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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Concentration of activated sludge: 30 ppm
Duration of test (contact time):
2 wk
Initial conc.:
100 other: ppm
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
aniline
Parameter:
other: BOD
Value:
0
Sampling time:
2 wk
Validity criteria fulfilled:
not specified
Interpretation of results:
under test conditions no biodegradation observed
Executive summary:

Melamine is not readily biodegradable.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: master's thesis with an insufficient description of amterials and methods but reviewed scientifically.
Qualifier:
equivalent or similar to
Guideline:
other: ISO 9888:1991
Deviations:
yes
Remarks:
Not DOC or CSB was determined but melamine itself, by capillary electrophoresis.
Principles of method if other than guideline:
Only the part of the thesis on biological degradation is available and reported here. (The first part reports chemical determination methods to detect by-products and degradation products of melamine.)
A Zahn-Wellens like test with various inocula was used.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: various, see below .
Details on inoculum:
Activated sludge samples were obtained from the communal sewage treatment plant Siggerwiesen, Salzburg.
The dry solid content, after washing, was adjusted to 0.5 g per L medium.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
Stock solutions of mineral medium, in accordance to ISO 9888, were prepared with and also without NH4Cl.
Medium was adjusted to pH 7.0 +- 0.5, if necessary.

Various experiments were performed:
1) Primary degradation of melamine with activated sludge of the communal WWTP Siggerwiesen, in the presence and also absence of NH4Cl.
1a) Addition of 1.8 g glucose / L medium.
2) The natural effluent of the WWTP Siggerwiesen was used spiked with melamine.
2a) Addition of 1.8 g glucose / L medium.
3) Activated sludge of the industrial WWTP of the melamine producer Agrolinz was used. The temperature was adjusted to 34 °C as it is in the WWTP. Samples were taken hourly.
4) Taking the natural effluent of the industrial WWTP Agrolinz, and also the activated sludge of the industrial WWTP.
Reference substance:
not specified

1) No relevant primary degradation of melamine was detected with activated sludge of the communal WWTP Siggerwiesen, independently if NH4Cl was present or not. Addition of 1.8 g glucose / L medium caused no degradation of melamine, if NH4Cl was present, but a complete primary degradation within 2 weeks if NH4Cl was absent.

2) Adding the natural waste water of the WWTP Siggerwiesen as energy source: No primary degradation was detected after 27 days. Addition of 1.8 g glucose / L caused a complete primary degradation within 12 days.

3) Activated sludge of the industrial WWTP of the melamine producer Agrolinz was used. The temperature was adjusted to 34 °C as it is in the WWTP. Samples were taken hourly. Melamine is not detectable any more after 8 hours.

4) Adding the natural waste water of the industrial WWTP Agrolinz: Melamine is not detectable after 8 hours.

Executive summary:

The primary degradation of melamine in a Zahn-Wellens like assay for biodegradation was investigated under various conditions.

Microorganisms from a communal WWTP can not use melamine as carbon source. Addition of glucose, in the absence of NH4+, enables the microorganisms to use melamine as only nitrogen source. NH4+ inhibits the degradation, facilitated by glucose.

An industrial WWTP at a location, where melamine is produced, is able to degrade melamine rapidly.

Degradation occurs by hydrolytic deamination to ammeline, ammelide and cyanuric acid, and lastly to CO2 and NH4+.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
key study
Justification for type of information:
Please refer to the analogue justification attached to section 13
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Parameter:
other: BOD
Value:
0
Sampling time:
14 d
Remarks on result:
other: Source, Key, RA-A, CAS 108-78-1, Nite, 2010
Parameter:
% degradation (test mat. analysis)
Value:
0
Sampling time:
28 d
Remarks on result:
other: Source, supporting, RA-A, CAS 108-78-1, Fimberger, 1997
Remarks:
No relevant primary degradation of melamine was detected with activated sludge of the communal WWTP Siggerwiesen, if NH4Cl was present or not.

Description of key information

The substance is not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Experimental studies investigating the biodegradability of diphosphoric acid, compound with 1,3,5-triamine (1:2) are not available. The substance will dissociate in aqueous environments under environmentally relevant conditions forming melamine and pyrophosphate ions. Pyrophosphate is an inorganic substance and thus biodegradation is no relevant pathway for the substance. The assessment of biodegradation is therefore based on read across data available for the substance compound melamine (CAS 108-78-1). The read across approach is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Further justification is given in the analogue justification in IUCLID section 13.

One key study investigating the biodegradability of melamine (CAS 108-7-1) is available. The test was conducted in accordance with OECD Guideline 301C (MITI Test, Nite, 2010). Activated sludge (adaption not specified) was used as inoculum. The biological oxygen demand was followed for 14 days. Biodegradation was not observed. Supporting data available for melamine demonstrate a rapid and complete primary degradation of the molecule within 8 h using activated sludge taken from an industrial waste water treatment plant from a producer of melamine. The test method was similar to ISO guideline 9888 (1991). Addition of glucose, in the absence of NH4+, enables the microorganisms to use melamine as the only nitrogen source. Degradation occurs by hydrolytic deamination to ammeline, ammelide and cyanuric acid, and finally to CO2 and NH4+ (Fimberger, 1997).

Based on the available read across data diphosphoric acid, compound with 1,3,5-triamine (1:2) is considered not readily biodegradable.