Dimethyl 5-[[1-[[(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)amino]carbonyl]-2-oxopropyl]azoterephthalate

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:

2011-08-29 to 2011-08-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to relevant guidelines and compliant to GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Remarks:

according to German Chemikaliengesetzt and directive 88/320/EEC

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: No vehicle, directly weighing, overnight stirring
- Eluate: Synthetic waste water acc. to OECD 209
- Differential loading: None, limit concentration of 1000 mg/L
- Controls: Triplicates at the beginning of the test + triplicates at the end of the test

Test organisms (species):

activated sludge

Details on inoculum:

- Preparation of inoculum for exposure: Non adapted activated sludge from the sewage plant at sarstedt (Municipal sewage treatment plant of 31157 Sarstedt, Germany)
- Pretreatment: Washed twice with autoclaved tap water and adjusted to a dry weight concentration of 3 g/L +/- 10 %
- Dry sludge concentration: 3.14 g/L (corresponding to 1.57 g/L suspended solids in the test vessels)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

Not determined

Test temperature:

21.4 °C

pH:

7.31 (activated sludge)
7.42 (synthetic waste water)

Salinity:

None, freshwater

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL Erlenmeyer flask, DIN 12380
- Aeration: Permanent
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Composition of test medium:
250 mL inoculum
16 mL synthetic waste water
234 mL autoclaved tap water
Test or reference item concentration (directly weighed into each test vessel)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Determination of respiration rates subsequently to an incubation period of 3 h

TEST CONCENTRATIONS

- Range finding study

Inhibition of Respiration (Preliminary Tests)
Nominal Test Item Concentration
[mg/L] Inhibition[%]
10 -4
100 -1
1000 -2

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a.

Duration:

3 h

Dose descriptor:

NOEC

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:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50: 110 mg/L (95 % CI = 105 - 117 mg/L)

Reported statistics and error estimates:

The coefficient of variation of the oxygen uptake rates of the control replicates was calculated with standard methods

Oxygen Uptake Rates, Specific Respiration Rates and Inhibition of the Respiration
                   of Control, Reference and Test Item Concentrations

Reference and Test Item Concentration [mg/L]	Repl.	Oxygen Uptake Rate R [mg O2/L×h]	Specific Respiration Rate Rs [mg O2/g×h]	Inhibition [%]	Mean Inhibition [%]
Control	1	19.6	12.5	-	-
	2	18.8	12.0
	3	18.0	11.5
	4	18.8	12.0
	5	18.0	11.5
	6	18.0	11.5
Reference Item 58	1	15.6		16	19
	2	15.6		16
	3	14.0		24
100	1	10.4		44	47
	2	9.2		50
	3	10.0		46
180	1	4.8		74	73
	2	5.2		72
	3	5.2		72
Test Item 1000	1	17.2		7	6
	2	17.6		5
	3	17.2		7

EC-Values with Confidence Interval for the test item

	EC-values	Confidence interval
	[mg/L]	P = 95 [%] [mg/L]
NOEC	1000	-
EC20	> 1000	-
EC50	> 1000	n.d.
EC80	> 1000	-

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of the test item is > 1000 mg/L. The test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit concentration of 1000 mg/L.

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 (2010) was carried out with the test item. Test system was activated sludge of the municipal treatment plant of D-31137 Hildesheim. The test was carried out under static conditions with the limit concentration 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The inhibition of respiration for the test item replicates ranged from 5 to 7 % .

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC₅₀-value for the reference item was 110 mg/L.

Validity criteria of the test guideline were fulfilled.

Table 1:           EC-Values with Confidence Interval for the test item

		EC-values		Confidence interval
		[mg/L]		P = 95 [%] [mg/L]
NOEC		1000		-
EC20		> 1000		-
EC50		> 1000		n.d.
EC80		> 1000		-

                                                         n.d. = not determinable

The NOEC of the test item is 1000 mg/L. The test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit concentration of 1000 mg/L.

Description of key information

The NOEC of the test item is > 1000 mg/L. The test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit concentration of 1000 mg/L.