Octadecan-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

Study period:

1992-01-24 to 1992-04-24

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The study was conducted according to a national standard method, and in compliance with GLP. The test loading rates were much higher than the limit of solubility and no analytical monitoring was carried out.

Qualifier:

according to guideline

Guideline:

other: German Industry Standard: DIN 38412, Part 9

Deviations:

not specified

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

no analytical monitoring, no range finding test, no reporting of water quality parameters.

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: unfiltered test solutions achieved nominal concentrations by direct addition of the test material into the test vessels. The filtered solutions were made from serial dilutions of a 1 g/L filtered stock solution.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM

- Strain: SAG 8681

- Source (laboratory, culture collection): Institute for plant physiology, University Gottingen

- Age of inoculum (at test initiation): 3 days

- Method of cultivation: not reported


ACCLIMATION - not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

range: 22-23.5 degC

Nominal and measured concentrations:

Nominal Loading Rate:  10, 30, 100 and 300 mg/L (Unfiltered)
Nominal Loading Rate: 0.1, 0.3, 1.0, 3.0, 10.0 mg/L (Filtrate)

Details on test conditions:

TEST SYSTEM

- Test vessel: Erlenmeyer flasks

- Material, size, headspace, fill volume: 300 ml with 100 ml fill volume

- Initial cells density: 1*10^4 cells/ml

- Control end cells density: 2.7*10^6

- No. of vessels per concentration (replicates): 3

- No. of vessels per control (replicates): 3



GROWTH MEDIUM

- Standard medium used: the medium was defined as Algae 10.10 / TFB Central laboratory soil nutrients.


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: not reported

- Culture medium different from test medium: not reported

- Intervals of water quality measurement: not reported


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: continuous

- Light intensity and quality: 2000 lux


EFFECT PARAMETERS MEASURED

- Determination of cell concentrations: cell numbers were determined at 24, 48, 72 and 96 h via the Thoms-Kammer method


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 3

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: non-toxic at the limit of solubility

Key result

Duration:

96 h

Dose descriptor:

EL10

Effect conc.:

> 21 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EL0

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: due to variability in cell density, the EL0 could not be reliably determined.

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: non-toxic at the limit of solubility

Duration:

96 h

Dose descriptor:

EL10

Effect conc.:

26 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

96 h

Dose descriptor:

EL0

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: due to variability in cell density, the EL0 could not be reliably determined.

Key result

Duration:

96 h

Dose descriptor:

EL0

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution with test material

Basis for effect:

growth rate

Remarks on result:

other: non-toxic at the limit of solubility

Key result

Duration:

96 h

Dose descriptor:

EL10

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution with test material

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EL0

Effect conc.:

<= 0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution with test material

Basis for effect:

biomass

Remarks on result:

other: non-toxic at the limit of solubility

Duration:

96 h

Dose descriptor:

EL10

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution with test material

Basis for effect:

biomass

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

other: filtered test solution with test material

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes

- Effect concentrations exceeding solubility of substance in test medium: the test was conducted at loading rates that were all much higher than the limit of solubility of the test substance (ca. 0.0011 mg/L).

Reported statistics and error estimates:

The analysis of the data was carried out in accordance with DIN regulation with a computer program by Mr. Holtmann, TFA / mathematical methods, Henkel KGaA.

Table 1. Summary of findings (average of 3 replicates).

Nominal Loading Rates (mg/L)		Cell concentrations (cells/ml)
filtered	unfiltered	24 h	48 h	72 h	96 h
0	-	8.3*10^4	5.1*10^5	1.2*10^6	2.7*10^6
10	-	1.2*10^5	5.2*10^5	1.1*10^6	2.1*10^6
30	-	8.3*10^4	5.6*10^5	1.1*1 0^6	2.2*10^6
100	-	7.3*10^4	5.1*10^5	9.3*10^5	1.9*10^6
300	-	2.3*10^4	6.7*10^4	6.2*10^5	1.1*10^6
-	0	6.0*10^4	3.5*10^5	1.4*10^6	2.6*10^6
-	0.1	5.3*10^4	3.3*10^5	1.2*10^6	2.4*10^6
-	0.3	7.7*10^4	3.1*10^5	1.4*10^6	2.7*10^6
-	1.0	5.0*10^4	3.3*10^5	1.2*10^6	2.4*10^6
-	3.0	8.0*10^4	3.8*10^5	1.4*10^6	2.4*10^6
-	10	7.3*10^4	3.8*10^5	1.5*1 0^6	2.2*10^6

EL values are said not be accurately identified in many cases since there was large variation in the cell concentrations measured (this is not clear from the table of results reported, identical to Table 1 here). All of the concentrations tested in the unfiltered and filtered solutions were above the limit of solubility. Any effect seen at these concentrations should be taken with caution as they may represent effects deriving from physical fouling rather than true toxicity of the test substance. The inconsistent EC values and cell concentrations may well be explained by the fact that the concentrations tested are much higher than the limit of solubility.

Validity criteria fulfilled:

not specified

Remarks:

the validity criteria for cell growth in the control was achieved, but there is no data on pH.

Conclusions:

The 96 h EL values could not be accurately determined due to large variations in cell concentrations. The EC50 values determined are reliant on confounding factors due to the concentrations used (very much higher than the limit of solubility) and therefore should be treated with caution. The water solubility of octadecan-1-ol is 0.0011 mg/L at 25oC [SIDS dossier on 1-octadecanol, 1993b; Budavari, 1996]. The results indicate that no toxic effects were present at the limit of solubility of the test substance, i.e. EL50 and NOEC >0.0011 mg/L (>LoS).

Description of key information

 Toxicity to aquatic algae: 96 h EL50 and NOEC >0.0011 mg/L (>LoS) for the effects of the test substance on growth rate of Scenedesmus subspicatus (new name: Desmodesmus subspicatus) in accordance with guidance German Industry Standard: DIN 38412, Part 9.

Additional information

A 96 h toxicity to algae test has been carried out with octadecan-1-ol (Henkel, 1992). The 96 h effect level values could not be accurately determined due to large variations in cell concentrations. The EL₅₀ values determined are reliant on confounding factors due to the concentrations used (much higher than the limit of solubility) and therefore should be treated with caution.

The water solubility of octadecan-1-ol is 0.0011 mg/L at 25˚C [SIDS dossier on 1-octadecanol, 1993b; Budavari, 1996]. The results indicate that no toxic effects were observed at the limit of solubility of the test substance, i.e. EL₅₀ and EL₁₀ >0.0011 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.