Octan-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:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The study was conducted according to an appropriate DIN standard method (38412 part 9). It was not compliant with GLP and no analytical monitoring was conducted.

Qualifier:

according to guideline

Guideline:

other: DIN 38412, Part 9

Deviations:

yes

Remarks:

guideline was modified for difficult substances.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

reduced exposure time, tetsing for difficult substance meant that the test medium preparation was slightly different, see below for details.

Principles of method if other than guideline:

Modified Test Procedure incorporating DIN 38 412, Part 9 and account being taken of the Test Methods using Water Organisms, DIN 38 412, Part 1. Also, a reduced exposure time was followed to ensure that pH did not shift exceedingly due to the use of closed vessels.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: The preparation of test solution was to quantitavely dissolve the substance using magnetic stirrers up to 24h, to produce optically clear stock solutions in 800 ml double distilled water.
250 ml wide-necked (34/35) bottles with ground-glass stoppers were used. The parallel dilution series (f=2) was: the volume of the dilution water (e.g. 27.5 ml) corresponding to the dilution level (e.g. 1:4 of the test medium) was pre-filled into each of the six bottles for the concentration level. Then, 5 ml of the 10-fold concentration of the nutrient solution and the corresponding volume of the stock solution (e.g. 12.5 ml) for the desired concentration was added to each test vessel. Bottles were closed immediately. Finally, the stopper was lifted briefly to add 5 ml of the algal suspension of the preliminary culture (10^5 cells/ml).

- Controls: In the same way as above without the test solution

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM

- Common name: Scenedesmus subspicatus

- Strain: 8681 SAG

- Source: maintained in the laboratory were the test was undertaken for a number of decades.

- Age of inoculum: the cultivation of the preliminary culture was undertaken 3 days before the test. Flasks were inoculated with 7-day-old stock cultures.

ACCLIMATION

- Acclimation period: 3 days

- Culturing media and conditions: lighting used Osram 40 W/30 tubes, irradiance E0, Sy = 24.9 W/m^2

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

N.R.

Test temperature:

24 +/- 1 degC

pH:

ph 8 at the beginning of test

Dissolved oxygen:

not reported

Nominal and measured concentrations:

Conc range: 1.6-200 mg/L

Details on test conditions:

TEST SYSTEM

- Test vessel: wide necked bottles

- Type: closed

- Material, size, headspace, fill volume: 250 ml wide-necked (34/35) bottles with ground-glass stoppes were used.

- Aeration: none

- Initial cells density: 10^4 cells/ml

- No. of vessels per concentration: 1

- No. of vessels per control: 1


GROWTH MEDIUM

- Standard medium used: yes



TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: double-distilled water

- Intervals of water quality measurement: pH was measured at 24 and 48h.


OTHER TEST CONDITIONS

- Sterile test conditions: flasks and nutrient solution were sterilised.

- Adjustment of pH: no

- Photoperiod: constant

- Light intensity and quality: Osram L 25/40 fluorescent tubes, each of the positions for the test preparation had an irradiance E = 17.0 W/m^2



EFFECT PARAMETERS MEASURED:

- Determination of cell concentrations: The extinction value of the monochromatic radiation (578 nm) of the cell suspension was determined for each concentration level of the test and control preparations. Biomass was measured via optical density (measurement of turbidity), using Eppendorf digital photometer 6115S, filter 587 nm. The measurements were taken at 24, 48, 72 and 96h.

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.5 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

biomass

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

14 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

growth rate

Key result

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

4.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

2.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control: yes

Reported statistics and error estimates:

The data was evaluated in line with the protocol.

Validity criteria fulfilled:

not specified

Remarks:

pH was not reported, however the study fulfilled the validity criteria for control growth.

Conclusions:

A reliable 48h EbC50 of 6.5 mg/L and ErC50 of 14 mg/L have been determined for the effect of the test substance on biomass and growth rate respectively of Pseudokirchnerella subcapitata.

Description of key information

Toxicity to aquatic algae: 48 h ErC₅₀ 14 mg/L and EC₁₀ 4.2 mg/l (nominal concentration) for the effects of the test substance on growth rate of Pseudokirchneriella subcapitata (guideline: DIN 38412, Part 9).

Key value for chemical safety assessment

EC50 for freshwater algae:

14 mg/L

EC10 or NOEC for freshwater algae:

4.2 mg/L

Additional information

A reliable 48h ErC₅₀ of 14 mg/L and ErC₁₀ of 4.2 mg/l, as well as an EbC₅₀ of 6.5 mg/L and EbC₁₀ of 2.8 mg/l, have been determined for the effect of octan-1-ol on growth rate and biomass respectively of Pseudokirchneriella subcapitata (Kuhn & Pattard, 1990). The study reflects the lowest reliable value that is available for this endpoint.

A reliable study has determined a 2 min EC₅₀ of 120 mg/l (QSAR) based on ion retention of Enteromorpha intestinalis [Schild et al, 1995].

Other studies which have been assigned reliability 3 have determined EC₅₀s in the range 1.9 to 6.3 mg/L:

8-d Toxicity Threshold (TT) Scenedesmus quadricauda = 6.3 mg/L (reliability 3) [ Bringmann G, Kuhn R, 1978].

8-d Toxicity Threshold (TT) Microcystis aeruginosa = 1.9 mg/L (reliability 3) [ Bringmann G, Kuhn R, 1978].

Biodegradation by algae

Rapid degradation in water is indicated by the difficulties encountered in long-term toxicity to invertebrates (Daphniareproduction) test 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.

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.