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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
5 June 2017 - 21 December 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- A sample of each test concentration was taken for chemical analysis from the freshly prepared media at 0 and 24 hours and from the old or expired media (pooled replicates) at 24 and 48 hours in order to determine the stability of the test item under test conditions. These samples were analysed on the day of receipt.
- A further two sets of samples were taken at 0, 24 and 48 hours and stored frozen should further analysis be required.
- Test samples were filtered through 0.2 μm cellulose acetate filters (discarding the first 10 mL).
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
A preliminary experiment was performed to determine the optimal stirring period for test solution preparation. A nominal amount of test item (780 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 was checked and adjusted to 6.0 ± 0.5, if necessary. Following each pH check a sample was taken for chemical analysis after any undissolved test item was removed by filtration through a 0.2 μm Gelman Acrocap filter (first approximate 100 mL discarded in order to pre-condition the filter). Based on the results of this experiment, the optimal stirring period was concluded to be 3 hours.
In the range finder as well as the definite test, the same test solution preparation method as described for the preliminary experiment was used, except that stirring was done only for 3 hours. After that, serial dilutions were made to obtain the required test solution concentrations for both experiments.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Scientific name: Daphnia magna
- Common name: Water flea
- Source: in-house laboratory culture
- Age at study initiation (mean and range, SD): juveniles < 24 hours old
- Feeding during test: no

ACCLIMATION
- Method of breeding: clone has been bred at Envigo Laboratories in Elendt M7 medium in a temperature controlled room maintaining water temperature at 18-22°C
- Lighting cycle: 16 h light + 8 h dark, 20-min dawn and dusk transition periods
- Type and amount of food: a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension
- Feeding frequency: daily
- Gravid adults were isolated the day before initiation of the test in order to guarantee that the young daphnids they produced overnight were less than 24 hours old for use in the test.
- Diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg CaCO3/L
Test temperature:
21-22°C
pH:
New test media:
0 h = 5.9-6.2
24 h = 6.0-6.2
Old test media:
24 h = 6.5-7.0
48 h = 6.4-6.9
Dissolved oxygen:
New test media: 5.1-7.8 mg/L
Old test media: 8.4-8.7 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
Nominal concentrations: Control + 1.0, 3.2, 10, 32 and 100 mg YCl3/L
Measured concentrations (mg/L) at t=0h (fresh): < LOQ, 0.307, 1.25, 4.27, 13.7, 44.4 mg Y/L
Measured concentrations (mg/L) at t=24h (old): < LOQ, < LOQ, 0.931, 3.67, 12.1, 40.5 mg Y/L
Measured concentrations (mg/L) at t=24h (fresh): < LOQ, 0.733 / 0.431*, 1.39, 1.44 / 4.98*, 14.4 mg Y/L
Measured concentrations (mg/L) at t=48h (old): < LOQ, < LOQ, 1.04, 4.28, 13.7 mg Y/L
* Duplicate sample analysed because result was inconsistent with 0-h fresh samples, original results considered to be anomalous, results from duplicate samples taken forward for calculation of geometric mean measured test concentrations

Geometric Mean Measured Test Concentration as yttrium (mg/L) = 0.094, 1.1, 4.3, 14 and 42
Geometric Mean Measured Test Concentration as yttrium trichloride (mg/L) = 0.13, 2.5, 9.4, 29 and 93
Geometric Mean Measured Test Concentration as yttrium trichloride hexahydrate (mg/L) = 0.34, 4.0, 15, 47 and 148

Given the decline in measured test concentrations over time it was considered justifiable to base the results on the geometric mean measured test concentrations in order to give a "worst case" analysis of the data.
Details on test conditions:
TEST SYSTEM
- Test vessel: 150-mL glass beakers filled with 100 mL of test medium
- Type (delete if not applicable): open, covered to reduce evaporation
- Aeration: The test water was aerated prior to the start of the study. No aeration during the study.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water (ISO medium), 294 mg/L CaCl2.2H2O, 123 mg/L MgSO4.7H2O, 65 mg/L NaHCO3, 5.8 mg/L KCl.
- Culture medium different from test medium: yes (culture medium Elendt M7)
- Intervals of water quality measurement: water temperature, pH and dissolved oxygen content were measured at the beginning of the test in the fresh media, after 24 hours in the old and fresh media and at the end of the test in the old media

OTHER TEST CONDITIONS
- Adjustment of pH: The reconstituted water had a pH of 7.8 ± 0.2 (adjusted (if necessary) with NaOH or HCl). Prior to use, the pH of the media was adjusted to pH 6.0 ± 0.5.
- Photoperiod: A 16-hour light to 8-hour dark cycle with a 20-minute transition period
- Light intensity: Light intensity during the light period was approximately between 200 and 1200 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): immobilisation, daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2 (spacing factor for serial dilutions)
- Range finding study: yes
- Test concentrations in range finding study: Control + 0.10, 1.0, 10 and 100 mg YCl3/L
- Results used to determine the conditions for the definitive study: yes, 8/10 and 10/10 daphnids immobilised after 48 h at 10 and 100 mg YCl3/L, respectively
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
2.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element (dissolved fraction)
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 1.8-3.4 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
5.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr. (dissolved fraction)
Remarks:
yttrium trichloride anhydrous
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 4.0-7.5 mg/L
Details on results:
Other effect concentrations:
24-h EC50 = 9.7 mg Y/L (21 mg YCl3/L)
48-h NOEC = 0.094 mg Y/L (0.13 mg YCl3/L)
48-h LOEC = 1.1 mg Y/L (2.5 mg YCl3/L)

Sub-lethal effects (reduced mobility, covered in debris):
- After 24 h in the 32 mg YCl3/L test solution, 1 (out of 5) daphnids had reduced mobility in replicate 4, whereas all other daphnids in this replicate and in the other replicates at this test concentration were immobilised.
- After 48 h in the 3.2 mg YCl3/L test solution, 1 (out of 5) daphnids was covered in debris in replicate 4, whereas 1 daphnid in this replicate was immobilised and the other 3 were normal in appearance.
- After 48 h in the 10 mg YCl3/L test solution, 1 (out of 5) daphnids had reduced mobility in both replicate 2 and 3, whereas all other daphnids in both replicates were immobilised.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- 24-h EC50: 0.83 mg/L (95% CI: 0.70-0.98 mg/L)
- 48-h EC50: 0.64 mg/L (95% CI not possible to determine)
- The results from the positive control with potassium dichromate were within the normal range for this reference item.
Reported statistics and error estimates:
The EC50 values and associated confidence limits at 24 and 48 h and the slope of the response curve and its standard error were calculated by Probit analysis using Linear Maximum-Likelihood regression. The LOEC and NOEC at 24 and 48 h were calculated using the Step-Down Cochran Armitage Test. All results were calculated using the ToxRat Professional computer software package (TOXRAT).
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of yttrium trichloride to Daphnia magna was investigated in accordance with OECD guideline 202 and conform GLP requirements. The 48-h EC50 based on geometric mean measured dissolved Y concentrations was determined to be 2.5 mg/L (corresponding to 5.5 mg/L of anhydrous yttrium trichloride).
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
20 december 1994 - 19 September 1995
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
Because dissolved Y analysis indicates that Y precipitates and disappears from the test solution, the study cannot be considered reliable. The absence of toxicity was probably due to a lack of exposure of the test organisms to dissolved Y as a result of precipitation of the test item out of the solution.
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Test solution samples were analysed at 0 and 24 hours (separate bottles without test organisms kept under similar conditions).
Vehicle:
no
Details on test solutions:
Test solutions were prepared by adding test substance to the medium to obtain a final concentration of 100 mg/L.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain: Strauss 1820 (IRCHA)
- Source: laboratory breed, laboratory of Ecotoxicology of CRIT/D
- Age at study initiation (mean and range, SD): not reported
- Size at study initiation (length definition, mean, range and SD): between 560 µm and 800 µm
- Feeding during test: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
Not reported.
Test temperature:
19.5-20°C
pH:
8.1-8.4
Dissolved oxygen:
95-97%
Salinity:
Not applicable.
Nominal and measured concentrations:
Nominal concentration: 100 mg/L
Measured concentration (in test solutions without test animals, kept under similar conditions): 23 mg Y/L at t=0h, <= 1 mg Y/L after 24 h. Test substance was clearly present in the precipitate at the bottom of the flasks (qualitative analysis).
Details on test conditions:
TEST SYSTEM
- Test vessel: 100-mL Pyrex beakers, 40 mL fill-volume
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: bidistilled water
- Composition of test medium:
* 0.297 g/l CaCl2.2H2O
* 0.167 g/l MgCl2.6H2O
* 0.200 g/l NaHCO3
* 0.026 g/l K2SO4
- Conductivity: 0.90 µS/cm (dilution water)
- Ca:Mg ratio: 2.5:1

OTHER TEST CONDITIONS
- Adjustment of pH: not reported
- Photoperiod: continuous darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mobility, daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test
- Range finding study: no
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- EC50(24h) > 100 mg/L
- After 24 hours a decrease of dissolved Y to <= 1 mg Y/L (detection limit) was observed. The initial dissolved Y concentration was 23 mg Y/L. Y was present in the precipitate at the bottom of the vessels.
Results with reference substance (positive control):
- EC50(24h) = 1.6 mg/L
Reported statistics and error estimates:
none
Validity criteria fulfilled:
yes
Conclusions:
This study reported an EC50 > 100 mg/L for Daphnia magna after a 48-h exposure to yttrium trinitrate in a limit test. The results cannot be considered reliable as dissolved yttrium analysis indicated that yttrium precipitated and disappeared from solution, with concentrations <= 1 mg Y/L (i.e. the detection limit) after 24 h of exposure. Consequently, there might have been a lack of exposure to dissolved yttrium, explaining the absence of effects.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
The study was performed according to a non-standard test setup (use of acidified metal AAS standards for Y addition to test solutions, non-simultaneous testing of different Y concentrations, no true replicates, dissolved Y concentrations not measured in all tests, feeding during the test, non-standard test duration, etc.).
Qualifier:
no guideline followed
Principles of method if other than guideline:
One-week toxicity tests were conducted with Hyalella that were fed during the test. This is sort of a hybrid test between a 48-h acute test without food and a 10-week chronic test with food, but should nevertheless be considered as an acute test. Instead of performing tests with a control and a concentration series of the metal under consideration, many metals were simultaneously tested at a single concentration, and depending on the results, the concentration of each metal was either increased (if non-toxic) or decreased (if toxic) by a factor of 10 in the next experiment. Once the toxic range was bracketed, intermediate concentrations (i.e. 3.15-fold higher or lower) were tested. This procedure was repeated until each metal was tested at least twice at a concentration resulting in < 25% survival and a concentration resulting in > 75% survival, as well as all intermediate concentrations relative to controls. Two sets of experiments were run, one in tap water, and another in soft water.
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
- No samples for metal analyses were collected from experiments conducted in tap water.
- Water samples from soft water experiments were taken at the end of the 7-d exposure period.
- All samples for metal analyses were filtered (0.45 µm) using disposable filter cartridges (Acrodisks) attached to polypropylene syringes and were acidified with high purity HCl and stored in 14-mL polypropylene disposable round bottom tubes with snap caps.
- Water samples were preserved in the same acid and concentration that was supplied with the metal standards (for Y: HCl at 2% v/v).
Vehicle:
no
Details on test solutions:
- An atomic absorption standard containing 1 g Y/L was used for preparation of the test solutions.
- A solution of 19 parts 1 M NaHCO3 and 1 part 1 M KOH (similar to the Na:K ratio of the dilution water) was used to neutralise excess acid in the metal standards and control pH. Sufficient buffer to control pH, if required, was added first, followed by addition of the metal standard. This resulted in better survival of acid controls than when the metal solution was added first.
- After addition of neutralising buffer and metal, the water was aerated gently overnight to allow equilibration of pH and CO2, and any rapid changes in metal speciation that might occur.
- Neutralisation was required primarily for tests in soft water.
- Acid controls consisted of acid and neutralising solution additions equal to the amount added in the tests with acidified metal standards.
- Each experiment consisted of 3 controls, 3 acid controls (if needed) and one replicate of each metal to be tested in that experiment.
Test organisms (species):
other aquatic crustacea: Hyalella azteca
Details on test organisms:
- Scientific name: Hyalella azteca
- Source: Test organisms orignated from Valens Conservation Area (ON, Canada), in 1985.
- Culturing: Test organisms were cultured as described in Borgmann et al. (1989).
- Culture medium: Dechlorinated Burlington City tap water (Lake Ontario, Canada) with water hardness 124 mg CaCO3/L, carbonate alkalinity 84 mg CaCO3/L, 35 mg Ca/L, 8.7 mg Mg/L, 13 mg Na/L, 1.6 mg K/L, 32 mg SO4/L, 25 mg Cl/L, 1.1 mg DOC/L.
- Culture conditions: Same as during the toxicity tests.
- Culture water was renewed and young separated from adults weekly.
- The initial age of the test animals was 1-11 d at the start of the tests.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
1 wk
Remarks on exposure duration:
A one-week toxicity test is used because 48-h tests without food are difficult to conduct with young Hyalella, which swim and stick to the surface if not fed, and because it fits well within a 7-d work week. The test is to be considered as an acute test.
Hardness:
Soft water: 18 mg/L
Tap water: 124 mg/L
Test temperature:
24-25°C
pH:
Soft water: 7.39 (6.44-8.52) in the test solutions and 7.37 (6.79-7.84) in the controls.
Tap water: 8.21 (7.23-8.83) in the test solutions and 8.39 (8.09-8.84) in the controls.
The above values are mean values obtained from the testing of several metal elements (including yttrium).
Dissolved oxygen:
7-10 mg/L
Conductivity:
Soft water: 66 (35-235) µS/cm2 in the test solutions and 46 (34-70) µS/cm2 in the controls.
Tap water: 345 (288-958) µS/cm2 in the test solutions and 311 (288-345) µS/cm2 in the controls.
The above values are mean values obtained from the testing of several metal elements (including yttrium).
Nominal and measured concentrations:
Metal-specific test concentrations were not reported.
A range was given for the nominal concentrations tested for all metals in the publication. This range was from 1000 μg/L (soft water) to 3150 μg/L (tap water).
Details on test conditions:
TEST SYSTEM
- Test vessel: 500-mL polyethylene cups (snap-top specimen containers)
- Type (delete if not applicable): open
- Fill volume: 400 mL
- Aeration: not during the test
- Substrate for the test organisms: A piece of 2.5x2.5-cm cotton gauze was added to each container before addition of test organisms.
- Feeding: 2.5 mg TetraMin fish food flakes were added to each container before addition of test organisms. An additional 2.5 mg of food was provided midweek.
- No. of organisms per vessel: 15
- No. of vessels per concentration (replicates): 1 (in the end however, each metal was required to have been tested at least twice at a concentration resulting in < 25% survival and a concentration resulting in > 75% survival, as well as all intermediate concentrations relative to controls).
- No. of vessels per control (replicates): 3 (3 controls and 3 acid controls were included in each experiment)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Two dilution waters were used: tap water (Lake Ontario, see Hyalella culture conditions for composition) and soft water consisting of 10% tap water and 90% Milli-Q deionised water (water hardness 18 mg CaCO3/L, carbonate alkalinity 14 mg CaCO3/L, 5.6 mg Ca/L, 0.90 mg Mg/L, 1.4 mg Na/L, 0.15 mg K/L, 3.4 mg SO4/L, 2.5 mg Cl/L, 0.28 mg DOC/L). Soft water tests were designed to simulate a reasonable worst-case condition for Canada (e.g., dilute waters of the Canadian Shield with a low DOC content), while still falling within the range tolerated by Hyalella.
- Culture medium different from test medium: tap water (Hyalella was not cultured in the soft test water though)
- Intervals of water quality measurement: After overnight equilibration of test solutions, initial pH and conductivity were measured. After 7 days, pH, conductivity, and ammonia and oxygen concentrations were measured.
- DOC measured in randomly selected samples of the test containers at the end of the 7-d exposure period averaged 1.4 mg/L.
- Based on ammonia measurements, it was concluded that ammonia could not have contributed noticeably to toxicity.

OTHER TEST CONDITIONS
- Adjustment of pH: neutralisation was done where needed to neutralise the acid present in the metal AAS standards but no strict pH control was done
- Photoperiod: 16L:8D

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality, after 7 days
Reference substance (positive control):
not specified
Duration:
1 wk
Dose descriptor:
LC50
Effect conc.:
183 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
mortality
Remarks on result:
other: Soft water, 95% CL = 136-245 µg Y/L
Duration:
1 wk
Dose descriptor:
LC50
Effect conc.:
66 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
element (dissolved fraction)
Remarks:
dissolved Y at the end of testing
Basis for effect:
mortality
Remarks on result:
other: Soft water, 95% CL = 44-101 µg Y/L
Duration:
1 wk
Dose descriptor:
LC50
Effect conc.:
549 µg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
mortality
Remarks on result:
other: Tap water, 95% CL = 394-764 µg Y/L
Details on results:
Survival in acid controls for metal stocks supplied in 2% HCl (such as the case for Y) was not reported but assumed to be higher than that in acid controls for metal stocks supplied in 10% HCl, which was reported to be 82%. Control survival was certainly >= 80% since only data from experiments with >= 80% control survival were used.

No analytical monitoring was performed for the assay in tap water, explaining why there is no result based on measured concentration for this medium. Anyway, the toxicity is higher in soft water and thus this medium represents a worst-case scenario as compared to tap water.
Reported statistics and error estimates:
The concentration resulting in 50% mortality (LC50) and 95% confidence limits were computed using the Trimmed Spearman-Karber method. In cases where the confidence limits could not be computed reliably (e.g., if there were no partial effect concentrations), the concentrations tested on either side of the LC50 were listed.
Validity criteria fulfilled:
yes
Remarks:
However, no standard test setup was followed.
Conclusions:
In this study, the toxicity of various metals, including Y, was studied in 1-wk Hyalella azteca tests following a non-standard test setup in two different test media. In tap water, with a water hardness of 124 mg CaCO3/L, the 1-wk LC50 was reported to be 549 µg Y/L, based on nominally added Y concentrations. In soft water, with a water hardness of 18 mg CaCO3/L, the 1-wk LC50 was reported to be 183 µg Y/L, based on nominally added Y concentrations, and 66 µg Y/L, based on dissolved Y concentrations measured at the end of testing. Because of the non-standard test setup the study is considered not reliable, however, its results can be regarded as supporting information for the endpoint.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
March 11, 2013 - April 29, 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Concentrations of dissolved Y were determined in at least one of the triplicate samples from each treatment per sampling time.
- Sampling method: Triplicate samples were taken from each treatment at the start and end of each test medium renewal period (after filtration through a membrane filter, Whatman, Type NC45, pore size 0.45 µm).
- Sample storage conditions before analysis: All samples were stored at room temperature in the dark after sampling until analysis.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
A dispersion with the loading rate of 138 mg/L (corresponding to 100 mg/L anhydrous yttrium trinitrate) was prepared at the start of the test and before each test medium renewal by dispersing 275.5 mg of the test item in 2000 mL of test water. This preparation was supported by ultrasonic treatment for 15 minutes and intense stirring on a magnetic stirrer over 3 hours in the dark, to dissolve a maximum amount of the test item in the dispersion. No auxiliary solvent or emulsifier was used.

An optimal stirring period of 3 hours was chosen based on the results of a pre-experiment, which showed that the solution equilibrium was reached after this time. In this pre-experiment, similar concentrations of dissolved elemental yttrium were analytically measured in filtrates after stirring for 3, 24 and 96 hours.

After stirring and pH adjustment, the dispersion of the test item was filtered through a membrane filter (Whatman, Type NC45, pore size 0.45 µm). The undiluted filtrate was used as highest concentrated test medium and as a stock solution for preparation of the test media with lower test concentrations. For preparation of the latter, the filtrate was diluted with pH adjusted test medium.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea (Daphnia magna)
- Strain: Straus
- Source: University of Sheffield / UK in 1992
- Age at study initiation (mean and range, SD): 6-24 hours (not first brood progeny)
- Feeding during test: no
- Method of breeding: clone has been bred at Harlan Laboratories in reconstituted water of the quality identical to the water quality used in the test

ACCLIMATION
- Type and amount of food: green algae Desmodesmus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the Collection of Algal Cultures or a mixture of this algal suspension and a commercial fish diet
- Feeding frequency: daphnids are generally fed three times a week
- Health during acclimation (any mortality observed): Good. No mortalities observed.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg CaCO3/L
Test temperature:
21°C
pH:
New test media:
0 h = 6.0-6.2
24 h = 6.0
Old test media:
24 h = 7.1-7.4
48 h = 6.7-6.9
Dissolved oxygen:
8.1-8.8 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
Analytically determined concentrations of dissolved yttrium in the test media (control, dilutions 1:1000, 1:320, 1:100, 1:32, 1:10 and 1:3.2) were as follows:
Day 0, 0 h (start of experiment) = < LOQ, 0.0337, 0.102, 0.318, 0.976, 3.14 and 9.7 mg Y/L (< LOQ, 0.104, 0.315, 0.983, 3.02, 9.70, 30.0 mg expressed in anhydrous Y(NO3)3/L)
Day 1, 24 h (end of 1st renewal period) = < LOQ, 0.0299, 0.0904, 0.294, 0.961, 2.69 and 7.91 mg Y/L (< LOQ, 0.0925, 0.280, 0.909, 2.97, 8.31, 24.5mg expressed in anhydrous Y(NO3)3/L)
Day 1, 0 h (beginning of 2nd renewal period) = < LOQ, 0.0338, 0.112, 0.330, 0.934, 3.05 and 9.80 mg Y/L (< LOQ, 0.105, 0.346, 1.02, 2.89, 9.44, 30.3 mg expressed in anhydrous Y(NO3)3/L)
Day 2, 24 h (end of 2nd renewal period) = < LOQ, 0.0315, 0.0915, 0.366, 0.934, 2.38 and 7.41 mg Y/L (< LOQ, 0.0974, 0.283, 1.13, 2.89, 7.36, 22.9 mg expressed in anhydrous Y(NO3)3/L)

Over the test medium renewal periods of 24 h, the concentrations of dissolved Y slightly decreased. Over the test medium renewal periods of 24 h, the concentrations of dissolved Y decreased (recovery 76 to 110% of initially measured concentrations, on average 79 to 101%).
Biological results were based on mean measured concentrations calculated as the arithmetic mean of the two geometric means determined for dissolved Y measured at the start and end of each test medium renewal period.
Mean measured concentrations were as follows (not mentioning the control, for which dissolved Y was < LOQ):
0.03, 0.1, 0.33, 0.95, 2.8 and 8.6 mg Y/L (0.09, 0.30, 0.99, 8.70, 26.73 mg expressed in anhydrous Y(NO3)3/L)
Details on test conditions:
TEST SYSTEM
- Test vessel: 100-mL glass beakers filled with 50 mL of test medium
- Type (delete if not applicable): open
- Aeration: The test water was aerated prior to the start of the study. No aeration during the study.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO 6341.
- Ca/mg ratio: 4:1
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: 1) adjustment of dispersion to pH 6.0 after the 3-h stirring period using 1 M NaOH, 2) adjustment of test medium (for dilution of the filtrate) to pH 6.0 using 1 M HCl
- Photoperiod: A 16-hour light to 8-hour dark cycle with a 30-minute transition period.
- Light intensity: Light intensity during the light period was approximately between 390 and 560 Lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): immobilisation, daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2 (spacing factor for serial dilutions)
- Range finding study: yes
- Test concentrations range finding study: undiluted filtrate, 1:10, 1:100, 1:1000 dilution, and control
- Results used to determine the conditions for the definitive study: 10% immobilisation at 1:1000 dilution, 20% immobilisation at 1:100 dilution, 100% immobilisation at 1:10 dilution, 100% immobilisation in undiluted filtrate
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
yttrium
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 2.8-4.9 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
11.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
other: yttrium trinitrate, anhydrous
Basis for effect:
mobility
Remarks on result:
other: 95%CL: 8.6-15 mg/L
Details on results:
The 48-hour EC0 and NOEC of dissolved yttrium were both 0.95 mg/L (corresponding to 2.95 mg/L when expressed as Y(NO3)3).
The 48-hour EC100 of dissolved yttrium was 8.6 mg/L (corresponding to 26.7 mg/L when expressed as Y(NO3)3).
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50/LC50: 48-hour EC50: 0.94 mg/L (within the internal historical range: 48-hour EC50 from 2000 to 2012: 0.43-1.1 mg/L)
Reported statistics and error estimates:
NOEC, EC0 and EC100 were determined directly from the raw data.
24-h EC50 could not be calculated due to absence of toxicity and was therefore also determined directly from the raw data.
48-h EC50 and 95% confidence limits were calculated using Weibull Analysis with linear weighted regression.
The two lowest treatments were excluded from the statistical evaluation, as they did not contribute to the dose-response relationship.
Validity criteria fulfilled:
yes
Conclusions:
The test item had acute toxic effects on Daphnia magna. The 48-hour EC50 was calculated to be 3.7 mg/L of dissolved yttrium with 95% confidence limits of 2.8 and 4.9 mg/L (corresponding to 11.5 mg/L of anhydrous yttrium trinitrate with 95% confidence limits of 8.6 and 15 mg/L).
Executive summary:

The acute toxicity of yttrium trinitrate to Daphnia magna was determined in a 48-hour semi-static test according to the OECD guideline 202 and in compliance with the principles of Good Laboratory Practice. Juvenile daphnids were exposed to a control treatment and the test chemical at various concentrations (a dispersion with the loading rate of 138 mg/L (corresponding to 100 mg/L of anhydrous yttrium trinitrate) was used as stock solution for test media preparation; the undiluted filtrate and dilutions 1:3.2, 1:10, 1:32, 1:100, 1:320 and 1:1000 of this undiluted filtrate were used as test media). Organisms were observed after 24 and 48 hours for immobility.

After 48 hours of exposure, no immobilised test organisms were recorded in the control and up to and including the mean measured concentration of 0.95 mg/L of dissolved yttrium, corresponding to 2.9 mg/L of anhydrous yttrium trinitrate. At the mean measured concentration of 2.8 and 8.6 mg/L of dissolved yttrium (corresponding to 8.7 and 27 mg/L of anhydrous yttrium trinitrate), 25% and 100% of the daphnids were found to be immobile, respectively. The 48-h EC50 was determined to be 3.7 mg/L for dissolved yttrium and 11.5 mg/L for anhydrous yttrium trinitrate, meaning this substance is harmful to aquatic invertebrates.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Experimental data on the acute toxicity of yttrium to aquatic invertebrates is available for both yttrium trinitrate (Hefner, 2014; Bazin, 1995) and yttrium trichloride, a related water-soluble yttrium compound (Ablitt, 2017). Further, data were also identified which were obtained with yttrium atomic absorption standard (Borgmann et al., 2005). Since the observed toxicity in the experiments is attributed to yttrium, with the counter anion not contributing in a significant way to the observed toxicity, it was considered justified to lump the aquatic ecotoxicity data set for both compounds for concluding on the potential hazards of yttrium to the aquatic environment. In this target record for read across, those data were summarised which were not obtained with yttrium trinitrate. The read across justification document is attached to IUCLID Section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
2.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
element (dissolved fraction)
Remarks:
yttrium
Basis for effect:
mobility
Remarks on result:
other: This is the 48-h EC50 for Daphnia magna, expressed as dissolved yttrium concentration, obtained in the single reliable read across study performed by Ablitt (2017) with yttrium trichloride as test material.
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
7.73 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr. (dissolved fraction)
Remarks:
yttrium trinitrate anhydrous
Basis for effect:
mobility
Remarks on result:
other: This 48-h EC50 value was recalculated based on the results (expressed as dissolved yttrium concentration) obtained in the single reliable read across study (Ablitt, 2017) performed with yttrium trichloride in Daphnia magna.
Remarks:
The results of the studies performed with yttrium trichloride and yttrium atomic absorption standard are considered relevant for yttrium trinitrate as well. The read across justification document is attached to IUCLID Section 13.

Description of key information

Based on the lumped data set on the acute toxicity of yttrium (from water-soluble yttrium compounds) to aquatic invertebrates, a key 48-h EC50 of 2.5 mg Y/L (equivalent to 7.73 mg Y(NO3)3/L) was obtained from the reliable studies in the data set. Consequently, yttrium trinitrate is considered to be toxic to aquatic invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
7.73 mg/L

Additional information

Since the observed toxicity of water-soluble yttrium compounds to aquatic invertebrates is attributed to exposure to (bioavailable) yttrium, with the counter anions of the tested compounds not significantly contributing to the observed toxicity, the available studies for water-soluble yttrium compounds were lumped into one data set for concluding on the endpoint. The read across justification document is attached to IUCLID Section 13.

Four studies have been identified as relevant for the endpoint. The first two studies were reliable and were included in a weight-of-evidence approach. The other two studies were considered as supporting studies.

In the first study included in the weight-of-evidence approach, the acute toxicity of yttrium trinitrate to Dahpnia magna was determined in a semi-static test performed according to OECD guideline 202 and in compliance with GLP-requirements. The 48-h EC50 obtained in this study was determined to be 3.7 mg/L when based on dissolved yttrium and 11.5 mg/L when expressed as anhydrous yttrium trinitrate. This study is considered reliable without restrictions (Klimisch 1).

In the second study included in the weight-of-evidence approach, the acute toxicity of yttrium trichloride, i.e. a similar water-soluble compound as yttrium trinitrate, was investigated in Daphnia magna according to OECD guideline 202 and in compliance with the principles of Good Laboratory Practices. The 48-h EC50 in this semi-static study was determined to be 2.5 mg/L when based on dissolved yttrium and 5.5 mg/L when expressed as anhydrous yttrium trichloride. This is equivalent to 7.73 mg anhydrous Y(NO3)3/L. This study is considered reliable without restrictions (Klimisch 1).

Based on these two reliable studies, the key 48-h EC50 was concluded to be 2.5 mg Y/L, equivalent to 7.73 mg Y(NO3)3/L. Consequently, yttrium trinitrate is considered to be toxic to aquatic invertebrates.

In the study of Borgmann et al. (2005), the toxicity of yttrium was studied in 1-wk Hyalella azteca tests following a non-standard test setup in two different test media. In tap water, with a water hardness of 124 mg CaCO3/L, the 1-wk LC50 was reported to be 549 µg Y/L, based on nominally added yttrium concentrations. In soft water, with a water hardness of 18 mg CaCO3/L, the 1-wk LC50 was reported to be 183 µg Y/L, based on nominally added yttrium concentrations, and 66 µg Y/L, based on dissolved yttrium concentrations measured at the end of testing. Because of the non-standard test setup (use of acidified metal AAS standards for yttrium addition to test solutions, non-simultaneous testing of different yttrium concentrations, no true replicates, dissolved yttrium concentrations not measured in all tests, feeding during the test, non-standard test duration, etc.) the study is considered not reliable, however, its results can be regarded as supporting information for the endpoint.

 

Finally, a study performed by Bazin (1995), investigating the acute toxicity of yttrium trinitrate to Daphnia magna according to the corresponding EC guideline at that time, reported a 48-h EC50 of > 100 mg Y(NO3)3/L. However, dissolved yttrium analysis indicated that yttrium precipitated and disappeared from the solution, with concentrations <= 1 mg Y/L (i.e. the detection limit) after 24 h of exposure. Unfortunately no further analyses were performed, hampering the interpretation of the study. The observation of precipitation in this study however suggests that there may have been an absence of exposure, which may explain the absence of adverse effects in the study. Therefore, the results of this study should not necessarily be concluded to be inconsistent with abovementioned information. Nevertheless, the study was considered not to be reliable and its results were therefore not taken forward in the weight-of-evidence approach.