Registration Dossier

Administrative data

Endpoint:
biodegradation in soil, other
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The studies are very well documented in this peer-reviewed publication.
Justification for type of information:
Category Approach; test material is reference substance LAS. LAS provides suitable read across for LAB Sulfonic Acids as both form the identical chemical species in aqueous solutions at neutral (environmental) pH, namely, the LAS ion (C10-13 linear alkyl benzene-SO3-) and would be expected to have similar biodegradation properties.

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
The concentrations and fate of linear alkylbenzene sulphonate in sludge amended soils.
Author:
Holt, M.S., Matthijs, E. and Waters, J.
Year:
1989
Bibliographic source:
Wat. Res. 23:749-759
Reference Type:
publication
Title:
Fate of LAS in sludge amended soils.
Author:
Waters, J., Holt, M.S., Matthijs, E.
Year:
1989
Bibliographic source:
Tenside Surfactants Detergents 26(2):129-135

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The disappearance of LAS from sludge-amended soils was investigated from 51 fields on 24 farms in the Thames Water Authority, U.K. Annual sludge spreading averaged 6 ton/ha. Application of sludge was made by subsurface injection, surface spreading onto arable land with or without ploughing, or surface spreading onto pasture land. Regular sampling was conducted for up to 122 days. LAS concentrations in the soil were analyzed with HPLC.
GLP compliance:
not specified
Test type:
field trial

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Commercial LAS as present in primary sludge or anaerobically digested sludge from WWTPs in the United Kingdom.
Radiolabelling:
no

Study design

Oxygen conditions:
not specified
Soil classification:
not specified
Details on soil characteristics:
51 fields on 24 farms in the Thames Water Authority, U.K. Annual sludge spreading averaged 6 ton/ha. Application of sludge was made by subsurface injection, surface spreading onto arable land with or without ploughing, or surface spreading onto pasture land.
Duration of test (contact time)
Duration:
<= 122 d

Results and discussion

Half-life / dissipation time of parent compound
DT50:
> 7 - < 22 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Temperature not given
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
In fields not recently spread with sludge, the concentrations of LAS found in the sludge amended soil were generally less than 1 mg/kg. This represents an estimated loss of LAS from soil of >98%. In fields recently spread, the concentrations in soil are in the range of <0.2 to 20 mg/kg, representing losses of LAS between 70 and 99% of the estimated total cumulative load. The identity of the degradation products was not analyzed.

Any other information on results incl. tables

Half-lives compare well with those for ultimate degradation in lab soil tests (with 14-C-evolution), indicating that the degradation of LAS does not lead to the formation of significant levels of break-down intermediates in soil.

Applicant's summary and conclusion

Conclusions:
The authors conclude that overall the data indicate that an adequate safety margin exists between the concentrations of LAS in sludge-amended soils and those likely to affect the growth of crop plants.
Executive summary:

The disappearance of LAS from sludge-amended soils was investigated from 51 fields on 24 farms in the Thames Water Authority. Sludge was applied by subsurface injection, or surface spreading. Sampling was conducted for up to 122 days. In fields not recently spread with sludge, the concentrations of LAS found in the sludge amended soil were generally less than 1 mg/kg.  In fields recently spread, the concentrations in soil are in the range of 0.2 to 20 mg/kg, representing losses of LAS between 70 and 99% of the estimated total cumulative load.