1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione

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:

2018-05-24 to 2018-05-25

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

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Test System: Activated sludge

Origin: Municipal sewage treatment plant of 31137 Hildesheim, Germany

Reason for the selection: Non-adapted activated sludge from the sewage plant at Hildesheim is well suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.

Pretreatment: The sludge was washed twice and was used within 24 h after sampling.

Date of receipt: 2018-05-24

Dry sludge concentration: 2.98 g/L, corresponding to 1.49 g/L in the test vessel for replicates without ATU and 2.94 g/L, corresponding to 1.47 g/L in the test vessel for replicates with ATU.

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Test temperature:

18 - 22°C, actual: 20.0°C. The temperature was determined in the first replicate at test start with the pH-meter. The room temperature during the test was recorded continuously.

pH:

The pH value of the activated sludge was determined prior to test start. The pH value of the synthetic waste water was determined prior to use. Adjustment to 7.5 ± 0.5 was not necessary.

Dissolved oxygen:

After 3 h incubation, the oxygen concentration of each control, reference item and test item replicate was determined by means of oximeter every 5 seconds after transferring the solution to the measuring chamber and the oxygen depletion was recorded for at least 5 minutes with the software PreSens Measurement Studio 2

Nominal and measured concentrations:

100 - 180 - 320 - 560 - 1000 mg/L were weighed out on bent object slides and were transferred into the test vessels.

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a (for total respiration) and N-Methylaniline (for nitrification)

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

218 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

88.7 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

805 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Details on results:

The NOEC of 2,4,6-Tris[3-(trimethoxysilyl)propyl] isocyanurate (CAS 26115-70-8) for total respiration is 180 mg/L.
The EC10 for total respiration is 218 mg/L.
The NOEC for heterotrophic respiration is 1000 mg/L.
The NOEC for nitrification is 100 mg/L.
The EC10 for nitrification is 88.7 mg/L and the EC50 is 805 mg/L.

Biotic and abiotic factors in the definitive study

The pH-values of the activated sludge and synthetic waste water, the dry sludge concentration and the test temperature are documented in Table 6.

Table 6: Biotic and abiotic factors

pH-value of the activated sludge for test without ATU	7.45
pH-value of the activated sludge for test with ATU	7.30
pH-value of the synthetic waste water	7.19
Dry solids concentration [g/L] of sludge for test without ATU	2.98
Dry solid concentration [g/L] in test solution for test without ATU	1.49
Dry solids concentration [g/L] of sludge for test with ATU	2.94
Dry solid concentration [g/L] in test solution for test with ATU	1.47
Test temperature [°C]	20.0

Oxygen uptake rates, specific respiration rates and inhibition of the respiration

From the oxygen depletion the oxygen uptake rates were calculated in mg O₂/L×h, additionally the spcific respiration rates based on the dry sludge concentration were calculated in mg O₂/g×h. The inhibition of the oxygen uptake rates of the test and reference item concentrations in % was calculated in comparison to the oxygen uptake rates of the control. The results are listed in Table 7 to Table 15.

Table 7: Oxygen Uptake Rates and Specific Respiration Rates of the total Respiration of the Control

	Repl.	Oxygen Concentration*	Oxygen Uptake Rate R	Specific Respiration Rate Rs
		[mg O2/L]	[mg O2/(L×h)]	[mg O2/g×h]
Control	1	7.85	30.8	20.7
	2	7.60	32.0	21.5
	3	6.92	29.0	19.5
	4	7.78	28.3	19.0
	5	7.69	28.6	19.2
	6	7.44	26.8	18.0
	Mean value		29.3	19.7
	Standard deviation		1.7
	CV [%]		5.8

*) determined at start of the measurement

Repl. = Replicate ; CV = Coefficient of variation

 

Table 8: Oxygen Uptake Rates and Inhibition of the total Respiration of the Test Item Concentrations

Test Item Concentration	Repl.	Oxygen Concentration*	Oxygen Uptake Rate R	Inhibition	Mean Inhibition
[mg/L]		[mg O2/L]	[mg O2/(L×h)]	[%]	[%]
100	1	7.54	29.7	-1	2
	2	7.36	29.8	-2
	3	6.51	27.8	5
	4**	-	-	-
	5	7.00	27.7	5
180	1	7.58	27.7	5	6
	2	7.86	28.3	3
	3	7.25	25.7	12
	4	8.11	28.5	3
	5	7.26	26.6	9
320	1	7.90	24.0	18	18
	2	7.53	25.0	15
	3	7.42	23.5	20
	4	8.03	25.1	14
	5	7.26	22.7	23
560	1	8.11	22.5	23	28
	2	7.91	22.5	23
	3	7.40	21.3	27
	4	8.14	22.7	23
	5	7.71	16.9	42
1000	1	8.17	19.5	33	36
	2	7.44	18.9	35
	3	7.36	17.7	40
	4	8.01	19.6	33
	5	7.37	18.0	39

*) determined at start of the measurement

**) Replicate was broken while shaking overnight,not included in calculation

Repl. = Replicate

Table 9: Oxygen Uptake Rates of the heterotrophic Respiration of the Control Replicates with ATU

	Repl.	Oxygen Concentration*	Oxygen Uptake Rate R
		[mg O2/L]	[mg O2/(L×h)]
Control	1	8.35	10.0
	2	8.43	11.1
	3	7.79	9.8
	4	8.27	10.7
	5	8.47	11.9
	6	7.68	11.2
	Mean value		10.8
	Standard deviation		0.72
	CV [%]		6.67

*) determined at start of the measurement

Repl. = Replicate

CV = Coefficient of variation

Table 10: Oxygen Uptake Rates and Inhibition of the heterotrophic Respiration of the Test Item Concentrations

Test Item Concentration [mg/L]	Repl.	Oxygen Concentration* [mg O2/L]	Oxygen Uptake Rate R [mg O2/L×h]	Inhibition [%]	Mean Inhibition [%]
100 + ATU	1	8.20	15.5	-44	-18
	2	8.48	12.8	-19
	3	7.75	11.3	-5
	4**	8.33	12.2	-13
	5	8.08	11.3	-5
180 + ATU	1	8.39	13.8	-28	-27
	2	8.23	16.3	-51
	3	7.83	13.0	-20
	4	7.98	12.9	-19
	5	8.02	12.6	-17
320 + ATU	1	8.13	13.8	-28	-21
	2	8.34	14.4	-33
	3	7.56	12.6	-17
	4	8.19	13.0	-20
	5	8.06	11.4	-6
560 + ATU	1	8.28	10.1	6	3
	2	8.23	11.3	-5
	3	7.84	10.3	5
	4	8.46	10.7	1
	5	7.92	10.1	6
1000+ ATU	1	8.32	10.7	1	6
	2	8.25	10.8	0
	3	7.54	10.4	4
	4	8.11	10.2	6
	5	7.94	8.8	19

*) determined at start of the measurement

**) Replicate without ATU was broken while shaking overnight,not included in calculation

Repl. = Replicate

Table 11: Calculated Oxygen Uptake Rates of the Nitrification of the Control

		Repl.		Oxygen Uptake Rate R
				[mg O2/(L×h)]
Control		1		20.8
		2		20.9
		3		19.2
		4		17.6
		5		16.7
		6		15.6
Mean value			18.5
Standard deviation			2.0
CV [%]			10.8

*) determined at start of the measurement

Repl. = Replicate

CV = Coefficient of variation

Table 12: Calculated Oxygen Uptake Rates and Inhibition of the Nitrification of the Test Item Concentrations

Test Item Concentration [mg/L]	Repl.	Oxygen Uptake Rate R [mg O2/L×h]	Inhibition [%]	Mean Inhibition [%]
100	1	14.2	23	13
	2	17.0	8
	3	16.5	11
	4*	-	-
	5	16.4	11
180	1	13.9	25	26
	2	12.0	35
	3	12.7	31
	4	15.6	16
	5	14.0	24
320	1	10.2	45	40
	2	10.6	43
	3	10.9	41
	4	12.1	35
	5	11.3	39
560	1	12.4	33	42
	2	11.2	39
	3	11.0	41
	4	12.0	35
	5	6.8	63
1000	1	8.8	52	54
	2	8.1	56
	3	7.3	61
	4	9.4	49
	5	9.2	50

Repl. = Replicate

*) Replicate (without ATU) was broken while shaking overnight, not included in calculation

EC Values:

The EC-values with confidence intervals are listed in Table 13.

Table 13: EC-Values with Confidence Interval of 2,4,6-Tris[3-(trimethoxysilyl)propyl] isocyanurate (CAS 26115-70-8)

	Total Respiration		Heterotrophic Respiration		Nitrification
	EC-values [mg/L]	Confidence interval P = 95 [%] [mg/L]	EC-values [mg/L]	Confidence interval P = 95 [%] [mg/L]	EC-values [mg/L]	Confidence interval P = 95 [%] [mg/L]
NOEC*	180	–	1000	–	100	–
EC10	218	170 – 270	¿ 1000	–	88.7	¿100 -113
EC20	367	307 – 446	¿ 1000	–	131	¿100 -178
EC50	¿ 1000	–	¿ 1000	–	805	494 - ¿1000
EC80	¿ 1000	–	¿ 1000	–	¿ 1000	–

                            *) No statistically significant inhibition (P < 0.001), ANOVA, Dunnett`s Method

Reference test:

Total respiration

Table 14: Oxygen Uptake Rates, Inhibition of the total Respiration of the Reference Item Copper (II) sulphate pentahydrate Concentrations

Reference Item Concentration	Repl.	Oxygen Concentration*	Oxygen Uptake Rate R	Inhibition	Mean Inhibition
[mg/L]		[mg O2/L]	[mg O2/(L×h)]	[%]	[%]
58	1	8.08	22.0	25	28
	2	8.27	21.1	28
	3	7.71	19.8	32
100	1	8.28	13.7	53	53
	2	8.31	14.7	50
	3	7.89	12.7	57
180	1	8.67	5.1	83	82
	2	8.63	5.5	81
	3	7.87	5.2	82

*) determined at start of the measurement

Repl. = Replicate

In the reference test the EC₅₀-value forcopper (II) sulphate pentahydrate was determined by linear regression with: EC₅₀= 92.2 mg/L, 95% Confidence Interval = 87.9 – 96.5 mg/L

 

This is in the recommended range of validity of 53 - 155 mg/L.

Nitrification:

Table 15: Calculated Oxygen Uptake Rates, Inhibition of the Nitrification of the Reference Item N-Methylaniline Concentrations

Reference Item Concentration	Repl.	Oxygen Uptake Rate R	Inhibition	Mean Inhibition
[mg/L]		[mg O2/(L×h)]	[%]	[%]
0.1	1	17.8	4	13
	2	17.4	6
	3	13.2	29
1.8	1	8.7	53	55
	2	7.6	59
	3	8.4	55
32	1	1.0	95	97
	2	1.4	92
	3	-0.7	104

*) determined at start of the measurement

Repl. = Replicate

 

In the reference test the EC₅₀-value for N- Methylanilinewas determined by linear regression with: EC₅₀= 1.25 mg/L, 95% Confidence Interval = 0.78 – 1.96 mg/L

Validity criteria fulfilled:

yes

Conclusions:

A 3 hour NOEC value of 180 mg/L was determined for the inhibition of total respiration of the substance using a relevant test method and in compliance with GLP. The result is considered to be reliable.

Description of key information

Toxicity to microorganisms: 3 hour NOEC 180 mg/L (OECD 209; ASRI)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

180 mg/L

Additional information

An activated sludge respiration inhibition 3 hour NOEC (total respiration) of 180 mg/L and EC₁₀ (total respiration) value of 218 mg/L were determined for the substance in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP. The result is considered to be reliable.