Hexadecan-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:

1992-02-18 to 1992-02-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate national standard method and was compliant with GLP. The test organisms are exposed to concentrations much higher than the limit of solubility and no analytical monitoring was carried out.

Qualifier:

according to guideline

Guideline:

other: German standard method; 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 range finding test, no analytical monitoring.

GLP compliance:

yes

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: test substance was directly weighed into test vessels

- Controls: test medium without test substance

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM

- Strain:  SAG 8681

- Source (laboratory, culture collection): Institute of Plant Physiology, University of Gottingen

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

- Method of cultivation: not reported


ACCLIMATION

- Acclimation period: not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

22-23 degC

Nominal and measured concentrations:

Nominal Loading Rate: 0, 10, 30, 100, 300 and 1000 mg/L.

Details on test conditions:

TEST SYSTEM

- Test vessel: Erlenmeyer flask

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

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

- Control end cells density: 2.1*10^6

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

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



GROWTH MEDIUM

- Detailed composition if non-standard medium was 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


OTHER TEST CONDITIONS

- Adjustment of pH: not reported

- Photoperiod: continuous

- Light intensity and quality: 2000 lux



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

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



TEST CONCENTRATIONS

- Spacing factor for test concentrations: 3

Reference substance (positive control):

no

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: non-toxic at the limit of solubility

Key result

Duration:

96 h

Dose descriptor:

EL0

Effect conc.:

100 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: non-toxic at the limit of solubility

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

690 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: non-toxic at the limit of solubility

Key result

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

> 1 000 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

Details on results:

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

- Effect concentrations exceeding solubility of substance in test medium: the effects observed are all above the limit of solubility (LoS) of the test substance.

Reported statistics and error estimates:

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

Table 1. summary of findings.

Nominal loading rate (mg/L)	Cell concentration
	24 h	48 h	72 h	96 h
0	2.7*10^4	1.4*10^5	7.3*10^5	2.1*10^6
10	3.7*10^4	2.5*10^5	9.8*10^5	2.2*10^6
30	1.7*10^4	9.7*10^4	5.8*10^5	1.1*10^6
100	1.7*10^4	9.7*10^4	4.5*10^5	1.2*10^6
300	3.7*10^4	1.0*10^5	4.9*10^5	9.0*10^5
1000	1.3*10^4	7.3*10^4	3.9*10^5	9.0*10^5

Validity criteria fulfilled:

not specified

Remarks:

no water quality data, however the test did meet the validity criteria for cell multiplication in the controls.

Conclusions:

A 96 h EL0 value of 100 mg/L and an EL50 value of >1000 mg/L have been determined for the effects of the test substance on growth rate of the test substance of S. subspicatus. These results are much higher than the limit of solubility of the test substance and should be treated with caution; the test substance did not appear to be toxic at the limit of solubility. Therefore the EL50 is >0.01 mg/L (>Limit of Solubility).

Description of key information

Toxicity to aquatic algae: Key: 96 h EL₅₀: >1000 mg/l and EL₀ 100 mg/l (nominal) in accordance with German standard method; DIN 38412 part 9, for effects of hexadecan-1-ol (C16, CAS 36653-82-4) on growth rate of Desmodesmus subspicatus (Henkel, 1992). Therefore the substance is non-toxic at the limit of solubility.

Additional information

A reliable 96 hour EL₅₀ value of >1000 mg/l and EL₀ value of 100 mg/l have been determined for the effects of hexadecan-1-ol (C16, CAS 36653-82-4) on growth rate of Desmodesmus subspicatus (Henkel, 1992) in accordance with German standard method; DIN 38412 part 9. The water solubility of C16 is 0.024 mg/L, therefore C16 can be considered non-toxic at the Limit of Solubility (LoS) and the EL₅₀ and EL₀values can be said to be >0.024 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.