Registration Dossier

Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 21, 1998 - June 29, 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Conducted in accordance with OECD 413 and GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): NBDI (liquid)

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River (UK)
- Age at study initiation: 6 weeks
- Weight at study initiation:
Group mean bodyweights (g): 258.6-260.6 (male) and 196.0-196.8 (female)
IN-LIFE DATES: From: June 14, 1999 To: September 14, 1999

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
The rats were housed 5 of the same sex to a cage in suspended stainless steel cages fitted with mesh front, back and floor with stainless steel sheet sides. Each cage was 35 cm wide, 53 com long and 25 cm high. Plastic trays lined with absorbent paper, were place below each cage to collect animal excreta. The paper was changed daily. Clean cages were introduced at intervals throughout the study. The rats were kept in a single room and, additionally, after the start of the exposure period, each group was positioned on an individual cage battery. Each battery was in a separate ventilated cabinet within the holding room to avoid the possibility of inhalation of the substance from the fur of rats in other groups. Exposure took place in the same room.

The rats were exposed to the control/test atmosphere in whole-body exposure chambers (internal volume: 0.75 m3)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
During the exposure (6 hours), samples were taken after 1, 3 and 5 hours.
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
The vapour of the test substance was administered for 6 hours a day, 5 days a week for 13 consecutive weeks.
Doses / concentrationsopen allclose all
Dose / conc.:
0.12 mg/L air
Dose / conc.:
0.55 mg/m³ air
Dose / conc.:
2.03 mg/m³ air
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on the results of the acute inhalation study
- Rationale for animal assignment (if not random): such that the group mean bodyweights were approximately equalised
Positive control:
No

Examinations

Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS: Yes
BODY WEIGHT: Yes, weekly
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, weekly
WATER CONSUMPTION: Yes
OPHTHALMOSCOPIC EXAMINATION: Yes, week 13
HAEMATOLOGY: Yes, prior to sacrifice
CLINICAL CHEMISTRY: Yes
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
During exposure, no treatment-related clinical signs were observed at 0, 0.12 and 0.55 ug/L. The highest dose group (2.03 ug/L) showed signs of irritation (some rubbing noses with paws and sneezing) starting from day 5 throughout the study. The highest dose group also showed to be less responsive to outside stimuli starting from day 22 throughout the study.
Mortality:
no mortality observed
Description (incidence):
There were no unscheduled deaths.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
No treatment-related effects observed.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
No treatment-related effects observed.
Food efficiency:
not examined
Description (incidence and severity):
No treatment-related effects observed.
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
No treatment-related effects observed.
Ophthalmological findings:
no effects observed
Description (incidence and severity):
No treatment-related effects observed.
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
For a small number of parameters the differences between control and the highest dose group attained a degree of statistical signifance:
HCt: 4.4%; RBC: 3.7% and MCHC: 2.4% (all 3 parameters in males only)
For the parameter LUC, the differences between control and dose groups 0.12 and 2.03 ug/L attained a degree of statistical signifance in the males:
0.12 ug/L: 47%; 0.55 ug/L: 13.9%; 2.03 ug/L: 36%
As the differences were not dose-related and inconsistent between the sexes, they are not considered as toxicological relevant.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Statistically significant observations:
-In males at the highest dose group, the parameter Ca Total was 3% decreased compared to the control;
-In females at the highest dose group, the parameter Phos was 21.8% decreased compared to the control;
As the differences were small, not dose-related and inconsistent between the sexes, they are not considered as toxicological relevant.
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
No statistically significant observations were done.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No treatment-related findings were seen at the terminal necropsy.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
No effects were seen in females at 0.12 and 0.55 ug/L and in males at 0.12 ug/L. Erosion (2/10)/hyperplasia (10/10) with (3/10) or without (7/10) inflammation (rhinitis) were detected in the transitional epithelium of male rats from the 2.03 ug/L dose group. Hyperplasia of the transitional epithelium was seen at a low incidence in male rats from the 0.55 ug/L dose group (2/10). Hyperplasia was detected in the respiratory epithelium of rats, of both sexes, from the 2.03 ug/L dose group (males: 7/10; females: 2/10), but only in male rats from the 0.55 ug/L dose group (2/10)
Histopathological findings: neoplastic:
not examined

Effect levels

open allclose all
Key result
Dose descriptor:
NOAEC
Remarks:
Systemic
Effect level:
>= 2.03 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse systemic effects seen at highest dose tested
Key result
Dose descriptor:
NOAEC
Remarks:
Local
Effect level:
>= 0.12 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male
Basis for effect level:
histopathology: non-neoplastic

Target system / organ toxicity

Key result
Critical effects observed:
no

Any other information on results incl. tables

Evaluation:

-No systemic effects observed of toxicological relevance

-Local effects observed starting from 0.55 ug/L in males:

Erosion/hyperplasia with or without inflammation (rhinitis) were detected in the transitional epithelium of rats from the 2.03 ug/L dosage group. Hyperplasia of the transitional epithelium was seen at a low incidence in male rats from the 0.55 ug/L dosage groups. Hyperplasia was detected in the respiratory epithelium of rats, of both sexes, from the 2.03 ug/L dosage groups, but only in male rats from the 0.55 ug/L dosage group.

Applicant's summary and conclusion

Conclusions:
In a sub-chronic (90-day) inhalation toxicity study in rats a NOAEC (local effects) of 0.12 mg/m3 was established based on hyperplasia with or without inflammation (rhinitis) in the transitional epithelium in males at 0.55 mg/m3. In the same study, a NOAEC (systemic effects) of ≥2.03 mg/m3 (highest dose tested) was established.