Lutetium oxide

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-11-28 to 2017-09-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: The OECD Series on Testing and Assessment No.23: Guidance document on aquatic toxicity testing of difficult substances and mixtures

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Lutetium oxide

EC Number:

234-764-3

EC Name:

Lutetium oxide

Cas Number:

12032-20-1

Molecular formula:

Lu2O3

IUPAC Name:

Lutetium oxide

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): dilutetium trioxide
- Physical state/Appearance: white solid
- Further information confidential.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling method: All samples were taken in triplicate. Samples were taken from the control and each test group from the bulk test preparation at 0 and 72 hours. At 24 and 96 hours, samples were collected from the old media of the control and each test group. Raw samples (i.e. unfiltered) were stored frozen prior to quantitative analysis. Only samples of the No Observed Effect Concentration were analysed along with the control.
- Sample storage conditions before analysis: All samples were stored frozen prior to analysis.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Due to the insolubility of the test item in test water, a saturated solution method of preparation was considered most appropriate.
- Stirring experiment: A nominal amount of test item (500 mg) was dispersed in 5 L of test water with the aid of vigorous magnetic stirring for 96 hours. After 3, 24 and 96 hours, the pH of the media was checked and a sample taken for chemical analysis after filtration through a 0.2 μm Gelman Acrocap filter (initial 100 mL discarded).
- The results of the stirring experiment indicated that a 3-hour stirring period was appropriate.
- The nominal test concentrations in the combined range finder-limit test were 1.0, 10 and 100% v/v saturated solutions. The 100% v/v saturated solution was prepared in a similar way as described for the stirring experiment (3000 mg test item in 30 L test water, 3 h stirring, 0.2-µm filtered using a Sartorius Sartopore filter). The 1.0 and 10% v/v saturated solutions were then prepared through serial dilution of the 100% saturated solution.

Test organisms

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Source: Brow Well Fisheries Limited, Hebden, near Skipton, Yorkshire, UK
- Length at the end of the combined range finder-limit test (length definition, mean, range and SD): mean: 4.8 cm; SD: 0.41
- Weight at study initiation (mean and range, SD): mean: 0.85 g; SD: 0.23
- Feeding during test: no

ACCLIMATION
- Acclimation period: 8 days before the test
- Acclimation conditions (same as test or not): yes, same as test
- Type and amount of food: commercial trout pellets (discontinued 24 h before start of the test)
- Feeding frequency: daily
- Health during acclimation (any mortality observed): no mortality in the seven days prior to the start of the test

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Test conditions

Hardness:

140 mg CaCO3/L

Test temperature:

t=0h (fresh media): 14-15°C
t=24h (old media): 14°C
t=24h (fresh media): 14-15°C
t=48h (old media): 14-15°C
t=48h (fresh media): 13-15°C
t=72h (old media): 14°C
t=72h (fresh media): 14-15°C
t=96h (old media): 14°C

pH:

t=0h (fresh media): 7.7-7.8
t=24h (old media): 7.9-8.1
t=24h (fresh media): 7.9-8.0
t=48h (old media): 7.3-7.6
t=48h (fresh media): 7.3-7.5
t=72h (old media): 7.5-7.6
t=72h (fresh media): 7.4-7.6
t=96h (old media): 7.8-8.0

Dissolved oxygen:

t=0h (fresh media): 10.6-11.7
t=24h (old media): 9.6-10.1
t=24h (fresh media): 10.4-11.3
t=48h (old media): 10.1-10.5
t=48h (fresh media): 11.0-12.2
t=72h (old media): 9.8-10.1
t=72h (fresh media): 10.8-11.5
t=96h (old media): 9.7-10.0

Salinity:

not relevant

Nominal and measured concentrations:

Combined range finder-limit test:
Nominal concentrations: Control, 1.0, 10 and 100% of SS (only control and 100% SS were analysed)
Measured concentrations at t=0h (fresh): < LOQ, 0.00348 mg/L Lu; < LOQ, 0.00395 mg/L test item
Measured concentrations at t=24h (old): < LOQ, 0.00339 mg/L Lu; < LOQ, 0.00385 mg/L test item
Measured concentrations at t=72h (fresh): < LOQ, 0.00189 mg/L Lu; < LOQ, 0.00215 mg/L test item
Measured concentrations at t=96h (old): < LOQ, 0.00198 mg/L Lu; < LOQ, 0.00225 mg/L test item

Details on test conditions:

TEST SYSTEM
- Test vessel: aquaria
- Material, size, headspace, fill volume: 25-30-L glass aquaria, filled with 20 L test solution, covered to reduce evaporation
- Aeration: yes, via narrow bore glass tubes
- No. of organisms per vessel: 7 (control and 100% v/v SS); 3 (1.0 and 10% v/v SS)
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.30 g fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Laboratory tap water, dechlorinated by passage through an activated carbon filter (Purite Series 500) and partly softened (Elga Nimbus 1248D Duplex Water Softener) giving water with a total hardness of approximately 140 mg/L as CaCO3.
- Culture medium different from test medium: no
- Intervals of water quality measurement: water temperature, dissolved oxygen and pH were recorded daily in fresh and old test media

OTHER TEST CONDITIONS
- Photoperiod: 16 h light and 8 h dark, with 20-min transition periods to mimic dusk and dawn transition periods

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Fish were considered to be dead when no reaction was observed after touching the caudal peduncle and visible breathing movements were absent. Mortality checks were performed after 1, 3, 6, 24, 48, 72 and 96 h.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10 (combined range finder-limit test)
- Range finding study: yes, the study was a combined range finder-limit test as no (adverse) effects were expected
- Test concentrations: 1.0, 10 and 100% of a saturated solution with nominal loading rate of 100 mg/L (test item)
- Results used to determine the conditions for the definitive study: no (the test was a combined range finder-limit test)

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 other: % v/v of a saturated solution with nominal loading rate of 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

No mortality was observed in any of the test solutions.
The 96-h LC50 was therefore > 100% v/v of a saturated solution with nominal loading rate 100 mg/L.
The mean measured dissolved Lu concentration in the 100% v/v saturated solution was 0.0027 mg Lu/L (i.e. 0.0031 mg Lu2O3)/L). Note that this dissolved concentration may have been slightly overestimated because the laboratory acidified the samples before filtration, consequently the measured Lu concentration might include some redissolved precipitated Lu.
There were no sub-lethal effects of exposure observed in the test.

Reported statistics and error estimates:

No statistics applied.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of lutetium oxide to juvenile rainbow trout was investigated in accordance with OECD guideline 203 and GLP. A semi-static combined range finder-limit test was performed, in which no adverse effects were observed up to and including the highest concentration tested (i.e., a 100% v/v saturated solution with nominal loading rate 100 mg/L). The 96-h LC50 was therefore > 100% v/v of a saturated solution with nominal loading rate 100 mg/L. The mean measured dissolved Lu concentration in this saturated solution was 0.0027 mg Lu/L (corresponding to 0.0031 mg Lu2O3/L). Note that this concentration may have been overestimated because acidification was by accident done before filtration, consequently, the measurement may include some redissolved precipitated Lu.