Octadecan-1-ol, ethoxylated, phosphates

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 April 2017 to 16 September 2019

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 211 (Daphnia magna Reproduction Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.20 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Physical State/Appearance: White waxy solid
Purity: 100%, UVCB substance
Storage Conditions: Room temperature in the dark

Analytical monitoring:

yes

Details on sampling:

After the addition of the test material, the test 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 95 hours and the mixture allowed to stand for 1 hour. Observations made on the WAF indicated that a significant amount of dispersed test material was present in the water column and hence it was considered justifiable to remove the WAF by filtering through a glass wool plug (2-4 cm in length). A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel, sealed end down, to a depth of approximately 5 cm from the bottom of the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal. A glass wool plug was inserted into the opposite end of the tubing and the WAF removed by mid-depth siphoning (the first approximate 75-100 mL discarded) to give the 100 mg/L loading rate WAF. Microscopic observations of the WAF were performed after filtering and showed that no undissolved test material remained.

The concentration and stability of the test material in the test preparations were verified by chemical analysis on Days 0, 9, 14 and 18 (fresh media) and Days 2, 11, 16 and 21.

Vehicle:

no

Details on test solutions:

After the addition of the test material, the test 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 95 hours and the mixture allowed to stand for 1 hour. Observations made on the WAF indicated that a significant amount of dispersed test material was present in the water column and hence it was considered justifiable to remove the WAF by filtering through a glass wool plug (2-4 cm in length). A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel, sealed end down, to a depth of approximately 5 cm from the bottom of the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal. A glass wool plug was inserted into the opposite end of the tubing and the WAF removed by mid-depth siphoning (the first approximate 75-100 mL discarded) to give the 100 mg/L loading rate WAF. Microscopic observations of the WAF were performed after filtering and showed that no undissolved test material remained.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using 1st instar Daphnia magna derived from in-house laboratory cultures. A clone of this test species was originally supplied by the University of Sheffield, UK and bred at Envigo – Shardlow.

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.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

21 d

Hardness:

248 to 288 mg/L as CaCO3

Test temperature:

21 deg.C to 22 deg.C

pH:

7.5 to 8.1

Dissolved oxygen:

7.2 to 8.7 mg O2/L

Nominal and measured concentrations:

100 mg/L

Details on test conditions:

Adult daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room at approximately 20 deg.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.

Key result

Duration:

21 d

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Key result

Duration:

21 d

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOELR

Effect conc.:

ca. 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Details on results:

There were no significant mortalities (immobilization) observed in the parental generation (P1) and that there were no significant differences (P>= 0.05) between the control and the 100 mg/L loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

Observations on the test media were carried out during the mixing and testing of the WAFs.

At the start of the mixing period the 100 mg/L loading rate was observed to be a clear colorless water column with test material floating on the surface and dispersed throughout. After 95 hours stirring and a 1-hour standing period the 100 mg/L loading rate was observed to be a clear, colourless water column with test material floating on the surface, dispersed throughout and settled on the bottom of the vessel, with the exception of the Day 14 preparation where no test material was observed to be on the bottom of the vessel.Visual examination of the WAF showed dispersed material throughout the water column and therefore it was considered justifiable to remove the WAF by filtering through a glass wool plug (2-4 cm in length). Microscopic examination after filtering showed the glass wool plug had removed all of the dispersed material. During the test, the control and 100 mg/L loading rate were observed to be clear, colorless solutions.

Validity criteria fulfilled:

yes

Conclusions:

Exposure of Daphnia magna to the test material resulted in no significant mortalities at the loading rate employed during the test. The 21-day EL50 (immobilization) value, based on nominal loading rates, for the parental daphnia generation (P1) was determined to be greater than 100 mg/L loading rate WAF.

No significant impairment of reproduction was observed at the loading rate employed during the test. The 21-day EL50 (reproduction) value, based on nominal loading rates, was determined to be greater than 100 mg/L loading rate WAF.

The "No Observed Effect Loading Rate" (NOEL) based on nominal loading rates was 100 mg/L loading rate WAF.

Description of key information

Exposure of Daphnia magna to the read across test material, Phosphoric acid, octadecyl ester (EC Number 254 -466 -7), resulted in no significant mortalities at the loading rate employed during the test. The 21-day EL50 (immobilization) value, based on nominal loading rates, for the parental daphnia generation (P1) was determined to be greater than 100 mg/L loading rate WAF.

No significant impairment of reproduction was observed at the loading rate employed during the test. The 21-day EL50 (reproduction) value, based on nominal loading rates, was determined to be greater than 100 mg/L loading rate WAF.

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.