L-(+)-lactic acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Specific details on test material used for the study:

80% lactic acid, batch no ZO 3456

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples taken at t= 0 and at end of exposure period (48 h for all concentrations except highest (24 h) since all organisms had died)
- Sampling method: 250 mL in glass bottles
- Sample storage conditions before analysis: None

Test organisms (species):

Daphnia magna

Details on test organisms:

The organism used was the fresh-water crustacean Daphnia magna, cultured in the laboratory under standard conditons, according to the principles of NPR 6503. The animals were less than 24 h old at the beginning of the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

220 mg/L CaCO3

Test temperature:

19.9 °C

pH:

Variable, depending on the concentration of lactic acid. Control pH 8.2

Dissolved oxygen:

≥ 7.9 mg/L

Nominal and measured concentrations:

Nominal test material (80 % lactic acid in water): 0, 32, 56, 180, 320, 560 mg/L
Nominal lactic acid concentrations: 0, 26, 144, 448 mg/L
Actual lactic acid concentrations: < 5, 15, 60-110, 340-350 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 150 mL glass beakers, open
- Renewal rate of test solution (frequency/flow rate): None
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dutch Standard Water (reconstituted water), prepared from Linschoten ground water
- Total organic carbon: 2 mg/L
- Metals: Na 1.26 mmol/L, K 0.23 mmol/L, Ca 1.41 mmol/L, Mg 0.78 mmol/L.
- Chlorine: 2.81 mmol/L,

OTHER TEST CONDITIONS
- Adjustment of pH: NA
- Photoperiod: 16 h light, 8 h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Immobilisation

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

130 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

Test solutions were not neutralised. Effects on the mobility of the daphnids are hence likely to be caused by the pH shift.

Validity criteria fulfilled:

yes

Conclusions:

The 48 h EC50 (immobilisation) of lactic acid to Daphnia magna is 130 mg/L, elicited by the pH shift.

Executive summary:

The acute toxicity of the test material, a solution of about 80 % L-(+)-lactic acid, to the fresh-water crustacean Daphnia magna was determined as described in the OECD guideline no. 202 and according to the OECD principles of Good Laboratory Practice. The test was carried out with 4 × 5 daphnias (quadruplicate test solutions) at each concentration, and the test solutions were not replaced. The exposure duration was 48 hours. The nominal concentrations tested were 32, 56, 100, 180, 320 and 560 mg/L. At the start of the test the test substance appeared to be completely dissolved at all concentrations tested (visually assessed). The actual concentrations of L-(+)-lactic acid were determined enzymatically with a Boehringer test kit. They were between 42 and 76 % of nominal just after dosing (average 59 %). To test the stability, the concentrations of L-(+)-lactic acid were also analysed at the end of the test and were between 58 and 78 % of nominal (average 71 %).

The results of the test were (as nominal concentrations):

24 h EC50 (mobility): 240 mg/L

48h EC50 (mobility): 240 mg/L

48h EC100 (mobility) 320 mg/L

The 48-h EC50 based on measured concentrations was 130 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): L(+) lactic acid
- Analytical purity: 80 % in water
- Isomers composition: Pure L-(+)-lactic acid

Analytical monitoring:

yes

Details on sampling:

No data

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Source: No data
- Age at study initiation (mean and range, SD): No data
- Weight at study initiation (mean and range, SD): No data
- Length at study initiation (length definition, mean, range and SD): No data
- Method of breeding: No data
- Feeding during test: No data
- Food type: No data
- Amount: No data
- Frequency: No data

ACCLIMATION
- Acclimation period: No data
- Acclimation conditions (same as test or not): No data
- Type and amount of food: No data
- Feeding frequency: No data
- Health during acclimation (any mortality observed): No data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

No data

Hardness:

No data

Test temperature:

No data

pH:

At 320 mg/L: pH 4.1
At 560 mg/L: pH 3.5

Dissolved oxygen:

No data

Salinity:

Not applicable - freshwater test

Nominal and measured concentrations:

No data

Details on test conditions:

TEST SYSTEM
- Test vessel: No data
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: No data
- Aeration: No data
- Renewal rate of test solution (frequency/flow rate): None; static test
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): No data
- No. of vessels per control (replicates): No data
- No. of vessels per vehicle control (replicates): No data
- Biomass loading rate: No data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: No data
- Total organic carbon: No data
- Particulate matter: No data
- Metals: No data
- Pesticides: No data
- Chlorine: No data
- Alkalinity: No data
- Ca/Mg ratio: No data
- Conductivity: No data
- Culture medium different from test medium: No data
- Intervals of water quality measurement: No data

OTHER TEST CONDITIONS
- Adjustment of pH: Not adjusted
- Photoperiod: No data
- Light intensity: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Immobility

TEST CONCENTRATIONS
- Spacing factor for test concentrations: No data
- Justification for using less concentrations than requested by guideline:
- Range finding study: None

Reference substance (positive control):

not specified

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 240 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % CL = 180-320

Details on results:

- Behavioural abnormalities: No data
- Observations on body length and weight: No data
- Other biological observations: No data
- Mortality of control: No data
- Other adverse effects control: No data
- Abnormal responses: No data
- Effect concentrations exceeding solubility of substance in test medium: No

Validity criteria fulfilled:

not specified

Conclusions:

The short-term toxicity testing of lactic acid on freshwater invertebrates (Daphnia magna) resulted in an EC50 (48 h) of 240 mg/L (nominal), which can be attributed to a pH effect.

Executive summary:

In a 48-h acute toxicity study, water fleas (Daphnia magna) were exposed to L-(+)-lactic acid at nominal concentrations of 0 (control), 320 and 560 mg/L (further information on the number of concentration levels not available) under static conditions. The 48-h EC50 was 240 mg/L. The observed effects can be attributed to a pH effect. Sublethal effects were not reported. Based on the results of this study, L-(+)-lactic acid would not be classified as hazardous to the aquatic environment according to the CLP Regulation (EC) No 1272/2008. This toxicity study is classified as supplementary information and does not satisfy the guideline requirement for an invertebrate short-term toxicity study but can nevertheless be used as supportive data or in a weight-of-evidence approach.

Results synopsis

Test organism: Water flea (Daphnia magna)

Test type: Static

EC50: 240 mg/L

Endpoint(s) effected: Mobility

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: EPA 660/3-75009

GLP compliance:

yes

Analytical monitoring:

no

Test organisms (species):

Daphnia magna

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 750 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 (48h) of Daphnia magna equals 750 mg/L.

Executive summary:

The acute toxicity of lactic acid (SY-83) to Daphnia magna was assessed using the methods outlined by the Committee on Methods for Toxicity Tests with Aquatic Organisms. Water quality parameters of temperature, dissolved oxygen and pH were measured at the termination of the test and were within acceptable limits.

The result of the 48 hour static Daphnia magna toxicity study is: LC50 (48h) = 750 mg/L. All reported values were based upon nominal concentrations. The no effect level observed for lactic acid (SY-83) was 320 mg/L after 48 hours, which was based on absence of mortality and abnormal effects.

Description of key information

In short-term toxicity test on L(+)-lactic acid in water fleas immobilisation was observed resulting in estimated EC₅₀ values ranging between 130 and 750 mg/L (nominal) which can be attributed to a pH effect. Lactate as such is considered not to exert any systemic effects on daphnids in the tested concentration range of up to 750 mg/L.

Additional information

In three studies on short-term toxicity of lactic acid to water fleas immobilisation was observed resulting in estimated EC50 values ranging between 130 (measured) and 750 mg/L (nominal). All studies are relatively poorly documented and therefore reliable only with restrictions. However, they can be used in a weight-of-evidence approach. In one of the studies (Bowmer et al., 1998) the observed mortality was explicitly attributed to pH effects: pH at the test concentrations of 320 and 560 mg/L was measured to be 4.1 and 3.5.

The theoretical pH shift caused by lactic acid at the lowest identified EC50 of 130 mg/L (= 1.443 mmol/L), considering a pKa of 3.9, would result in a final pH of 3.43. This compares quite well to the measured pH values of 4.1 and 3.5 at test concentrations of 320 and 560 mg/L in a slightly buffered system (Bowmer et al., 1998).

Therefore, the immobilisation observed in the available short-term tests on water fleas can undoubtfully be attributed to a pH shift instead of being a toxic effect of the lactate ion/molecule. Accordingly, since any toxic effects of the lactate are of interest instead of acidification it can be concluded that within the tested concentration range (up to 750 mg/L) lactic acid does not cause adverse effects on invertebrates, except pH related toxicity. A key value (EC50) for chemical safety assessment hence cannot be identified.