Lutetium trinitrate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From September 25th, 2017 to January 31st, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study performed in accordance with international accepted test guidelines and in compliance with Good Laboratory Practice.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

June 12th, 2015

Test material

Test material information

Constituent 1

Reference substance name:

Lutetium trinitrate

EC Number:

233-241-7

EC Name:

Lutetium trinitrate

Cas Number:

10099-67-9

Molecular formula:

HNO3.1/3Lu

IUPAC Name:

lutetium trinitrate

Test material form:

solid: crystalline

Details on test material:

- Name of test material: Lutetium trinitrate

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples for analyses were collected in control treatment and all test item exposed treatments (100%, 45.5%, 20.7%, 9.39% and 4.27% of the filtrate prepared at a loading rate of 125 mg test item/L).
- Sampling method: Samples were taken:
* at the start of exposure in fresh test solutions,
* after 24 hours before renewal in aged test solutions,
* after 24 hours after renewal in fresh test solutions,
* at the end of exposure in aged test solutions.
Control and test solutions were sampled in duplicate (nominal volume per sample: 50 mL). Duplicate samples of the test solutions were stored as additional reserve.
- Sample storage conditions before analysis: After sampling and before shipment, the samples were stored in glass bottles at ambient temperature.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: As the test item is poorly water-soluble at the test medium pH, a saturated solution was prepared. With this aim in view, aspects of OECD Guidance Document 23 (OECD 2000) were taken into account for the preparation of the test solutions. First the pH of the test medium was adjusted to pH 6.5 with 1-M HCl. Afterwards, a stock solution at a loading rate of 125 mg test item/L (corresponding to 100 mg anhydrous Lu(NO3)3/L) was prepared by mixing the test item in the test medium which was adjusted to pH 6.5 with 1-M HCl. The adjustment to pH 6.5 was intended to maximize the test item dissolution whilst maintaining conditions appropriate for the test organisms. The stock solution was stirred for two minutes and ultrasonicated for 5 minutes. After initial ultrasonication, the pH was measured again. The pH had decreased to 6.1–6.2 and was adjusted to 6.5 using 1-N NaOH. The stock solution was ultrasonicated for additional 10 minutes. The stock solution was then stirred for 3 hours, a period of time determined based on the results of a preliminary non-GLP stirring experiment performed in order to determine the optimal conditions to prepare the test solutions. The pH was measured again and was found to be 6.4. Then, the stock solution was filtered (nylon membrane, 0.45 μm pore-size). The undiluted filtrate corresponded to a saturated solution and was used as the highest concentration. Lower concentrations were prepared as a series of dilutions of the filtrate in pH-adjusted test medium. The first 150 mL filtrate were discarded and the filtrate was checked for its pH (pH: 6.5). The dilution medium (without test item) was adjusted to pH 6.5 again, before the dilution series was prepared. The undiluted filtrate of a saturated solution at the loading rate of 125 mg test item/L (corresponding to 100 mg anhydrous Lu(NO3)3/L) and its dilutions were prepared once at the beginning of the test, and once prior to renewal of the test solutions on day one of exposure.
- Controls: Yes, test medium without test item.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea.
- Strain/clone: Daphnia magna STRAUS (clone M10).
- Source: Originally supplied by KU Leuven (Belgium), cultured at ECT Oekotoxikologie GmbH since December 22, 2011.
- Age of parental stock: Less than 35 days.
- Age of test organisms: On the day of test start (day 0), < 24 hours old and not first brood of the parental daphnids.
- Feeding during test: No.

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

14.2 °dH, equivalent to 254 mg/L CaCO3

Test temperature:

20.9 to 21.5 °C

pH:

Start of the test at 0h (fresh test solutions): 6.4 to 6.6
End of the first renewal period at 24h (aged test solutions): 6.8 to 7.3
Start of the second renewal period at 24h (fresh test solutions): 6.4 to 6.6
End of the second renewal period at 48h (aged test solutions): 6.6 to 7.1

Dissolved oxygen:

5.9 to 8.9 mgL dissolved oxygen

Nominal and measured concentrations:

Nominal concentrations:
100%, 45.5%, 20.7%, 9.39%, 4.27%, 0% (control) of a filtrate prepared at a loading rate of 125 mg/L test item being pentahydrated lutetium trinitrate (corresponding to 100 mg anhydrous lutetium trinitrate/L, and to 48.6 mg lutetium/L).

Measured concentrations:
The concentrations below are time-weighted mean (TWM) measured concentrations over 48 hours:
100%: 34.5 mg Lu/L
45.5%: 15.9 mg Lu/L
20.7%: 7.75 mg Lu/L
9.39%: 3.59 mg Lu/L
4.27%: 1.56 mg Lu/L
0% (control): < Limit of Detection (LOD < 0.3 mg Lu/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass vessels (nominal volume: 100 mL), covered with watch glasses.
- Aeration: No.
- Renewal rate of test solution: Renewal of test solutions after 24 hours by carefully transferring the test organisms by using an upside-down glass pipette from the first to the second set of test vessels.
- 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 test water according to OECD guideline No. 202) was used to dilute the test item and to maintain the test organisms in the control during the period of the test. Local tapwater is treated by reverse osmosis and ion-exchanger to prepare deionised water. Therefore a contamination with heavy metals, pesticides and TOC can be excluded. The reconstituted water consists of deionised water and salts in the following final concentrations: CaCl2 × 2 H2O: 294.0 mg/L, MgSO4 × 7 H2O: 123.0 mg/L, NaHCO3: 64.8 mg/L, KCl: 5.75 mg/L.
- Culture medium different from test medium: Yes (Elendt medium M4 was used for daphnids culture).
- Intervals of water quality measurement: Temperature and dissolved oxygen were measured at start of the test, after temperature adaptation of the test solutions, and at the end of the test in one replicate test vessel of the control and all treated test concentration. In addition, the pH was measured and recorded once in all test vessels (control & all test item exposed treatments) at start of the test, immediately before and after the 24-h renewal, and at the end of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: pH was adjusted to ca. 6.5 in the freshly prepared solutions (at the beginning of the test and at renewal) in order to maximize the test item dissolution whilst maintaining conditions appropriate for the test organisms.
- Photoperiod: 16 hours light : 8 hours dark.
- Light intensity: 571 - 700 lx.

EFFECT PARAMETERS MEASURED
After 24 and 48 hours of exposure, the number of mobile daphnids, the cumulative number of immobile daphnids and abnormal behaviours (in comparison with the controls) were determined for each test vessel.

RANGE-FINDING STUDY
- Test concentrations: 100%, 10%, 1%, 0.1%, 0% (control) of a filtrate prepared at a loading rate of 125 mg test item/L.
- Results used to determine the conditions for the definitive study: The results of the preliminary non-GLP range finding test showed immobilities at the highest tested concentration. The concentrations for the definitive test (100%, 45.5%, 20.7%, 9.39%, 4.27% of a filtrate prepared at a loading rate of 125 mg test item/L) were thus defined on this basis.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.25 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

element (dissolved fraction)

Remarks:

mean measured dissolved lutetium concentrations in mg Lu/L

Basis for effect:

mobility

Remarks on result:

other: lower and upper 95%-confidence limits: 1.40 to 3.05 mg/L

Effect concentrations 2

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

4.64 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

other: Calculated concentrations of anhydrous lutetium trinitrate in mg Lu(NO3)3/L.

Basis for effect:

mobility

Remarks on result:

other: lower and upper 95%-confidence limits: 2.89 to 6.29 mg/L

Effect concentrations 3

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.79 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

other: Calculated concentrations of test item being pentahydrated anhydrous lutetium trinitrate in mg Lu(NO3)3.5H2O/L.

Basis for effect:

mobility

Remarks on result:

other: lower and upper 95%-confidence limits: 3.60 to 7.85 mg/L

Details on results:

BIOLOGICAL RESULTS:
- Cumulative number of immobilised Daphnia magna after 24 and 48 h are given in "Any other information on results incl. tables".
- A clear concentration-response relationship was observed with 10%, 35%, 70%, 90%, 100% and 100% immobility after 48 hours in daphnids exposed to control treatment, 4.27%, 9.39%, 20.7%, 45.5% and 100% of the filtrate, respectively.
- Behavioural abnormalities: Sublethal observations on the mobile daphnids were recorded. Surviving daphnids showed reduced swimming activity at 45.5 and 100 % of filtrate after 24 h and at 4.27, 9.39, 20.7 % of filtrate after 48 h.

Results with reference substance (positive control):

- EC50(24 h) = 1.29 mg/L.
- Results with reference substance valid? Yes. According to the OECD guideline No. 202 (OECD, April 2004) 24h-EC50 values for potassium dichromate obtained from different laboratories should range between 0.6 mg/L and 2.1 mg/L. The toxicity of the reference item is within this range. Therefore the results of this reference test are acceptable, the test conditions are reliable and the sensitivity of the test system could be demonstrated.

Reported statistics and error estimates:

Mortality as assessed by immobility of the daphnids was evaluated. Probit analysis using linear maximum likelihood regression was used to estimate the ECx values, based on the time weighted mean measured dissolved lutetium concentrations. The statistical software package ToxRat 2.10 Professional (ToxRat Solutions GmbH, Naheweg 15, D-52477 Alsdorf) was used for these calculations.

Any other information on results incl. tables

Cumulative number of immobilised Daphnia magna and abnormal behaviours after 24 and 48 h:

Nominal concentration (% of filtrate*)	Total number of introduced daphnids	Total number of immobilised daphnids after 24 hours	Immobilised daphnids (% of introduced) after 24 hours	Total number of immobilised daphnids after 48 hours	Immobilised daphnids (% of introduced) after 48 hours
0 (Control)	20	0	0	2	10
4.27	20	0	0	7 (3)	35
9.39	20	5	25	14 (1)	70
20.7	20	2	10	18 (2)	90
45.5	20	8 (7)	40	20	100
100	20	16 (4)	80	20	100

*filtrate prepared at a loading rate of 125 mg test item/L (corresponding to 100 mg/L anhydrous lutetium trinitrate)

Numbers in italics between brackets corresponds to the numbers of mobile daphnids showing reduced swimming activity

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Percentage of immobilised daphnids in the control should be =< 10% (here: 10%). Dissolved oxygen concentration in control and test vessels at the end of the test should be >=3 mg/L (here: 8.9 mg/L).

Conclusions:

Under the conditions of this study, lutetium trinitrate is toxic to Daphnia magna with a 48h-EC50 of 4.64 mg/L when expressed in anhydrous lutetium trinitrate (calculated from a 48h-EC50 of 2.25 mg/L when expressed in dissolved lutetium).

Executive summary:

The acute toxicity of pentahydrated lutetium trinitrate (= test item) to Daphnia magna was investigated during a GLP-compliant study performed in accordance with OECD Test Guideline 202.

Daphnids were exposed to a saturated solution and several dilutions for 48 hours. The saturated solution corresponded to 100% of a filtrate prepared at a loading rate of 125 mg/L test item (corresponding to 100 mg/L anhydrous lutetium trinitrate and to 48.6 mg/L lutetium). Dilutions corresponded to 45.5%, 20.7%, 9.39% and 4.27% of this filtrate. A control treatment was run in parallel under similar conditions. A semi-static test design was used with a renewal of the test solutions after 24 hours. Four replicates of five daphnids each were used per treatment. After 24 and 48 hours, the number of immobile/mobile daphnids were recorded as well as the abnormal behaviours in comparison to controls.

Analytical monitoring was conducted in parallel in order to determine the actual test concentrations. For this purpose, samples of test solutions were taken at the start (fresh test solutions) and at the end (aged test solutions) of each renewal period and analysed using ICP-OES. Time-weighted means (TWM) of the dissolved lutetium concentrations were calculated based on these measurements; giving the following analytical results:

Control: < Limit of Detection (LOD < 0.3 mg Lu/L)

4.27% of the filtrate: 1.56 mg Lu/L

9.39% of the filtrate: 3.59 mg Lu/L

20.7% of the filtrate: 7.75 mg Lu/L

45.5% of the filtrate: 15.9 mg Lu/L

100% of the filtrate (saturated solution): 34.5 mg/L.

A clear concentration-response relationship was observed with 10%, 35%, 70%, 90%, 100% and 100% immobility after 48 hours in daphnids exposed to control treatment, 4.27%, 9.39%, 20.7%, 45.5% and 100% of the filtrate, respectively. The following EC50 values were determined based on TWM measured lutetium, anhydrous lutetium trinitrate (Lu(NO3)3) and pentahydrated lutetium trinitrate (Lu(NO3)3.5H2O):

48h-EC50 = 2.25 mg Lu/L when expressed in dissolved lutetium

48h-EC50 = 4.64 mg Lu(NO3)3/L when expressed in anhydrous lutetium trinitrate

48h-EC50 = 5.79 mg Lu(NO3)3.5H2O/L when expressed in pentahydrated lutetium trinitrate (= test item)

Anhydrous lutetium trinitrate is thus toxic to Daphnia magna under the conditions of this study.