Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts

Endpoint summary

Additional information

Abiotic degradation

Phototransformation and hydrolysis are the main abiotic degradation pathways for a substance. Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts (generic name: C20-24 sodium sulfonate) is neither susceptible for phototransformation in air, water and soil nor for hydrolysis under environmental conditions. Based on the results of the study according to OECD Guideline 111 (Fox, 2015a), it was concluded that the test item was hydrolytically stable for greater than a year at 25 °C at pH 4, pH 7 and pH 9. Less than 10 % hydrolysis occurred after 5 days at the indicated pH values, respectively. Furthermore, the representative structure of the test substance contains a phenyl sulphonate functional group and this suggests that hydrolysis at environmentally relevant pH levels and temperatures would not readily occur.

Biotic degradation

Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts (generic name: C20-24 sodium sulfonate) is not expected to be readily biodegradable based on different biodegradation studies performed with three structural analogues. The calcium sulfonate read-across substance (Analogue of CAS 70024 -69 -0) was experimentally investigated according to OECD Guideline 301D (key information; Douglas, 1989). The effects of the test substance were assessed based on chemical oxygen demand (COD) measurements using activated sludge from a domestic wastewater plant as inoculum. The test substance attained 8 % degradation during 28 days. This key information is supported by two additional studies. 8.6 % degradation was determined for the calcium sulfonate read-across substance (CAS 61789 -86-4) after 28 days (OECD Guideline 301F; Sanitised, O., 1996) while 9.1 % degradation was attained for the calcium sulfonate read-across substance (CAS 68783-96-0) after 28 days (OECD Guideline 301B; Sanitised, P., 1995). Based on these findings, the C20-24 sodium sulfonate is not expected to be readily biodegradable.

Bioaccumulation

Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts (generic name: C20 -24 sodium sulfonate) is not expected to bioaccumulate. Bioaccumulation in aquatic biota is expected for substances possessing a partition coefficient (logPow) in the range of 4.5 to 6 (ECHA REACH Guidance R.11 - PBT Assessment, November 2012). A higher logPow is probably more an effect of solubility than lipophilicity. The experimentally determined logPow value for the sodium sulfonate (C20 -24) amounts to a range of 7.06 - 12.53 (Tait and Laud, 2000), concluding that no strong potential to bioaccumulation is expected. This is supported by the predicted Bioconcentration Factor (BCF) of 70.79 L/kg using BCFBAF v3.00 (Chemservice S.A., 2015c).

Transport and distribution

The adsorption coefficient was not determined according to EU Method C.19 and OECD Guideline 121 as they were considered as not applicable because the test item was highly surface active. However, the soil adsorption has been be calculated by using KOCWIN v2.00 (Chemservice S.A., 2015a). With regard to the MCI method, LogKoc values of 5.63 (first representative) and 7.174 (second representative) were calculated. Thus, a high affinity to the soil/sediment compartment is expected.

The Henry´s Law constant of the test substance was determined by HENRYWIN v3.20 (EPIWIN software) for two different representative structures (Chemservice S.A., 2015b). Using the Bond Method a Henry´s Law Constant of 3.49 E-2 Pa*m³*mol^-1(first representative) and 1.91 E-1Pa*m³*mol^-1(second representative) is calculated for the substance Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts at 25 °C.

Based on these findings, the substance will mainly be present in soil/sediment and is likely to persist there rather than in other environmental compartments.