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Environmental fate & pathways

Biodegradation in soil

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Endpoint:
biodegradation in soil
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1966
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Publication with limited detail available
Justification for type of information:
Grouping of structurelly similar substances (category approach)
Qualifier:
no guideline available
Principles of method if other than guideline:
64-day aerobic laboratory test using soil inoculum and spectrophotometric measurement as parameter to measure biodegradation. Soil inoculum was done as a 1% suspension of the soil
GLP compliance:
not specified
Test type:
laboratory
Oxygen conditions:
aerobic
Soil classification:
other: Niagra silt loam
Year:
1966
Soil type:
silt loam
Details on soil characteristics:
no details provided
Duration:
64 d
Initial conc.:
75 other: mg/L
Based on:
test mat.
Initial conc.:
31 other: mg/L
Based on:
other: Carbon
Temp.:
25C
Details on experimental conditions:
25C
Culturing apparatus was 45 mm X 80 mm screw-cap bottles containing 40 mL of solution.
2 bottles for test substance + inoculum
2 bottles for test substance + inoculum + HgCl2 (abiotic control)
2 bottles for 1% glucose control
The inoculum was 1 mL of a 1% suspension of the soil.
The composition of the mineral solution used in the inoculum was 1.6g K2HPO4, 0.40g KH2PO4, 0.5g NH4NO3, 0.2g MgSO4, 25 mg CaCl2, 2.3 mg FeCl3 in 1L distilled water.
Sampling at time 0, then at 3 and 6 hours, and then at 1, 2, 4, 8, 16, 32 and 64 days
Key result
% Degr.:
100
Parameter:
test mat. analysis
Sampling time:
32 d
Transformation products:
not measured
Details on results:
The test substance was completely degraded in 32 days. The degradation was due to biological activity because no decreased absorbance was seen in vessels with HgCl2.

The time necessary for complete degradation was established to be 32 days. The degradation was due to biological activity because no decreased absorbance was seen in vessels with HgCl2.

Conclusions:
Hydroxybenzene sulfonic acid is biodegradable to a substantial degree in soil under the conditions of this test.
Endpoint:
biodegradation in soil: simulation testing
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance is readily biodegradable

Description of key information

biodegradable under aerobic soil conditions

Key value for chemical safety assessment

Half-life in soil:
16 d
at the temperature of:
25 °C

Additional information

A single, non-guideline study published in 1966. A soil microorganism inoculum was used in an aerobic water-based medium at 25C. Duplicate flasks of a single test substance concentration, 75 mg/L hydroxybenzene sulfonic acid, were sampled and analyzed over 64 days for change in spectral absorbance as the measure of test substance presence. An abiotic control using HgCl2 was run in parallel. The time necessary for complete degradation was 32 days. The degradation was due to biological activity because no decreased absorbance was seen in the abiotic control. The half-life of the test substance under the conditions of this study would be less than 32 days. This is a non-guideline study, however, the study design is sufficiently representative and there are sufficient details to support a conclusion that the test substance, hydroxybenzene sulfonic acid is biodegradable under aerobic soil conditions. The study is considered to be of value in providing weight of evidence to support this conclusion.