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

Endpoint summary

Additional information

General considerations

Ecotoxicological investigations concerning fish, aquatic invertebrates and algae were mostly performed with structural analogues of Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts (generic name: C20-24 sodium sulfonate). For the substance itself, experimental data are available concerning toxicity towards algae. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement by Chemservice S.A. (2016).

Based on the intrinsic properties of the used substances, Water Accommodated Fractions (WAFs) were prepared for testing. This procedure is in accordance with the OECD Guidance document on aquatic toxicity testing of difficult substances and mixtures (Series on testing and assessment - Number 23; OECD, 2000). The term WAF is applied to aqueous media containing only the fraction of multi-component substances that is dissolved and / or present as a stable dispersion or emulsion. These fractions are prepared individually and not by serial dilution of a single stock WAF. As the term indicates, only a fraction of the total mass of multi-component substances responsible for the composition may be present in the WAF. The "loading rate" is the mass to volume ratio of the mixture to medium used in the preparation. The obtained LL50/ EL50 values are comparable to LC50/ EC50 values, as well as the NOELR (No Observable Effect Loading Rate) to NOEC (No Observable Effect Concentration).

Toxicity to fish

The sodium sulfonate read-across substance (CAS 68608-26-4) was used in an experiment according to OECD 203 with Oncorhynchus mykiss as test organism (Goodband 2005a; key study). The NOELR (96h) is reported as 100 mg/L WAF and the LL50 (96h) is > 100 mg/L WAF. The calcium sulfonate read-across substance (CAS 115733-09-0) was also used to investigate the acute toxicity towards Oncorhynchus mykiss according to OECD 203 (Goodband 2005b; key study). The NOEC (96h) is reported as 100 mg/L WAF and the LL50 (96h) is > 100 mg/L WAF.

Cyprinodon variegatus served as saltwater fish species in experiments in order to determine the toxicity potential of the calcium sulfonate read-across substances CAS 70024-71-4 and CAS 61789-86-4 (Nicholson, 1986a; Nicholson, 1986b). Both tests are assigned as key studies. In these limit tests, the LL50 (96h) is > 10000 mg/L WAF with a corresponding NOELR of 10000 mg/L WAF. The toxicity data available for several acute fish studies (quantified as Water Accommodated Fractions (WAFs)) demonstrate that the substance is not toxic to fish even at the highest test substance concentrations tested.The weight-of-evidence indicates that the lower NOECs for O. mykiss are not an indicator of toxicity per se, but are the result of dose selection. Long-term investigations are not triggered based on the observations in acute tests.

Toxicity to aquatic invertebrates

In the first key study, the toxicity of the sodium sulfonate read-across substance (CAS 68608-26-4) under static conditions was investigated by Goodband (2005c) in accordance with OECD Guideline 202 under GLP compliance. Daphnids were exposed to control and test chemical at nominal concentration of 100 mg/L WAF for 48 hours. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours. No immobilisation was observed in any daphnids at 100 mg/L nominal WAF loading rate. The EL50 (48h) for the test material to Daphnia magna based on nominal loading rates was greater than 100 mg/L loading rate WAF and correspondingly the No Observed Effect Loading rate was 100 mg/L loading rate WAF.

The calcium sulfonate read-across substance (CAS 115733-09-0) was used in an experiment conducted in accordance to US EPA Guideline OTS 797.1300 with Daphnia magna (Ward, 1993). This additional key study was performed with nominal concentrations of 100, 300 and 1000 mg/L as WAF loading rates under static conditions. As result, an EL50 (48h) > 1000 mg/L WAF is reported. The revealed results demonstrate that the substance is not toxic to daphnids even at the highest test substance concentrations tested.

In a further key study with Sulphonic acids, petroleum, calcium salts (CAS 61789-86-4), Daphnia magna was also exposed under static conditions for 48 hours following OECD Guideline 202 (Goodband, 2005d). Beside control, Daphnids were exposed to a single nominal test substance concentration of 100 mg/L WAF for 48 hours. No immobilisation was observed in any daphnids at 100 mg/L nominal WAF loading rate. The EL50(48h) is considered as > 100 mg/L.

Long-term investigations are not triggered based upon the chemical safety assessment for freshwater invertebrates. In all acute studies with daphnids, no toxic effects were observed - even at the highest concentration levels tested.

Toxicity to aquatic algae

In a key study, Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts (generic name: C20 -24 sodium sulfonate) was tested at nominal concentrations of 33, 65, 130, 250, 500, and 1000 mg/L as WAF loading rates under static conditions (Boeri et al., 2000). The study was performed according to OECD Guideline 201 and U.S. EPA (TSCA) 797.1050 with GLP compliance. Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) served as algae species. No insoluble material was observed during the toxicity test. The algal population grew well, resulting in an average of 2,427,000 cells/mL in the control after 96 hours. No effects (size differences, unusual cell shapes, colors, flocculations, adherence of cells to test containers, or aggregation of cells) were noted during the test. The exposure of freshwater algae to the test substance resulted in an EbC50 (96h) of 720 mg/L (95% CL = 500 to >1000 mg/L) and ErC50 (96h) of >1000 mg/L. The NOEC (96h) is reported as 130 mg/L when determined using the number of cells/mL and 500 mg/L using the average specific growth rate. The EbC50 (72h) was determined as 490 mg/L (95% CL = 260 to 920 mg/L) and the ErC50 (72h) amounts to >1000 mg/L.

In another key study, the calcium sulfonate read-across substance (CAS 115733-09-0) was tested at nominal concentrations of 100, 300 and 1000 mg/L as WAF loading rates under static conditions (study according to EPA OTS 797.1050 by Ward, 1994). Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) served as algae species.After 72 hours, biomass measurements were 80 %, 62 % and 70 % of the control at 100, 300 and 1000 mg/L WAF, respectively. At 96-hours, biomass measurements were 70 %, 66 % and 88 % of the control at 100, 300 and 1000 mg/L WAF, respectively. Based on these findings, the ErL50(72h), ErL50(96h), EbL50(72h) as well as the EbL50(96h) value are > 1000 mg/L. The NOEL amounts to 1000 mg/L WAF for each sampling period.

In the third key study, the sodium sulfonate read-across substance (CAS 68608-26-4) was tested at a single nominal concentration of 100 mg/L as WAF loading rate under static conditions (Mead, 2005a). The study was performed according to OECD Guideline 201 referenced as Method C.3 of Commission Directive 92/69/EEC under certificated GLP compliance. Scenedesmus subspicatus served as test organism. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a haemocytometer and light microscope. It was clear that neither the growth (r) nor the biomass (b) of Scenedesmus subspicatus were affected by the presence of the test material over the 72h exposure period. As final results, an EbL50 and ErL50 value of greater than 100 mg/L loading rate WAF (respectively) and a No Observed Effect Loading rate of 100 mg/L loading rate WAF were determined.

In a 72 hour toxicity study, also assigned as key study, the cultures of the green algae (Scenedesmus subspicatus) were exposed to sulphonic acids, petroleum, calcium salts (CAS 61789-86-4) at nominal concentrations of 0 and 100 mg/L nominal WAF loading rate under static conditions. The test was performed by Mead (2005b) according to OECD Guideline 201 (Alga, Growth Inhibition Test). The EL50 based biomass was >100 mg/L and the EL50 based on growth rate was >100 mg/L. There were no compound related phytotoxic effects.

Toxicity to aquatic microorganisms

The calcium sulfonate read-across substance CAS 61789-86-4 was used in an experiment according to OECD Guideline 209 by Goodrich (1994). The study design comprised five nominal exposure concentrations: 1, 10, 100, 1000 and 10000 mg/L, a duplicate control group; and an assessment of the sensitivity of the inoculum used in the test to a reference toxicant (3,5 - dichlorophenol).

No toxicity was observed, hence EC50 (3h) amounts to > 10000 mg/L. The corresponding NOAEC (3h) is 10000 mg/L.

Toxicity towards other aquatic organisms

No further investigations are triggered under REACH.