1,3,5-triazine-2,4,6(1H,3H,5H)-trione, compound with 1,3,5-triazine-2,4,6-triamine (1:1)

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study performed according to guideline, but no data on substance available and no GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

no reference substance tested

GLP compliance:

no

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: the substance was directly added in the test medium with the activated sludge
- Controls: yes (without test substance)

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: no preparation
- The activated sludge came from the communal sewage treatment plant of Bleidenstadt (Germany)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Nominal and measured concentrations:

Nominal concentration: 10000 mg/L

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 3

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Respiration rate (mg O2/L.min)

Reference substance (positive control):

no

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 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:

NOEC

Effect conc.:

>= 10 000 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 did not inhibit the respiration rate of the activated sludge.

Results with reference substance (positive control):

no data

Concentration of test substance (mg/L)	Respiration rate (mg O2/L*min)	Percentage of inhibition (%)
0 (control)	0.80^1)	n.a.
10000	0.83^2)	-3.8^3)

1) average of 3 parallel assays

2) average of 2 parallel assays

3) negative data mean increase of the respiration rate

Validity criteria fulfilled:

no

Conclusions:

The 3h-EC50 of the test substance is > 10000 mg/L.

Description of key information

 The inhibition of the degradation activity of activated sludge is not anticipated when introduced to biological treatment plants in appropriate low concentrations.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

EC10 or NOEC for microorganisms:

10 000 mg/L

Additional information

The toxicity to microorganisms was assessed in a key study conducted with the test item. The test substance did not inhibit the respiration rate of the activated sludge at concentrations of 10000mg/L (nominal).

 

Furthermore, two studies with melamine (CAS 108-78-1) are available. Hockenbury 1977: Inhibition of nitrification by Nitrosomonas sp.: EC0, 2h >100 mg/L. Tillmann 1990: Inhibition of respiration of Pseudomonas putida: EC0 >10000 mg/L. Each of the studies with different endpoints and microorganisms indicates a low toxicity of melamine.