Trilithium orthophosphate

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:

experimental study

Adequacy of study:

key study

Study period:

2010-04-30 to 2010-07-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: 1125

Analytical monitoring:

yes

Details on sampling:

In order to confirm correct dosage and stability of exposure concentration samples (about 50 mL) of the control and all test concentrations were taken from separate vessels including culture medium (controls), test solutions and algae at 0 h and 72 h. In order to remove the algae from the test solutions, AES-analysis was performed after centrifugation of the samples at 3950 rpm for 10 minutes, followed by dilution of the samples in deionised water to meet the linear range of the calibration lines.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test solutions were prepared in a dilution series from a stock solution of 100 mg/L of the test Item in culture medium for the range-finding test and from a stock solution of 400 mg/L of the test item in culture medium for the definitive test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The range-finding test and the definitive test were performed as static tests, i.e., without renewal of the test solutions. The controls were kept in culture-medium. Vessels including culture-medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. Concentration-analysis was performed at 0 h and 72 h. The Alga-test was carried without adjustment of the pH.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus (Chlorophyceae, Chlorococcales),
- Strain: SAG 86.81
- Source (laboratory, culture collection): Albrecht von Haller Institut für Pflanzenwissenschaften der Universität Göttingen
- Method of cultivation: Sterile on agar tubes (0.8 % Agar). Transferred to a new agar tube every 2 months.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24.2 to 24.7 °C

pH:

in the flasks at 0 h:
8.0 to 10.9

in the flasks at 72 h:
9.6 to 10.6

The test item had a significant effect on the pH of the test solutions at the start of the exposure period.

Nominal and measured concentrations:

Nominal test concentrations: Control, 25.0 mg/L, 50.0 mg/L, 100 mg/L, 200 mg/L, 400 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks (test volume 100 mL)
- Aeration: none
- Initial cells concentration: 5000 cells/mL
- No. of vessels per test group (replicates): 3
- No. of vessels per control group (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Li2CO3

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

90 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Li2CO3

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Li2CO3

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Li2CO3

Basis for effect:

growth rate

Details on results:

The test item had a significant effect on the pH of the test solutions at the start of the exposure period. The increase of pH in the control and test concentration of 25.0 mg/L during the exposure period is caused by the growth of the algae in the test vessels. In common with other species of fresh-water algae, Desmodesmus subspicatus gains CO2 from HCO3-, leading to a release of hydroxide ions, that raised the pH of the medium. After 72 hours, the pH at test concentration of 100 mg/L had remained stable, a slight decrease of the pH was observed at test concentrations of 50, 200 and 400 mg/L when compared to the 0 hour measurements. In the test the increase of pH in the control of 2.6 (> 1.5 units as recommended in OECD-Guideline 201) had no effect on the growth of the algae as the validity criteria for algal growth were fulfilled.

Reported statistics and error estimates:

The Kolmogorov-Smirnov-test determined normality of the data (α = 0.05). The results of a one-way ANOVA showed a significant effect on the specific growth rate [µ] in the presence of lithium carbonate (F = 66.04; F critical = 5, 12, α = 0.05 = 3.11). Bartlett`s test detected homogeneity of variances (α = 0.05). Dunnett`s test for comparison of the treatment groups with the control showed significant differences between the control and the effective concentrations of 100, 200 and 400 mg/L (α = 0.05).

Concentration of the test item, cells/mL in the test flasks at 72 h, average specific growth rate [µ]over the whole testing period 0-72 h, mean value of the average specific growth rate [µ], standard deviation and coefficient of variation Vc[%], inhibition [%] and mean value of inhibition [%] of the average specific growth rate [µ] in the definitive test:

Concentration [mg/L]	Cells / mL	Average Specific growth rate [µ]	Average Specific growth rate [µ] Mean value	Standard deviation	Coefficient of variation Vc [%]	Inhibition of Average Specific growth rate [%]	Inhibition of Average Specific growth rate Mean value [%]
	72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h
Control 1	720000	1.66	1.66	0.01	0.90
Control 2	752000	1.67
Control 3	688000	1.64
25.0	752000	1.67	1.68	0.01	0.82	-0.89	-1.37 *
25.0	808000	1.70				-2.33
25.0	752000	1.67				-0.89
50.0	512000	1.54	1.57	0.08	5.02	6.85	5.15
50.0	728000	1.66				-0.24
50.0	464000	1.51				8.83
100	312000	1.38	1.44	0.06	3.93	16.8	13.0 **
100	432000	1.49				10.3
100	400000	1.46				11.8
200	320000	1.39	1.33	0.06	4.49	16.3	20.0 **
200	224000	1.27				23.5
200	264000	1.32				20.2
400	136000	1.10	1.09	0.02	2.22	33.5	34.4 **
400	136000	1.10				33.5
400	120000	1.06				36.0

* Remark: A negative inhibition value means an enhancement of the parameter.

** Significant difference compared to the control according to Dunnett`s test (p = 0.05).

Validity criteria fulfilled:

yes

Conclusions:

In this 72-h algal growth inhibition test with Desmodesmus subspicatus the 72-h EC50 of lithium carbonate based on growth rate was determined as greater than 400 mg/L. The overall NOEC was determined to be 50 mg/L. The results are based on the nominal concentrations.

Executive summary:

A toxicity study on aquatic algae with lithium phosphate is not available. Consequently, read-across was applied using a characteristically similar compound, lithium carbonate.

The effect of lithium carbonate on the growth of an algal species Desmodesmus subspicatus over a 72-hour static exposure period was assessed according to OECD guideline 201. The test solutions were prepared in a dilution series from a stock solution of 100 mg/L of the test item in culture medium for the range-finding test and from a stock solution of 400 mg/L of the test item in culture medium for the definitive test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The controls were kept in culture medium. Vessels including culture medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. Concentration analysis was performed at 0 h and 72 h. The Alga-test was carried without adjustment of the pH. AES-analysis confirmed that the test solutions were correctly dosed, i.e., the recoveries were within 92.4 to 103 % of the nominal concentrations at study start. At the end of the exposure, i.e., after 72 hours, the recoveries ranged from 95.9 to 103 % of the nominal concentrations demonstrating that the lithium concentrations were stable throughout the exposure period. Consequently, the results of the definitive test were based on nominal concentrations. In this 72-h algal growth inhibition test with Desmodesmus subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg/L for lithium carbonate. The overall NOEC was determined to be 50 mg/L for lithium carbonate (the calculated NOEC for lithium ion: 9.39 mg/L). The results are based on the nominal concentrations.

Based on these data, the calculated EC50 and NOEC values for lithium phosphate are 94.02 mg/L and 52.24 mg/L, respectively.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-04-30 to 2010-07-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: 1189

Analytical monitoring:

yes

Details on sampling:

In order to confirm correct dosage and stability of exposure concentrations samples (about 50 mL) of the control and all test concentrations were taken from separate vessels including culture-medium (controls), test solutions and algae at 0 h and 72 h. In order to remove the algae from the test solutions, AES-analysis was performed after centrifugation of the samples at 3950 rpm for 10 minutes, followed by dilution of the samples in deionised water to meet the linear range of the calibration lines.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test solutions were prepared in a dilution series from a stock solution of
100 mg/L of the Test Item in culture-medium for the range-finding test and from a stock solution of 400 mg/L of the Test Item in culture-medium for the Definitive Test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The Range-Finding Test and the Definitive Test were performed as static tests, i.e., without renewal of the test solutions. The controls were kept in culture-medium. Vessels including culture-medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. Concentration-analysis was performed at 0 h and 72 h. The algae-test was carried without adjustment of the pH.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus (Chlorophyceae, Chlorococcales),
- Strain: SAG 86.81
- Source (laboratory, culture collection): Albrecht von Haller Institut für Pflanzenwissenschaften der Universität Göttingen
- Method of cultivation: Sterile on agar tubes (0.8 % Agar). Transferred to a new agar tube every 2 months.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24.2 to 24.7 °C

pH:

in the flasks at 0 h:
7.7 to 8.0

in the flasks at 72 h:
9.6 to 10.5

The test item had a significant effect on the pH of the test solutions at the start of the exposure period.

Salinity:

NA

Nominal and measured concentrations:

Nominal test concentrations: Control, 25.0 mg/L, 50.0 mg/L, 100 mg/L, 200 mg/L, 400 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks (test volume 100 mL)
- Aeration: None
- Initial cells concentration: 5000 cells/mL
- No. of vessels per test group (replicates): 3
- No. of vessels per control group (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiCl

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

80 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiCl

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiCl

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiCl

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

112 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiCl

Basis for effect:

other: yield

Details on results:

The test item had no significant effect on the pH of the test solutions at the start of the exposure period. The increase of pH in the control and test concentrations of 25.0 to 400 mg/L during the exposure period is caused by the growth of the algae in the test vessels. In common with other species of freshwater algae, Desmodesmus subspicatus gains CO2 from HCO3-, leading to a release of hydroxide ions, that raise the pH of the medium. In the test the increase of pH in the control of 2.6 (> 1.5 units as recommended in OECD-Guideline 201) had no effect on the growth of the algae as the validity criteria for algal growth were fulfilled.

Reported statistics and error estimates:

The Kolmogorov-Smirnov-test determined normality of the data (α = 0.05). The results of a one-way ANOVA showed a significant effect on the specific growth rate [µ] in the presence of Lithium chloride (F = 132.8; F critical = 5, 12, α = 0.05 = 3.11). Bartlett`s test detected homogeneity of variances(α = 0.05). Dunnett`s test for comparison of the treatment groups with the control showed significant differences between the control and the effective concentrations of 50.0, 100, 200 and 400 mg/L (α = 0.05).

Concentration of the test item, cells/mL in the test flasks at 72 h, average specific growth rate [µ] over the whole testing period 0-72 h, mean value of the average specific growth rate [µ], standard deviation and coefficient of variation Vc [%], inhibition [%] and mean value of inhibition [%] of the average specific growth rate [µ] in the Definitive Test:

Concentration [mg/L]	Cells / mL	Average Specific growth rate [µ]	Average Specific growth rate [µ] Mean value	Standard deviation	Coefficient of variation Vc [%]	Inhibition of Average Specific growth rate [%]	Inhibition of Average Specific growth rate Mean value [%]
	72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h
Control 1	720000	1.66	1.66	0.01	0.90
Control 2	752000	1.67
Control 3	688000	1.64
25.0	720000	1.66	1.66	0.01	0.87	-0.01	-0.52 *
25.0	720000	1.66				-0.01
25.0	776000	1.68				-1.52
50.0	576000	1.58	1.56	0.02	1.26	4.48	5.65 **
50.0	544000	1.56				5.63
50.0	512000	1.54				6.85
100	288000	1.35	1.42	0.07	4.59	18.4	14.2 **
100	424000	1.48				10.6
100	368000	1.43				13.5
200	248000	1.30	1.28	0.03	2.64	21.4	22.6 **
200	248000	1.30				21.4
200	208000	1.24				25.0
400	144000	1.12	1.11	0.02	2.05	32.4	33.2 **
400	128000	1.08				34.8
400	144000	1.12				32.4

* Remark: A negative inhibition value means an enhancement of the parameter.

** Significant difference compared to the control according to Dunnett`s test (p = 0.05).

Validity criteria fulfilled:

yes

Conclusions:

In this 72-h algal growth inhibition test with Desmodesmus subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg/L. The overall NOEC was determined to be 25 mg/L. The results are based on the nominal concentrations.

Executive summary:

A toxicity study on aquatic algae with lithium phosphate is not available. Consequently, read-across was applied using a characteristically similar compound, lithium chloride.
The effect of lithium chloride on the growth of an algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201. The test solutions were prepared in a dilution series from a stock solution of 100 mg/L of the test item in culture-medium for the range-finding test and from a stock solution of 400 mg/L of the test item in culture medium for the definitive test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The controls were kept in culture medium. Vessels including culture-medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. AES-analysis confirmed that the test solutions were correctly dosed, i.e., the recoveries were within 91.9 to 98.2 % of the nominal concentrations at study start. At the end of the exposure, i.e., after 72 hours, the recoveries ranged from 92.4 to 97.8 % of the nominal concentrations demonstrating that the lithium concentrations were stable throughout the exposure period. Consequently, the results of the definitive test were based on nominal concentrations. In this 72-h algal growth inhibition test with Desmodesmus subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg lithium chloride/L. The overall NOEC was determined to be 25 mg lithium chloride/L. The results are based on the nominal concentrations.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchnerella subcapitata
- Strain: No. ATCC 22662; UTEX 1648
- Method of cultivation: An OECD culture medium was deluted to produce the biomass of 1 X 10^4 cells/mL and then sub-cultured continuously at intervals of 3 to 4 days. For pre-cultivation, the test algae were inoculated into the OECD culture medium at a biomass of 0.5-1.0 X 10^4 cells/mL 2 to 4 days prior to study initiation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.1 - 24.2 °C

pH:

7.50 - 9.08

Nominal and measured concentrations:

- Nominal: 4, 9, 21, 45 and 100 mg/L
- Calculated test concentration based on measured calcium concentrations: 0.08 - 0.88 and 0.61 - 1.56 mg/L at 0 and 72 hours, respectively.

Details on test conditions:

TEST SYSTEM
- Initial cells density:0.5-1.0 X 10^4 cells/mL

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity: 4,440 - 8,880 Lux

TEST CONCENTRATIONS
- Range-finding study: Yes. The range-finding test was conducted at control, 0.1, 1, 10 and 100 mg/L, and the percent inhibition of growth rates was 19% for the average specific growth rate and 59% for the area under growth curve method at the highest dose of 100 mg/L.
- Test concentrations: the definitive test was conducted using the nominal concentrations of 0, 4, 9, 21, 45 and 100 mg/L.
- Results used to determine the conditions for the definitive study: The percent inhibition of growth rates was 19% for the average specific growth rate and 59% for the area under growth curve method at the highest dose of 100 mg/L. Therefore, the definitive test was conducted using the nominal concentrations of 0, 4, 9, 21, 45 and 100 mg/L

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: measured concentration: >1.56 mg/L

Reported statistics and error estimates:

Statistical anaylsis was not performed, since less than 50% of growth inhibition at 100 mg/L (nominal) was observed in the test.

Conclusions:

In all the test concentrations, the growth rates of algal cells were higher than those of the control. Therefore, it was determined that the test substance would cause growth stimulation rather than growth inhibition.
In the alga growth inhibition test, the 72 hours EC50 was calculated to be >100 mg/L (measured concentration: >1.56 mg/L) using the average specific growth rate and the area under the growth curve method. Based on these data, the calculated LC50 for lithium phosphate is >74.66 mg/L.

Executive summary:

A toxicity study on aquatic algae with lithium phosphate is not available. Consequently, read-across was applied using a characteristically similar compound, tricalcium phosphate.

The effect of tricalcium phosphate on the growth of an algal species Pseudokirchnerella subcapitata over a 72-hour static exposure period was assessed according to OECD guideline 201.The test was conducted using the nominal concentrations of 4, 9, 21, 45 and 100 mg/L. The mean concentrations of the test substance were 0.08 -0.88 and 0.61 -1.56 mg/L at 0 and 72 hours, respectively, ranging between 0.8 and 15.3% of the nominal concentrations. Therefore, all the test results were expressed as nominal concentration because the test substance was insoluble in water. Algal cells were observed after 72 hours of exposure, and the results showed that there were no morphological changes at control, maintaining a semicircular shape. In all the test concentrations, the growth rates of algal cells were higher than those of the control. The algal growth inhibition test, the 72 hours EC50 was calculated to be >100 mg/L (measured concentration: >1.56 mg/L) using the average specific growth rate and the area under the growth curve method.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchnerella subcapitata
- Strain: No. ATCC 22662; UTEX 1648
- Method of cultivation: An OECD culture medium was deluted to produce the biomass of 1 X 10^4 cells/mL and then sub-cultured continuously at intervals of 3 to 4 days. For pre-cultivation, the test algae were inoculated into the OECD culture medium at a biomass of 0.5-1.0 X 10^4 cells/mL 2 to 4 days prior to study initiation.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

23.1 - 24.2 °C

pH:

7.50 - 9.08

Nominal and measured concentrations:

- Nominal: 0.3, 1, 3.1, 9.8, 31.3 and 100 mg/L
- Measured: 0.3, 0.4, 0.3, 0.8, 1.7 and 4.4 mg/L at the beginnung of the test. At 72 hours the test substance in the test solution was not detected at 0.3, 1.0 and 3.1 mg/L (nominal), but its concentrations at 9.8, 31.3 and 100 mg/L (nominal) were estimated to be 0.3, 1.6 and 4.7 mg/L.

Details on test conditions:

TEST SYSTEM
- Initial cells density:0.5-1.0 X 10^4 cells/mL

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity: 4,440 - 8,880 Lux

TEST CONCENTRATIONS
- Range-finding study: Yes. In the rang-finding test the algal were exposed to the following test item concentrations: 0, 0.1, 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: The percent inhibition of growth rates was 13.5% for the average specific growth rate and 51.4% for the yield at the highest dose of 100 mg/L. Therefore, the definitive test was performed using nominal concentrations of 0, 0.3, 1, 3.1, 9.8, 31.3 and 100 mg/L.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CaHPO4

Basis for effect:

growth rate

Remarks on result:

other: measured concentration: >4.4 mg/L

Reported statistics and error estimates:

Statistical anaylsis was not performed, since less than 50% of growth inhibition at 100 mg/L (nominal) was observed in the test.

Conclusions:

The 72 hours EC50 was estimated to be > 100 mg/L (measured concentration: > 4.4 mg/L) using the average specific growth rate and yield.

Executive summary:

A toxicity study on aquatic algae with lithium phosphate is not available. Consequently, read-across was applied using a characteristically similar compound, calcium hydrogen phosphate.

The effect of calcium hydrogen phosphate on the growth of the algal species Pseudokirchneriella subcapitata over a 72-hour static exposure period was assessed according to OECD guideline 201. The algal were exposed to the nominal concentrations of 0.3, 1, 3.1, 9.8, 31.3 and 100 mg Ca3HPO4/L. The test substance was detected to be significantly lower during the test. The measured concentrations of the test substance were 0.3, 0.4, 0.3, 0.8, 1.7 and 4.4 mg/L at the beginning of the test (0 hours). At 72 hours, the test substance in the test solution was not detected at 0.3, 1.0 and 3.1 mg/L (nominal), but its concentration at 9.8, 31.3 and 100 mg/L (nominal) were estimated to be 0.3, 1.6 and 4.7 mg/L. Algal cells were observed to maintain a similar shape to the control in all test solutions, and microorganisms other than algae were not observed. The 72 hours EC50 was estimated to be > 100 mg/L (measured concentration: > 4.4 mg/L) using the average specific growth rate and yield.

Description of key information

Based on the results of the read-across from lithium chloride, the calculated EC50 and NOEC values for lithium phosphate are >364.21 mg/L and 22.76 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

364.21 mg/L

EC10 or NOEC for freshwater algae:

22.76 mg/L

Additional information

A short-term toxicity study on aquatic invertebrates with lithium phosphate is not available. Consequently, read-across was applied using characteristically similar compounds: lithium carbonate and lithium chloride as well as tricalcium phosphate and calcium hydrogen phosphate. The lithium compounds were considered as key studies, because phosphate shows at low concentrations a growth-promoting effect on algae.

Key studies:

Read-across with lithium chloride (Steinbeis-Transferzentrum 2010)
The effect of lithium chloride on the growth of the algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201. The algae were exposed to a control (culture medium) and the test item at concentrations of 25, 50, 100, 200 and 400 mg/L. In this 72-h algal growth inhibition test with D. subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg/L. The 72-h EC50 on yield was 112 mg/L. The overall NOEC was determined to be 25 mg/L. The results are based on the nominal concentrations. Based on the results of the read-across from lithium chloride, the calculated EC50 and NOEC values for lithium phosphate are >364.21 mg/L and 22.76 mg/L, respectively.

Read-across with lithium carbonate (Steinbeis-Transferzentrum 2010)
The effect of lithium carbonate on the growth of the algal species Desmodesmus subspicatus over a 72-hour static exposure period was assessed according to OECD Guideline 201. The algae were exposed to a control (culture medium) and the test item at concentrations of 25, 50, 100, 200 and 400 mg/L. Concentration analysis was performed at 0 h and 72 h and demonstrated that the lithium concentrations were stable throughout the exposure period. In this 72-h algal growth inhibition test with D. subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg/L for lithium carbonate. The overall NOEC was determined to be 50 mg/L for lithium carbonate. Based on these data, the calculated EC50 and NOEC values for lithium phosphate are >417.88 mg/L and 52.24 mg/L, respectively.

Supporting studies:
Read-across with tricalcium phosphate (Kim et al. 2013)

The effect of tricalcium phosphate on the growth of an algal species Pseudokirchnerella subcapitata over a 72-hour static exposure period was assessed according to OECD Guideline 201.The test was conducted using the nominal concentrations of 4, 9, 21, 45 and 100 mg/L. The mean concentrations of the test substance were 0.08 - 0.88 and 0.61 - 1.56 mg/L at 0 and 72 hours, respectively, ranging between 0.8 and 15.3% of the nominal concentrations. Therefore, all the test results were expressed as nominal concentration because the test substance was insoluble in water. Algal cells were observed after 72 hours of exposure, and the results showed that there were no morphological changes at control, maintaining a semicircular shape. In all the test concentrations, the growth rates of algal cells were higher than those of the control. The algal growth inhibition test, the 72 hours EC50 was calculated to be >100 mg/L (measured concentration: >1.56 mg/L) using the average specific growth rate and the area under the growth curve method. Based on these data, the calculated LC50 for lithium phosphate is >74.66 mg/L.

Read-across with calcium hydrogen phosphate (Kim et al. 2013)
The effect of calcium hydrogen phosphate on the growth of the algal species Pseudokirchneriella subcapitata over a 72-hour static exposure period was assessed according to OECD Guideline 201. The algae were exposed to the nominal concentrations of 0.3, 1, 3.1, 9.8, 31.3 and 100 mg Ca3HPO4/L. The test substance was detected to be significantly lower during the test. The measured concentrations of the test substance were 0.3, 0.4, 0.3, 0.8, 1.7 and 4.4 mg/L at the beginning of the test (0 hours). At 72 hours, the test substance in the test solution was not detected at 0.3, 1.0 and 3.1 mg/L (nominal), but its concentration at 9.8, 31.3 and 100 mg/L (nominal) were estimated to be 0.3, 1.6 and 4.7 mg/L. Algal cells were observed to maintain a similar shape to the control in all test solutions, and microorganisms other than algae were not observed. The 72 hours EC50 was estimated to be >100 mg/L (measured concentration: >4.4 mg/L) using the average specific growth rate and yield. Based on these data, the calculated LC50 for lithium phosphate is >85.95 mg/L.

Conclusion:

The effect concentrations of lithium and phosphate compounds were evaluated in different algae tests. The results for the phosphate compounds showed, that phosphate has the potential to cause increased algal growth at low concentrations. Therefore, lithium was considered as the relevant toxicological moiety of lithium phosphate. The lowest observed EC50 of >364.21 mg Li3PO4/L was chosen as key value for chemical safety assessment.