Octadecan-1-ol, ethoxylated, phosphates

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 5 - September 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The target substance, Octadecan-1-ol, ethoxylated, phosphates, and the analogous reference substances, Phosphoric acid, octadecyl ester, and Alcohols, C16-18, ethoxylated, phosphates, are fatty alcohol phosphate esters and weak anionic surfactants with extremely low water solubility and very high lipophilicity. None of them is expected to be bioavailable.

The target and reference substances, are anionic surfactants, with low water solubility and high log Kow. The literature cited in the read-across document suggests that the MOA for aquatic toxicity of AEs is nonspecific membrane disruption, which is related to the hydrophobicity of the specific AE homologue. The SAR analysis shows that both target and reference substances are similar in this respect and may be hydrolyzed in water, releasing phosphoric acid and fatty AEs or fatty alcohols under neutral conditions. The SAR analysis for ER binding also shows that both target and reference substances, their aqueous hydrolysates, and skin metabolites are considered non-estrogen binders. Additionally, numerous acute aquatic toxicity tests indicate that the toxicity of AEs to aquatic organisms tends to decrease with increasing EO units and increase with increasing hydrocarbon chain length as long as the AEs remain soluble in water. The reference substances, which have structures and hydrocarbon chain lengths that are comparable to or shorter than the target substance and have fewer EO units, are expected to be conservative analogs for the aquatic toxicity of the target substance.

Based upon all of the information presented, read-across from the existing experimental data for the analogous reference substances to the target substance is scientifically justified for this endpoints.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Principles of method if other than guideline:

Due to low aqueous solubility and complex nature of the test material, for the purposes of the test, the test material was prepared as aq water accommodated Fraction (WAF).
In view of the difficulties associated with the evaluation of aquatic toxicity of poorly water soluble test materials, a modification of the standard method for the preparation of aqueous media was performed. An approach endorsed by several important regulatory authorities in the EU and elsewhere (ECETOC 1996, OECD 200 and Singer et al 2000), is to expose organisms to a Water Accomodated Fraction (WAF) of the test material in cases where the test material is a complex mixture and is poorly soluble in water and in the permitted auxiliary solvents and surfactants.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100 mg/L
- Sampling method: Water samples were taken from the control and the 100 mg/L loading rate WAF test group (replicates R1-R4 pooled) at 0 and 48 hours for quantitative analysis.
- Sample storage conditions before analysis: The samples were stored at approximately -20℃ prior to analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Using a Water Accommodated Fraction (WAF) approach, aqueous media are prepared by mixing the test material with water for a prolonged period. Pre-study work showed that the maximum amount of dissolved test material was achieved after a preparation period of 24 hours. At the completion of mixing and following a 1-Hour settlement period, the test material phase is separated by siphon and the test organisms exposed to the aqueous phase or WAF (which may contain dissolved test material and/or leachates from the test material). Exposures are expressed in terms of the original concentration of test material in water at the start of the mixing period (loading rate) irrespective of the actual concentration of the test material in the WAF.

Pre-solubility work was carried out to determine whether stirring for a prolonged periods produced significantly higher measured test concentrations in the WAF.

A WAF of nominal loading rate of 100 mg/L was prepared, in duplicate, in deionized reverse osmosis water. One loading rate was stirred for a period of 23 hours and the other for a period of 95 hours. After a 1-Hour standing period the mixtures were then removed by siphon and the concentration of the test material in the 100 mg/L loading rate WAFs was verified by chemical analysis.

Amounts of test material (10, 40 and 200 mg) were each separately added to the surface of 10, 4 and 2 litres of reconstituted water to give the 1.0, 10 and 100 mg/L loading rates respectively. After the addition of the test material, the reconstituted water was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixtures allowed to stand for 1 hour. A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal. Microscopic inspection of the WAFs showed no micro-dispersions or undissolved test material to be present. The aqueous phase or WAF was removed by mid-depth siphoning (the first approximate 75-100 mL discarded) to give the 1.0, 10 and 100 mg/L loading rate WAFs.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: in-house laboratory cultures
- Age at study initiation (mean and range, SD): less than 24 hours old

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

250 mg/L

Test temperature:

21-22°C

pH:

7.6 - 8.2

Dissolved oxygen:

8.6 - 8.7mg O2/L

Nominal and measured concentrations:

Range finding test: Nominal 1, 10, 100 mg/L
Definitive test: Nominal 100 mg/L

Details on test conditions:

Range-finding test:
Due to the low aqueous solubility and complex nature of thr test material, for the purposes of the range-finding test the test material was prepared as a Water Accomodated Fraction (WAF).
The loading rate to be used in the definitive test was determined by a preliminary range-finding test.
In the range-finding test Daphnia magna were exposed to a series of nominal loading rates of 1.0, 10 and 100 mg/L.

TEST SYSTEM
- Test vessel: 250 mL glass jar
- Type: open but covered to reduce evaporation.
- Material, size, headspace, fill volume: 200 mL test preparation
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light 8 hours darkness (20 minute dawn and dusk transition periods
- Light intensity: 561 - 389 lux

EFFECT PARAMETERS MEASURED :
The criterion of effect used was that Daphnia magna were considered to be immobilized if they were unable to swim for approximately 15 seconds after gentle agitation.

TEST CONCENTRATIONS
- Range finding study:
No immobilization was observed in the range finding study at 1.0, 10 and 100 mg/L loading rate WAF. Based on this information, a single loading rate of four replicates, of 100 mg/L, using a stirring period of 95 hours followed by a 1-Hour standing period, was selected for the definitive test.
Chemical analysis of the 100 mg/L loading rate WAF at 0 and 48 hours showed measured concentrations of 5.5 and 6.0 mg/L, respectively, indicating that the test material was stable under test conditions.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities:
There was no immobilization in 20 daphnids exposed to a 100 mg/L loading rate WAF for a period of 48 hours.

- Effect concentrations exceeding solubility of substance in test medium:
Observations on the test media were carried out during the mixing and testing of the WAF.
At the start of the mixing period the 100 mg/L loading rate was observed to be a clear colourless water column with test material floating on the surface. After a 95 hour stirring period the 100 mg/L loading rate was observed to remain a clear colourless water column with test material floating on the surface, settled at the base of the vessel and dispersed throughout. After a1 hour standing period the 100mg/L loading rate was observed with the test material floating on the surface of the vessel. Microscopic inspection of the WAF showed dispersions or undissolved test material to be present and therefore it was thought justifiable to remove the WAF by filtering through a glass wool plug (2-4cm). Microscopic examination showed that the glass wool plug had removed all microscopic particles of the test material. After siphoning and for the duration of the test, the 100 mg/L loading rate was observed to be a clear, colourless solution.

Chemical analysis of the 100 mg/L test preparations at 0 hours showed a measured concentration of 6.3mg/L and analysis at 48 hours showed measured test concentrations of 6.5mg/L.

Given that toxicity cannot be attributed to a single component or mixture of components but to the test material as a while, and the dissolved test material was below the quantifiable limit of the analytical method, the results were based on nominal loading rates only.

Results with reference substance (positive control):

- Results with reference substance valid? Yes

- EC50/LC50:
EC50 (24 h) : 1.0 mg/L; 95% confidence limits 0.91 – 1.2 mg/L
EC50 (48 h) : 0.71 mg/L; 95% confidence limits 0.65 – 0.76 mg/L

- Other:
No Observed Effect Concentration (NOEC-24 h): 0.56 mg/L
No Observed Effect Concentration (NOEC-48 h): 0.32 mg/L
Lowest Observed Effect Concentration (LOEC-24 h): 1.0 mg/L
Lowest Observed Effect Concentration (LOEC-48 h): 0.56 mg/L

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour Effective Loading Rate (EL50) value of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading rate is 100 mg/L loading rate WAF.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 Mar - 25 Mar 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Justification for type of information:

The target substance, Octadecan-1-ol, ethoxylated, phosphates, and the analogous reference substances, Phosphoric acid, octadecyl ester, and Alcohols, C16-18, ethoxylated, phosphates, are fatty alcohol phosphate esters and weak anionic surfactants with extremely low water solubility and very high lipophilicity. None of them is expected to be bioavailable.

The target and reference substances, are anionic surfactants, with low water solubility and high log Kow. The literature cited in the read-across document suggests that the MOA for aquatic toxicity of AEs is nonspecific membrane disruption, which is related to the hydrophobicity of the specific AE homologue. The SAR analysis shows that both target and reference substances are similar in this respect and may be hydrolyzed in water, releasing phosphoric acid and fatty AEs or fatty alcohols under neutral conditions. The SAR analysis for ER binding also shows that both target and reference substances, their aqueous hydrolysates, and skin metabolites are considered non-estrogen binders. Additionally, numerous acute aquatic toxicity tests indicate that the toxicity of AEs to aquatic organisms tends to decrease with increasing EO units and increase with increasing hydrocarbon chain length as long as the AEs remain soluble in water. The reference substances, which have structures and hydrocarbon chain lengths that are comparable to or shorter than the target substance and have fewer EO units, are expected to be conservative analogs for the aquatic toxicity of the target substance.

Based upon all of the information presented, read-across from the existing experimental data for the analogous reference substances to the target substance is scientifically justified for this endpoints.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Analytical monitoring:

yes

Details on sampling:

Water samples were taken from the control and the 100% v/v saturated solution test group (replicates R1 – R4 pooled) at 0 and 48 hours for quantitative analysis. Samples were stored at approximately -20 °C prior to analysis. Duplicate samples were taken and stored at approximately -20 °C for further analysis if necessary.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Pre-study solubility work showed that the test item was insoluble in deionized reverse osmosis water when using traditional methods of preparation e.g. ultrasonication and high shear mixing. Based on this information the test item was categorized as being a ‘difficult substance’ as defined by the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000). Therefore a media preparation trial was conducted in order to determine the solubility of the test item under test conditions.

An amount of test item (550 mg) was added to 11 liters of reconstituted water and stirred using a propeller stirrer at approximately 1500 rpm for 24 hours. After stirring, any undissolved test item was removed by filtration through a 0.2µm Sartorius Sartopore filter (initial 2 liters discarded) to produce the 100% v/v saturated solution test concentration.

ENVIRONMENT DIRECTORATE, ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT (OECD) (2000) Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: in-house laboratory cultures
- Age at study initiation (mean and range, SD): 1st instar, less than 24 hours old
- Method of breeding: Adult Daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room at approximately 20 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing.
- Feeding during test: none

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

20 - 22 °C

pH:

7.7 - 8.2

Dissolved oxygen:

8.7 - 9.4 mg O2/L

Nominal and measured concentrations:

control, 50 mg/L (=100% v/v) (WAF, nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 250 mL glass jars containing approximately 200 mL of test preparation
- Aeration: none
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (Elendt M7 Medium) was used for both the range-finding and definitive test
- Culture medium different from test medium: no
- Intervals of water quality measurement: Water temperature and light intensity were recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods
- Light intensity: 590 to 595 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Any immobilization or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure

TEST CONCENTRATIONS
- Range finding study:
- Test concentrations: 0.10, 1.0, 10, and 100% v/v
- Results used to determine the conditions for the definitive study: A "Limit test" was conducted at a concentration of 100% v/v saturated solution to confirm that at the highest attainable test concentration, no immobilization or adverse reactions to exposure were observed, as was seen in the range-finding test.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

> 0.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 0.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

0.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

mobility

Details on results:

Throughout the test, the test preparation was observed to be a clear colorless solution.

Results with reference substance (positive control):

EC50(48h) = 0.45 mg/L (95% CL: 0.42 - 0.48)

Range-finding Test:

No immobilization was observed at the test concentrations of 0.10, 1.0, 10 and 100% v/v saturated solution. Based on this information, a single test concentration of four replicates, of 100% v/v saturated solution was selected for the definitive test. This experimental design conforms to a "Limit test" to confirm that at the highest attainable test concentration, no immobilization or adverse reactions to exposure were observed.

Chemical analysis of the 100% v/v saturated solution test preparations at 0 and 48 hours showed that measured concentrations of 0.159 and 0.158 mg/L were obtained, indicating that the test item was stable under test conditions.

Limit Test:

Analysis of the test preparations at 0 and 48 hours showed measured test concentrations of 0.169 and 0.159 mg/L respectively and so it was considered appropriate to estimate the EC50 values in terms of the mean measured test concentrations only.

There was no immobilization in 20 daphnids exposed to a mean measured test concentration of 0.164 mg/L for a period of 48 hours.

Description of key information

The acute toxicity of the freshwater invertebrate Daphnia magna to the read across test material, Phosphoric acid, octadecyl ester (EC Number 254 -466 -7), has been investigated and gave a 48-Hour Effective Loading Rate (EL50) value of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading rate is 100 mg/L loading rate WAF.

The acute toxicity the freshwater invertebrate Daphnia magna to the read across test material, Alcohols, C16 -18, ethoxylated, phosphates (EC Number 500 -295 -0), has been investigated and gave a 48-Hour Effective Loading Rate (EL50) value of greater than 0.16 mg/L loading rate WAF. The No Observed Effect Loading rate is 0.16 mg/L loading rate WAF.

As a worst case scenario, the results for the read across substance, Alcohols, C16 -18, ethoxylated, phosphates (EC Number 500 -295 -0), will be used as the key value.

The target substance, Octadecan-1-ol, ethoxylated, phosphates, and the analogous reference substances, Phosphoric acid, octadecyl ester, and Alcohols, C16-18, ethoxylated, phosphates, are fatty alcohol phosphate esters and weak anionic surfactants with extremely low water solubility and very high lipophilicity.  None of them is expected to be bioavailable.

The target and reference substances, are anionic surfactants, with low water solubility and high log Kow.  The literature cited in the read-across document suggests that the MOA for aquatic toxicity of AEs is nonspecific membrane disruption, which is related to the hydrophobicity of the specific AE homologue.  The SAR analysis shows that both target and reference substances are similar in this respect and may be hydrolyzed in water, releasing phosphoric acid and fatty AEs or fatty alcohols under neutral conditions.  The SAR analysis for ER binding also shows that both target and reference substances, their aqueous hydrolysates, and skin metabolites are considered non-estrogen binders.  Additionally, numerous acute aquatic toxicity tests indicate that the toxicity of AEs to aquatic organisms tends to decrease with increasing EO units and increase with increasing hydrocarbon chain length as long as the AEs remain soluble in water.  The reference substances, which have structures and hydrocarbon chain lengths that are comparable to or shorter than the target substance and have fewer EO units, are expected to be conservative analogs for the aquatic toxicity of the target substance.

Based upon all of the information presented, read-across from the existing experimental data for the analogous reference substances to the target substance is scientifically justified for this endpoints.