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Environmental fate & pathways

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Description of key information

The key study on biodegradation in water (Schorbel 1994) examined the biodegradability of LAB Sulfonic Acid. A concentration of 11.3 mg/L LAB Sulfonic Acid was added to flasks containing activated sludge and DOC analyzed at time 0 and 3 hours and days 7, 14, 21, 27 and 28 over a 28-day period. The reference substance (sodium benzoate) was 96% degraded in 28 days, signifying a valid test. LAB Sulfonic Acid was found to be 94% degraded in 28 days, and met the 10-day window criteria. Therefore, LAB Sulfonic Acid is readily biodegradable.

The supporting study examined the biodegradability of LAS (read across) in the OECD 301B Modified Sturm Test (CO2 evolution test). A concentration of 34.3 mg/L LAS was added to flasks containing activated sludge and CO2 evolution was measured over a 29-day period. The reference substance (sodium benzoate) was 89% degraded in 29 days, signifying a valid test. LAS was found to be 85% degraded in 29 days. Therefore, LAS is readily biodegradable, supporting the conclusion (read across) that LAB Sulfonic Acid is readily biodegradable.

The biodegradation of C12-LAS (read across) in natural sediments was evaluated in two aerobic die-away studies. The key study on biodegradation in sediment (Itrich 2010) examined the biodegradability of LAS (read across). Biodegradation in sediment was evaluated in an aerobic die-away study using sediment from Lytle Creek, Wilmington, Ohio. Radiolabeled test material (14C) was used in a test design that was similar to OECD 308 and OECD 314. The test material was added to the sediment at 1.5 mg/Kg dry weight. After 148 days, 60.8% was mineralized, 14.4% was associated with solids, 1.4% was metabolites, and 24.5% remained as parent. The rate constants for primary biodegradation and mineralization were 1.5 day-1 and 0.06 day-1, respectively.

The second die-away study used the same methodology as above but with sediment collected from the Ohio River near Cincinnati, Ohio. Again, primary degradation was best described by a two compartment first order model and the process was biphasic, with two compartments of material exhibiting different degradation rates. After 92 days, 42.1% was mineralized, 28.5% was associated with solids, 0% was metabolites, and 29.8% remained as parent LAS. Calculated half-lives (DT50) of the parent LAS were 1.4 days (primary biodegradation, compartment 1), 77 days (primary biodegradation, compartment 2), and 11.6 days (first order aerobic mineralization). Rate constants for primary degradation and mineralization were 0.5 day-1and 0.06 day-1, respectively.

The key study on biodegradation in soil (Holt et al 1989) examined the biodegradability of LAS (read across). The disappearance of LAS from sludge-amended soils was investigated from 51 fields on 24 farms in the Thames Water Authority (U.K.). 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.

Additional information

Biodegradation is the primary means of degradation for LAB Sulfonic Acid. LAB Sulfonic Acid is considered readily biodegradable. Read across studies (LAS) demonstrate that LAB Sulfonic Acid biodegrades in water, sediment and soil.