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Environmental fate & pathways

Biodegradation in soil

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Administrative data

Endpoint:
biodegradation in soil
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 27 - August 16, 1979
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is well-reported, and conducted prior to established guidelines with no information on GLPs.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1979

Materials and methods

Principles of method if other than guideline:
Soil was treated with 14C-TBPA. At 0, 1, 2, 4, 7, 14 and 28 d soil was sampled and analyzed. 3 replicates at each dose.
GLP compliance:
not specified
Test type:
laboratory

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
14C-TBPA: uniformly labeled in aromatic ring. Specific activity: 11.6 mCi/mM; radiochemical purity 98%. Synthesized by Midwest Research Institute.
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Soil classification:
USDA (US Department of Agriculture)
Soil properties
Soil no.:
#1
Soil type:
sandy loam
% Clay:
28.4
% Silt:
23.2
% Sand:
48.4
% Org. C:
0.2
pH:
6.3
CEC:
36 meq/100 g soil d.w.
Bulk density (g/cm³):
1.67
Duration of test (contact time)
Soil No.:
#1
Duration:
28 d
Initial test substance concentrationopen allclose all
Soil No.:
#1
Initial conc.:
1 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#1
Initial conc.:
10 mg/kg soil d.w.
Based on:
test mat.
Experimental conditions
Soil No.:
#1
Temp.:
28 degrees C
Humidity:
70%

Results and discussion

Material (mass) balance
Soil No.:
#1
Remarks on result:
other: No statistical difference between the 14C-activity at D 0 and 28.
% Degradation
Key result
Soil No.:
#1
Remarks on result:
other: See text below
Half-life / dissipation time of parent compound
Soil No.:
#1
Remarks on result:
other: See text below - Details on Results
Transformation products:
yes
Identity of transformation products
No.:
#1
Reference
Reference substance name:
Unnamed
IUPAC name:
Tetrabromophthalic acid
Identifier:
common name
Identity:
Tetrabromophthalic acid
Evaporation of parent compound:
no
Details on results:
Very slight volatilization (0.038% at the 10 ug/g level). Soil-bound 14C-activity increased in both levels between 0 and 28 d (~24 and 32% of applied 14C at 28 d in the 1 and 10 ug/g doses, respectively). Due to the high amount bound, soil further extracted with NaOH. All of bound 14C-activity soluble in NaOH at both doses at d 0 and 28. At the 10 ug/g level, the 28 d sample contained 94% TBPA-acid and 4% TBPA. Concluded TBPA-acid binds to soil particles.

TLC resulted indicated no evidence of biodegradation. 95% of 14C-activity identified as TBPA-acid at both d 0 and 28. 1% identified as TBPA, and 4% unknown. In summary, there was no difference in the 0 and 28 d samples, indicating little or no biodegradation of TBPA over the 28 d. However, hydrolysis of TBPA to TBPA-acid was observed.

Applicant's summary and conclusion

Conclusions:
TBPA rapidly hydrolyzed to TBPA-acid. Little volatilization was observed, and a large proportion (24 -32%) of the 14C-activity became soil-bound after 28 days. The soil-bound radiocarbon was identified as TBPA acid (94.0%) and TBPA (4.0%). Biodegradation was not observed. Hydrolysis to TBPA-acid was observed.
Executive summary:

When introduced to soil, TBPA rapidly hydrolyzed to TBPA-acid. Little volatilization was observed, and a large proportion (24 -32%) of the 14C-activity became soil-bound after 28 days. The soil-bound radiocarbon was identified as TBPA acid (94.0%) and TBPA (4.0%). Biodegradation was not observed. Hydrolysis to TBPA-acid was observed.