Fatty acids, C5-9, hexaesters with dipentaerythritol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

13 Jun - 16 Jul 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions: No analytical purity is given.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(1984)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom (date of inspection 23 Mar 1998)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control - 100 mg/L
- Sampling method: Water samples were taken (replicates R1-R3 and R4-R6 pooled) at 0 and 72 h for quantitative analysis.
- Sample storage conditions before analysis: Duplicate samples were taken at 0 h and stored frozen (approx. -20 °C) for further analysis if necessary.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: An amount of test material (2000 mg) was added to the culture medium and stirred for 23 h to give the 100 mg/L loading rate. The stirring was stopped after 23 h and the mixture allowed to stand for 1 h. The water accommodated fraction (WAF) was then removed by filtration through 0.45 µm filters to give the 100 mg/L loading rate WAF. An aliquot (2 L) of the 100 mg/L loading rate WAF was mixed with algal suspension (20 mL).
- Controls: The control group was maintained under identical conditions but not exposed to the test material.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: CCAP 276/20
- Source: Culture Centre for Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ferry House, Ambleside, Cumbria
- Method of cultivation: Cultures were maintained in the laboratory by a periodic replenishment of culture medium at a temperature of 21 ± 1 °C under continuous illumination (approx. 7000 lux) and constant aeration.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

24 ± 1 °C

pH:

Control: 7.5 (0 h), 8.9 - 9.0 (72 h)
100 mg/L: 7.4 (0 h), 9.4 - 9.7 (72 h)

Nominal and measured concentrations:

Nominal: 100 mg/L loading rate WAF
Measured: < 0.18 mg/L (limit of quantification)

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flasks
- Type: covered with aluminium foil
- Material: glass, Size: 250 mL, Fill volume: 100 mL
- Aeration: constantly shaken at 100 rpm for 72 h
- Initial cells density: 10^4 cells/mL
- Control end cells density: 9.18E+5 cells/mL
- No. of vessels per concentration: 6
- No. of vessels per control: 3

GROWTH MEDIUM
- Standard medium used: yes according to OECD guideline

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: revese osmosis purified deionised water (Elga Optima 15+), pH adjusted to 7.5 ± 0.1

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: approx. 7000 lux

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Samples were taken at 0, 24, 48 and 72 h and the cell densities determined by using a haemocytometer and light microscope.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: The results showed no effect on growth at the 100 mg/L loading rate WAF.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

biomass

Details on results:

- Exponential growth in the control: yes
- Any stimulation of growth found in any treatment: yes, 4% stimulation of growth after 72 h (100 mg/L)
- Effect concentrations exceeding solubility of substance in test medium: The effect concentrations exceeded the water solubility of the test substance.

Reported statistics and error estimates:

A Students t-test was performed for statistical analysis.

The test exhibited an EL50 of > 100 mg/L (nominal) based on the growth rate. No effects were observed in the range of water solubility. Chemical analysis of the 100 mg/L loading rate WSFs at 0 and 72 h showed the measured test concentrations to be less than the limit of quantification of the analytical method (0.18 mg/L). Exceeding the duration of stirring did not result in significant increase in TOC in test solutions.

Table 1: Cell densities in the definitive study

Nominal loading rate [mg/L]	Cell densities [cells/mL]
	0 h	24 h	48 h	72 h
Control R1	6.65x10³	3.61 x10^5	6.94 x10^5	8.33 x10^5
Control R2	5.00 x10³	3.89 x10^5	5.83 x10^5	9.18 x10^5
Control R3	5.00 x10³	3.89 x10^5	5.56 x10^5	8.33 x10^5
Control Mean	5.55 x10³	3.80 x10^5	6.11 x10^5	8.61 x10^5
100 R1	3.35 x10³	4.72 x10^5	5.56 x10^5	1.17 x10^6
100 R2	5.00 x10³	3.89 x10^5	5.56 x10^5	9.18 x10^5
100 R3	5.00 x10³	3.89 x10^5	5.83 x10^5	1.00 x10^6
100 R4	6.65 x10³	4.17 x10^5	5.28 x10^5	6.68 x10^5
100 R5	5.00 x10³	4.17 x10^5	6.11 x10^5	8.33 x10^5
100 R6	3.35 x10³	4.17 x10^5	5.56 x10^5	9.18 x10^5
100 Mean	4.73 x10³	4.17 x10^5	5.56 x10^5	9.18 x10^5

Table 2: Inhibition of growth rate and biomass

Nominal loading rate [mg/L]	Area under curve at 72 h	% inhibition	growth rate (0-72 h)	% inhibition
Control	3.38x10^7	-	0.070	-
100	3.43x10^7	[2]	0.073	[4]

[increase in growth as compared to the controls]

Description of key information

EL50 (72 h) > 100 mg/L for Scenedesmus subspicatus (WS: < 0.05 mg/L OECD 201)

Additional information

In accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to the structurally similar analogue substance dipentaerythritol with fatty acids, C5 and C9iso (CAS 647028-25-9) was conductedtofulfil the data requirements according to Annex VII-IX ofcarboxylic acids, C5 -9, hexaesters with dipentaerythritol (CAS 67762-52-1)in regard to toxicity to aquatic algae. This read across is justified in detail in the overall summary (IUCLID section 6.1) and within the analogue justification in IUCLID section 13. The substance consists of the same alcohol component (dipentaerythritol) and similar fatty acid chain lengths as the target substance (C5-9 for the target substance compared to C5,9iso for the source substance).

The study with the read-across substance dipentaerythritol with fatty acids, C5 and C9iso (CAS 647028-25-9) investigated the toxicity to algae in a GLP guideline study. The test was performed according to OECD 201 (Mead and Mullee, 2000) with Scenedesmus subspicatus exposed to a water accommodated fraction with a limit concentration of 100 mg/L. The test substance concentration was analysed using GC-analysis and resulted in a concentration of < 0.18 mg/L (limit of quantification). No inhibition was observed after 72 h. Therefore, this study resulted in an EL50 of > 100 mg/L (nominal). The NOELR was derived to be 100 mg/L (nominal).

Based on the results from a structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5), characterized by a similar ecotoxicological profile and structure, it can be concluded thatcarboxylic acids, C5 -9, hexaesters with dipentaerythritolwill not exhibit toxic effects to aquatic algae up to the limit of water solubility.