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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:
2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Field study not conducted under GLPs.

Data source

Reference
Reference Type:
publication
Title:
Effect of sewage-sludge application on concentrations of higher-brominated dipheny ethers in soils and earthworms.
Author:
Sellstrom et al.
Year:
2005
Bibliographic source:
Environ Sci Technol 39(23): 9064-70

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Soil and earthworms collected from 3 research stations and 2 farms in Sweden. Soils amended with sewage sludge containing DecaBDE or periodically flooded with river sediment containing DecaBDE. Soil and earthworms analyzed for PBDE content. At least one analysis performed 20+ years after last application of sewage sludge containing DecaBDE.
GLP compliance:
no
Test type:
field trial

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
no

Study design

Oxygen conditions:
not specified
Soil classification:
not specified
Details on soil characteristics:
See Sellstrom et al. for details on this field study.
Details on experimental conditions:
See Sellstrom et al. for details on this field study.

Results and discussion

% Degradation
% Degr.:
0
Sampling time:
20 yr
Transformation products:
no
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
yes
Details on results:
[BDE209] in background (reference) soils ranged from 0.015 -0.75 ng/g dw, except for 1 farm which was impacted by river sediment flooding was 1.9 ng/g dw. At the 3 research stations which had been amended with sewage sludge, the concentrations ranged from 0.028 -1.0 ng/g dw. One farm where sewage-sludge had been applied had [BDDE209] of 2200 ng/g dw. The other farm which was periodically flooded by the River Visken, which received effluents from textile industries, had [BDE209] of 350 ng/g dw. The farm with the highest [BDE209] had last recieved sludge application 20 yr prior to sampling. The authors concluded no evidence of photolytic breakdown of BDE209 was seen based on the chromatograms of the soils, in contrast to their previous work indicating photolytic debromination of BDE209 applied to "artificially to soil with solvent in laboratory and field experiments (Soderstrom et al. 2004). Further, laboratory experiments with the high-BDE209 -soil showed no change in peak patterns with the lenght of UV exposure. The authors indicated soil ageing ahs been shown to encapsulate and shield contminants so they are less accessible to microbial breakdown, and also probably sunlight. The fact that the soils were plowed under was also thought to impact sunlight exposure. The authors concluded "The results with soils collected in the field show the importance of following up laboratory studies with field studies." Although microbial degradation was not specifically studied, it is reasonable to conclude as there was no evidence of photolytic degradation to lower brominated congeners, a similar conclusion can ge reached for microbial degradition.

Any other information on results incl. tables

[BDE209] in background (reference) soils ranged from 0.015 -0.75 ng/g dw, except for 1 farm which was impacted by river sediment flooding was 1.9 ng/g dw. At the 3 research stations which had been amended with sewage sludge, the concentrations ranged from 0.028 -1.0 ng/g dw. One farm where sewage-sludge had been applied had [BDDE209] of 2200 ng/g dw. The other farm which was periodically flooded by the River Visken, which received effluents from textile industries, had [BDE209] of 350 ng/g dw. The farm with the highest [BDE209] had last recieved sludge application 20 yr prior to sampling. The authors concluded no evidence of photolytic breakdown of BDE209 was seen based on the chromatograms of the soils, in contrast to their previous work indicating photolytic debromination of BDE209 applied to "artificially to soil with solvent in laboratory and field experiments (Soderstrom et al. 2004). Further, laboratory experiments with the high-BDE209 -soil showed no change in peak patterns with the lenght of UV exposure. The authors indicated soil ageing ahs been shown to encapsulate and shield contminants so they are less accessible to microbial breakdown, and also probably sunlight. The fact that the soils were plowed under was also thought to impact sunlight exposure. The authors concluded "The results with soils collected in the field show the importance of following up laboratory studies with field studies." Although microbial degradation was not specifically studied, it is reasonable to conclude as there was no evidence of photolytic degradation to lower brominated congeners, a similar conclusion can ge reached for microbial degradition.

Applicant's summary and conclusion

Conclusions:
No evidence for the degradation of DecaBDE was found in agricultural soils exposed via application of sewage sludge or periodic flooding via river sediments. Ananalysis occurred over 20 years after the last application of sewage sludge to one of the soils.
Executive summary:

Sellstrom et al. (2005) reported there was no evidence for the photolytic degradation of BDE209 in agricultural soil on which sewage sludge containing the substance had been spread or on soils subject to periodic flooding with river sediment. Both the sludge and river sediment were known to contain DecaBDE. Analysis occurred some 20+ years after the last application of sludge. Although Sellstrom et al. did not specifically address microbial degradation, it is reasonable to conclude that no evidence for microbial degradation was found based on the author’s statement regarding photolysis.