Dibismuth trioxide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Insufficient documentation on method and results (no statistics, no standard guidelines, no info on test medium, no measured Bi-concentrations)

Justification for type of information:

Read-across is considered justified based on the structural similarity between bismuth sodium oxide and bismuth oxide. Both subdtance contain bismuth, the moiety of toxicological concern.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline followed

Principles of method if other than guideline:

120 days growth inhibition test with algae Chlorella vulgaris

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

not reported

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

green algae

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

120 d

Test temperature:

room temperature

Nominal and measured concentrations:

nominal concentrations not reported. At least two concentrations tested.

Details on test conditions:

test water is artificial medium

Reference substance (positive control):

not specified

Duration:

120 d

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

growth rate

Details on results:

120days LOEC for growth is 7.2 mg Bi/L

Validity criteria fulfilled:

no

Conclusions:

Insufficient documentation on method and results (no statistics, no standard guidelines, no info on test medium, no measured Bi-concentrations). Study is disregarded.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: ISO 6341 method, but insufficiently documented of test conditions (temperature, O2-values, number of replicates, preparation of WAF,…)

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

test in water accommodated fraction (WAF)

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

green algae

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Nominal and measured concentrations:

nominal total concentrations: 0-0.125-0.35-0.70-1.40 mg Bi2O3/L. Not clear if these are total or dissolved concentrations.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1.26 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

growth rate

Remarks:

growth inhibition

Details on results:

1.4 mg Bi2O3/L is the maximum concetration that can be dissolved (corresponds to 1.26 mg Bi/L).
pH values, oxygen concentration and inhibtion concentration of potassium dichromate are valid for this test (no numerical data given).

Validity criteria fulfilled:

no

Conclusions:

ISO 8692 method, but insufficiently documented incubation conditions (temperature, number of replicates, initial biomass concentration, preparation of WAF,…). Study is disregarded.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: According to OECD 201, but concern on physical effect (shading) of undissolved Bi powder on algae growth

Justification for type of information:

Please see read-across justification attached below.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

The test solutions are prepared by weighing the test substance directly in 150 mL Erlenmeyers (5 Erlenmeyers at each concentration). The amount og Bi added to each Erlenmeyer ranged between 1 and 16 mg Bi/L. The powder could not be dissolved.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The pre-culture which is used for the inoculation of the test cultures is incubated under the conditions of the test. After an incubation of 3 days, the cell density of the pre-culture is 4.33 x 10^6 cells/mL.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

24 mg CaCO3/L

Test temperature:

22.3-23.2 °C

pH:

7.56-9.67

Dissolved oxygen:

not reported

Nominal and measured concentrations:

nominal addedconcentrations: 0-1-2-4-8-16 mg/L; measured total dissolved concentration is <0.05 mg Bi/L for the 4 and 8 mg Bi/L treatments.

Details on test conditions:

Initial algae cell concentration is 1 x 10^4 cells/mL. Algae are introduced into 150 mL Erlenmeyers containing 100 mL of test solution. Test medium is according to OECD 201 guidelines. Erlenmeyers are placed on a laboratory shaker. Three replicates per concentration.
One of the replicates is not shaked during the test in order to detect the influence of shaking on the toxicity of Bismuth to algae.
Uniform illumination is provided by Phillips TL-33 lamps yielding approx. 10 000 lux at the surface of the test solutions. Sampling of algae is performed by pouring the test solution (including the settled fraction) through a filter. The filtrate is analysed to determine the concentration of dissolved Bi and the filter is analysed to determine the sum of the dispersed and the settled fractions. Samples are stored at room temperature. Inhibition of algae growth is the effect parameter measured.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

29 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 16.4-51.0; for shaken samples; based on nominal added concentrations

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

growth rate

Remarks on result:

other: for shaken samples; based on nominal added concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

54.7 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 16.5-223.8; for not shaken samples; based on nominal added concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.5 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 2.1-6.1; for shaken samples; based on nominal added concentrations

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

biomass

Remarks on result:

other: for shaken samples; based on nominal added concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

14.3 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Bi

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 9.1-22.6; for not shaken samples; based on nominal added concentrations

Details on results:

Concern on physical effect on Bi powder which is stirred up.

Reported statistics and error estimates:

EC50 values and their confidence intervals were calculated by probit analysis
NOEC is determined by a one way ANOVA followed by Dunnett's test

Validity criteria fulfilled:

yes

Conclusions:

Study is performed according to OECD 201, but concern on physical effect (shading) of Bi powder on algae growth. Study is disregarded.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

11 May 2010 - 22 May 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP test according to OECD guidelines. Rated as Klimisch 2 because it is a read-across study.

Justification for type of information:

Please see read-across justification below.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
- Melting point: > 500 degrees C
- Vapour pressure: 3.4 x 10-5 Pa at 20 degrees C
- Water solubility (under test conditions): 900.7 mg/L at 20 degrees C

Analytical monitoring:

yes

Details on sampling:

Samples from control and the test item concentration were taken at the start end the end of the exposure period and analysed to determine the actual test item concentrations in comparison to the nominally applied concentrations.
Before analysis, the samples were stored in a refrigerator in polyethylene bottles.

Vehicle:

no

Details on test solutions:

A stock solution (water-accommodated fraction, WAF) at a loading rate of nominal 137 mg test item/L (=100 mg Bi/L) was prepared by dissolving 137.4 mg of the test item in 1004 mL of test medium. This stock solution was agitated for seven days by using a horizontal laboratory shaker at ambient temperature in the dark. The shaker was set to a frequency of 100 rpm to keep the test item in permanent suspension according to OECD guideline. After that, the stock solution was filtered (glass fibre filter, pore size 0.4 µm). The filtrate was used to prepare the desired test item concentrations.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

common name: green algae (SAG 61.81)
breeder: Georg-August-Universität Göttingen

To adjust the algae to the test conditions a pre-culture was inoculated by an agar stock culture and incubated under test conditions:
pH-value of the algal medium: 5.9
Amount of liquid stock culture per pre-culture vessel: 100 mL
Pre-culture vessels: 300 mL Erlenmeyer flasks
Number of replicates: 2
Light: light/dark (24/0 h); fluorescent tubes of universal white type
Light intensity: 60 – 120 µE/m2 * s
Shaker: 100 ± 5 oscillations/min
Temperature in the test room: 21 - 24°C, controlled at ± 2°C

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

No data

Test temperature:

22.3-24.0 °C

pH:

5.9-6.1

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

nominal added concentrations: control, 1, 3, 10, 30 and 100% of water-accommodated fraction (100 mg Bi/L), corresponding to measured dissolved Bi concentrations of <0.003, <0.003, <0.003, 0.006, 0.02 and 0.046 mg Bi/L (calculated as geometric mean of measured concentrations at start and end of exposure).

Details on test conditions:

-Age of the pre-culture: 4 days
-Number of cells per mL in the pre-culture before inoculating the test solution: 277 x 10^4
-Number of cells per mL test solution at the beginning of the test: 0.5 x 10^4
-Number of replicates per test item concentration: 3
-Number of replicates in the control: 6
-Number of replicates for stability check (limit concentration without algae): 2
-Light cycle: 24/0 hours light/dark
-Types of light: fluorescent tubes of universal white type (Osram Lumilux 58W/865)
-Light intensity: mean value of six measurements: 94.6 µE/m2s (required 60 to 120 µE*m2s1 equivalent to 4440 – 8880 lx)
-Shaker: 100 ± 5 oscillations/min; the test vessels were placed randomly on the shaker
-Counting of algae: daily
-Effect parameter: yield and growth rate

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 137 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 137 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 137 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 137 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

Effect parameter, EC50 and NOEC for yield and growth rate, values based on mean measured dissolved Bismut concentrations are all higher than 0.046 mg Bi/L.

Results with reference substance (positive control):

results of the reference test performed in january 2010: 72h-EC50 for growth rate is 0.85 mg/L. Based on an international ring test (ISO 2004) mentioned in OECD guideline 201, the 72h-EC50 value for potassium dichromate obtained from different laboratories should be 1.19 mg/L with a standard deviation of 0.27 mg/L. The experimentally obtained value of 0.85 mg/L is within the historical range of the results of the testing laboratory (mean EC50 value = 1.15 +- 0.42 mg/L) and within the upper (2.54 mg/L) and lower (0.44 mg/L) warning limit. The warning limits were calculated as two standard deviations from the historical mean of the EC50. Furthermore, the EC50 value is within the refined range of 1.10 +- 0.48 mg/L, recommended based on an international ring test (pattard et al. 2009). Therefore, the results of this reference test are acceptable and the test conditions are reliable.

Reported statistics and error estimates:

The data were evaluated for homogeneity of variances by Levene's Test, and by Williams' test to calculate whether there were significant differences between the growth of algae in the controls and the algae exposed to the test item concentrations.

Treatment [% of WAF]	%Inhibition of Yield (72 h)	Significant difference from control (p≤0.05)	%Inhibition of Growth Rate (72 h)	Significant difference from control (p≤0.05)
Control	0.0	No	0.0	No
1	-13.5	No	-2.3	No
3	-12	No	-2	No
10	-10.6	No	-1.7	No
30	4.4	No	0.8	No
100	2.0	No	0.4	No

Validity criteria fulfilled:

yes

Conclusions:

GLP test according to OECD 201 guideline. The 72h-EC50 for growth rate and biomass yield of Pseudokirchneriella subcapitata are both > 137 mg/L test item (> 100 mg Bi/L).

Executive summary:

This was a GLP test according to OECD 201 guideline using the related substance, bismuth subnitrate.

The 72h-EC50 for growth rate and biomass yield of Pseudokirchneriella subcapitata are both > 137 mg/L test iten (100 mg Bi/L).

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

A reliable GLP-conform study according to the OECD 201 guideline is available for the effect of the water-accommodated fraction of bismuth subnitrate (Bi₅O(OH)₉(NO₃)₄) after seven days equilibration on the biomass and growth rate of the alga Pseudokirchneriella subcapitata (Egeler and Kiefer, 2010). No statistically significant differences were found for the parameters growth rate and biomass yield between the control and the test item concentrations up to the water-accommodated fraction at a loading rate of 100 mg Bi/L and the EC50 (72 h) was determined to be higher than the highest tested concentration. The results of the study demonstrate that the no-observed effect concentration (NOEC) at p ≤ 0.05 for Pseudokirchneriella subcapitata for the parameters yield and growth rate is also ≥ the water-accommodated fraction at a loading rate of 100 mg Bi/L (nominal concentration), corresponding to ≥ a measured dissolved Bi concentration of 0.046 mg Bi/L.

No data are available for the toxicity of bismuth to marine algae.