Reaction mass of (4R)-isopropenyl-1-methylcyclohexene and (4S)-isopropenyl-1-methylcyclohexene and 1-isopropyl-4-methylcyclohexa-1,3-diene and 1-isopropyl-4-methylcyclohexa-1,4-diene and 4-isopropylidene-1-methylcyclohexene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Study period:

2014-05-26 to 2014-05-28

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

Calculation method is used; calculation method applicable for the endpoint.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Calculation method

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

yes

Remarks:

Calculation method

Principles of method if other than guideline:

The growth inhibition of algae was determined using a validated calculation method for the Mode of Action in question. This algorithm is based on a QSAR model which has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004). Further to this the effect loading rate of the WAF is determined by using a series of calculation steps using phase equilibrium thermodynamics and excluding the non-bioavailable fraction, this approach is based on validated data derived from 72 h ErL50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

GLP compliance:

no

Specific details on test material used for the study:

No data

Analytical monitoring:

no

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

other: Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda

Details on test organisms:

Not applicable

Test type:

other: calculation method

Water media type:

not specified

Total exposure duration:

72 h

Remarks on exposure duration:

72h-ErL50 (effective loading rate of WAF)

Post exposure observation period:

Not applicable

Hardness:

Hardness is not a necessary component of the WAF calculation.

Test temperature:

The Temperature is not a necessary component of the WAF calculation but extremely low or high temperatures could influence the solubility of certain constituents. Therefore, the calculation method is considered acceptable to determine EL50s for algae between 12 and 28 °C.

pH:

The pH is not a necessary component of the WAF calculation.

Dissolved oxygen:

The oxygen concentration is not a necessary component of the WAF calculation.

Salinity:

Salinity is not a necessary component of the WAF calculation. However as the fish QSAR for the constituents calculation was based on data from freshwater studies, the resulting calculation is considered valid for freshwater organisms.

Nominal and measured concentrations:

The calculation determines measured concentrations.

Details on test conditions:

Calculation method

Reference substance (positive control):

not required

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

3 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Not applicable

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

Table 6.1.5/2: Expected concentrations at this 72 h-ErL50

Constituents	Concentration in the WAF (mg/L)
limonene	1.22
α-terpinene	0.55
γ-terpinene	0.32
terpinolene	0.38
isoterpinolene	0.14
paracymene	0.06
camphene	0.15
α-phellandrene	0.04
α-pinene	0.03

Validity criteria fulfilled:

yes

Conclusions:

The 72 h-ErL50 for dipentene multiconstituent is 3.0 mg/L.

Executive summary:

A calculation method was used to predict the inhibition of growth to algae of test item dipentene multiconstituent, a multiconstituent substance, using the WAF method. This calculation method predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guidelines OECD 201 and EU method C.3 adapted for testing as a mixture using the WAF method. The criterion measured was the effective loading rate of the mixture ErL₅₀ (Median Effective Loading for specific growth rate), a statistically derived loading rate which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 h.

 

The growth inhibition of algae was determined using a validated calculation method for the Mode of Action in question. This algorithm is based on a QSAR model which has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004). Further to this the effect loading rate of the WAF is determined by using a series of calculation steps using phase equilibrium thermodynamics and excluding the non-bioavailable fraction, this approach is based on validated data derived from 72 h ErL₅₀ tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

 

The iSafeRat® mixture module first uses Phase Equilibrium Thermodynamics to determine the analytically measurable concentrations in aqueous solutions expected from known WAF loading rates of characterised mixtures for fish, daphnids or algae. These loading rates are then divided into two parts: the bioavailable and non-bioavailable fractions per constituent. Existing experimental ecotoxicity endpoint values or predictions of these (from the single constituent ecotoxicity modules) are then used to determine the mixture ecotoxicity based on the sum of the chemical activities of the remaining bioavailable fractions of the individual constituents. The resulting value is converted back to the equivalent loading rate providing a ErL₅₀ value.

 

The ErC50s of each constituent are already known from literature or predicted using the iSafeRat® QSAR model. QMRF and QPRF have been attached in the endpoint study record. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

 

Using this approach, the 72 h ErL₅₀ for dipentene multiconstituent to algae is 3.0 mg/L.

 

Based on the results of this study, dipentene multiconstituent would not be classified as acute 1 to aquatic organisms in accordance with CLP regulation (EC) No. 1272/2008.

 

Description of key information

Using a calculation method, the 72h-ErL50 for the registered substance to algae is 3.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

3 mg/L

Additional information

A calculation method was available and it was used to predict the inhibition of growth to algae of test item dipentene multiconstituent, a multiconstituent substance, using the WAF method. This calculation method predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guidelines OECD 201and EU methodC.3 adapted for testing as a mixture using the WAF method. The criterion measured was the effective loading rate of the mixture ErL50 (Median Effective Loading for specific growth rate), a statistically derived loading rate which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 h.

The algorithm used for the purpose of this study is based on a QSAR model which has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004).

The 72h - ErC50s of each constituent were predicted using the iSafeRat® QSAR model and the QMRF/QPRF have been attached to the dossier:

- α-phellandrene = 0.65 mg test item/L with 95 % - Confidence Limit of 0.39 - 1.07 mg test item/L.

- Limonene = 1.13 mg test item/L with 95 % - Confidence Limit of 0.72 - 1.76 mg test item/L.

- Terpinolene = 1.13 mg test item/L with 95 % - Confidence Limit of 0.72 - 1.76 mg test item/L.

- Camphene = 0.45 mg test item/L with 95 % - Confidence Limit of 0.26 - 0.78 mg test item/L.

- α-pinene = 0.45 mg test item/L with 95 % - Confidence Limit of 0.26 - 0.78 mg test item/L.

- α-terpinene = 0.65 mg test item/L with 95 % - Confidence Limit of 0.39 - 1.07 mg test item/L.

- p-cymene = 1.70 mg test item/L with 95 % - Confidence Limit of 1.13 - 2.55 mg test item/L.

- Isoterpinolene = 0.45 mg test item/L with 95 % - Confidence Limit of 0.39 - 1.07 mg test item/L.

- γ-terpinene = 1.13 mg test item/L with 95 % - Confidence Limit of 0.72 - 1.76 mg test item/L.

An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF. Using this approach, the 72h-ErL50 for the registered substance to algae is 3.0 mg/L. Based on the results of this study, the substance would not be classified as acute 1 to aquatic organisms in accordance with CLP regulation (EC) No. 1272/2008.