Hexanoic acid, 3,5,5-trimethyl-, 1,1'-[2-ethyl-2-[[(3,5,5-trimethyl-1-oxohexyl)oxy]methyl]-1,3-propanediyl] ester

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 June 2013 - 11 September 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP in accordance with recognised guidelines

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 or 100 mg/L nominal loading rate
- Sampling method:
- Sample storage conditions before analysis: The samples were stored frozen prior to analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: An amount of test item (1000 mg) was added to the surface of 10 L of reconstituted water to give the 100 mg/L loading rate. After the addition of the test item, 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 ours and the mixture allowed to stand for 1 hour. 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 Nescoseal. Microscopic inspection of the WAF showed no micro-dispersions or undissolved test item to be present. The aqueous phase or WAF was removed by mid-depth siphoning (the first approximate 75-100 mL discarded) to give the 100 mg/L loading rate WAF.
- Eluate: Reconstituted water
- Differential loading: N/A
- Controls: Reconstituted water
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water Flea (Daphnia)
- Strain: Daphnia magna
- Source: In house laboratory cultures
- Age at study initiation (mean and range, SD): 1st instar
- Weight at study initiation (mean and range, SD): NDA
- Length at study initiation (length definition, mean, range and SD): NDA
- Method of breeding: parthenogenises
- Feeding during test: The daphnids received no food during exposure

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

not applicable

Hardness:

The reconstituted water had an approximate theoretical total hardness of 250 mg/l as CaCO3.

Test temperature:

The temperature was maintained at 22-25°C throughout the duration of the test.

pH:

Control: 7.8-8.2
Test item: 7.9-8.1

Dissolved oxygen:

The dissolved oxygen concentration was approximately air-saturation value

Salinity:

NDA

Nominal and measured concentrations:

nominal concentrations: 0 or 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL covered jar
- Material: glass
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): N/A
- Renewal rate of test solution (frequency/flow rate): N/A
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): N/A
- Biomass loading rate:NDA


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water
- Total organic carbon: NDA
- Particulate matter: NDA
- Metals:NDA
- Pesticides:NDA
- Chlorine:NDA
- Alkalinity:NDA
- Ca/mg ratio:NDA
- Conductivity:NDA
- Culture medium different from test medium: No difference
- Intervals of water quality measurement: N/A


OTHER TEST CONDITIONS
- Adjustment of pH: Using NaOH or HCl were necessary
- Photoperiod: 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods
- Light intensity: NDA


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The criterion of effect used was that Daphnia were considered to be immobilised if they were unable to swim for approximately 15 seconds after gentle agitation.

Reference substance (positive control):

yes

Remarks:

potassium dichromate (non-concurrent)

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:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: none
- Observations on body length and weight: N/A
- Other biological observations: none
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: NDA
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: NDA
- Effect concentrations exceeding solubility of substance in test medium: N/A

Results with reference substance (positive control):

- Results with reference substance valid? Yes
The results from the positive control with potassium dichromate were within the normal range for this reference material. The mean 48-Hour EC50 value calculated from all positive controls was 0.71 mg/L.

The No Observed Effect Concentration after 48 hours was 0.32 mg/L. The No Observed Effect Concentration is based upon zero immobilisation at this concentration.

Time (h) 24
EC50 (mg/L) = 1.0
95% Confidence limits (mg/L) = 0.91-1.2

Time (h) 48
EC50 (mg/L) = 0.71
95% Confidence limits (mg/L) = 0.65-0.76

Validity criteria fulfilled:

yes

Conclusions:

The 48-h EL50 based on nominal loading rates was > 100 mg/L loading rate WAF. The No Observed Effect Loading rate was 100 mg/L loading rate WAF.

Executive summary:

Introduction

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, 'Daphnia sp., Acute Immobilisation Test' referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Methods

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test, the test item was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to a Water Accommodated Fraction (WAF) of the test item at single nominal loading rate of 100 mg/L for 48 hours at a temperature of 22 °C to 25 °C under static test conditions. The number of immobilized Daphnia and any adverse reaction to exposure were recorded after 24 and 48 hours.

Results

Exposure of Daphnia magna to the test item gave EL*50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF. It was considered unnecessary and unrealistic to test at loading rates in excess of 100 mg/L loading rate WAF.

Analysis of the 100 mg/L loading rate WAF at 0 and 48 hours showed that measured concentrations of 0.0213 and 0.00463 mg/L were obtained respectively. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

*EL = Effective Loading Rate

Description of key information

One reliable study is available. In this study Daphnia magna were exposed to a Water Accommodated Fraction of the substance at a nominal loading rate of 100 mg/L under static conditions for 48 hours. The EL50(48 h) value was > 100 mg/L loading rate WAF. The substance is not acutely harmful to aquatic invertebrates.

Additional information

One reliable study is available. In this study (Harris, 2013) performed under GLP according to OECD TG 202 and EC Method C.2, Daphnia magna were exposed to the substance under static conditions for 48 hours at a temperature of 22 °C to 25 °C. Due to the low aqueous solubility and complex nature of the test item, the test medium was prepared as a Water Accommodated Fraction (WAF). Following a preliminary range-finding test, twenty daphnids ( 4 replicates of 5 animals) were exposed to a WAF of the test material at a nominal loading rate of 100 mg/L. The number of immobilized Daphnia and any adverse reaction to exposure were recorded after 24 and 48 hours. The EL50 (48 h) value was > 100 mg/L loading rate WAF.

The results of this study are supported by data available for read-across substances fatty acid polyols (Fatty acids, C5-9, esters with pentaerythritol (EC 270-290-3, CAS 68424-30-6) and Decanoic acid, ester with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol octanoate (EC 234-392-1, CAS 11138-60-6)). The substance with the CAS No. 131459-39-7 is a structural analogue of one of the read-across substances (CAS No. 68424-30-6) and can be used for read-across also.

The justification for read-across is presented in Section 13 Assessment reports- Read-across justification.

Four studies, investigating the short-term toxicity to aquatic invertebrates of Decanoic acid, ester with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol octanoate (CAS-No. 11138-60-6), were available. These studies were conducted with Daphnia magna and according to OECD 202. All measured results from 48 -hour toxicity studies indicate the test substance is of low toxicity to Daphnia magna.

Häner (2007) determined EL 50 (48h) > 100 mg/L (WAF loading rate) and Kuttler (1998) observed no immobilisation at 10000 mg/L (EL50 > 10000 mg/L, WAF loading rate). Both other studies (Källquist 1995 and Craig 2005) calculated EL50 > 1000 mg/L (WAF loading rate) with an immobilisation under 50% at 1000 mg/L (Källquist: 32%; Craig: 45%). In addition, a 15-day reproduction test (Low, 1996, entered in 6.1.4) showed no immobile daphnia during the whole test duration at a WAF loading rate of 2570 mg/L. One other available test result (EC50 = 15.86 mg/L) should be evaluated with caution because the original report was not available and therefore the documentation was insufficient for assessment (Draguez, 1991). Nonetheless, all data show toxicities of Decanoic acid, ester with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol octanoate (CAS-No. 11138-60-6) far in excess of natural occurring concentrations (water solubility < 0.3 mg/L). Therefore, the substance is not harmful to aquatic invertebrates.

In an addition study on 3,5,5-trimethylhexanoic acid mixed tetraesters with PE and valeric acid (CAS-No. 131459-39-7). In this GLP-study withDaphnia magnaaccording to OECD 202 (1984) no effect on immobilisation was observed at the tested WAF loading rates (Sewell and McKenzie, 2003). The observed EL50 (48h) > 1000 mg/L with a NOELR ≥ 1000 mg/L. Chemical analysis of the WAF loading rates at 0 and 48 h showed measured test concentrations less than or at the limit of quantification of the analytical method (< 0.032 mg/L).