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Toxicity to aquatic algae and cyanobacteria

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toxicity to aquatic algae and cyanobacteria
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
The result is calculated using a suitably validated QSAR method.
Justification for type of information:
Background information on derivation of the result is found in the Ecotoxicity Alcohols C6-24 Category report’; validation of long-term invertebrates QSAR, discussed in Annex I of that report.
Principles of method if other than guideline:
Validation set derived from 48-hour to 72-hour results from reliable studies conducted in accordance with OECD 201.
GLP compliance:
Test organisms (species):
other: Green algae
Details on test organisms:
Validation set data are taken from tests with P. subcapitata and D. subspicatus.
72 h
Dose descriptor:
Effect conc.:
0.02 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: >LoS
72 h
Dose descriptor:
Effect conc.:
0.014 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: >LoS
ErC50 of 0.02 mg/l and ErC10 of 0.014 mg/l (>LoS) in green algae are predicted for docosan-1-ol based on test results for analogous aliphatic alcohols. These values are considered to be reliable.

Description of key information

Toxicity to aquatic algae: EC50 96h 0.02 mg/l and EC10 0.014 mg/l (calculated by QSAR) (non-toxic at the limit of solubilty) for the effects of docosan-1-ol on growth rate of aquatic algae.

Key value for chemical safety assessment

Additional information

No reliable measured data are available for toxicity of docosan-1-ol to algae, therefore, a quantitative prediction has been performed. A 72h ErC50 value of 0.02 mg/L and ErC10 of 0.014 mg/L have been estimated for the effects of docosan-1-ol on growth rate of green algae (Fisk et al., 2017).

The solubility limit of docosan-1-ol is approximately 0.001 mg/l therefore the EC50 is >0.001 mg/l (>LoS).

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

The data for single carbon chain length LCAAs show toxicity to increase from an ErC50 of 80 mg/L for C6 to 0.33 mg/L for C12. The C14 and C16 LCAAs were not toxic to algae, indicating a toxicity cut-off at C14 and above. Two of the studies determined NOECs that are suitable for assessing long-term toxicity. A NOEC of 11 mg/L has been reported for hexan-1-ol based on measured exposure concentrations. A test with dodecanol resulted in a 72-h EC0 (equivalent to a NOEC) value of 0.085 mg/L.

Other algal studies used a WAF methodology and/or used test concentrations greater than the limit of water solubility and/or did not report a NOEC or equivalent statistic.

The data for mixed carbon chain length LCAAs (commercial products) shows that substances containing LCAAs with carbon numbers in the ranges of C7-9 to C12-15 exerted toxicity at concentrations of between 3.1 and 0.043-0.092 mg/L. At these concentrations all the constituents are likely to have been fully dissolved. For the C12-18 and C14-15 multi-constituent substances there was evidence of toxic effects in tests conducted on water-accommodated fractions prepared at loading rates that will have exceeded the solubility of some constituents.

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