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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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:
29 May 2015 to 29 May 2015
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculation method is used; calculation method applicable for the endpoint.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
Calculation method
Qualifier:
equivalent or similar to
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). The QSAR is based on validated data derived from 72-hour ErC50 test on algae. 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:
No data
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
Not applicable
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Not applicable
Test type:
other: calculation method
Water media type:
not specified
Limit test:
no
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
Remarks:
Calculation method
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
3.3 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)

dl-limonene

1.5

β-phellandrene

1.1

carene (Δ3)

0.21

β-pinene

0.22

p-cymene

0.13

α-terpinene

0.083

myrcene

0.067

Validity criteria fulfilled:
yes
Conclusions:
The 72 h-ErL50 for Reaction mass of β-phellandrene and d-limonene and l-limonene is 3.3 mg/L.
Therefore, the registered substance would not be classified as acute 1 to aquatic organisms in accordance with the CLP regulation.
Executive summary:

A calculation method was used to predict the inhibition of growth to algae of test item Reaction mass of β-phellandrene and d-limonene and l-limonene, 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 OECD Guideline 201 and EU method C.3 adapted for testing as a mixture using the WAF method.

The criterion predicted 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). The QSAR is based on validated data derived from 72-hour ErC50 test on algae. 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. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

 

Therefore, the 72-h ErL50 to algae for Reaction mass of β-phellandrene and d-limonene and l-limonene is 3.3 mg/L.

 

Therefore, the registered substance 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.

Description of key information

Using a calculation method, the 72-h ErL50 to algae for Reaction mass of beta-phellandrene and d-limonene and l-limonene is 3.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
3.3 mg/L

Additional information

A calculation method was used to predict the inhibition of growth to algae of test item Reaction mass of β-phellandrene and d-limonene and l-limonene, 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 OECD Guideline 201 and EU method C.3 adapted for testing as a mixture using the WAF method.

The criterion predicted 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). The QSAR is based on validated data derived from 72-hour ErC50 test on algae. 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 ErC50s of each constituent are already known from existing data 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 to algae for Reaction mass of β-phellandrene and d-limonene and l-limonene is 3.3 mg/L. Based on the results of this study, the substance 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.