6,6',6''-(1,3,5-triazine-2,4,6-triyltriimino)trihexanoic acid, compound with 2,2',2''-nitrilotriethanol (1:3)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989-06-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Non GLP study. Deviations from the updated OECD-guideline (adopted 2010): The coefficient of analysis of the control was not reported and a reduced number of replicates in the treatment groups were used. Settled sludge was used. Direct weighted amounts were added to the test medium instead of a stock solution.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

Non GLP study. The coefficient of analysis of the control was not reported and a reduced number of replicates in the treatment groups were used. Settled sludge was used. Direct weighted amounts were added to the test medium instead of a stock solution.

GLP compliance:

no

Analytical monitoring:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Differential loading: 20.21, 6.51, 2.66, 0.93 rsp. 0.32 mg of the test substance were weighed and added to the test medium.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Pretreatment: The sludge was separated from the aqueous layer by settling instead of centrifugation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 +/- 2 °C

Nominal and measured concentrations:

101, 32.5, 13.3, 4.7 and 1.6 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL BOD flasks with glas inlet
- No. of vessels per concentration: one
- No. of vessels per control: two blank and three reference controls
- Biomass loading rate: 1.7- 1.8 g/L

TEST MEDIUM / WATER PARAMETERS
- according to the guideline

EFFECT PARAMETERS MEASURED :
inhibition

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 101 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: IC20

Effect conc.:

> 101 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: IC80

Effect conc.:

> 101 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: IC50 > 100 mg/L

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Results published in peer-reviewed journal; study performed according to guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions (0.5 to 5.0 g/L) of the test chemical were prepared in deionized water. When necessary, the stock solutions were adjusted to pH 7.5 ± 0.5 by the addition of 1N H2SO4 or 1N NaOH as required

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of inoculum: municipal wastewater treatment plant (sampling: one day prior to test start)
- Preparation of inoculum for exposure: after sampling of activated sludge, solids were allowed to settle, waste liquor was discarded, solids diluted to 8.5 L with deionised water, aerating (0.5 L/min), concentration of mixed liquor suspended solids (MLSS) was determined; again solids were allowed to settle, liquor was discarded, sludge was washed three times with with deionised water. MLSS adjusted to 4000±400 mg dry weight per liter, aerated (0.5 L/min), incubated at 21 °C; synthetic sewage stock solution (50 mL/L; similar to OECD, but increased K2HPO4 concentration)
- Initial biomass concentration: MLSS adjusted to 4000±400 mg dry weight per liter

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21 °C

pH:

7.5±0.5

Nominal and measured concentrations:

Nominal: no data

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 1L-bottle, final volume 500 mL
- Aeration: 0.5 - 1.0 L/min

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Adjustment of pH: yes, 7.5 ± 0.5

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Respiration rate: Orion model 97.08 polarographic oxygen electrode and Orion model 701 Ionanalyzer (respiration rate determined ove 5 minute period; mg O2/L/min)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Duration:

3 h

Dose descriptor:

IC50

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 synthetic sewage stock solution was prepared similar to OECD 209, but contained a higher K2HPO4 concentration. This concentration was modified after performance of a number of preliminary inhibition studies. It was observed that the pH of a test reaction often changed during the 3-hour incubation period. Thus, decreases in the respiration rate may have been due to a combination of both the effects of pH and toxicity of the test chemical. As a consequence, the buffering capacity of the synthetic sewage nutrient medium was increased to prevent changes in pH of reaction mixtures.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: IC50 for 3,5-dichlorphenol: 12.2 ± 2.2 mg/L (18% variance) (municipal sewage)

Reported statistics and error estimates:

Inhibition data were analyzed using Thompson's method of moving averages to estimate IC50 values. The experimental data were also analyzed using a probit-transformation model similar to that described by Larson and Schaeffer (1982). A nonlinear curve-fitting program (Procedure NLIN of SAS) was used to estimate IC50 values and associated 95% confidence intervals.

Validity criteria fulfilled:

yes

Description of key information

The compound consists of a triazine part and an amine part. Under environmental conditions it is present in its dissociated form. Therefore, separate assessments were conducted for the triazine and the amine part, respectively.  

CAS 80584-91-4: The inhibition of the degradation activity of activated sludge is not anticipated when introduced to biological treatment plants in appropriate low concentrations.

CAS 102-71-6: The inhibition of the degradation activity of activated sludge is not anticipated when introduced to biological treatment plants in appropriate low concentrations.

Additional information

The compound consists of a triazine part and an amine part. Under environmental conditions it is present in its dissociated form. Therefore, separate assessments were conducted for the triazine and the amine part, respectively.

CAS 80584-91-4

The respiration inhibition rate was assessed in a 3 hour respiration inhibition test in accordance to OECD guideline 209. The test item was exposed to activated sludge at nominal concentrations of 101, 32.5, 13.3 4.7 and 1.6 mg/L. The IC50 was determined to be > 101 mg/L.

CAS 102-71-6

Concerning the acute toxicity to microorganisms a test performed by Klecka et al. (1985) according to OECD TG 209 was identified as key study. Using activated, predominantly municipal sludge as inoculum in a static procedure an EC50 of > 1000 mg/l after 180 minutes of exposure was calculated.