hydrogenation products of (esterification products of 2-ethylhexan-1-ol with (Estolide formation products of oleic acid and Fatty acids, C8-18 and C18-unsatd. (branched or linear)).

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Test performance: February 25th, 2015. Experimental completion date: February 25th, 2015.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Description of the test item
Name: SE7B
Lot Nr. of test item: 0000140602
Hydrotox No.: 14/4956
CAS-Nr.: 1365345-64-7
Origin: Innospec Limited
Certificate of analysis: not available

Characterisation of the test item
Purity: >98%
Appearance: clear, light yellow liquid
Densitiy: not available
Volatility: negligible (information from the sponsor)
Stability: Stable (information from the sponsor)
Storage conditions: do not store near heat, sources of ignition or oxidizing agents
Expiration date: not available
Solubility in water: insoluble (information of the sponsor)
Safety directions: None

Date of receipt of the test item
November 25th, 2014
Storage at room temperature

Test of identity of the test item
The identity was confirmed visually. The test item is a clear, light yellow liquid. The designation on the flask of the test item was confirmed.

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

500 mg of the test item were added directly into the test vessels to obtain final concentration of 1000 mg/L.

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant Staufener Bucht was used as test system. The treatment plant has a capacitiy of 140 000 inhabitant equivalents and clarifies predominantly domestic wastewater. Sampling date of activated sludge was February 23rd, 2015. The activated sludge was kept aerated and fed with synthetic sewage (50 ml per litre and day) until use. Dry solids of the activated sludge was determined as 6.5 g/l by weight measurements before and after 3 h drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice by settling the sludge, decanting the supernatant, and re-suspending the sludge in aerated tap water. Before using, the activated sludge was diluted to 3 g/l dry solids with tap water, in order to obtain a final concentration of 1.5 g/l dry solids in the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20.7 - 22.1°C

pH:

7.0 - 7.3

Nominal and measured concentrations:

1000 mg/L

Details on test conditions:

The different vessels must be started separately with an interval of exactly 15 min in order to be able to measure the respiration rates one by one while making sure that the aeration time is 3 h in every vessel. At time "0", 16 ml synthetic sewage and the test item or reference compound was added to the test vessel and made up to 250 ml with tap water. After a measurement and adjustment of pH 250 ml of activated sludge (3 g/l dry solids) were added thereby obtaining a total volume of 500 ml with 1.5 g/l dry solids. For the controls the same procedure was made as in the test vessels just without test or reference substance. All vessels were stirred and aerated throughout the contact time with room air at a rate of 0.5-1 litre per minute using a membrane pump. Before starting the test the aeration rate was measured in all test vessels.
After 3 h the aeration of the first vessel was shut off and the respiration rate was measured in a BOD-bottle with an oxygen electrode while mixing with a magnetic stirrer.
This determination was repeated for each vessel at 15-min intervals in such a way, that the contact time in each vessel was 3 h.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

Test item
At a concentration of 1000 mg/L there was no inhibition of SE7B on the respiration rate of the inoculum. On the contrary, there was a negative inhibition of -8 to -15% in the test vessels (1000 mg/L) which is caused by a slight promotion of the respiration.


Blanks
The respiration rate of the six blanks were within 24.0 – 35.3 mg/(l*h) and differed less than 30% from each other.
The temperature range was between 20.7°C and 22.1°C, the pH in the vessels were between 7.0 and 7.3 in all vessels.

Results with reference substance (positive control):

Reference item
The EC50 of 3,5-dichlorphenol was calculated as 8.58 mg/l (ToxRat software by probit analysis using linear max. likelihood regression) and was therefore within the acceptable range of 2 to 25 mg/l.

Reported statistics and error estimates:

Criteria met for the validity of the study
> The respiration rates of the six blanks were less than 30% different from each other.
> The blank controls oxygen uptake rate was higher than 20 mg oxygen per one gram of activated sludge per hour.
> The EC50 of the reference item was within the acceptable range of 2 to 25 mg/l.

Oxygen concentration in the test- and reference vessels and in the blanks

Vessel	Concentration	Ineterval of measurement [sek]	Measurement after 180 Min
			O2-concentration [mg/l] at time [sec]
1	Blank 1	30	6.25	5.99	5.72	5.46	5.22	4.99
2	Blank 2	30	5.92	5.65	5.42	5.24	5.08	4.90
3	Blank 3	30	6.26	6.02	5.81	5.62	5.43	5.26
4	test item 1 (1000 mg/l)	30	4.85	4.50	4.21	3.94	3.70	3.48
5	test item 2 (1000 mg/l)	30	4.25	3.90	3.59	3.30	3.03	2.79
6	test item 3 (1000 mg/l)	30	4.28	3.98	3.70	3.40	3.12	2.86
7	3,5-D 1 mg/l	30	6.44	6.25	6.06	5.88	5.71	5.52
8	3,5-D 10 mg/l	30	7.00	6.83	6.72	6.59	6.46	6.34
9	3,5-D 30 mg/l	30	7.77	7.65	7.56	7.48	7.41	7.35
10	Blank 4	30	6.00	5.65	5.33	5.04	4.78	4.53
11	Blank 5	30	6.70	6.52	6.34	6.17	5.78	5.26
12	Blank 6	30	6.51	6.15	5.83	5.54	5.30	5.06

Respiration rate of activated sludge after application of SE7B

Vessel	O2 concentration in [mg/l]		Consuption rate [mg/(l*h)]	Inhibition [%]
	First measurement	Last measurement
Blank 1	6.25	4.99	30.2
Blank 2	5.92	4.90	24.5
Blank 3	6.26	5.26	24.0
Blank 4	6.00	4.53	35.3
Blank 5	6.70	5.26	34.6
Blank 6	6.51	5.06	34.8
test item 1 (1000 mg/l)	4.85	3.48	32.9	-8
test item 2 (1000 mg/l)	4.25	2.79	35.0	-15
test item 3 (1000 mg/l)	4.28	2.86	34.1	-12
coefficient of variation of blanks:		0.16

Respiration rate of activated sludge after application of 3,5-dichlorphenol

Vessel	O2 concentration in [mg/l]		Consuption rate [mg/(l*h)]	Inhibition [%]
	First measurement	Last measurement
Blank 1	6.25	4.99	30.2
Blank 2	5092.00	4.90	24.5
Blank 3	6.26	5.26	24.0
Blank 4	6.00	4.53	35.3
Blank 5	6.70	5.26	34.6
Blank 6	6.51	5.06	34.8
3,5-D 1 mg/l	6.44	5.52	22.1	28
3,5-D 10 mg/l	7.00	6.34	15.8	48
3,5-D 30 mg/l	7.77	7.35	10.1	67

Validity criteria fulfilled:

yes

Conclusions:

At a concentration of 1000 mg/L there was no inhibition of SE7B on the respiration rate of the inoculum. On the contrary, there was a negative inhibition of -8 to -15% in the test vessels (1000 mg/L) which is caused by a slight promotion of the respiration.

Description of key information

At a concentration of 1000 mg/L there was no inhibition of SE7B on the respiration rate of the inoculum. On the contrary, there was a negative inhibition of -8 to -15% in the test vessels (1000 mg/L) which is caused by a slight promotion of the respiration.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L