1,3-bis(1-isocyanato-1-methylethyl)benzene

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Dec. 14, 1987 to Mar. 18, 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,3-bis(1-isocyanato-1-methylethyl)benzene

EC Number:

220-474-4

EC Name:

1,3-bis(1-isocyanato-1-methylethyl)benzene

Cas Number:

2778-42-9

Molecular formula:

C14H16N2O2

IUPAC Name:

1,3-bis(1-isocyanato-1-methylethyl)benzene

Details on test material:

Name of test material (as cited in study report): CT-255-86

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. (Kingston, NY)
- Age at study initiation: 68-70 d
- Housing: Individually; stainless steel, wire-mesh cages
- Diet: Pelleted feed (Pro Lab RMH 3000, Agway, Inc., Syracuse, NY) during exposure period and powdered feed during urine collection period, ad libitum
- Water: Water supplied by municipal authority, ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature: 20-22.2 °C
- Humidity (%): 32-72 %
- Photoperiod (hrs dark / hrs light): 12 h dark/12 h light

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: No data

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel with glass windows
- Method of holding animals in test chamber: Whole body
- Temperature, humidity in air chamber: 18.5-28.9 °C, 24.9-59.1 %
- Air flow rate: 250 L/min
- Air change rate: 17 air changes/h
- Method of particle size determination: TSI Aerodynamic Particle Sizer


TEST ATMOSPHERE
- Brief description of analytical method used: At least three times a day by HPLC
- Samples taken from breathing zone: Yes


VAPOR GENERATION
- Apparatus: Syringe pump (Sage Instruments, Cambridge, MA)
- Method: Liquid test material was introduced at the top of the evaporator into a spiral groove of the inner wall and allowed to flow downward

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- Reverse phase HPLC was performed using 501 Waters liquid chromatograph equipped with an SP 8400 ultraviolet/visible detector and an SP 4290 Computing Integrator.
- Detection limit: 0.014 ppm

Duration of treatment / exposure:

6 h/d, 5 d/wk for 13 wk, and for the 2 d during the 14 wk

Frequency of treatment:

Daily (6 h/d), 5 d/wk

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0.31 ± 0.061, 0.72 ± 0.096 and 1.46 ± 0.146 ppm
Basis:
analytical conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0 (air-exposed control), 0.4, 0.8 and 1.6 ppm
Basis:
other: target conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
0.68 ± 0.097, 1.33 ± 0.086 and 2.29 ± 0.198 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

Ten

Control animals:

yes

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Once daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At the time of body weight collection and just preceding sacrifice

BODY WEIGHT: Yes
- Time schedule for examinations: Pre-exposure, once a wk during exposure and immediately preceding sacrifice

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Prior to first exposure and following each exposure
- Dose groups that were examined: All

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Prior to terminal sacrifice
- Anaesthetic used for blood collection: Yes (Methoxyflurane)
- Animals fasted: Yes
- How many animals: All

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Prior to terminal sacrifice
- Animals fasted: Yes
- How many animals: All

URINALYSIS: Yes
- Time schedule for collection of urine: At the end of the exposure regimen
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
- Organ weights: Brain, liver, kidneys, lungs and adrenal glands from all surviving animals and testis from male

HISTOPATHOLOGY: Yes

Statistics:

Bartlett's test for homogeneity of variances, ANOVA, Duncan's multiple range test or t- test

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

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:

effects observed, treatment-related

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

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
- Clinical signs: Reddening of the ears and paws; blepharospasm (squinting of the eyes) and alopecia (abnormal deficiency of hair) observed in 0.8 and 1.6 ppm group mice
- Mortality: 7 males and 9 females found dead in 1.6 ppm; 2 each in 0.8 ppm and 1 female in 0.4 ppm group

BODY WEIGHT AND WEIGHT GAIN
Decreased body weight gain in 0.4, 0.8 and 1.6 groups


OPHTHALMOSCOPIC EXAMINATION
- Central white opacities or diffuse cloudiness of the cornea were observed only in females in control, 0.4 and 0.8 ppm group
- Significance of the results was not clear

HAEMATOLOGY
No treatment-related effects


CLINICAL CHEMISTRY
No treatment-related effects


ORGAN WEIGHTS
Biologically significant increase in absolute lung weights in females at 0.8 ppm


GROSS PATHOLOGY
- Alopecia and color changes in the lung,
- Color change of the ears in a few of the 0.8 ppm group males and in both of the 1.6 ppm group males

HISTOPATHOLOGY: NON-NEOPLASTIC
- Necrosis, ulceration, squamous metaplasia and inflammatory changes in the nasal cavity
- Necrosis and inflammatory changes in the trachea and larynx
- Submucosal fibrosis of the trachea in one male mouse (0.8 ppm)
- Congestion and hemorrhage, necrosis, inflammatory changes, squamous metaplasia, bronchiolar submucosal fibrosis in the lungs at 1.6 and 0.8 ppm group
- Macrophage infiltration (alveolar histiocytosis) and Clara cell hypertrophy in 1 male of 0.4 ppm group
- Degeneration, necrosis, squamous metaplasia and inflammatory changes occurred in the nasal cavity of test material exposed mice sacrificed at the end of the exposure regimen
- Pulmonary fibrosis occurred in the 2 male (1.6 ppm), in 4 female (0.8 ppm) and in 1 mouse of the 0.4 ppm group

Effect levels

1

Key result

Dose descriptor:

NOAEC

Remarks on result:

not determinable

Remarks:

no NOAEC identified

2

Key result

Dose descriptor:

LOAEC

Effect level:

0.4 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Effects observed at all dose levels: Clinical signs; mortality; body weight; haematology; clinical chemistry; urinalysis; ophthalmoscopic examination; gross pathology; organ weights; histopathology

Target system / organ toxicity

Key result

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Under the test conditions, mice exposed to vapor of test material had evidence of toxicity at all exposure concentrations. A NOAEC could not be established, although the incidence, severity and depth of histological lesions within the respiratory tract generally decreased with decreasing exposure concentration. The LOAEC for the study can be considered to be 0.4 ppm, the lowest dose tested.

Executive summary:

A study was conducted to evaluate the toxic effects of 14 weeks of repeated exposure to vapour from test substance in mice. The study was performed according to OECD Guideline 413, in compliance with GLP. CD-1 mice(10/sex/group) received whole-body exposures for 6 h/d, 5 d/week, for 14 weeks to either filtered air or test substance vapour at target concentrations of 0 (control), 0.4, 0.8 or 1.6 ppm. All animals were monitored for toxic effects including clinical observations, body and organ weights, haematology, serum chemistry, urinalysis evaluations, ophthalmic changes, and macroscopic and microscopic evaluations. Mean analytical concentrations of 0.31, 0.72 and 1.46 ppm of test substance were obtained. Respiratory difficulty (e.g. gasping), reddening of the ears and paws, blepharospasm and alopecia were observed in mice at 0.8 and 1.6 ppm. The incidence of mortality was 5, 20, and 80% for the 0.4, 0.8, and 1.6 ppm groups, respectively. Effects on body weight gain were generally concentration related, being depressed at 1.6 ppm and sporadically depressed at 0.8 and 0.4 ppm. No concentration-related changes in haematology, serum chemistry and urinalysis parameters were observed. At necropsy, the principal changes included pulmonary congestion and alopecia. Biologically- significant organ weight changes in the lungs, absolute and/or relative lung weight values were increased for female mice at 0.8 ppm. In the nasal cavity, the lesions included necrosis, ulceration, squamous metaplasia and inflammatory changes; necrosis and inflammatory changes generally occurred in the larynx and trachea; pulmonary changes included congestion, haemorrhage, necrosis, inflammation and in several of the animals, bronchiolar submucosal fibrosis. Inflammatory changes and fibrosis in the lungs were seen at all dose levels. Under the test conditions, mice exposed to vapor of test substance had evidence of toxicity at all exposure concentrations. A NOEC could not be established, although the incidence, severity and depth of histological lesions within the respiratory tract generally decreased with decreasing exposure concentration. The LOAEC for the study can be considered to be 0.4 ppm, the lowest dose tested (Klonne, 1990).