Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17 March 2016 - 07 July 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Qualifier:
according to
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Females nulliparous and non-pregnant: yes
- Age at study initiation: Sighting study 11 weeks; main study 8 weeks
- Weight at study initiation: signthing: 402 g (male), 244 g (female); main study
- Fasting period before study: Not recorded
- Housing: Polycarbonate solid floor cages with stainless steel mesh. 5 animals per cage, separated by sex
- Diet: Unrestricted supply
- Water: Unrestricted supply
- Acclimation period: Animals were acclimated to laboratory conditions for 27 days (sighting study) or 14 days (main study) prior to involvement in the study. Animals were also acclimatised to the test apparatus (restrain procedures) for a short period prior to testing in order to lessen the stress during exposure.

ENVIRONMENTAL CONDITIONS
- Temperature: 19.0 - 25.9°C
- Humidity: 34 - 74% RH
- Air changes: At least 15 air changes per hour
- Photoperiod: 12 hours of continuous artificial light in each 24-hour period (from 6.00 a.m. to 6.00 p.m.)

IN-LIFE DATES: From: 12 May 2016 (receipt of first animals) To: 07 July 2016 (last necropsy occasion)

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
clean air
Mass median aerodynamic diameter (MMAD):
>= 1 - <= 4 µm
Geometric standard deviation (GSD):
>= 1.5 - <= 3
Remark on MMAD/GSD:
Measurements of aerodynamic particle size were performed from the animal’s breathing zone using a cascade impactor.
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
The test item was aerosolized using a dust generator according to Wright located at the top of the exposure chamber. In this device a fixed blade scrapes continuously the surface of the test item compacted by hydraulic press in a rotating reservoir. Dispersion was carried out by a high velocity air flow inside the outlet nozzle.
Dried compressed air was supplied by means of an oil-free compressor and passed through a suitable filter system prior to introduction to the nebuliser.

TEST ATMOSPHERE
- Brief description of analytical method used: Dust concentration was measured gravimetrically. Samples were collected at 10-20 minute intervals during the 4-hour exposure period
- Samples taken from breathing zone: yes

TEST ATMOSPHERE
- MMAD (Mass median aerodynamic diameter): 3.71 µm (sighting study); 3.92 µm (main study)
Analytical verification of test atmosphere concentrations:
no
Duration of exposure:
4 h
Concentrations:
Achieved concentration: 4.23 mg/L sighting study, 4.19 mg/L main study
No. of animals per sex per dose:
5 main study, 1 (sighting study)
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Animals were checked hourly during exposure, 1 hour after exposure and twice daily (early and late in the working day) during the 14-day observation period for morbidity and/or mortality.
- Necropsy of survivors performed: yes
- Other examinations performed:
Individual body weights were recorded prior to treatment on the day of exposure (Day 0) and on Days 1, 3, 7 and 14.

All animals were observed for clinical signs at hourly intervals during exposure whilst the animals were still restrained. Following exposure, clinical observations were performed twice on the day of exposure (following removal from the restrainer and approximately one hour after completion of the exposure) and subsequently once daily for 14 days. Observations included changes in the skin and fur, eyes and mucous membranes and also respiratory, circulatory, autonomic and central nervous system, somato-motor activity and behaviour pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 4.19 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
No mortality occurred during the study.
Clinical signs:
other: Fur staining by the test item occurred anywhere in study animals were considered to be related to the restraint and exposure procedures but not to be toxicologically significant. Laboured respiration (slight) was recorded in both animals of the Group 0.1
Body weight:
Slight body weight losses, noted in any study animals of both Group 0.1 and Group 1 on Day 0-1, were considered to be related to the restraint and exposure procedures.
From Day 3, positive body weight gain was recorded in all rats of the study.
Gross pathology:
A single four hours nose-only exposure of B331 to Crl:WI rats followed by a 14-day observation period produced test item-related gross changes. Red discoloration of the non-collapsed lungs and blue/dark blue discoloration of the lung-associated lymph nodes were noted at the concentration of 4.23 mg/L during sighting exposure. In main study, blue diffuse discoloration of the non-collapsed lungs and blue diffuse discoloration of the tails were recorded at the dose level of 4.19 mg/L. The blue discoloration was related to the administration of the test item and was attributed to its appearance (blue powder)

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Under the experimental conditions of this study, no mortality occurred in Group 1 (main study) when exposed to a test atmosphere concentration of 4.19 mg/L as a maximum feasible concentration for 4 hours. The acute inhalation median lethal concentration (LC50) of B331 in Crl:WI rats was therefore considered to be above 4.19 mg/L.