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Biodegradation in soil

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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
biodegradation in soil, other
Type of information:
experimental study
Adequacy of study:
supporting study
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: It was a study of primary degradation. This study was not a standardized method and no information was available about the test substance.
no guideline followed
Principles of method if other than guideline:
The rate of degradation of substituted benzenes by soil microorganisms was determined by a spectrophotometric technique (loss of UV absorbancy).
GLP compliance:
Test type:
other: primary degradation assay
Oxygen conditions:
Soil classification:
not specified
Details on soil characteristics:
Soil microorganisms used were from suspension of Niagara silt loam. No more data on the soil characteristics
64 d
Initial conc.:
15 other: mg/l
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
aqueous suspension of soil
Microbial biomass:
no data
Details on experimental conditions:
The solution contained the test compound as the sole carbon source to support microbial proliferation and 1.6 g K2HPO4, 0.4 g of KH2PO4, 0.5 g of NH4NO3, 0.2 g of MgSO4,7H2O, 25 mg of CaCl2,2H2O, 2.3 mg of FeCl3,6H2O and 1000 ml of distilled water. 40 ml aliquots of the medium were placed in 4-oz. screww cap bottles, 45 mm diameter x 80 mm high and these were inoculated with 1 ml of a 1% suspension of Niagara silt loam. A parallel series of reaction vessels was set up identical to the first except that each bottle also contained 8 mg of HgCl2 and 5.10exp-7 M Tween 80. readings were made on these flasks at the same time intervals. Aniother series identical to the first was set up to determine if the chemical at the concentrations employed were toxic to the microflora; these vessels received glucose to a finalconc. of 1% and growth in the tube was recorded visually. The bottles were incubated in the dark at 25°C. At intervals of 3h, 6h, 1, 2, 4, 8, 16, 32 and 64 days after inoculation, the solutions were mixed, an aliquot was removed and the suspension was centrifuged.
% Degr.:
test mat. analysis
Sampling time:
4 d
Guaiacol was found to be 100% biodegraded by a mixed soil microflora within 4 days, based on loss of UV absorbancy.

Description of key information

Key value for chemical safety assessment

Additional information

According to column 2 of REACH Annex IX, study does not need to be conducted since Guaiacol is readily biodegradable. However, a study quoted as Klimisch 3 (Alexander & Lustigman, 1966) indicated biodegradation of substituted benzenes by soil microflora. Based on loss of UV absorbancy, the authors found that guaiacol was degraded by soil microorganisms in 4 days.