Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP and appropriate guidelines
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
yes (incl. certificate)
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
SOL-DP (Batch No. 869090084), a white powder. Stored at room temp, dry, closed container.

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Animals' age was 8 weeks old at the begining of the study
Males weight: 286 - 334g
Females weight: 192 - 236g

Housing and Husbandary:
5 of one sex animals per cage
Temp: 19-23 Deg C
RH: 40-70%
Air flow: 15 air changes/hr
12 light/dark cycle
Food: Rat and Mouse (modified) No. 1 Diet SQC Expanded was provided ad libitum throughout the study, except during designated procedures.
Water: Taken from the public supply (Scottish Water, Edinburgh, Midlothian, UK). Available ad libitum, except during designated procedures, throughout the study

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
air
Details on inhalation exposure:
Animals were targeted to be exposed to the maximum concentration (up to a limit of 5 mg/L) which could be reasonably maintained over the exposure period while also maintaining an acceptable particle size distribution: Target mass median aerodynamic diameter (MMAD) in the range of 1-4m with a range of 1.5-3 for the geometric standard deviation (GSD).

The test aerosol was generated using a rotating brush generator (RBG-1000, Palas, Germany). The performance characteristics of the aerosol generation and exposure system to be used were assessed prior to animal exposure. These investigations were undertaken to establish:
- Aerosol concentration assessment (including appropriate collection media)
- Temporal variation in chamber concentration
- Test item utilisation (where appropriate)
- Particle size distribution measurements (within the target range 1-4 μm)

Exposures to test aerosols were performed using a two tier modular snout only stainless steel flow past system (see attached Fig. 1). The exposure chamber was operated to sustain a dynmic air flow sufficient to ensure an evenly distributed exposure aerosol. Chamber air was exhausted via a double filter system with a fibre glass coarse prefilter and a HEPA ultimate particulate filter. All air flow rates (delivered and extract) were monitored visually using pressure gauges and calibrated fow meters. Chamber air flow rates, temperature and relative humidity levels were recorded at regular intervals (targeted at every 30 min) during the exposure period.
For inhalation exposure, the rats were restrained in clear, tapered, polycarbonate tubes with an adjustable back-stop to prevent the animals from turning in the tubes. The animals’ snouts protruded through the anterior end of the restrait tubes which were connected to the exposure chamber aerosol delivery port by way of push-fit through an inhalation port in the chamber wall.

Test Item Utilisation: The amount of test item used to generate the aerosols was measured and recorded (by weight).

Nominal Test Aerosol Concentration: The nominal exposure chamber test aerosol concentration (mg/L) for each group was calculated based on the total amount of test item utilised durig aerosol generation and the total air flow through the exposure chamber.

Gravimetric Aerosol Concentration Sampling: The gravimetric exposure chamber aerosol concentration in the animals’ breathing zone was estimated 11 times during the 4 h exposure period usig a suitable gravimetric method (glass fibre filter). Chamber air was drawn through Whatman GF B 47 mm filters at a target sampling flow rate of approimately 0.5 L/min via a gas meter, flow meter and vacuum pump. The filters were weighed before and after sampling and the aerosol concentration calculated using the weight of material collected and the volume of air sampled. Samples were collected from a reference port representative of the animal exposure ports over 2 minutes; to ensure that the filters were not overloaded. After weighing the filters were retained in amber glass jars and stored in the dark in a refrigerator set to maintain 4°C. Chemical analysis was undertaken on all retained gravimetric filters to determine the aerosol concentration of SOL- DP.

Particle Size Distribution Investigations: Particle size distribution was measured twice during the 4 h exposure period using a Marple Cascade Impactor. The device was positioned on the exposure chamber at the animals’ breathing zone and test aerosol sampled at a target flow rate of approximately 2 L/min for 30 seconds; to ensure that the plates/filters were not overloaded. Before and after sampling, the substrate collection plates and back up filter were weighed to determine the total amount of material collected in each particle size range. After weighing the substrate collection plates and back up filter were retained in amber glass jars and stored in the dark in a refrigerator set to maintain 4°C. Chemical analysis was undertaken to determine the amount of SOL- DP at each collection stage. The particle size distribution of the test aerosols was determined from the plot of the cumulative percentage (by mass) of particles smaller than the cut point of each impactor stage against the logarithm of each stage cut point. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of the test aerosols was derived by Probit analysis using a computerised linear regression programme.

Chemical Analysis: The gravimetric filters and particle size samples were subjected to chemical analysis using a High performance liquid chromatography (HPLC) method supplied by the Sponsor and validated at Charles River under Charles River Study No. 427276 (Method No. 2727).
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Remarks on duration:
one occasion of exposure
Concentrations:
Exposure aerosol concentrations of SOL-DP (mean ± standard deviation) were:
Gravimetric: 5.23 ± 0.772 mg/L
Analytical: 5.17 ± 0.852 mg/L
The target concentration was 5.0 mg/L which is the accepted OECD maximum limit test concentration. The mean achieved aerosol concentration for SOL-DP was within 5% of target by both analytical and gravimetric assessment.
No. of animals per sex per dose:
5 animals per each sex
Control animals:
no
Details on study design:
Animals were exposed to a single dose of the test item aerosol in concentration of 5.23 mg/L (gravimetric) for approximately 4h with a 14 day post exposure observation period. All animals were checked early morning and as late as possible each day for viability whilst on study.

Clinical Observations: Observations included changes in skin, fur, eyes and mucous membranes; effects on respiratory, circulatory, autonomic and central nervous systems; effects on somato motor activity and behaviour patterns; observations of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma; timing of death was recorded if directly observed, otherwise time last seen alive was recorded

Observations During Exposure: The animals were observed, immediately on commencement of exposure and frequently during exposure, for reaction to treatment. The onset, intensity and duration of any signs were recorded as appropriate.

Pre Exposure and Post Exposure Observation Period: The animals were examined for reaction to treatment; before exposure, immediately post completion of exposure, approximately 1-2 hours after exposure and then at least once daily. Animals may have been observed more frequently as appropriate. The interval of the observation period post exposure was not extended as the animals did not show prolonged effects following treatment. The onset, intensity and duration of any signs were recorded as appropriate.

Body Weights: Body weights were recorded prior to commencement of exposure on Day 0 and then on Days 1, 2, 3, 7, 10 and 14 following exposure. The body weights taken on Day 2 were surplus to protocol requirement but have been reported.

Necroscopy: Animals were subjected to a complete necropsy examination, which included evaluation of the carcass and musculoskeletal system; all external surfaces and orifices; cranial cavity and external surfaces of the brain; and thoracic, abdominal, and pelvic cavities with their associated organs and tissues. Necropsy examinations were conducted by a trained technician and consisted of an external and internal examination and recording of
observations for all animals. The respiratory tract was closely examined for signs of gross irritation.

Organ Weights: The lungs were weighed at necropsy for all animals. Terminal body weights were used for calculation of lung:body weight ratio.On completion of the necropsy, the animals’ carcasses were disposed of and no tissues were retained.



Statistics:
Means and standard deviations were calculated for body weight, lung weight and selected
inhalation data. As there was no mortality no formal statistical analysis for LC50 was conducted.

Results and discussion

Effect levelsopen allclose all
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.23 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: Gravimetric
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.17 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
There was no mortality on this study
Clinical signs:
Salivation was noted from 108 minutes into exposure. Immediately post exposure all animals were noted to have unkempt coats and stained fur on the nose, hunched posture was also noted for all females.
The animals were all recorded as having no abnormalities detected by approximately 1 hour post exposure and throughout the remainder of the 14 day post
exposure observation period.
Body weight:
There were some post exposure body weight losses followed by good recovery and all animals had gained body weight by Day 14.
Gross pathology:
One male had two dark foci in the left lung lobe and another male had pinpoint dark foci in all lobes. Two males and one female had enlargement of the mandibular lymph nodes. All other animals were recorded as normal at necropsy.
Other findings:
Lung:body weight ratios for all animals were considered to be close to the expected values noted for this age and strain.

Any other information on results incl. tables

See attached Table 1.

Applicant's summary and conclusion

Interpretation of results:
practically nontoxic
Remarks:
Migrated information
Conclusions:
The mean achieved aerosol concentration for SOL-DP was within 5% of target by both analytical and gravimetric assessment. The mean mass aerodynamic diameter (MMAD) achieved was higher than target but is considered to appropriately represent the particle size of SOL-DP (as supplied) when aerosolised.
Following the 4 hour inhalation exposure to SOL-DP, animals showed no exposure related findings in clinical signs and only a minor effect on bodyweight profile. Limited necropsy findings were observed in the lungs and mandibular lymph nodes of some animals. Lung:Body Weight ratios were considered to be normal. As there was no mortality the LC50 of SOL-DP is considered to be in excess of 5.23 mg/L.
Executive summary:

The objective of this study was to determine the acute inhalation toxicity of SOL-DP in rats following a single 4 hour exposure and a 14 day post exposure observation period.The patrameters evaluated were: clinical observations, body weights, gross necropsy and lung: body weight ratio. Following the 4 hour inhalation exposure to SOL-DP, animals showed no exposure related findings in clinical signs and only a minor effect on bodyweight profile. Limited necropsy findings were observed in the lungs and mandibular lymph nodes of some animals. The Lung:body weight ratios were considered to be normal. As there was no mortality the LC50 of SOL-DP is considered to be in excess of 5.23 mg/L