Reaction mass of (1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene and (1R,6S)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

supporting study

Justification for type of information:

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.05 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: 95% CL

Remarks:

0.033-0.075

Details on results:

None.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

95 % CL [0.033-0.075] QSAR statistical parameters are given in the QMRF and QPRF.

   Evaluation and statistics

The evaluation of the effect was based on regression line derived from a training set of 30chemicals with MechoA 1.1 using a validated dataset on subcooled solubility versus the maximum acceptable toxicant concentration (MATC) based on reproducibility of Daphnia magna following the methodology outlined in ECETOC (2013) and Thomas et al.(2015). In brief, the algorithm used was an updated (improved) version of that used by ECETOC for non-polar narcotic compounds and then validated using an external test set. The modelling algorithm was derived using a simple linear regression with the following general equation:

logEC10 = a X logWater Solubility +b

The correlation coefficient R²and Root Mean Standard Error (RMSE) values for this model were 0.9628 and 0.3203, respectively. As discussed in the QSAR Model Reporting Format, closer the R² is to 1 and lower the RMSE values are, better is the goodness-of-fit for the model. Therefore, the model was considered as reliable for providing accurate predictions falling within its applicability domain. Further statistical evidence of high prediction accuracy are provided in the QSAR Prediction Reporting Format (QPRF) for the substance provided in Annex Iand the QSAR Model Reporting Format (QMRF)(KREATiS, 2019).Other MechoAs are being added to the KREATiS database as sufficient evidence for high accuracy predictions becomes available.

Validity criteria fulfilled:

yes

Conclusions:

The test item falls within the applicability domain of the model and can therefore be considered a reliably prediction for chronic toxicity (21d-EC10) to daphnids. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.
The 21d-EC10 of the test item to daphnids was predicted as 0.050 mg/L.
95% confidence interval (α = 0.05): 0.033 – 0.075 mg/L.

Based on the results of this study, delta-3-carene is classified hazardous to the aquatic environment according to Regulation (EC) No 1272/2008 (CLP) - Chronic Category 2.

Executive summary:

A QSAR model was used to calculate the chronic toxicity of test item delta-3 -carene to daphnid. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 211, "Daphnia magna Reproduction Test" (OECD, 2012). The criterion predicted was the EC10 (10% Effective Concentration), a concentration which isexpected to cause an effect of 10% onreproducibility within a period of 21 days.

The result below is the chronic toxicity value anticipated during to a 21-day EC10 study on daphnids reproducibility.The 21-day EC10 is predicted as follows:

 

Time (d)	EC10 (mg test item.L^-1)	95% confidence limits (mg test item.L^-1)
21	0.050	0.033 – 0.075

Description of key information

The test item falls within the applicability domain of the model and can therefore be considered a reliably prediction for chronic toxicity (21d-EC10) to daphnids. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

The 21d-EC10 of the test item to daphnids was predicted as 0.050 mg/L.

95% confidence interval (α = 0.05): 0.033 – 0.075 mg/L.

Based on the results of this study, delta-3-carene is classified is classified hazardous to the aquatic environment under Regulation (EC) No 1272/2008 (CLP) - Acute Category 1 and Chronic Category 2.

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances. Therefore, DELTA-2-CARENE is classified hazardous to the aquatic environment under Regulation (EC) No 1272/2008 (CLP) - Acute Category 1 and Chronic Category 2.