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Description of key information

The acute toxicity of the target substance Cerium doped Lutetium Yttrium Orthosilicate was assessed after exposure via the dermal and inhalation route. In both studies, conducted according to current OECD guidelines (OECD 402, 403), no mortality was observed. Thus, the LC50 after acute inhalation and LD50 after acute dermal exposure can considered to be greater than 5.19 mg/L and 2000 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015-11-03 to 2016-01-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test type:
traditional method
Limit test:
no
Specific details on test material used for the study:
- Name: Lyso
- Batch: C14-193
- Storage: at room temperature
- Composition: 100%
- EC number: 941-731-3
- Physical description: Crystal odorless
- Stability: stable
- Expiration date: not applicable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
The test substance, as received, was a solid. Prior to aerosolization, the test substance was ground in a ball mill for 506 hours. The ground material was removed from the grinding media using a 3/8" polyethylene separator and then ground using a mortar and pestle.
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Received from SAGE® Labs on October 28, 2015
- Number of animals: 10 (5 male/5 female)
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 9-10 weeks
- Weight at study initiation: males 274-326 grams and females 177-230 grams
- Housing: animals were singly housed in suspended stainless steel caging, which conforms to the size recommendations in the most recent Guide for the Care and Use of Laboratory Animals (Natl. Res. Council, 2011). Enrichment (e.g., toy) was placed in each cage. Litter paper was placed beneath the cage and was changed at least three times per week.
- Diet (e.g. ad libitum): Envigo Teklad Global 16% Protein Rodent Diet® #2016. The diet was available ad libitum, except during the exposure.
- Water (e.g. ad libitum): Filtered tap water was supplied ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23
- Relative Humidity (%): 49-61
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12 / 12
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
clean air
Mass median aerodynamic diameter (MMAD):
2.23 µm
Geometric standard deviation (GSD):
2.12
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber: ADG Developments LTD (Nose-only Inhalation Chamber)
- Exposure chamber volume: 28 liter
- Method of holding animals in test chamber: Animals were individually housed in polycarbonate holding tubes which seal to the chamber with an "O" ring during exposure. The base unit terminates the chamber with a 0.5-inch diameter tube for discharged air.
- Air supply: Filtered generator air was supplied to the spray atomization nozzle by an air compressor (Powerex Air Compressor), and measured with a Mass Flow Controller (Omega Mass Flow Controller). Additional filtered mixing air from the same air compressor, measured with a Mass Flow Controller, was introduced into the chamber to help uniformly distribute the test atmosphere by creating a vortex at the chamber inlet. Chamber airflow (Aalborg Mass Flow Controller) was monitored throughout the exposure period and recorded periodically. The exposure was conducted under slight negative pressure.
- System of generating particulates/aerosols: The test substance was aerosolized using a Jet-Mill. The test substance was delivered from the hopper using a variable speed motor and a 3/8- nch, closed pitch inch helix into the Jet-Mill. Compressed generator and mixing air were both supplied. The aerosolized dust was then fed directly into the chamber through the dust outlet assembly.

- Method of particle size determination: An eight-stage 1 ACFM Andersen Ambient Particle Sizing Sampler was used to assess the particle size distribution of the test atmosphere. Samples were withdrawn from the breathing zone of the animals at two intervals. The filter paper collection stages were weighed before and after sampling to determine the mass collected upon each stage. The mass median aerodynamic
diameter (MMAD) and geometric standard deviation (GSD) were calculated using two-cycle logarithmic probit axes.

- Temperature, humidity, pressure in air chamber: The temperature and relative humidity within the exposure chamber as well as the room were monitored continuously during exposure, and were measured with a temperature-humidity monitor. Temperature and relative humidity values were recorded every 15 minutes for the first hour of exposure and approximately every 15 or 30 minutes thereafter.

TEST ATMOSPHERE
- Brief description of analytical method used: Gravimetric samples were withdrawn at 6 intervals from the breathing zone of the animals. Samples were collected using 37 mm glass fiber filters (Whatman™ GF/B) in a filter holder attached by 1/4 inch Tygon® tubing to a vacuum pump. Filter papers were weighed before and after collection to determine the mass collected. This value was divided by the total volume of air sampled to determine the chamber concentration. Sample airflows were measured using a Mass Flow Controller.
- Samples taken from breathing zone: yes
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
Chamber concentration: 5.19 mg/L
Nominal chamber concentration: 19.22 mg/L
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: All animals were observed for mortality during the exposure period. The animals were examined for signs of gross toxicity and behavioural changes upon removal from the exposure tube and at least once daily thereafter for 14 days.
- Frequency of weighing: Individual body weights of the animals were recorded prior to test substance exposure and gain on days 1, 3, 7 and 14.
- Necropsy of survivors performed: Yes. all rats were euthanized via CO2 inhalaion on day 14. Gross necropsies were performed on all animals. Tissues and organs of the thoracic and abdominal cavities were examined.

Statistics:
Statistical analysis was limited to the calculation of the mean and standard deviation.
Preliminary study:
pre-test trial to establish the desired generation procedures
Key result
Sex:
female
Dose descriptor:
LC50
Effect level:
> 5.19 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Mortality:
There were no unscheduled deaths.
Clinical signs:
other: Following exposure, all rats exhibited irregular respiration. However, all animals recovered by Day 1 and appeared active and healthy for the remainder of the 14-day observation period.
Body weight:
All animals gained body weight during the study.
Gross pathology:
No gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.

Particle Size and Test item concentrations:

The chamber and nominal chamber concentrations were 5.19 mg/L and 19.22 mg/L, respectively. The average mass median areodynamic diameter was estimated to be 2.23 µm based on graphic analysis of the particle size distribution as measured with a 1 ACFM Anderson Ambient Particle Sizing Sampler with an average geometric standard deviation of 2.12.

Interpretation of results:
GHS criteria not met
Conclusions:
Based on the results from an acute inhalation toxicity study, the LC50 can be considered to be greater than 5.19 mg/L.
Executive summary:

In an acute inhalation toxicity study conducted according to OECD 403, groups of young adult Sprague-Dawley rats (5 males/5 females) were exposed nose only to 5.19 mg/L Cerium doped Lutetium Yttrium Orthosilicate (100%) in clean air for 4 hours. Animals then were observed for 14 days. No mortality occurred. Following exposure, all rats exhibited irregular respiration. However, all animals recovered by Day 1 and appeared active and healthy for the remainder of the 14-day observation period. No effects were observed during gross pathology and on the body weight development. Based on the results, the LC50 can be considered to be greater than 5.19 mg/L.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
GLP guideline study

Acute toxicity: via dermal route

Link to relevant study records
Reference
Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-04-11 to 2016-06-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Version / remarks:
adopted 24 Feb1987
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test type:
standard acute method
Limit test:
yes
Specific details on test material used for the study:
- Name: Lyso
- Chemical Name: Cerium doped Lutetium Yttrium Orthosilicate
- EC No.: 941-731-3
- Batch No.: C14-193
- Expiry date: not applicable
- Physical state: solid (crystal)
- Colour: Colourless
- Purity: theoretical composition based on starting materials: 81.25% Lu2O3, 13.51% SiO2, 5.2% Y2O3 and 0.039% CeO2
- Molecular weight: 440.7 g/mol
- Stability in water at room temperature: stable
- Storage Conditions: at room temperature

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
The test item was used as delivered by the sponsor. In order to ensure good skin contact, it was moistened with the vehicle.

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Females (if applicable) nulliparous and non-pregnant: no
- Age at study initiation: males: 9-10 weeks old; females: 12-13 weeks old
- Weight at study initiation: males: 227-258 g; females: 201-216 g
- Fasting period before study: no
- Housing: The animals were kept individually in IVC cages, type III H, polysulphone cages on Altromin saw fibre bedding
- Diet (e.g. ad libitum): Altromin 1324 maintenance diet, ad libitum
- Water (e.g. ad libitum): ad libitum: tap water, sulphur acidified to a pH value of approximately 2.8 (drinking water, municipal residue control, microbiological controls at regular intervals)
- Acclimation period: at least five days under laboratory conditions

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 10
- Air changes (per hr): 10 x
- Photoperiod (hrs dark / hrs light): 12 / 12
Type of coverage:
semiocclusive
Vehicle:
water
Details on dermal exposure:
TEST SITE
- Area of exposure: dorsal area of the trunk
- % coverage: approx. 10 of the body surface
- Type of wrap if used: gauze-dressing and non-irritating tape, both fixes with an additional dressing in a suitable manner.

REMOVAL OF TEST SUBSTANCE
- At the end of the exposure period the residual test item was removed using water.

TEST MATERIAL
- Amount(s) applied: single dose of 2000 mg/kg body weight

VEHICLE
- Aqua ad injectiabilia (AlleMan Pharma, lot no. 505651, expiry date: 30/04/2018). This vehicle was chosen due to its non-irritating characteristics.
Duration of exposure:
24 hours
Doses:
2000 mg/kg bw
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: A careful clinical examination was made several times on the day of dosing (at least once during the first 30 minutes and with special attention given during the first 4 hours post-dose). Thereafter, the animals were observed for clinical signs once daily until the end of the observation period.
- Frequency of weighing: The animals were weighed on day 1 (prior to the application) and on days 8 and 15
- Necropsy of survivors performed: Yes, at the end of the observation period the animals were sacrificed with an overdosage of pentobarbital injected intraperitoneally at a dosage of 250-400 mg/kg bw. All animals were subjected to gross necropsy and examined macroscopically for gross pathological changes.
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Remarks on result:
no indication of skin irritation up to the relevant limit dose level
Mortality:
No mortality has occurred during and after the treatment of the test animals with Cerium doped Lutetium Yttrium Orthosilicate.
Clinical signs:
No specific clinical signs of toxicity were recorded.
Body weight:
A slight weight loss was recorded for 4 out of 5 female animals during the first week and all but one female animals showed weight gain during the second week (see table 1 in box "Any other information on results incl. tables). The effects on weight development might be secondary to the dressing, and toxicological relevance of this finding cannot clearly be concluded. The male animals showed weight gain during the first and the second week of the observation.
Gross pathology:
With the exception of acute injection of blood vessels in the abdominal region, which is due to the euthanasia injection, no specific gross pathological changes were recorded for any animal.

Table 1: Absolute Body Weights in g and Body Weight Gain in %

Test Group Animal No. Dose (mg/kg bw) Body weight (g) on Day BW gain in Comparison to Day 1 (%)
Day 1 Day 8 Day 15 Day 15
Males 21 2000 258 279 304 18
22 238 267 300 26
23 235 261 284 21
24 227 243 263 16
25 242 263 282 17
Females 26 2000 201 200 205 2
27 206 205 207 0
28 208 204 211 1
29 216 219 220 2
30 212 210 206 -3
Interpretation of results:
GHS criteria not met
Conclusions:
Under the conditions of the present study, a single dermal application of the test item to rats at the limit dose of 2000 mg/kg body weight was associated with no mortality and neither signs of toxicity nor signs of skin irritation. Thus, the LD50 is considered to exceed 2000 mg/kg bw.
Executive summary:

In an acute dermal toxicity study conducted according to OECD 402, groups of young adult Wistar rats (5 male/5 female) were dermally exposed to Cerium doped Lutetium Yttrium Orthosilicate in water for 4 hours at dose of 2000 mg/kg bw. Animals then were observed for 14 days. No mortality occurred during the test period. Further, there were no treatment related clinical signs and necropsy findings. The slight weight loss might be secondary to the dressing and toxicological relevance of this finding cannot clearly be concluded. Based on the results, the LD50 can be considered to exceed 2000 mg/kg bw.

 

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
GLP guideline study

Additional information

The acute toxicity of the target substance Cerium doped Lutetium Yttrium Orthosilicate was assessed after exposure via the dermal and inhalation route. In both studies, conducted according to current OECD guidelines (OECD 402, 403), no mortality was observed. Thus, the LC50 after acute inhalation and the LD50 after acute dermal exposure can considered to be greater than 5.19 mg/L and 2000 mg/kg bw.

Justification for classification or non-classification

Based on data from suitable acute toxicity studies conducted in accordance with OECD 402 (dermal) and OECD 403 (inhalation), no classifation for acute toxicity is warranted.