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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication/study report which meets basic scientific principles (also assessed by OECD)
Qualifier:
no guideline followed
Principles of method if other than guideline:
Degradation investigated in 1 soil type under aerobic conditions in the laboratory
GLP compliance:
not specified
Test type:
other: laboratory, aerobic test system
Radiolabelling:
yes
Oxygen conditions:
aerobic
Soil classification:
other: BBA standard soil 2.2 (loamy sand)
Soil no.:
#1
Soil type:
loamy sand
% Org. C:
2.2
Details on soil characteristics:
This is standard soil with well known characteristics
Soil No.:
#1
Duration:
101 d
Soil No.:
#1
Initial conc.:
5 mg/kg soil d.w.
Parameter followed for biodegradation estimation:
test mat. analysis
Soil No.:
#1
Temp.:
20±2 °C
Humidity:
40% of max. water capacity
Microbial biomass:
373 mg microbial carbon/kg soil (dw)
Details on experimental conditions:
Portions of soil were placed in Erlenmayer flasks and adjusted to 40% maximum water capacity which was controlled every 2 - 4 weeks. The flasks were equipped with traps containing glass wool soaked with parafin oil, to trap volatiles, and soda lime to trap carbon dioxide. Flasks were incubated in the dark for 0, 13, 32, 60 and 101 days after treatment.
Soil No.:
#1
% Recovery:
101.3
Remarks on result:
other: After 101 days
Soil No.:
#1
% Degr.:
>= 79.8 - <= 84.4
Parameter:
test mat. analysis
Sampling time:
101 d
Soil No.:
#1
DT50:
37 d
Type:
(pseudo-)first order (= half-life)
Temp.:
> 18 - < 22 °C
Transformation products:
yes
Details on transformation products:
Carbon dioxide accounted for 11.6±1.5% of the applied radioactivity at 13 days, 24.8±0.1% at 32 days, 34.2±0.9% at 60 days and 48.3% at 101 days
The amounts of diphenyl hydrogen phosphate always <1% of the applied material
Volatile metabolites:
yes
Residues:
yes
Details on results:
No organic volatiles were found
Radiolabelled carbon dioxide increased to 48.3% of the applied at 101 days
Only traces (0.2%) of diphenyl hydrogen phosphate were found
Triphenyl phosphate accounted for 20.2% (HPLC) and 15.6% (TLC) of the applied at 101 days
After 101 days the amounts of the applied radioactivity were: 
48.3 % as CO2,  
26.4 % non-extractable from soil, 
26.6 % extractable from soil. 
The  amount of CO2 formed increased steadily during the whole incubation time, 
whereas the amount of non-extractable residues increased steadily and  then 
slowed down after an incubation time of 32 days. Only 0.2 % of the  applied 
radioactivity accounted to diphenylphosphate after 101 days.
 

    
In the heat-sterilized soil mainly unchanged triphenyl phosphate was recovered 
within the 101 days of incubation, which indicates that the degradation of triphenyl 
phosphate in soil is mainly due to microbial action. Only 1.4 % of the applied 
radioactivity was accounted for as diphenylphosphate after 101 days.
Conclusions:
Extensive and rapid degradation of triphenyl phosphate occurs in soil under aerobic conditions in the dark. This degradation is mainly due to microbial action.
Executive summary:

Extensive and rapid degradation of triphenyl phosphate occurs in soil under aerobic conditions in the dark. This degradation is mainly due to microbial action.

The degradation under aerobic conditions in soil of TPP is between 79.8 - 84.4 % in 101 d and a half-life of 37 d is determined.

Description of key information

Extensive and rapid degradation of triphenyl phosphate occurs in soil under aerobic conditions in the dark. This degradation is mainly due to microbial action.

The degradation under aerobic conditions in soil of TPP is between 79.8 - 84.4 % in 101 d and a half-life of 37 d has been determined.

Key value for chemical safety assessment

Half-life in soil:
37 d
at the temperature of:
20 °C

Additional information