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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: guideline study - well documented

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report date:
1993

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Principles of method if other than guideline:
Ten male and female rats per group were exposed nose/head only to mean analytical concentrations of 0.35, 0.83, 2.79 and 10.07 mg phenyl isocyanate/m³ for 4 weeks (6h/d, 5 exposures per week). During the study, the body weights were determined and clinical signs were recorded. At the end of the study ophthalmological examinations were performed and clinicochemical and hematological parameters were determined and a urinalysis performed. During sacrifice, gross pathological examinations of rats were made and selected organs were collected for gravimetric and histopathological examinations.
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Phenyl isocyanate
EC Number:
203-137-6
EC Name:
Phenyl isocyanate
Cas Number:
103-71-9
Molecular formula:
C7H5NO
IUPAC Name:
isocyanatobenzene
Details on test material:
content: 99.9 % purity

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
nose/head only
Vehicle:
air
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
4 weeks
Frequency of treatment:
6h/d, 5d/w
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/m³ air
Dose / conc.:
0.35 mg/m³ air (analytical)
Dose / conc.:
0.83 mg/m³ air (analytical)
Dose / conc.:
2.79 mg/m³ air (analytical)
Dose / conc.:
10.07 mg/m³ air (analytical)
Dose / conc.:
0.2 mg/m³ air (nominal)
Dose / conc.:
0.7 mg/m³ air (nominal)
Dose / conc.:
2.5 mg/m³ air (nominal)
Dose / conc.:
7.5 mg/m³ air (nominal)
No. of animals per sex per dose:
10 male and 10 female animals/group
Control animals:
yes, concurrent vehicle
Details on study design:
Post-exposure period: no
Positive control:
None

Examinations

Observations and examinations performed and frequency:
Body weights, clinical signs, rectal temperature, ophthalmological examinations, clinicochemical, hematological parameters, urinalysis.
Sacrifice and pathology:
Gross pathological examinations, selected organs were collected for gravimetric and histopathological examinations.
Statistics:
A statistical calculation of the determined parameters was conducted.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Up to 7.5 mg/m³ no findings. In the 7.5 mg/m³ group a decrease of the general condition was observed.
Mortality:
mortality observed, treatment-related
Description (incidence):
In the 7.5 mg/m³ group 70% of the male rats and 50% of the female rats died intercurrent or were killed in moribund state.
Description (incidence and severity):
In the 2.5 mg/m³ group no toxicological relevant influence on the body weights were observed. In the 7.5 mg/kg bw group a statistical significant decrease of the body weights were seen.
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:
effects observed, treatment-related
Description (incidence and severity):
In the 2.5 mg/m³ no findings. In the 7.5 mg/m³ group a hyperemia of the iris and a reddened ocular fundus were observed.
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
In the 7.5 mg/m³ group the erythrocyte concentration, hematocrit and, hemoglobin and reticulocyte concentration were increased. Additional the rats revealed an increased coagulation time. the differential blood count showed an increase of the monocytes.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
In the 7.5 mg/m³ group a statistically relevant decrease of the albumin, protein and chloride concentration of the plasma was observed, as well as an increase of the plasma ASAT (aspartate aminotransferase) and GLDH (glutamate dehydrogenase) activity. Additional the bilirubin and sodium concentrations were increased.
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
Urine was more acidic in the 7.5 mg/m³ group.
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
In the 7.5 mg/m³ a decrease of the reflexes were observed.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
In the 7.5 mg/m³ group, the weights of liver, thymus, testis/ovaries and spleen were decreased, the liver weights were increased. No findings in the 2.5 mg/m³ group.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
In the 7.5 mg/m³ group, lungs was dark red discoloured, congestion of the cerebral blood vessels, dark spleen and decreased thymus. No findings in the 2.5 mg/m³ group.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
<= 2.79 mg/m³: no findings
2.79 mg/m³: histopathological alterations in the nasal septum (hyperplasia) 
10.07 mg/³:  metaplasia of the epithelium (nasal septum, larynx, trachea, stem bronchus), increased number of alveolar macrophages and swollen septum (lung), proliferating connective tissue, perivascular infiltration of round cells and accumulation of mucus (lobar bronchus).
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed

Effect levels

open allclose all
Key result
Dose descriptor:
NOAEC
Effect level:
0.83 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no effects observed
Key result
Dose descriptor:
LOAEL
Effect level:
2.79 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
gross pathology
histopathology: non-neoplastic

Target system / organ toxicity

Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
2.79 mg/m³ air (analytical)
System:
other: respiratory tract
Organ:
lungs
nasal cavity
trachea
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
yes

Any other information on results incl. tables

<= 2.79 mg/m³:  no mortality, no clinical signs;  2.79 mg/m³: histopathological alterations in the nasal septum (hyperplasia)  10.07 mg/³: 5/10 (females) and 7/10 (males) died, elevated temperature, decreased body weights, changed haematological and clinical biochemistry parameters, decreased organ weights (liver, thymus, gonads, spleen), increased lung weight, metaplasia of the epithelium (nasal septum, larynx, trachea, stem bronchus), increased number of alveolar macrophages and swollen septum (lung), proliferating connective tissue, perivascular infiltration of round cells and accumulation of mucus (lobar bronchus).

Applicant's summary and conclusion

Conclusions:
At a concentration <= 2.79 mg/m³ no mortality and  no clinical signs were seen. Starting with 2.79 mg/m³ histopathological alterations in the nasal septum (hyperplasia) were evident. At a concentration of 10.07 mg/m³ 5/10 females and 7/10 males died. An elevated temperature, decreased body weights, changed haematological and clinical biochemistry parameters, decreased organ weights (liver, thymus, gonads, spleen), increased lung weight, metaplasia of the epithelium (nasal septum, larynx, trachea, stem bronchus), increased number of alveolar macrophages and swollen septum (lung), proliferating connective tissue, perivascular infiltration of round cells and accumulation of mucus (lobar bronchus) were observed.
The effects observed in the respiratory system are mainly caused by irritation/corrosion. Therefore according to CLP classification criteria (Regulation (EC) No 1272/2008) a classification is not justified.
Executive summary:

Ten male and female rats per group were exposed nose/head only to mean analytical concentrations of 0.35, 0.83, 2.79 and 10.07 mg phenyl isocyanate for 4 weeks (6h/d, 5 exposures per week). During the study, the body weights were determined and clinical signs were recorded. At the end of the study ophthalmological examinations was performed and clinicochemical and hematological parameters were determined and an urinalysis performed. During sacrifice, gross pathological examinations of rats were made and selected organs were collected for gravimetric and histopathological examinations.

The NOAEL = 0.83 mg phenyl isocyanate/m³ air is based on the most sensitive parameter (hyperplasia of goblet cells in the turbinalia area).