Bis[C5-(linear and branched)-alkyl] benzene-1,4-dicarboxylate

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:

2014-10-01 to 2016-07-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

(2004)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

(2008)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: The saturated solution and the control were analytically verified via LC-MS/MS at the start (0 and 24 h) and at the end of both exposure intervals (24 and 48 h). At the start of the exposure intervals (0 and 24 h), sampling was carried out immediately after preparation of the saturated solution. At the end of the exposure intervals (24 and 48 h), samples were taken directly from the test vessels.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A saturated solution with a nominal loading of 1 ml test item/L was prepared with dilution water four days prior to the start of the exposure phase (0 h) and the renewal of the test media after 24 h. The test item was placed by pipetting (5 ml I 5 L) on the surface of the dilution water. A slow stirring procedure was applied. Gentle stirring (to avoid formation of an emulsion) was carried out for 4 days with magnetic stirrer at approximately 25 °C. After separation of the phases, after 1 hour of standing, the saturated solution was taken from the homogeneous phase, cooled down to test temperature and used for testing without further dilution.
- Controls: Dilution water without test item tested under the same conditions as the test groups
- Reference Item: Potassium dichromate
- Evidence of undissolved material: The saturated solution was clear throughout the exposure intervals.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Daphnia magna STRAUS (Clone 5)
- Justification for species other than prescribed by test guideline: Daphnia magna is the preferred species in accordance with the test guidelines and is bred at the test facility.
- Source: lnstitut für Wasser-, Boden- und Lufthygiene (WaBolu), D-14195 Berlin
- Age of parental stock (mean and range, SD): 2 to 24 h old daphnids from a healthy stock were used for the study. They were obtained by removing the juvenile daphnids from the
culture vessels latest 22 h before the start of the exposure. The juveniles born within the 22 h preceding the exposure were used for the test after an acclimatisation phase of 2 h in the dilution water. No first brood progeny was used for the test.
- Food type: The culture daphnids were fed at least 5 times per week ad libitum with a mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus, with an algae cell density of >10^6 cells/ml. The algae were cultured at the test facility.
- Origin of the food: Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches lnstitut der Universitat Gottingen, D-37073 Göttingen
- Culture: In glass vessels (2 - 3 L capacity) with approximately 1.8 L culture medium, at 20 ± 2°C, in an incubator, 16 h illumination; light intensity of max. 20 µE·m-z . s-1
- Culture medium: Elendt M4, according to ELENDT (1990) is used. The composition was modified to a total hardness of approximately 160 to 180 mg CaC03/L.
- Acclimation period:At least 2 h in dilution water

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Remarks on exposure duration:

The test solutions were renewed after 24 h. For this purpose, the freshly prepared test solutions were filled in-to a second set of test vessels and the daphnids were transferred by pipette.

Hardness:

267-269 mg CaCO3/L

Test temperature:

18 - 22°C, constant within ± 1 °C

pH:

7.62 - 7.68

Dissolved oxygen:

9.06-8.82 mg/L

Conductivity:

678-680 µS/cm

Nominal and measured concentrations:

The saturated solution and the control were analytically verified via LC-MS/MS at the start (0 and 24 h) and at the end of both exposure intervals (24 and 48 h). The measured concentrations of the test item at the start of the exposure intervals were 66.5 µg/L (at 0 h) and 60.0 µg/L (at 24 h). At the end of the exposure intervals, the measured concentrations were 27.0 µg/L (24 h) and below the limit of quantification of 15.0 µg/L of the test item (at 48 h).
The geometric mean measured concentration of the test item was calculated to be 30.0 µg/L. All effect levels are given based on the nominal loading of the test item Di-(iso)-pentyl terephthalate of 1.00 ml/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beaker (4 (ID) x 7 (H) cm), 50 ml capacity, loosely covered with a watch glass
- Material, size, headspace, fill volume: 50 ml capacity
- Aeration: None
- Renewal rate of test solution: The test solutions were renewed after 24 h.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 2mL per test organism

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4
- Intervals of water quality measurement: Prior to the start of the exposure intervals (0 and 24 h), the water quality parameters (i.e. pH value, dissolved oxygen concentration, temperature, conductivity and total hardness) of the dilution water were measured. At the start of the exposure intervals (0 and 24 h), the water quality parameters of the fresh media (i.e. pH value, dissolved oxygen concentration) were measured in one additional replicate of the saturated solution and the control. At the end of the exposure intervals (24 and 48 h), the water quality parameters of the old media were measured in all replicates of the saturated solution and the control.

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16/8 h light/dark cycle
- Light intensity: Diffuse light, light intensity of max. 20 µE * m^-2 * s^-1

EFFECT PARAMETERS MEASURED: lmmobilisation was determined in all groups after 24 and 48 h. An animal was considered to be immobile, if it was not able to swim in the water phase within 15 seconds after gentle agitation of the test vessel.

RANGE-FINDING STUDY
- Test concentrations: nominal loading of 1.00 mL/L
- Results used to determine the conditions for the definitive study: In the preliminary range finding test, two replicates with 10 daphnids each were tested. The percentage immobility was determined at the saturated solution and the control after 24 and 48 h of exposure. No immobilised daphnids have been observed.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

24 h

Dose descriptor:

EL10

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EL100

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL10

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: (saturated solution

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL100

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 1 other: mL/L

Nominal / measured:

nominal

Conc. based on:

other: saturated solution

Basis for effect:

mobility

Details on results:

The percentage immobility, determined at the saturated solution of the test item Di-(iso)-pentyl terephthalate (OPT) with a nominal loading of 1.00 ml!L and the control after 24 and 48 h under semi-static conditions. There was no effect observed at the saturated solution and the control group. The saturated solution was clear throughout the exposure intervals.
The measured concentrations of the test item at the start of the exposure intervals were 66.5 µg/L (at 0 h) and 60.0 µg/L (at 24 h). At the end of the exposure intervals, the measured concentrations were 27.0 µg/L (24 h) and below the limit of quantification of 15.0 µg/L of the test item (at 48 h). The geometric mean measured concentration of the test item was calculated to be 30.0 µg/L.

Results with reference substance (positive control):

The percentage immobility for the reference item was determined after 24 h. The EC50-value with 95 % confidence interval (CI) was calculated by sigmoidal dose-response regression. The EC50 value for the most recent of the monthly performed reference tests was: EC50: 1.64 mg/L (CI 1.62 - 1.66 mg/L) The EC50-value of the reference item potassium dichromate after 24 h is within the prescribed concentration range of 0.6 - 2.4 mg/L of quality criteria according to AQS P 9/2 (02/2000) for daphnids clone 5 cultured in Elendt M4 medium. The EC50-value of the reference item is also within
the recommended range of 0.6 - 2.1 mg/L according to OECD-Guideline 202.

Immobilisation Rates of the Definitive Test after 24 and 48 hours of Exposure

Di-(iso )-pentyl terephthalate Nominal loading of the test item (mg/L)	Immobilisation (%)
	24 h					48 h
	Replicates					Replicates
	1.	2.	3.	4.	MV	1.	2.	3.	4.	MV
1.00 (Saturated solution)	0	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0	0

Validity criteria fulfilled:

yes

Remarks:

In the control group, no daphnids were immobilized (required: not more than 10 percent of the daphnids in the control). The dissolved O2 concentration at the end of the exposure intervals was >=8.49 mg/L (required: > 3 mg/L at test end).

Conclusions:

At a saturated solution of the test item Di-(iso)-pentyl terephthalate (DPT) with a nominal loading of 1.00 mL/L, no effects were observed on Daphnia magna. The geometric mean measured concentration of the test item was calculated to be 30.0 µg/L.
According to OECD Guidance Document No 23 (2000) if an effect cannot be detected in a test with a saturated solution the result has to be reported as no toxic effects at saturation.

Description of key information

No effects on Daphnia magna has been observed at a saturated solution with a nominal loading of 1.00 mL/L

Additional information

A short-term toxicity test with Daphnia magna under semi-static conditions has been conducted according to OECD TG 202 and GLP compliance with analytical monitoring of the test substance. Due to the poor water solubility of the test substance, the daphnids has been exposed to a saturated solution with a nominal loading of 1 mL test item/L, which has been generated in a slow stirring procedure according to the OECD Guidance Document No 23 (2000).

At a saturated solution of the test item Di-(iso)-pentyl terephthalate (DPT) with a nominal loading of 1.00 mL/L, no effects were observed on Daphnia magna. Therefore the EL10 and EL50 (48h) has been reported to be greated than 1.00 mL/L of the nominal loading of the test substance. The geometric mean measured concentration of the test item was calculated to be 30.0 µg/L. According to OECD Guidance Document No 23 (2000) if an effect cannot be detected in a test with a saturated solution the result has to be reported as no toxic effects at saturation.