Barium chloride

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-03-29 to 2010-09-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples from test solutions were taken for analysis of actual test item concentrations in comparison to the nominal concentrations. The test solutions were vigorously stirred by use of a steel blade in order to homogenise the suspension. Samples were taken immediately after stirring. Samples of the test concentrations (incl. control) were taken at the start and end of the test period. Immediately after sampling and before shipment, the samples were stored in polyethylene bottles in the refrigerator.

Vehicle:

no

Details on test solutions:

Reconstituted water according to OECD guideline No. 203 was used to dilute the test item and to keep the fish before and during the period of the test. Local tapwater was treated by reverse osmosis and ion-exchanger to prepare deionised water. Therefore a contamination with heavy metals, pesticides and TOC is excluded.
The reconstituted water consists of deionised water and salts in the following final concentrations:
A) CaCl2 * 2 H2O: 294.0 mg/L
B) MgSO4 * 7 H2O: 123.0 mg/L
C) NaHCO3: 64.8 mg/L
D) KCl: 5.75 mg/L

Prior to use, the reconstituted water was diluted with deionised water (1:1; v/v), and supplemented with 1% of artificial seawater. Reconstituted water was used for the control. The test item was weighed in a plastic weighing boat. The test concentrations were prepared by dissolving 1289.4 mg of the test item in 10.998 L of reconstituted water (100 mg/L nominal) and 1957.7 mg in 11.011 L of reconstituted water (152 mg/L nominal) directly in the respective test vessel. The test solutions were stirred for approx. one minute before use. The test solutions appeared as milky suspension.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Supplier: ECT Oekotoxikologie GmbH, Germany (own breed; since November 2009)
- Average body weight of fish: 0.168 - 0.271 g (mean: 0.201 g/fish; assessed from the total weight of a sample consisting of 11 fish)
- Average standard length of fish: 1.8 - 2.7 cm (assessed in a sample consisting of 11 fish)

ACCLIMATION
- Acclimation period: 14 days
- Acclimation conditions: same as test conditions, reconstituted water (see section above on details of test solutions)
- Temperature of water: min/max 25.1/26.5°C (during 14 days before start of exposure)
- Type and amount of food during acclimation: Tetramin®, Artemia nauplius larvae
- Feeding frequency during acclimation: daily ration fed in 3 portions on working days
- Health during acclimation (any mortality observed): No morttalities observed

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

171 - 179 mg/L as CaCO3

Test temperature:

21.5 - 22.4°C

pH:

7.1 - 7.5

Dissolved oxygen:

94 - 105 %

Nominal and measured concentrations:

nominal: 66 and 100 mg Ba/L - 100 and 152 mg BaCl2/L - 117 and 178 mg/L test item
measured dissolved at t=0: below detection limit, 1.44, 3.35 mg Ba/L
measured dissolved at t=4d: below detection limit, 1.42, 3.68 mg Ba/L
measured total Ba at t=0: below detection limit, 62, 100 mg Ba/L
measured total Ba at t=4d: below detection limit, 64, 95 mg Ba/L
total expressed as test item (t=0): below detection limit, 111, 178 mg/L test item
total expressed as test item (t=4): below detection limit, 113, 170 mg/L test item

Details on test conditions:

TEST SYSTEM
- Test vessel: 18 L-stainless steel tanks covered by glass lids, filled with 10 L test solution, depth of test solution in the test vessels approx. 12.5 cm
- Aeration: yes, permanent. Aeration was controlled daily in all test vessels, and - if necessary - adjusted.
- Feeding: Food was withheld from the fish for one day prior to the start of exposure. The fish were not fed during the test.
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Renewal of test solutions during exposure: none
- Biomass loading rate: 0.14 g/L. The fish were added to the test vessels in a randomised manner

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 12 h light / 12 h dark
- Light intensity: 100 - 1000 lx; measured: 244 - 327 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): All fish in the test were observed 3 hours, and 1, 2, 3 and 4 days after start of exposure. Any dead fish were recorded and removed from the test vessels. Fish were considered dead if there was no visible movement (e.g. gill movement) and if touching of the caudal peduncle produced no reaction. Since the test solutions were milky suspensions, a net was used to collect potential dead fish from the vessel bottom. This procedure was performed at all observation time points. All fish in the test were observed daily for other than lethal effects: effects on the appearance, size and behaviour of the fish that make them clearly distinguishable from the control animals, e.g. different swimming behaviour, different reaction to external stimuli, changes in appearance of the fish were recorded. However, since the test solutions were milky suspensions, the fish were barely visible, and such observations were only possible when fish were close to the water surface. After the end of the exposure period the fish were netted from the test solution; dead and surviving fish were counted; the surviving fish were killed with buffered MS222 (3-aminobenzoic acid ethyl ester methanesulfonate salt, Tricain) and disposed according to currently valid local regulations.

TEST CONCENTRATIONS
- Test concentrations: 100 and 152 mg BaCl2/L plus control (limit test)

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 3.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Remarks:

as Ba

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 97.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Remarks:

total Ba

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 174 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There were no mortalities and abnormalities observed in the fish of the control group and the treatment group during the test. The fish were barely visible due to the milky appearance of the test suspensions.

Analytical measurements:
The recovery of the test item in the 0.45 µm-filtered test solutions was between 2 and 4% of the nominal concentrations. The characteristics of the test item may have led to a precipitation in the test medium, probably as barium sulfate.
The recovery of the test item in the non-filtered test solutions was between 95 and 100% of the nominal concentrations.

Validity criteria:
- No mortality was observed in the control during the test (required: ≤ 10%, or one out of seven fish);
- Dissolved oxygen concentration in control and test vessels: ≥ 94% (required: ≥ 60% of air saturation value (ASV))

Reported statistics and error estimates:

No statistical method was used to evaluate the fish mortalities because no mortality was observed during the test period in the control or the test item treatments.

Validity criteria fulfilled:

yes

Conclusions:

The test results showed that the 96h LC50 for barium chloride to Danio rerio was higher than 152 mg/L based on nominal barium chloride concentrations.

Executive summary:

The acute toxicity of Barium chloride dihydrate to zebrafish (Danio rerio) was investigated in a GLP compliant OECD guideline 203 study. The study was performed as an extended limit test at two concentration levels (100 and 152 mg BaCl2/L, nominal concentrations) and a control. The treatment groups and control group had one replicate, each containing 7 fish and the test duration was 96h. During the test period, the test solutions were not renewed. Observations for mortality and abnormalities were made after 3, 24, 48, 72 and 96 hours. The test solutions appeared as milky suspensions due to precipitation of the test substance in the test medium, probably as barium sulfate.

To study exposure to the test substance, samples of the test solution were taken and analysed with ICP-OES at the beginning (on day 0) and at the end of the test (on day 4). Samples of the test solutions were either filtered (0.45 µm) or extracted to determined the concentration of dissolved and total barium, respectively. The recovery of the test item in the 0.45 µm-filtered test solutions was between 2 and 4% of the nominal concentrations. The recovery of the test item in the non-filtered test solutions was between 95 and 100% of the nominal concentrations.

No mortality occurred in the control during the test and the dissolved oxygen concentration was greater than 60% of the air saturation value throughout the test duration. Hence the test was considered to be valid.

Because neither mortality, nor abnormalities were observed in the fish exposed to the test substance, the 96h-LC50 was higher than 152 mg BaCl2/L based on nominal concentrations which corresponds to a 96h-LC50 of >3.5 mg/L as dissolved barium.

Description of key information

One reliable acute toxicity data point (Klimisch 1, GLP) with the zebrafish (Danio rerio) has been identified. No effect (mortality) was noted at a nominal test concentration of 100 mg Ba/L. Both the dissolved and total fraction of barium was measured. A white substance was noted in the solution upon addition of BaCl2, most likely caused by the formation of the poorly soluble barium sulfate. At a nominal concentration of 100 mg Ba/L, the dissolved and total Ba concentration were 3.5 and 97.5 mg/L, respectively.

- 96h-LC50 > 97.5 mg barium/L based on total barium concentration.

- 96h-LC50 > 3.5 mg barium/L based on dissolved barium concentration.