1-ethynylcyclohexyl acetate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2017

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

Justification for type of information:

The executive summary of the QSAR prediction is presented in the endpoint summary. The QMRF and QPRF documentation files are included in the Attached justification section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance R.6: QSARs and grouping of chemicals. Version May 2008.

Version / remarks:

In the QMR attached the model specifications are presented. In this QMR is referenced to the Methodology document for the Ecological Structure-Activity Relationship model (ECOSAR) Class Program MS Windows v1.11'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2012).

Deviations:

not applicable

GLP compliance:

no

Remarks:

not required

Test organisms (species):

Daphnia sp.

Water media type:

freshwater

Total exposure duration:

48 h

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

14.1 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Log Kow 2.82; ECOSAR class: Esters

Validity criteria fulfilled:

yes

Remarks:

The ECOSAR-Ester equation is valid when using the OECD criteria. In addition, N=40 and R2 is 0.798

Conclusions:

The Daphnia 48-h EC50 is 14.1 mg/L

Executive summary:

The acute Daphnia EC50 for the ester Herbacet #1 is predicted to be 14.1 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 48h-LC50 (mmol/L) = -0.6305 (log Kow) + 0.7049. The LC50 in ECOSAR is considered equivalent to the EC50 as defined in OECD TG 202.

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 5); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted EC50 value of this ECOSAR analogue is 18.6 mg/L and the measured value is 37 to 45 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for acute Daphnia toxicity on esters. The adequate and reliable documentation, presented in the attached justification section, further supports this prediction.

Description of key information

The acute Daphnia EC50 for the ester Herbacet #1 is predicted to be 14.1 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 48h-LC50 (mmol/L) = -0.6305 (log Kow) + 0.7049. The LC50 in ECOSAR is considered equivalent to the EC50 as defined in OECD TG 202.

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 5); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted EC50 value of this ECOSAR analogue is 18.6 mg/L and the measured value is 37 to 45 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for acute Daphnia toxicity on esters. The adequate and reliable documentation, presented in the attached justification section of the study record, further supports this prediction.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

14.1 mg/L