Propanoic acid, 2-hydroxy-, propyl ester, (2S)-

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:

supporting study

Justification for type of information:

The acute aquatic effect concentration was predicted using an equation developed by the authors, using the log Kow as the predictive variable. The relationship between log Kow and acute aquatic effect concentrations for algae was developed using four different lactates (ethyl lactate, butyl lactate, 2-ethylhexyl lactate, octyl lactate), see table attached as image. The derived equation implies that acute algae toxicity is solely driven by the log Kow. The use of the log Kow as the predictive variable for acute aquatic toxicity was not justified by Bowmer et al. (1998).
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:

96 h

Dose descriptor:

EC50

Effect conc.:

2 400 mg/L

Basis for effect:

cell number

Details on results:

Based on the equations shown in the table attached as an image, an effect value for growth inhibition based on cell counts were calculated for algae.

Validity criteria fulfilled:

not applicable

Conclusions:

This derivation on basis of the log Kow was not sufficiently justified and thus the predicted ErC50 value of propyl lactate was regarded as not reliable

Executive summary:

On the basis of equations with the log Kow as the predictive variable, an effect value for growth inhibition based on cell counts was calculated for algae, ErC50 = 2400 mg/L.

The derivation of acute aquatic toxicity on basis of the log Kow was based on seven data points only (measured EC50 values for algae). The approach using the log Kow as the basis for prediction of algal toxicity was not justified by the authors. Therefore, predicted EC50 value of propyl lactate was regarded as not reliable.

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:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Qualifier:

according to guideline

Guideline:

other: ECHA guidance on information requirements and chemical safety assessment, chapter R.6: QSARs and grouping of chemicals

Deviations:

no

GLP compliance:

no

Specific details on test material used for the study:

SMILES: C(=O)(C(C)O)OCCC

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

177 mg/L

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The ErC50 for algal growth inhibition by propyl (S)-lactate was estimated by QSAR to be > 100 mg/L.

Executive summary:

For the determination of the acute toxicity to algae value the 'SciMatics SciQSAR model for acute toxicity to microalgae (72-h growth inhibition, EC50)' as included in the Danish QSAR Database, has been applied. Based on the calculated 72-h ErC50 value of 177 mg/L it can be concluded that propyl (S)-lactate shows very low acute toxicity to algae with an effect value of > 100 mg/L.

Description of key information

The 72-h ErC50 of propyl-(S)-lactate for algae is predicted to be 177 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

177 mg/L

Additional information

A recent and valid QSAR calculation (Leadscope, Danish QSAR data base) is used as the key study, resulting in a 72-h E_rC₅₀ of 177 mg/L. An older publication, reporting a non-validated simple QSAR model (regression based, scarce data set) is considered unreliable hence used as supportive data only. The corresponding E_rC₅₀ is reported to be 2400 mg/L.