density of 0.917, this is equivalent to 91.7 mg/kg bw/day (Springborn, 1980).

Inhalation

A study was conducted to determine the repeated dose toxicity of the read across substance, vinyl toluene, by inhalation in F344 rats. Groups of 10 male and 10 female rats were exposed to the substance at concentrations of 0, 25, 60, 160, 400 and 1000 ppm, daily for 6 h, 5 d a week for 13 weeks (total of 64 exposures). Clinical observations were recorded daily and body weight was monitored weekly. At the end of the study, all animals were subject to necropsy.  Histopathology was conducted on the control group and all rats in high dose group. Clinical signs of excessive lacrimation, palpebral closure, and rough coats were observed at 1000 ppm only. Bodyweight gain was reduced at 160 ppm and greater. Liver weight was increased at 1000 ppm only, but not associated with any histopathological changes. Histology was restricted to male animals where a mild nephropathy characterized by increased tubular casts was found in male rats exposed to 160 ppm or greater. The study report did not cite a NOAEC but this can be considered to be 60 ppm, equivalent to 290.04 mg/m3 based on a molecular weight of 118.19 (NTP, 1990).

A dose range-finding study was conducted to determine the toxicity of the test substance in Sprague-Dawley rats exposed by inhalation for 14 d. The substance was administered to groups of 10 male and 10 female rats at target concentrations of 0, 125, 250, 500, 1000 and 1600 ppm daily for 6 h (total 10 exposures). Animals were observed daily and bodyweight was recorded on Days 1, 4, 7, 11 and 15. All animals were subject to a full necropsy. Analytical dose verification confirmed mean measured cumulative exposure concentrations of 107, 251, 498, 1057 and 1612 ppm. There were notable clinical signs at 1000 and 1600 ppm including ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors and hypoactivity. At 250 ppm and above, clinical signs were restricted to increased secretions and respiratory abnormalities. Bodyweight remained comparable to the controls. Liver weight was increased at 1000 and 1600 ppm. No treatment-related findings at necropsy were noted. The doses for the main 90 d study were selected to be 0, 100, 500 and 1600 ppm (Ben-Dyke, 1980).

A study was conducted to determine toxicity of the test substance in Sprague Dawley rats exposed by inhalation for 90 d.  The substance was administered to groups of 15 male and 15 female rats at target concentrations of 0, 100, 500 and 1600/1300 ppm daily for a 6 h exposure period (total 64 exposures). Animals were observed daily, body weight was measured on Days 1, 4, 7, 11 and 15. All animals were subject to a full necropsy. Cumulative mean analysed concentrations were 101 and 505 ppm for the target concentration of 100 and 500 ppm respectively. The dose for the 1600 ppm group was dropped to 1300 ppm on Day 28 and the analysed concentrations were 1538 and 1313 ppm, respectively. There were notable clinical signs at 1300 and 1600 ppm including ocular and oral secretions, respiratory abnormalities, prostration, neuromuscular impairment, tremors and hypoactivity. At 500 ppm and above clinical signs were restricted to increased secretions and respiratory abnormalities. Body weight remained comparable to the controls. Liver weight was increased at 500 and 1600 ppm, and alkaline phosphatase levels were increased at 1600 ppm but there were no pathological changes. No histopathological changes and treatment-related findings at necropsy were noted. Under the study conditions, the 90 d inhalation NOAEC was determined to be 100 ppm. Based on a molecular weight of 118.19, this is equivalent to 483.4 mg/m3 (Ben Dyke, 1980).

Dermal

A study was conducted to determine the toxicity of the test substance when applied to the skin of albino rabbits during a period of 21 consecutive days. The test substance was applied dermally to groups of 3 male and 3 female New Zealand rabbits, daily, at dose volumes of 0.5 or 2.0 mL/kg bw/day. Controls received 2.0 mL/kg bw/day of distilled water. The test substance was in contact with the skin, non-occluded, for 6 h each day. Clinical signs were recorded daily and body weight weekly. Blood samples for haematology and clinical chemistry were taken prior to treatment and at termination. All rabbits were subject to necropsy and limited histopathology. Under the study conditions, there were no results to suggest systemic toxicity. However, the test substance caused moderate to severe skin irritation. Further, the irritation resulted in pain, reduced body weight, elevated white blood cells and increase in segmented and non-segmented neutrophils. By Day 9, the surface layer of skin sloughed or peeled off and the underlying skin was golden to black colour. The severity of skin response was similar in both test groups. The only effect on the clinical chemistry parameters was an elevation in the serum glutamic oxaloacetic transaminase (SGOT) enzyme which was probably related to the skin cell damage at the application site. The renal collecting tubules of some of the rabbits were more visible than normally observed and they were white and the renal medulla was brownish – pink (pale) colour rather than a normal red colour. No NOAEL was established for the study (Adamik, 1977).

Justification for classification or non-classification

Based on repeated dose oral and inhalation studies in rodents, the substance is not considered to warrant classification for repeated dose toxicity according to CLP (EC 1272/2008) criteria.