2,2-bis[[(2-hexyl-1-oxodecyl)oxy]methyl]-1,3-propanediyl bis(2-hexyldecanoate)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see chapter 13 read-across justification

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

16 h

Dose descriptor:

other: EL10

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

growth inhibition

Key result

Duration:

16 h

Dose descriptor:

other: EL50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

growth inhibition

Key result

Duration:

16 h

Dose descriptor:

other: NOELR

Effect conc.:

>= 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WAF)

Basis for effect:

growth inhibition

Reported statistics and error estimates:

The percentage inhibitory effect on cell multiplication was calculated for each test material concentration using the equation stated in the ISO guideline. A Students t-test was carried out on the absorbance values after approx. 16 h exposure for the control and 10000 mg/L loading rate WAF test concentration.

Table 1: Mean absorbance values from the definitive study (n.d. = not determined)

Nominal Loading Rate [mg/L]	Absorbance Value
	0 h	16 h
Control	0.011	1.247
10000	n.d.	1.246

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see chapter 13 read-across justification

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The test substance showed no inhibitory effect on the respiration rate of activated sludge at any of the concentrations employed in the test. Respiration rates of mixtures containing the test substance showed an increase in respiration rate above that of the controls.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (3h) = 6.4 mg/L (4.1 - 9.6 mg/L)

Table 1: Preparation of test solutions

Treatment	Test substance [µL] or reference substance [mL]	Synthetic sewage [mL]	RO water [mL]	Microbial Inoculum [mL]
Control 1	0	16	284	200
Control 2	0	16	284	200
Test substance [mg/L]
10	5.1	16	284	200
100	50	16	284	200
1000	505	16	284	200
Reference substance [mg/L]
3	3	16	281	200
10	10	16	274	200
32	32	16	252	200

Table 2: Dissolved oxygen concentration and measurement times

Treatment	Initial dissolved oxygen conc. in culture [mg O2/L]	Initial measured dissolved oxygen conc. [mg O2/L]	Final measured dissolved oxygen conc. [mg O2/L]	Measurement time [min]
Control 1	6.9	6.5	2.5	8.5
Control 2	6.9	6.5	2.5	9.0
Test substance [mg/L]
10	4.5	4.2	1.5	5.3
100	5.0	4.8	1.5	6.3
1000	5.8	5.5	2.5	5.7
1000	4.9	4.6	1.5	5.8
1000	5.5	4.9	2.0	5.8
Reference substance [mg/L]
3	7.0	6.5	3.2	9.5
10	8.0	7.8	5.8	9.9
32	7.4	8.1	7.7	8.1

Table 3: Measurement of respiration rate

Treatment	Specific respiration rate [mg O2/g/h]	% inhibition or stimulation ()
Control 1	17.6	-
Control 2	16.7	-
Test substance [mg/L]
10	19.1	0 (11)
100	19.6	0 (14)
1000	19.7	0 (15)
1000	20.0	0 (17)
1000	18.8	0 (9)
Reference substance [mg/L]
3	13.0	24
10	7.6	56
32	1.9	89

Description of key information

EL50 (16 h) > 10000 mg/L (ISO 10712)

Additional information

In accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to two structurally related sub-category members pentaerytritol tetraoleate (CAS 19321-40-5)and decanoic acid, mixed esters with heptanoic acid, octanoic acid, pentaerythritol and valeric acid (CAS No. 71010-76-9) was conducted to fulfill the data requirements according to Annex IX forfatty acids, C16-18 and C18-unsatd., tetraesters with pentaerythritol (CAS 68604-44-4) in regard to toxicity to microorganisms.This read-across is justified in detail in the overall summary (IUCLID chapter 6.1) and within the category justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substances were used for the assessment. The fatty acid chain length of C16 and C18 of the first read-across substances are identical to those of the target substance. The second read-across substance covers the other end of the sub-category with shorter fatty acid chain lengths (C5-10). All substances contain the same alcohol (pentaerythritol) and are tetra-esters. As it can be seen in the data matrix of the category justification in section 13 and the overall summary, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.

The first study with the read-across substancepentaerytritol tetraoleate (CAS 19321-40-5)was conducted under static conditions according to ISO 10712 investigating aquatic microorganisms (Mead, 1997). In this GLP study an aqueous suspension of Pseudomonas putida was used as inoculum. A nominal test concentration of 10000 mg/L was used (prepared as WAF). The test substance did not inhibit the growth of Pseudomonas putida. Hence, the 16 h-EL50 was determined to be > 10000 mg/L based on the nominal test concentration.

The second study with the read-across substance decanoic acid, mixed esters with heptanoic acid, octanoic acid, pentaerythritol and valeric acid (CAS No. 71010-76-9) supports this result. It was conducted under static conditions according to OECD 209 investigating aquatic microorganisms (Dickinson, 2008). In this GLP studynon-adapted activated sludge obtained from a domestic sewage treatment plant was used as inoculum. Test concentrations of 10, 100 and 1000 mg/L were prepared. Test substance was added directly to the test vessels. The test substance did not inhibit the respiration rate of activated sludge microorganisms at any of the concentrations employed in the test. Hence, the 3 h-EC50 was determined to be > 1000 mg/L based on the nominal test concentration. Therefore it can be concluded that the test substance will not exhibit effects on the respiration rate of microorganisms.

Based on these results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile, it can be concluded that 2,2-bis[[(2-hexyl-1-oxodecyl)oxy]methyl]-1,3-propanediyl bis(2-hexyldecanoate) will not exhibit inhibitory effects to aquatic microorganism.