Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental Phase: 01 February 2018 to 13 March 2018. Report Issued: 30 Aug 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
Deviations:
yes
Remarks:
Two deviations from the study plan were not ocnsidered to have affected the purpose or validity of the study.
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

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Male and female WISTAR RccHan™ : WIST strain rats were supplied by Envigo RMS (UK) Limited, Oxon, UK
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 8 to 12 weeks
- Weight at study initiation: 200 to 350g
- Fasting period before study: No
- Housing: The animals were housed in groups of up to three by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes.
- Diet (e.g. ad libitum): ad libitum (except during exposure)
- Water (e.g. ad libitum): ad libitum (except during exposure)
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25 °C
- Humidity (%): 30 to 70%
- Air changes (per hr): At least 15 per hour
- Photoperiod (hrs dark / hrs light): 12 hours continuous light and 12 hours darkness

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
air
Mass median aerodynamic diameter (MMAD):
3.82 µm
Geometric standard deviation (GSD):
3.29
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Dynamic System for Nose Only Exposure of Rats ((ADG Developments Ltd, Hitchin, Herts, UK)
- Exposure chamber volume: Approximately 30 litres
- Equilibration: The theoretical chamber equilibration time (T99) was 4 minutes. The test atmosphere was generated for 9 minutes prior to animal insertion to ensure test item concentration was being achieved.
- Method of holding animals in test chamber: During the exposure period, each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber ‘O’ ring.
- Source and rate of air: Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters. The air flow rate into the chamber was 40 litres/min.
- System of generating particulates/aerosols:A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator (TOPAS GmbH, Dresden, Germany) located adjacent to the exposure chamber.
- Method of particle size determination: The particle size of the generated atmosphere inside the exposure chamber was determined three times during the exposure period using a Marple Personal Cascade Impactor (Westech IS Ltd, Beds., UK).
- Treatment of exhaust air: The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter (Hanna Instruments Ltd, Beds., UK) located in a vacant port in the animals’ breathing zone of the chamber and recorded every 30 minutes throughout the 4-Hour exposure period.

TEST ATMOSPHERE
- Samples taken from breathing zone: yes

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: Based on preliminary study using two rats.
Analytical verification of test atmosphere concentrations:
no
Duration of exposure:
4 h
Concentrations:
4.94 mg/L
No. of animals per sex per dose:
3 male and 3 female
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: All animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, 1 hour after termination of exposure and subsequently once daily for 14 days. Any evidence of overt toxicity was recorded at each observation.
- Weighing: Individual body weights were recorded on arrival, prior to treatment on the day of exposure (Day 0) and on Days 1, 3, 7 and 14.
- Necropsy of survivors performed: yes

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 4.94 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Mortality:
No mortality was observed on the study.
Clinical signs:
other: Signs of hunched posture and pilo-erection were observed following removal from the chamber. Such signs are commonly seen in animals for short periods on removal from the chamber following 4-hour inhalation studies. Wet fur was noted both during and for
Body weight:
All males showed body weight loss on Day 1 post-exposure and expected gains in body weight during the remainder of the recovery period. With the exception of two animals that showed body weight loss on Day 1 post-exposure and one animal that showed no gain in body weight from Days 1 to 3 post-exposure, all females showed expected gains in body weight during the recovery period
Gross pathology:
At necropsy macroscopic observations were seen in the lungs of all animals and consisted of: pale colour, abnormal red colour, dark patches.

Any other information on results incl. tables

Exposure Chamber Concentration

The test atmosphere was sampled nine times during the exposure period and the actual concentration of the test item calculated. The mean values obtained were as follows:

 Group Number           Atmosphere Concentration
 Mean Achieved (mg/L)  Standard Deviation  Nominal (mg/L
 1  4.94 0.15   37.99

The chamber flow rate was maintained at 40 L/min providing 80 air changes per hour.

Particle Size Distribution

The particle size analysis of the atmosphere drawn from the animals’ breathing zone was as follows:

 Group Number  Mean Achieved Atmosphere Concentration (mg/L)  Mean Mass Median Aerodynamic Diameter µm  Inhalable Fraction (%<4 µm) Geometric Standard Deviation 
 1  4.94  3.82  51.6  3.29

Mortality Data

The mortality data were summarised as follows:

 Group Number      Mean Achieved Atmosphere Concentration (mg/L)     Deaths      
 Male  Female  Total
 1 4.94  0/3  0/3  0/6

There were no deaths on the study.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 4.94 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hour LC50) of the test item in the Wistar strain rat was greater than 4.94 mg/L.
Executive summary:

Introduction

The study was performed to assess the acute inhalation toxicity of the test item. The method used was designed to be compatible with that described in the OECD Guideline for Testing of Chemicals (2009) No. 436 “Acute Inhalation Toxicity – Acute Toxic Class Method” and Method B.52. Acute Inhalation Toxicity – Acute Toxic Class Method, 2014, of Commission Regulation (EC) No. 440/2008.

Methods

A group of six Wistar (RccHan™:WIST) strain rats (three males and three females) was exposed to a dust atmosphere of the test item. The animals were exposed for 4 hours using a nose only exposure system, followed by a 14 day observation period.

Results

The mean achieved atmosphere conctration was as follows:

 Group Number           Atmosphere Concentration
 Mean Achieved (mg/L)  Standard Deviation  Nominal (mg/L
 1  4.94 0.15   37.99

The charateristics of the achieved atmosphere were as follows:

 Group Number  Mean Achieved Atmosphere Concentration (mg/L)  Mean Mass Median Aerodynamic Diameter µm  Inhalable Fraction (%<4 µm) Geometric Standard Deviation 
 1  4.94  3.82  51.6  3.29

The mortality data were summarised as follows:

 Group Number      Mean Achieved Atmosphere Concentration (mg/L)     Deaths      
 Male  Female  Total
 1 4.94  0/3  0/3  0/6

Clinical Observations: Common abnormalities noted during the study included decreased respiratory rate, hunched posture, pilo-erection and wet fur, there were frequent instances of red/brown staining around the snout and/or eyes. All animals appeared normal on Day 1 post-exposure.

 

Body Weight: All males showed body weight loss on Day 1 post-exposure and expected gains in body weight during the remainder of the recovery period. Two females showed body weight loss on Day 1 post-exposure and one female showed no gain in body weight from Days 1 to 3 post-exposure. Females showed expected gains in body weight during the remainder of the recovery period.

Necropsy: The following macroscopic abnormalities were detected at necropsy: Lungs – Pale, abnormally red, dark patches.

Conclusion

None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 4.94 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hour LC50) of the test item in the Wistar strain rat was greater than 4.94 mg/L.