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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Reference
Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: guideline study (also assessed by OECD)
Qualifier:
according to
Guideline:
OECD Guideline 303 A (Simulation Test - Aerobic Sewage Treatment. A: Activated Sludge Units)
Deviations:
yes
Remarks:
for the determination of the DOC-analysis on the carbon analyzer a 0.45 µm filter was used instead of the 1.2 µm filter; The concentration was 5 mg/L test substance instead 20 mg DOC/L
GLP compliance:
yes
Radiolabelling:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: synthetic mixture of activated sludge, from sewage treatment plant, river, and garden soil, adapted
Details on inoculum:
Activated sludge was produced in the test apparatus from a mixed inoculum obtained from a sewage treatment plant, river water and garden soil. Adaptation period 14 days at 23±2C
Duration of test (contact time):
20 d
Initial conc.:
5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
other: Amount of parent determined by GC or HPLC
Details on study design:
The test was carried out in an all glass Husmann-Apparatus with a 3 litre aeration vessel. A stock solution of TPP was prepared by emulsifying 125 mg TPP in 1 ml octanol, 0.25 ml Tween and 1000ml bidistilled water and applying ultrasound during 30 seconds; nutrient solution was prepared fresh every day. The average retention time in the aeration vessel was 3 h by continuous feeding of the solutions at a rate of 1 litre/h for 24h per day; temperature 23±2°C; pH: 7.4 - 8.2, measurement of dissolved oxygen (7.0 - 8.9 mg/l), DOC, and TPP; analysis of sludge at the end of the test for accumulated TPP. A blank test was set up using nutrient solution not containing TPP.
% Degr.:
93.8
Parameter:
other: LC/GC
Sampling time:
20 d
Transformation products:
not measured
Volatile metabolites:
not measured
Residues:
yes
Details on results:
6.3% triphenyl phosphate measured in effluent plus sludge.
The mean of the elimination rate was determined with 93.8 % of the 
initial TPP concentration. Less than 1 % of the total applied TPP 
was found in the sludge.
Conclusions:
Interpretation of results: inherently biodegradable
Executive summary:

The study was conducted for 20 d according to OECD 303 A (Simulation Test -Aerobic Sewage Treatment: Coupled Units Test). The mean of the elimination rate was determined with 93.8 % of the initial TPP concentration. Less than 1 % of the total applied TPP was found in the sludge. Thus triphenyl phosphate is shown to be inherently biodegradable.

Description of key information

Triphenyl phosphate is shown to be inherently biodegradable with a degradation rate of 93.8 % in 20 d by adapted sludge.

Key value for chemical safety assessment

Additional information