Sodium (S)-lactate

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:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

< 100 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: EC10 derived as <100mmol/L which induces 16 and 38% effect

Duration:

7 d

Dose descriptor:

other: EC80

Effect conc.:

200 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: Effect reported and not statistically derived

Duration:

7 d

Dose descriptor:

other: EC16

Effect conc.:

100 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: Effects reported in the light and not statistically derived

Duration:

7 d

Dose descriptor:

other: EC38

Effect conc.:

100 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: Effect reported under dark and not statistically derived

Details on results:

The rate and extent of growth of Euglena gracilis under both auto- and heterotrophic conditions diminished when 100 and 200 mM NaCl were included in the growth media. Cells grown in the light were more resistant to the inhibitory effects of NaCl: 100 mM NaCl caused a 16% reduction in cell density after 7 days in the light vs a 38% reduction for cells grown in the dark, while the rate of growth from day 2 to day 3 decreased from 2 to 1.4 X 10E-6 cells/ day (30% inhibition) in light-grown cells, and from 2.7 to 1.7 x 10E-6 cells/ day (37% inhibition) in dark-grown cells. At a higher (200 mM) NaCl concentration, cell growth was inhibited to a similar extent (80% inhibition) either in the dark or under illumination.

Validity criteria fulfilled:

not applicable

Conclusions:

100 mM (5800 mg/L) NaCl caused a 16% reduction in cell density after 7 days in the light vs a 38% reduction for cells grown in the dark.

Executive summary:

A non-guideline study was conducted to investigate the effect of NaCl on the growth and other parameters of the protist Euglena gracilis. Cells were grown in the dark or under illumination and were exposed to the chemical for 7 days. The rate and extent of growth of Euglena gracilis under both auto- and heterotrophic conditions diminished when 100 and 200 mM NaCl were included in the growth media. Cells grown in the light were more resistant to the inhibitory effects of NaCl. 100 mM (5844 mg/L) NaCl caused a 16% reduction in cell density after 7 days in the light vs a 38% reduction for cells grown in the dark. At a higher (200 mM or 11688 mg/L) NaCl concentration, cell growth was inhibited to a similar extent (80% inhibition) either in the dark or under illumination. In conclusion, NaCl reduced the cell number of Euglena gracilis resulting in 38% (EC38) at 100 mM and 80% (EC80) at 200 mM but the ECx values were not statistically derived.

 

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

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:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 533 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.9 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.5 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL= 2.8-4.4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.8 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

By visual comparison of the measured and the calculated growth curves of algal suspensions exposed to the test substance with those of the algal controls the no-observed-effect-concentration (NOEC) of the 80 % aqueous solution of L(+)-lactic acid was estimated to be 1.9 g/L. Microscopic examination of the cells at the start and end of the incubation period revealed no abnormalities, however many bacteria were found in the cultures exposed to test substance concentrations of 1.0, 1.9 and 2.8 g/L.
The pH of the algal medium containing different test substance concentrations was adjusted to the range pH 7.5–8.0 at the start of the test. It was found to remain constant (pH 8.0–8.1) during the test. In the presence of algae the pH was found to slightly increase with algal cell density (pH 8.2–8.7).

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of lactic acid (pH adjusted to approximately 8) to green algae is higher than 533 mg/L actual concentration of lactate (TWA).

Executive summary:

In a 72 hour acute toxicity study, cultures of Selenastrum capricornutum (ATCC 22662) were exposed to L(+) lactic acid (80 % a.i.) at nominal concentrations of 0, 0.10, 0.33, 0.56, 1.0, 1.9 and 2.8 g/L under static conditions in accordance with the OECD 201 guideline. The NOEC and EC₅₀ values based on growth rate were 1.9 g/L and 3.5 g/L, respectively. There were no compound related phytotoxic effects. This toxicity study is classified as acceptable and satisfies the guideline requirements for alga growth inhibition study with S. capricornutum.

Results synopsis

Test organism: Selenastrum capricornutum

Test type: Static

72-hr E_bC₅₀: > 2.8 g/L (95% C.I.: 2.24–3.52 g/L), in terms of lactic acid

72-hr NOEC: > 533 mg/L, in terms of lactic acid

Endpoint(s) effected: Growth, abnormalities of the cells

An effect on the inoculum viability, as found in this test, may be expected when a substance loses its toxicity during the test, in this case probably due to biodegradation. The concentrations quoted in this report are the nominal concentrations of the test substance (a solution of about 80 % L(+) lactic acid) as supplied by sponsor. At the start of the test 65–82 % of the nominal test substance concentrations were found by chemical analysis. At the end of the test the concentrations were considerably lower: 15, 57 and 73 % at the three concentrations analysed. The actual concentrations of lactic acid tested at the start of the test were < 0.005, 0.020–0.065, 0.44–0.62, 1.45–1.74 g/L. According to the calculated time-weighted mean (see formula below from the OECD guideline 211: TWM = (conc0 – conc1)/(LN(conc0) – (LN(conc1))) the concentrations which should be used for effect calculations are 31 mg/L, 533 mg/L, and 1620 mg/L. The EC₅₀ and the NOEC from the test report have to be regarded as invalid, as they were calculated on the basis of nominal values. Concerning the NOEC of 1.9 g/L, the replicates with the test concentration of 1.9 g/L were not verified analytically. Therefore, no conclusion on the actual concentration can be drawn. However, the next lower concentration was assessed analytically, revealing that the NOEC is above 533 mg/L (time-weighted mean of the measured lactic acid concentration).

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

120 h

Dose descriptor:

EC50

Effect conc.:

2 430 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Reported statistics and error estimates:

No statistic described, no error estimates provided.

Validity criteria fulfilled:

not specified

Conclusions:

EC50 (120 hr, Nitzschia linearis, cell counts) = 2430 mg/L

Executive summary:

In a 120 hour acute toxicity study, cultures of Nitschia linearis (diatom) were exposed to Sodium chloride. The EC50 value for 120 hours based on cell number was 2430 mg/L, respectively. 

Results synopsis

Test Organism: Nitschia linearis                 

120 hr EC50: 2430 mg/L             

 

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Description of key information

By way of read-across from lactic acid and sodium chloride, it is concluded that Sodium (S)-lactate is non-toxic to algae.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

533 mg/L

Additional information

Sodium (S)-lactate fully dissociates into Na+ ions and lactate. The ecotoxicology of Sodium (S)-lactate can thus be understood in terms of the ecotoxicology of sodium chloride and lactic acid.

The NOEC (72 h) for algal growth inhibition by lactic acid is > 533 mg lactate/L (measured TWA; Hanstveit, 1992).

Experiments were performed in buffered solutions, i.e., the adjusted pH of the algal medium containing different test substance concentrations (pH 7.5–8.0 at the start of the test) remained largely constant (pH 8.0–8.1, pH 8.2–8.7 in the presence of algae) during the tests. Effects can therefore be assigned to lactate since lowering the pH as a result of administration of lactic acid was compensated.

For sodium chloride, two different studies were considered. Both studies reported similar effect values ranging from 2430 to 5800 mg/L, demonstrating only weak effects of sodium chloride on different algae and cyanobacteria species.

Based on the effect values for two suitable read-across partners, the target substance would neither be classified as acutely nor chronically toxic to algae and cyanobacteria in accordance with the CLP Regulation.