Icosan-1-ol

Toxicity to aquatic algae and cyanobacteria

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.

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.03 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: >LoS

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.018 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: >LoS

Conclusions:

ErC50 of 0.03 mg/l and ErC10 of 0.018 mg/l (>LoS) in green algae are predicted for icosan-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 0.03 mg/l and EC₁₀ 0.018 mg/l (calculated by QSAR) (non-toxic at the limit of solubilty) for the effects of icosan-1-ol on growth rate of aquatic algae.

Additional information

No reliable measured data are available for toxicity of icosan-1-ol to algae, therefore, a quantitative prediction has been performed. A 72h ErC₅₀ value of 0.03 mg/L and ErC₁₀ of 0.018 mg/L have been estimated for the effects of icosan-1-ol on growth rate of green algae (Fisk et al., 2017).

The solubility limit of icosan-1-ol is approximately 0.001 mg/l therefore the EC₅₀ and EC₁₀ are >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.