Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
Adequacy of study:
key study
Study period:
March 30th, 2018
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

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
other: REACH Guidance on QSARs R.6 (QSAR model adapted specifically from test guideline: OECD 201, EU C.3)
Principles of method if other than guideline:
The purpose of this QSAR model is to accurately predict the toxicity to algae as would be expected in a laboratory experiment following the OECD Guideline 201 and EC method C.3 for specific, named modes of action to provide a value that can effectively replace a 72-hour ErC50 value from an experimental study. The regression is method used to achieve this has been fully validated following the OECD (2004) recommendations (refer to the QMRF with JRC/KREATiS QMRF identifier: Q19-46-51-448 for further details).

Results from the following species were used in the regression:
Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda
No difference in relationship between solubility and ecotoxicity between algae (or indeed other) aquatic species is expected. Any observed differences may be attributed to lifestyle related parameters and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences.

Test duration:
Results from a test duration of 72 hours only were used for this algorithm.

The temperatures varied from approximately 20 to 25 °C depending on the species used to construct the algorithm. This small difference is not expected to contribute to the variability of the ErC50 values found in experimental data.

Test type:
Following the guideline OECD 201, all studies were from a static test design. For suspected volatile substances only tests performed in closed vessels were accepted unless accompanying analytical monitoring proved such a design was not necessary.

Test results were preferably taken from studies with measured pHs between 6 - 9. However it is recognized that in some cases (due to high luminosity) the pH may increase in the control and lower concentrations (which do not cause significant effect over the study period). This pH increase did not generally disqualify the study from being used in the test and validation set for non-polar chemicals.
GLP compliance:

Test material

Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Melting point (if solid) 66.8 °C
log KOW log KOW = 7.8
Water Solubility 4.26E-03 mg/L

Results and discussion

Effect concentrations
Key result
72 h
Dose descriptor:
Nominal / measured:
Conc. based on:
test mat.
Remarks on result:
not determinable
the EC50 was > to the solubility limit

Applicant's summary and conclusion

Validity criteria fulfilled:
Executive summary:

The growth inhibition of algae was determined using validated QSAR model for the Mechanism of Action (MechoA) in question (MechoA 1.1, i.e. non-polar narcosis) (4). The QSAR model is based on validated data for a training set of 40 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

The result below is the toxicity values anticipated during a 72-hour study on algae based on measured concentrations. The 72-hour ErC50 is calculated as follows:

72h EC50 > solubility limit (0.00426mg/l).