(R)-lactic acid

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

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

Parameter:

% degradation (CO2 evolution)

Value:

75.5

Sampling time:

28 d

Details on results:

Relative biodegradation values calculated from measurements performed during the test period revealed 75% and 76% biodegradation of PURAC Sanilac 80, for vessel A and B, respectively (based on ThCO2).

Validity criteria fulfilled:

yes

Remarks:

All criteria for acceptability of the test were met: 92% of procedural control item was biodegraded within 14 days; difference between duplicated values: 2%; total CO2 release in blank did not exceed 40 mg/L (value was 31.2 mg CO2/L).

Interpretation of results:

readily biodegradable

Conclusions:

In an OECD 301B study, L-(+)-lactic acid proved to be readily biodegradable.

Executive summary:

The biodegradation of lactic acid was studied. The aim of this study was to provide data on the degradation time scale of the lactic acid, in the presence of activated sludge as inoculum, folliwing the guideline of OECD 301B. Relative biodegradation values calculated from measurements performed during the test period revealed 75% biodegradation of PURAC Sanilac 80 (based on ThCO2). 
In the toxicity control, PURAC Sanilac 80 was found not to inhibit microbial activity.
In conclusion, PURAC Sanilac 80 is considered readily biodegradable. 

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:

biodegradation in water: ready biodegradability

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

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

linear biodegradability

Value:

0.936

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

Remarks:

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

Details on results:

Biowin1 (Linear Biodeg Probability) 0.9361
Biowin2 (Non-Linear Biodeg Probability) 0.9704
A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast
A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

Biowin3 (Survey Model - Ultimate Biodeg) 3.5247
Biowin4 (Survey Model - Primary Biodeg) 4.2328
Result Classification: 5.00 -> hours 4.00 -> days 3.00 -> weeks
(Primary & Ultimate) 2.00 -> months 1.00 -> longer

Biowin5 (MITI Linear Biodeg Probability) 0.7362
Biowin6 (MITI Non-Linear Biodeg Probability) 0.8791
A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable
A Probability Less Than 0.5 indicates --> NOT Readily Degradable

Biowin7 (Anaerobic Linear Biodeg Prob) 0.9102
A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast
A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

L-(+)-lactic acid is predicted to be readily biodegradable by the (Q)SAR model BIOWIN v4.10, which seems also applicable for the enantiomer D-(-)-lactic acid.

Executive summary:

As QSAR analysis predict L-(+)-lactic acid to be readily biodegradable it is likely the same for the enantiomer D-(-)-lactic acid.

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:

biodegradation in water: ready biodegradability

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

Details on results:

BOD 20 = 0.60 mg O2 per mg test substance

Parameter:

BOD5

Value:

0.45 g O2/g test mat.

Parameter:

COD

Value:

0.85 g O2/g test mat.

Parameter:

BOD5*100/COD

Value:

50

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Lactic acid is readily biodegradable.

Executive summary:

The biodegradation of lactic acid and lactate esters was studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. Lactic acid and its alkyl esters were degraded for more than 60% in the ready biodegradability tests and from the data presented, it is evident that lactic acid and the majority of alkyl lactates are readily biodegradable.

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 4

Endpoint:

biodegradation in water: ready biodegradability

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

GLP compliance:

yes

Duration of test (contact time):

d

Test performance:

The oxygen concentrations measured in the various bottles of the BOD determination are given in Annex B and discussed in detail in sections 3.1 and 3.2. Table l lists the mean oxygen concentrations measured and the oxygen consumption and BOD values calculated for lactic acid (referring to the test substance as such, containing 80% L(+) lactic acid).
The pH of the medium in the BOD bottles was 7.0-7.1 at the start of the test, 6.6-6.9 after twenty days. The pH values in bottles with glucose added were generally lower 6.1-6.3. The temperatures measured in the BOD bottles varied between 19.9 and 20.7 °C.

Parameter:

% degradation (O2 consumption)

Value:

50

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

67

Sampling time:

20 d

Details on results:

The BOD5 and BOD20 values of the various concentrations of L(+) lactic acid were in the ranges 0.44-0.45 mg O2/l and 0.54-0.60 mg O2/l respectively; it was therefore concluded that the BOD5 and BOD20 of L(+) lactic acid are 0.45 and 0.60 mg O2/mg respectively.
A simular oxygen consumption by the test substance was also found in the presence of glucose and glutamic acid, confirming the results presented. The COD values of L(+) lactic acid was found to be 0.902 mg O2/mg. (duplicate values: 0.873 and 0.930 mg 02/mg). The theoretical oxygen demand was calculated to be 0.85 mg O2/mg.
Comparison of the BOD and COD values indicates that degradation was about 50% after 5 days and about 67% after 20 days.

Parameter:

BOD5

Value:

0.45 g O2/g test mat.

Parameter:

COD

Value:

0.9 g O2/g test mat.

Results with reference substance:

The BOD5 and BOD20 values of the glucose/glutamic acid control were 3.02 mg O2/L and 7.29 mg O2/L respectively; these values indicate that the activity of the inoculum was not quite sufficient. According to ref. (3) a 150 mg/L glucose/ glutamic acid mixture should have a BOD5 value of 200 ± 37 mg O2/L; this corresponds to a value of 4.0 ± 0.75 mg O2/L for a 3 mg/L mixture). Since the BOD values were similar at both test substance concentrations and only slightly lower than the value found in the presence of glucose/glutamic acid with its higher microbial activity, the test was regarded as valid.
The results obtained by adding allylthiourea showed that some nitrification had taken place.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

With a BOD5 of 50% and BOD20 of 67% of COD, and considering the function of lactic acid in biological systems, it can be concluded that lactic acid is readily biodegradable.

Executive summary:

BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) determina- tions were carried out for L(+)lactic acid using the method described in the Dutch guidelines 'Water-Determination of Biochemical Oxygen Demand after n days (BODn)' (NEN 6634) and 'Water-Determination of Chemical Oxygen Demand (COD)' (NEN 6633) respectively, these methods are similar to those referred to in the EC test guidelines C.5 and C.6. The study was carried out in accordance with the OECD principles of Good Laboratory Practice.

The test substance was a pure chemical with a high solubility in water. Two concentrations (2 and 4 mg/L) were tested. An inoculum was prepared from activated sludge. The microbial activity appeared to be sufficient although the control substance glucose and glutamic acid had a BOD5 of slightly less than the required value of 4.00 ± 0.75 mg O₂/h.

No toxic effects were found.

The BOD5 of L(+)lactic acid was 0.45 mg O₂mg^-1 and the BOD20 was 0.60 mg O₂ mg^-1; the COD was 0.90 mg O₂ mg^-1. These data indicate a degradation of 50 and 67 % after 5 and 20 days respectively.

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

D-lactic acid is considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

L-(+)-lactic acid has proven as readily biodegradable in a test according to OECD guideline 301B. This is additionally supported by the validated QSAR model BIOWIN v4.10 and supportive experimental studies (BOD5 and COD measurements) not satisfying recent standards for ready biodegradability tests. It is established textbook knowledge that D-(–)-lactic acid is metabolically almost equivalent to L-(+)-lactic acid. Thus, D-(–)-lactic acid is considered as readily biodegradable.