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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6

Data source

Reference
Reference Type:
publication
Title:
Improved method for estimating water solubility from octanol/water partition coefficient
Author:
Meylan, W.M. and Howard, P.H.
Year:
2012
Bibliographic source:
Environ. Toxicol. Chem. 15: 100-106.

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs R.6, May/July 2008

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.452 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.431 mg/L
Details on results:
validity of model:1.defined endpoint: acute toxicity to algae
2.unambigous algonthm: linead regression QSAR: Log Toxicity (mmol/L) = -0.8981(log Kow) + 1.7108, Log ChV (mmol/L) = -0.1958 (log Kow) - 2.2582 (GREEN ALGAE ChV)
3. applicability domain: In the development of the ECOSAR equations for neutral organics and classes with excess toxicity, the training sets generally include chemicals with log Kow values in the range of -3 to 8 and molecular weights less than 1000. However, the domain of the model is considered to be larger than the descriptor range of the training set of chemicals. As discussed in previous sections it has been determined through empirical data that for acute toxicity endpoints, chemicals with a log Kow value >5.0 are generally expected to have no effects at saturation
4.statistical characteristic: the parameter for ester is unknown
5.mechanistic interpretation: The QSARs in ECOSAR for both neutral organics and classes with excess toxicity are based on a linear mathematical relationship between the predicted log Kow values and the corresponding log of the measured toxicity values (mmol/L) for a suite of training set chemicals within each class of interest. The studies collected for the training set chemicals in ECOSAR undergo an extensive data validation step to ensure appropriateness for inclusion in the model.
The QSAR for neutral organics is based on the assumption that all chemicals have a minimal toxicity based on the interference of the chemical with biological membranes, which can be modelled by the octanol-water partition coefficient (Kow). All other chemical classes show excess toxicity compared to the neutral organics. The chemical classes are empirically derived. Nevertheless, a mechanistic basis is often apparent, e.g. reactive chemicals will be more toxic than neutral organics

Applicant's summary and conclusion

Conclusions:
the substance coumarin was predicted to have log (EC50) of 1.452mg/L and log(ChV) of 0.431mg/L in algae. The prediction should be used for classification and risk assessment.