Benzenesulfonic acid, mono-C11-13-branched alkyl derivs.

Endpoint summary

Additional information

Endpoint records reflect data from BABS Acid and BABS Na salt where available, and in some cases, from the analogue sodium salt of linear alkylbenzene sulfonate (commonly known as LAS).Read Across between BABS acid and its sodium salt is scientifically justified as BABS Na salt will readily dissociate in water. LAS is the sodium salt of linear alkylbenzene sulfonic acid with alkyl carbon chain lengths ranging from C₁₀to C₁₃and averaging 11.6. The primary structure is a C₁₀to C₁₃linear alkyl chain with apara-substituted benzene sulfonic acid sodium salt group attached at any of the secondary alkyl carbon positions. BABS Na salt is the sodium salt of branched alkylbenzene sulfonic acid with alkyl chain lengths ranging from C₁₁to C₁₃.The primary difference between the two moieties is the alkyl chain, branched vs. linear. Given their structural and functional similarities, the LAS material is a good analogue for read-across for instances where data are available on it but not on BABS Na salt. In both cases the alkyl chain length varies and so specific LAS and BABS Na salt may be used in some of the testing for which data are provided in this section. When available the specific LAS or BABS Na salt is identified in the endpoint record and the tables in this chemical safety report. For ease of reading, the general terms LAS, BABS Acid and BABS Na salt are used in the text.

Based on well accepted principles of modeling (D.W. Roberts, Sci. Total Environ. 109/110: 557-68, 1991), linear structures are more toxic that branched structures of the same carbon chain number.  This is illustrated by the acute toxicity data for fish where LAS has a lower toxicity value (96-hr LC50 = 1.67 mg/L, Lewis and Perry, 1979, 1981) than BABS Na salt (96-hr Tm = 4-6 mg/L, Trzebiatowski, 1973) plus four supporting studies demonstrating BABS Na salt is 2-4 times less toxic that LAS when directly compared.  This is further illustrated by the acute toxicity data for algae where LAS has a lower toxicity value (96-hr EC50 = 29 mg/L, Lewis, 1986; Lewis and Hamm, 1986, Larson and Schaeffer, 1987) than BABS Na salt (72 -hour EC50 > 37 mg/L, Vryenhoef, 2013).  An apparent exception are theDaphniadata where a supporting study (Gard-Terech and Palla, 1986) indicates that BABS Na salt is 2 -4 times less toxic that LAS when directly compared but BABS Na salt gave an unexpectedly lower toxicity value (48 -hr EC50 = 0.83 mg/L, Vryenhoef, 2013) compared to LAS (48 -hr EC50 = 2.9 mg/L, Hooftman and van Drongelen-Sevenhuijsen, 1990).

 

It should be noted that the BABS Na saltDaphniaacute toxicity study is the single exception to the weight of evidence from the well accepted principles of modeling and from acute toxicity studies of fish and algae, including five studies with direct comparisons of activities that indicate that LAS may be considered as the worst case scenario.  Based on this consideration, LAS data will be used extensively for read-across for environmental toxicity data, including aquatic toxicity data.

 

In some studies, BABS Na salt is referred to as alkylbenzene sulfonate (ABS), or sometimes sodium tetrapropylenebenzene sulfonate (TBS) or branched alkylbenzene sulfonate (BAS) while LAS is sometimes referred to as sodium dodecylbenzene sulfonate (DBS).