Reaction mass of 2-(cis-4-methylcyclohexyl)propan-2-ol and 2-(trans-4-methylcyclohexyl)propan-2-ol and cis-1-methyl-4-(propan-2-yl)cyclohexanol and trans-1-methyl-4-(propan-2-yl)cyclohexanol

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:

1 (reliable without restriction)

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

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 (Freshwater Alga and Cyanobacteria, 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-hour 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:

Not applicable

Analytical monitoring:

no

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

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.:

63 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 6.1.5/1: Expected concentrations at this 72 h-ErL50

Constituents	Concentration in the WAF (mg/L)
cis-p-menthan-8-ol	21.67
trans-p-menthan-8-ol	18.52
cis-p-menthan-1-ol	13.23
trans-p-menthan-1-ol	7.81

Validity criteria fulfilled:

yes

Conclusions:

72 h-ErL50 for dihydroterpineol multiconstituent is 63 mg/L.
Based on the results of this study, dihydroterpineol multiconstituent would not be classified as acute 1 to aquatic organisms in accordance with the CLP regulation.

Executive summary:

The acute toxicity of dihydroterpineol multiconstituent to aquatic algae has been investigated using an in-house calculation method that replaces an OECD 201 study and guideline for Testing of Chemicals No. 23 (i.e. WAF conditions).

The first step of the iSafeRat mixture toxicity calculation employs phase equilibrium thermodynamics in order to determine the concentrations of each constituent within the WAF. This fraction equates to the analyzable fraction of a WAF study. In the calculation the second step is to remove this non-bioavailable fraction. Within the WAF, the constituents also partition between themselves further reducing the bioavailable fraction and thus the toxicity of the mixture compared to the individual constituents.

The final step is to determine the truly bioavailable fraction of the WAF per constituent. The ErC50s of each constituent were predicted using the iSafeRat QSAR model. Each value has been included in the record and QPRF as well as the QMRF has been attached in the iuclid. 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 was 63 mg test material/L. ErL50 was based on growth rate.

Based on the results of this study, dihydroterpineol multiconstituent would not be classified as acute 1 to aquatic organisms in accordance with the CLP regulation.

This toxicity study is acceptable and can be used for that endpoint.

 

Results Synopsis

Test Type: Calculation method

ErL50: 63 mg test item/L

Description of key information

Using a calculation method, the 72h ErL50 for dihydroterpineol multiconstituent to algae is 63 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

63 mg/L

Additional information

A calculation method was used to predict the inhibition of growth to algae of test item dihydroterpineol 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 Guideline 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 72h. 

The ErC50s of each constituent are already known from literature or predicted using the iSafeRat® QSAR model. 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 dihydroterpineol multiconstituent to algae is 63 mg/L.

This toxicity study is acceptable and can be used for that endpoint.