Lithium acetate

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:

2010-09-20 to 2010-10-22

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

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.: 1047

Analytical monitoring:

yes

Details on sampling:

At the start of the experiment five parallel samples were taken from each concentration level and from the control. At the end two samples were taken from each replicate test vessel and from the control. Representative samples (in duplicate series) were taken at the start and at the end of the experiment. One series are stored frozen (approx. -20 °C) in the testing laboratory, one series was sent for analysis, and was analysed immediately after sampling. The analysis was performed according to the results of the validated analytical method (Ion Selective Electrode (ISE) based on potentiometry).

Vehicle:

no

Details on test solutions:

A solution of the test item with a concentration of 160 mg/L in Algal Mineral Salts Test Medium (“OECD Medium”) was prepared just before the main experiment by mechanical dispersion. The Algal Mineral Salts Test Medium (according to OECD 201) was prepared by adding the appropriate volumes of following stock solutions to deionised water.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Source: SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Nikolausberger Weg 18, 37073 Göttingen, Germany
- Method of cultivation: The stock cultures are small algal cultures that are planted on agar regularly. These are transferred to fresh medium at least once every two months under standardized conditions according to the test guidelines. The pre-culture is intended to give an amount of algae suitable for the inoculation of test cultures. The pre-culture was prepared with Algal Mineral Salts Culture Medium, incubated under the conditions of the test and used when still exponentially growing, normally after an incubation period of about three days. The pre-cultured algal cultures were healthy and did not contain deformed or abnormal cells.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

Determination of Cell Number
The cell number was determined at 24, 48 and 72 hours after starting the test by manual cell counting using a microscope with a counting chamber.
The cell morphology was examined in parallel.

Behavior of the test item
The behavior of the test item in test medium was determined daily (at the cell counting) in all test concentrations.

Test temperature:

The cultures were maintained at a temperature in the range of 21 – 24 °C controlled at ± 2 °C, which was checked at the beginning of the study and every 24 hours in a flask filled with water. In addition, the temperature was continuously measured (with a min/max thermometer) within the climate chamber.

pH:

The pH of the stock solution was adjusted to the pH of the Algal Mineral Salts Test Medium (to ca. 7.83) using 1N HCl at the start of the test. The pH should normally not vary by more than 1.5 units in any one test. However, due to the test item character, the pH variation in this test at the concentrations of 0, 5, and 20 mg/L was more than 1.5 units during adjustment.

Nominal and measured concentrations:

The nominal test item concentrations were 5; 10; 20; 40; 80 and 160 mg test item/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks of 250 mL volume with 100 mL test medium
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: Yes
- Light intensity and quality: 8000 lux (in average of 8015 lux)

Equipment:
Normal laboratory equipment and the following were necessary for determination of the parameters of the test:
- balance
- pH meter
- thermometer
- light-meter
- laboratory orbital shaker
- microscope with counting chamber
- climate chamber

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

41.62 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 36.78 - 47.09

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

153.44 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 120.05 - 196.12

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: biomass and growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: biomass and growth rate

Details on results:

Analytical Results:
At the start and at the end of the test the four highest (nominal) concentrations, 20, 40, 80 and 160 mg/L were above the quantification limit (the limit of quantification of the analytical method was 0.5 mmol Li+/L, equivalent to 20 mg lithium hydroxide monohydrate /L) of the analytical method, and these measured test item concentrations were 96-102 % of the nominal at the start and 94-101 % of the nominal at the end of the test. The concentrations of 5 and 10 mg/L were out of the measurable range.
There is evidence that the concentrations of the tested substance (20-160 mg/L) were satisfactorily maintained within ± 20 % of the nominal concentrations throughout the test. The two lowest not analysed concentration levels were considered as being within the ± 20 % of the nominal range; therefore the analysis of the results was based on the nominal concentration values. All reported biological results are related to the nominal concentrations of the test item.

Biological Results:
The test item had a statistically significant inhibitory effect on the growth based on the average specific growth rate, yield and areas under the growth curves of Pseudokirchneriella subcapitata after the exposure period of 72 hours in the concentration range of 20–160 mg test item/L. The test concentration of 20 mg/L was determined as the 72-hour LOEC.

Microscopic Examinations:
Shape of the Algal Cells: The shape of the algal cells growing was obviously not affected.
Cell Density in Control: In the control the cell density has increased from nominal N = 1E4 cells/mL at the start of the test (0 hours) to N = 82.67E4 cells/mL (mean value) after 72 hours by a factor of 82.67. Thus, the algal growth in the control was high enough to pass the validity criteria in this assay.


pH-Values: pH 7.80 to 7.83 at test start; pH 8.08 to 9.92 at test end
Temperature in the test media: 22.8 - 23.1 °C
Behaviour of the Test Item: There were no remarkable observations

Results with reference substance (positive control):

Reference Standard
For the evaluation of the quality of the algae and the experimental conditions potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.
The ErC50 value of potassium dichromate of the last study is: 1.05 mg/L (95 % confidence limits: 0.96 - 1.16 mg/L).
The growth rate, 72h value is in accordance with the accepted 1.10 ± 0.48 mg/L range for Pseudokirchneriella subcapitata.

Reported statistics and error estimates:

Statistical analysis:
Mean values and standard deviations were calculated for each treatment at the start, and at the end of the test using Excel for Windows software. Percentage inhibition of area (A), yield (Y) and growth rate (r) were calculated using Excel for Windows software. The EC50 values of the test item and their confidence limits were calculated using Probit analysis. The analysis was done using the TOXSTAT statistical software program. For the determination of the LOEC and NOEC, the calculated mean biomass b (area under the growth curve), growth rates r and yield at the test concentrations were tested on significant differences to the control values by Dunnett’s Test (at the 24-hour average specific growth rates and areas under the growth curves), Bonferroni t-Test and Williams’test by TOXSTAT software. The data were checked for normality by Chi-Square Test, for homogeneity of variance by Levene’s Test.

Influence of lithium hydroxide monohydrate on the growth of Pseudokirchneriella subcapitata:

Parameter (0-72 h)	Calculation based on
	Biomass b	Growth rate r
	[mg/L]	[mg/L]
EC 50	41.62	153.44
95 % conf. limits	36.78 - 47.09	120.05 - 196.12
NOEC	10	10
LOEC	20	20

Validity criteria fulfilled:

yes

Conclusions:

Lithium hydroxide monohydrate was tested for toxicity to algae in a 72 h static test according to EU Guideline C.3 and OECD Guideline 201. The results showed an EC50 value of 41.62 mg/L based on biomass and 153.44 mg/L based on growth rate (equivalent to 23.75 mg/L resp. 87.57 mg/L referred to lithium hydroxide anhydrous). The NOEC based on growth rate for lithium hydroxide monohydrate was 10 mg/L. The NOEC calculated for lithium hydroxide anhydrous was 5.71 mg/L.

Executive summary:

The influence of the test item lithium hydroxide monohydrate on the growth of Pseudokirchneriella subcapitata was investigated in a 72 h static test according to EU method C.3 and OECD Guideline No 201. The test item had a statistically significant inhibitory effect on the growth based on the average specific growth rate, yield and areas under the curves of Pseudokirchneriella subcapitata after the exposure period of 72 hours in the concentration range of 20 - 160 mg/L test item/L (Bonferroni t-Test, alpha=0.05). The test concentration of 20 mg/L was determined as the 72-hour LOEC. The results showed an EC50 value of 41.62 mg/L based on biomass and 153.44 mg/L based on growth rate (equivalent to 23.75 mg/L resp. 87.57 mg/L referred to lithium hydroxide anhydrous). The NOEC based on growth rate for lithium hydroxide monohydrate was 10 mg/L. The NOEC calculated for lithium hydroxide anhydrous was 5.71 mg/L.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH
Lithium acetate completely dissociates in water forming lithium cation and the corresponding acetate anion. Thus, lithium salts with different anion moieties were found to be suitable candidates for read-across. (Eco)toxicological properties were extrapolated to different endpoints by using the lowest effect concentration.
For further information, please refer to the read-across justification in chapter 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

241.31 mg/L

Nominal / measured:

nominal

Conc. based on:

other: recalculated for lithium acetate anhydrous

Basis for effect:

growth rate

Remarks on result:

other: Based on LiOH*H2O (559.820.2267, 2010)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

373.03 mg/L

Nominal / measured:

nominal

Conc. based on:

other: recalculated for lithium acetate dihydrate

Basis for effect:

growth rate

Remarks on result:

other: Based on LiOH*H2O (559.820.2267, 2010)

Description of key information

Lithium hydroxide monohydrate was tested for toxicity to algae in a 72 h static test according to EU Guideline C.3 and OECD Guideline 201. The results showed an EC50 value of 41.62 mg/L based on biomass and 153.44 mg/L based on growth rate (equivalent to 23.75 mg/L resp. 87.57 mg/L referred to lithium hydroxide anhydrous). The NOEC based on growth rate for lithium hydroxide monohydrate was 10 mg/L. The NOEC calculated for lithium hydroxide anhydrous was 5.71 mg/L.

Based on these data, the calculated EC50 values for lithium acetate anhydrate and dihydrate are 241.31 and 373.03 mg/L. The NOEC values for both substances were 15.73 and 24.31 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

241.31 mg/L

EC10 or NOEC for freshwater algae:

15.73 mg/L

Additional information

A toxicity study on aquatic algae with lithium acetate is not available. Consequently, read-across was applied using a characteristically similar compound, lithium hydroxide monohydrate (see IUCLID section 13 for read-across justification).

The influence of the test item lithium hydroxide monohydrate on the growth of Pseudokirchneriella subcapitata was investigated in a 72 h static test according to EU method C.3 and OECD Guideline No. 201. The test item had a statistically significant inhibitory effect on the growth based on the average specific growth rate, yield and areas under the curves of Pseudokirchneriella subcapitata after the exposure period of 72 hours in the concentration range of 20 - 160 mg/L test item/L (Bonferroni t-Test, alpha=0.05). The test concentration of 20 mg/L was determined as the 72-hour LOEC. The results showed an EC50 value of 41.62 mg/L based on biomass and 153.44 mg/L based on growth rate (equivalent to 23.75 mg/L resp. 87.57 mg/L referred to lithium hydroxide anhydrous). The NOEC based on growth rate for lithium hydroxide monohydrate was 10 mg/L. The NOEC calculated for lithium hydroxide anhydrous was 5.71 mg/L.

Based on these data, the calculated EC50 values for lithium acetate anhydrate and dihydrate are 241.31 and 373.03 mg/L. The NOEC values for both substances were 15.73 and 24.31 mg/L, respectively.