Sodium (S)-lactate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

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

Adequacy of study:

supporting 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

Dose descriptor:

NOEC

Effect conc.:

< 35 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: suspended solids and COD in effluent.

Remarks on result:

other: 35000 mg/L sodium chloride had only a slight adverse effect on the performance of the activated sludge process

Details on results:

The results indicated that relatively high concentrations of sodium chloride (up to 35000 mg/L) have only a slight adverse effect on the performance of the activated sludge process.

Conclusions:

A NOEC < 35000 mg/L was derived for the effect of Sodium chloride on the performance of activated sludge.

Executive summary:

The effect of Sodium chloride concentrations on activated sludge performance was investigated using a stepwise increasing concentration design over a duration of 7 months. The effect was studied based on concentration of suspended solids and COD in effluent. The results indicated that relatively high concentrations of Sodium chloride (up to 35000 mg/L) have only a slight adverse effect on the performance of the activated sludge process. Further increases in Sodium chloride beyond 35000 mg/L caused abrupt increases in effluent suspended solids. A NOEC < 35000 mg/L was derived for the effect of Sodium chloride on the performance of activated sludge.

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:

activated sludge respiration inhibition testing

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

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 88.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: corrected for lactic acid content of the test material (88.2 %)

Key result

Duration:

3 h

Dose descriptor:

EC0

Effect conc.:

>= 88.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: corrected for lactic acid content of the test material (88.2 %)

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 = 5.9 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Lactic acid does not inhibit activated sludge respiration at concentrations up to 88.2 mg/L (corrected for lactic acid content of the test material). Inhibition was -1.1 % (i.e. slight stimulation).

Executive summary:

The influence of L-(+)-lactic acid on the respiration rate of activated sludge was investigated after a contact time of 3 hours. The study procedure was based on OECD guideline 209 (adopted April 4, 1984), EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L133, adopted May 30, 1988 and ISO Standard 8192 (1986). The batch of the test material was a clear and colourless liquid (88.2 % aqueous solution of lactic acid) that could easily be mixed with water. A stock solution of 500 mg/L was prepared by adding 126.0 mg test substance to 250 ml of Milli-RO water. A stirring period of 30 minutes was used to accelerate dissolution and to ensure homogeneity. Volumes of the stock solution corresponding to the test concentration were then added to the test media. A concentration of 100 mg/L of the test material was tested in duplicate. Optimal contact between the test substance and test medium was ensured applying continuous aeration and stirring. No significant inhibition of the respiration rate of the sludge was recorded at 100 mg test material per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed. Since all criteria for acceptability of the test were met, this study was considered to be valid. In conclusion, under the conditions of this present test, L-(+)-lactic acid was not toxic to waste water (activated sludge) bacteria at a concentration of 88.2 mg/L (corrected for lactic acid content of the test material).

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

Sodium (S)-lactate fully dissociates into Na+ ions and lactate. The ecotoxicology of Sodium (S)-lactate can be understood in terms of the ecotoxicology of sodium ions and lactic acid. Sodium ions are known as an essential nutrient for microorganisms; they are non-toxic. No inhibition of activated sludge respiration was observed for lactic acid (88.2 %) at 100 mg/L. Thus, no toxic effects of sodium (S)-lactate on STPs are expected.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

109 mg/L

Additional information

Sodium (S)-lactate fully dissociates into Na+ ions and lactate. The ecotoxicology of Sodium (S)-lactate can be understood in terms of the ecotoxicology of sodium ions and lactic acid. Sodium ions are known as an essential nutrient for microorganisms; they are non-toxic. 

Lactic acid does not inhibit activated sludge respiration at concentrations up to 100 mg/L test material (88.3 mg/L pure lactic acid). Inhibition was -1.1% (stimulation). Note that lactic acid is produced by certain micro-organisms in sewage treatment plants, and removed by other micro-organisms in the same 'ecosystem'. As such, lactic acid is a ubiquitous and abundant natural component of active sewage treatment systems. No toxic effects of lactic acid on STPs are expected.

The NOEC for respiration inhibition by sodium (S)-lactate can be calculated from the NOEC for lactic acid: 88.2 × 1.24 = 109 mg sodium (S)-lactate/L. Note that the NOEC for lactic acid, thus also the NOEC for sodium (S)-lactate, is expected to be much higher because lactic acid is produced by certain micro-organisms in sewage treatment plants and removed by other micro-organisms in the same 'ecosystem'.

No toxic effects of sodium (S)-lactate on STPs are expected.