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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
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:
no
Test organisms (species):
other: Green algae
Details on test organisms:
Validation set data are taken from tests with P. subcapitata and D. subspicatus.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.02 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: >LoS
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.014 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: >LoS
Conclusions:
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 solubility) 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.

Biodegradation by algae

Rapid degradation in water is indicated by the difficulties encountered in aquatic toxicity tests (chronic Daphnia reproduction) for long chain aliphatic alcohols (Section 6.1.4). Alcohols in the range C10-C15 were found to be rapidly removed from the test medium. This was attributed to metabolism by algae present as a food source in tests, and in later stages of the 21-day tests to bacterial degradation by microbes adsorbed onto the carapace of the test daphnids, despite daily cleaning of the animals.