Niobium

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because a long-term aquatic toxicity study on invertebrates is available

Reference 2

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:

other: see 'Remark'

Remarks:

The test performance does not represent a standardized method; the test performance lacks also documentation. The there was a large variation of age at test initiation (1-11 days). The results are therefore not considered to be reliable to cover the endpoint for acute aquatic toxicity. Results might be used as an indicator for the toxicity range of several metal species.

Qualifier:

no guideline followed

Principles of method if other than guideline:

As many metals as possible were tested in each experiment. Depending on the test results, the concentration of each metal was either increased (if nontoxic) 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, at a concentration resulting in > 75% survival, and at all intermediate concentrations, relative to controls. Only data from experi-ments with > 80% control survival were used. Using this pro-cedure made it possible to cover the toxic range of a much larger number of metals than would have been possible if each metal had been tested sequentially in a concentration series.

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Filtered samples were collected using disposable filter cartridges attached to polypropylene syringes, acidified with high purity nitric or hydrochloric acid, and stored in 14 ml capacity Falcon 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.
Metal analysis were performed by inductively coupled plasma mass spectrometry by the National Laboratory for Environmental Testing. Quality assurance/quality control methodology included calibration checks at the initiation and completion of each run, and verification and drift standards.
Certified reference standards also were included when available.
Also included were machine blanks, sample blanks, control samples, and acid controls

Vehicle:

no

Test organisms (species):

other: Hyalella azteca

Details on test organisms:

- Common name: Hyalella azteca
- Origin: Valens Conservation Area (ON, Canada)
- Age at study initiation: 1-11 days
- Feeding during test: yes
- Food type:cotton fish food flakes
- Amount:at the start of the test: 2.5 mg per test container; an additional 2.5 mg of food was provided midweek

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Hardness:

1) Tap water (Lake Ontario): 124 mg CaCO3/L
2) Soft water consisting of 10% culture medium and 90% deionised water: 18 mg CaCO3/L

Test temperature:

24-25°C

Nominal and measured concentrations:

Concentration range (nominal/measured) not specifically reported

Details on test conditions:

TEST SYSTEM
- Test vessel: polyethylene cups (snap-top specimen containers), 500-mL with 400 mL of test water
- Aeration: no
- Renewal rate of test solution: no
- No. of organisms per vessel: 15
- No. of vessels per concentration (replicates): 2 to 5 (no exact number given)
- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: Two sets of experiments were run, one inLake Ontario Tap water (1) and another in soft water consisting of 10% culture medium and 90% deionised water (2).


OTHER TEST CONDITIONS
- Adjustment of pH: yes
- Photoperiod: 16:8 light:dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): lethality

Reference substance (positive control):

no

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: Soft water; 95% CL: 0.177-0.354

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

0.026 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: Soft water; 95% CL: 0.016-0.043

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

1.938 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: Tap water; 95% CL: 1.692-2.219

Description of key information

 A study on the long-term toxicity according to OECD guideline 211 is available for niobium metal.

Additional information

In accordance with column 2 of Annex VII and VIII of Regulation (EC) No 1907/2006, short-term studies for the aquatic ecotoxicity do not need to be conducted if there are mitigating factors indicating that aquatic toxicity is unlikely to occur, for instance if the substance is highly insoluble in water. However, a study on the long-term toxicity according to OECD guideline 211 is available for niobium metal, showing no chronic effects to Daphnia magna up to the highest concentration tested. The 21 d NOEC values for the reproductive performance, immobilisation, growth (adult length at test termination), development rate and intrinsic rate r of population increase were determined as ≥10 mg/L (nominal). Therefore, it is concluded that niobium is not chronically toxic to aquatic invertebrates.