Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
In this justification, the read-across (bridging) concept is applied, based on the chemical structure of the potential analogues, their toxicokinetic behaviour and other available (eco-)toxicological data.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
C20-24 calcium sulfonate and Benzenesulfonic acid, C14-24-branched and linear alkyl derivs., calcium salts (CAS 115733-09-0) are members of a category of chemicals described as alkaryl sulfonates, which was established as part of the U.S. Environmental Protection Agency High Production Volume (HPV) Challenge Program. The substances of this category have a common functional group - the salt of aryl sulfonic acid. Furthermore, they all have a divalent alkaline earth metal, one or more linear and/or branched alkyl groups of variable chain length and branching characteristics or extended heterocyclic carbon system from the sulfonated benzene ring. Finally, they have common precursors and/or the likelihood of common breakdown products via physical and biological processes, resulting in structurally similar chemicals, and similar physicochemical properties, environmental fate, ecotoxicity and mammalian toxicity.
Concerning short-term toxicity to aquatic invertebrates, it is believed that both substance will be metabolised by the same mechanisms by microorganisms and by other classes of living organisms. Therefore they are expected to follow the same pattern. For the detailed procedure of the read-across principle and justifications, please refer to the analogue approach justification depicted below and the separate Read-Across Statement (Chemservice S.A., 2017).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical: Benzenesulfonic acid, C14-24-branched and linear alkyl derivs., calcium salts (CAS 115733-09-0, EC No none)
Target chemical: Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts (C20-24 calcium sulfonate, CAS No none, EC No none)

3. ANALOGUE APPROACH JUSTIFICATION
C20-24 calcium sulfonate and Benzenesulfonic acid, C14-24-branched and linear alkyl derivs., calcium salts (CAS 115733-09-0) are UVCB substances that are produced using similar manufacturing process and raw materials and are manufactured in mineral oil. They are members of a category of chemicals described as alkaryl sulfonates, which was established as part of the U.S. Environmental Protection Agency High Production Volume (HPV) Challenge Program. These substances are similar in that they have a common functional group, the salt of aryl sulfonic acid. TOXMATCH and OECD Toolbox QSAR structure similarity assessments using Tanimoto distance fingerprint, Hellinger distance atom environment, Euclidian distance and Dice calculations indicate that these substances are very similar. Likewise, they have similar physicochemical properties, similar environmental fate characteristics, and similar ecotoxicity and mammalian toxicity profiles. For example, these substances can dissociate only in the presence of strong acids such as in the stomach but are not expected to dissociate under environmental conditions. For further details on this, please refer to the separate Read-Across Statement (Chemservice S.A., 2017). The similar toxicity profiles indicate that they have a similar MOA. C20-24 calcium sulfonate and Benzenesulfonic acid, C14-24-branched and linear alkyl derivs., calcium salts (CAS 115733-09-0) are not classified for environmental toxicity.
The similar findings (refer to data matrix outlined below and the separate Read-Across Statement) for both substances support the conclusion that similar molecules are expected to be formed from both substances, and in consequence, similar effects can be reasonably expected. Hence, the analogue may perfectly serve as a read-across substance for the C20-24 calcium sulfonate and vice versa. So, based on the WOE of these data, the available data on CAS 115733-09-0 can be used to cover the systemic endpoints currently lacking for C20-24 calcium sulfonate and read across is scientifically justified, making further testing obsolete.

4. DATA MATRIX
There is mainly data available on the toxicological properties of the analogues CAS 61789-86-4 / its overbased version CAS 68783-96-0 and for CAS 70024-69-0 / its overbased version CAS 70024-71-4. Data on Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts covers merely the physico chemical properties. Hence, the identification and discussion of common properties of the analogues and the C20-24 calcium sulfonate will be mainly based on this physicochemical data.
The available data for the following physico-chemical properties, which are relevant for absorption into living organisms, are very similar. The substances are rather huge molecules and have a similar molecular weight range, which triggers already similarities in their absorption/adsorption and desorption behaviour. Furthermore, the physico-chemical properties like their partition coefficient, water solubility and vapour pressure are similar. Regarding the application of these substances, the substances are usually solved in an inert mineral oil to enable handling. The C20-24 calcium sulfonate and all analogous substances are hydrolytically stable in the natural environment, as they do not contain hydrolysable groups. In addition, at least CAS 70024-69-0 and CAS 61789-86-4 are not readily biodegradable, and the available data suggests this to apply also for C20-24 calcium sulfonate. Taking into account the vast amount of data available for partition coefficient data on various calcium sulfonates it can be concluded that they do not have a significant potential for bioaccumulation in aquatic and terrestrial organisms. However, they are expected to be adsorbed to a significant extent to the sediment and soil and to be thereby not bioavailable, which was confirmed by the results of short-term toxicity tests to fish, daphnia and algae for CAS 70024-71-4; CAS 115733-09-0 and CAS 61789-64-4, in which the lowest LL50 was already > 100 mg/L WAF.
For the following toxicological endpoints there is data available derived from CAS 70024-69-0/ CAS 70024-71-4, Analogue of CAS 70024-69-0, CAS 115733-09-0, CAS 61789-86-4/ CAS 68783-96-0 and CAS 75975-85-8: Acute toxicity, Skin irritation / corrosion, Eye irritation /corrosion, Skin sensitization, Repeated dose toxicity, Genetic toxicity in vitro and in vivo and Toxicity to reproduction (fertility / developmental toxicity). Furthermore a rather extensive data package is available concerning the human sensitization potential of numerous analogous substances. For the acute oral toxicity, the values for all read across substances are very high, all LD50 values being above 2000 mg/kg (reaching in older tests up to greater than 20,000 mg/kg) and the values for the substances can be considered as similar within normal biological variations. The substances are also not toxic via the inhalation or the dermal route of exposure. Regarding Skin/Eye Irritation, the available data on CAS 70024-69-0 and CAS 61789-86-4 shows both substances to be not irritating to the skin or the eyes. The skin sensitization data in animals and humans (for CAS 75975-85-8; CAS 61789-86-4 and EC 939-141-6) evaluated in a weight-of-evidence approach indicates that low TBN calcium sulfonates (TBN < 300) are skin sensitizers with a specific concentration limit (SCL) of 10% and that high TBN calcium sulfonates (TBN ≥ 300) are not skin sensitizers. Last but not least, the available genetic toxicity data for Analogue of CAS 70024-69-0, CAS 61789-86-4 and its overbased version CAS 68783-96-0 prove all of these substances to be not mutagenic. The NOAELs derived for the endpoints Repeated dose toxicity (Analogue of CAS 70024-69-0 and CAS 61789-86-4) and Toxicity to reproduction (fertility / developmental toxicity for CAS 115733-09-0)) have been also found to be in a similar range.
For further details please refer to the seperate Read-Across Statement (Chemservice S.A., 2017) and/or the robust study summaries of the respective studies in this IUCLID file.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

EL0

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF loading rate

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF loading rate

Basis for effect:

mobility

Details on results:

Control immobilisation did not exceed the test validity criterion (i.e. < 10 % immobilisation in the controls).
At 24-hours, no immobilised or dead organisms were observed in the control or treatments. At 48-hours, 5, 0, 20 and 5 % immobilisation were reported for control, 100, 300 and 1000 mg/L, respectively.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

The statistical analysis of survival data is not warranted.

Validity criteria fulfilled:

yes

Remarks:

Scientifically validity criteria are fulfilled.

Conclusions:

The report describes a valid guideline study with GLP compliance. The calcium sulfonate Read-Across substance (CAS 115733-09-0) was not toxic to Daphnia magna at a loading rate up to 1000 mg/L nominal WAF, therefore the EC50 is considered to be > 1000mg/L. These results can be used to fulfill the information requirements for the chemical substance Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, due to the high structural similarity of these substances. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement (Chemservice S.A., 2017).

Executive summary:

The acute toxicity within 48-hour Benzenesulphonic acid, C14-24 branched / linear alkyl derivative, calcium salt (CAS 115733-09-0) to Daphnia magna was investigated under static conditions in accordance to US EPA Guideline OTS 797 -1300 (Ward, 1993). Water Accommodated Fractions (WAFs) were prepared, based on the intrinsic properties, i.e. low water solubility. The waterflea was exposed to the test substance at nominal concentrations of 100, 300 and 1000 mg/L WAF. A control group was also included. Mortality, immobilisation and sublethal effects were observed daily. After 24 h, no immobilised or dead organisms were observed. At the end of the experiment, 5 %, 0 %, 20 % and 5 % immobilisation were reported for the control, 100, 300 and 1000 mg/L WAF, respectively. Therefore, Benzenesulphonic acid, C14-24 branched / linear alkyl derivative, calcium salt (CAS 115733 -09 -0) is considered as non-toxic to daphnids at WAF loading rates up to 1000 mg/L. The EC50(48h) is > 1000 mg/L WAF.

These results can be used to fulfill the information requirements for the chemical substance Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, due to the high structural similarity of these substances. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement (Chemservice S.A., 2017).

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
In this justification, the read-across (bridging) concept is applied, based on the chemical structure of the potential analogues, their toxicokinetic behaviour and other available (eco-)toxicological data.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
C20-24 calcium sulfonate and Sulfonic acids, petroleum, calcium salts (CAS 61789-86-4) are members of a category of chemicals described as alkaryl sulfonates, which was established as part of the U.S. Environmental Protection Agency High Production Volume (HPV) Challenge Program. The substances of this category have a common functional group - the salt of aryl sulfonic acid. Furthermore, they all have a divalent alkaline earth metal, one or more linear and/or branched alkyl groups of variable chain length and branching characteristics or extended heterocyclic carbon system from the sulfonated benzene ring. Finally, they have common precursors and/or the likelihood of common breakdown products via physical and biological processes, resulting in structurally similar chemicals, and similar physicochemical properties, environmental fate, ecotoxicity and mammalian toxicity.
Concerning short-term toxicity to aquatic invertebrates, it is believed that both substance will be metabolised by the same mechanisms by microorganisms and by other classes of living organisms. Therefore they are expected to follow the same pattern. For the detailed procedure of the read-across principle and justifications, please refer to the analogue approach justification depicted below and the separate Read-Across Statement (Chemservice S.A., 2017).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical: Sulfonic acids, petroleum, calcium salts (CAS 61789-86-4, EC 263-093-9)
Target chemical: Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts (C20-24 calcium sulfonate, CAS No none, EC No none)

3. ANALOGUE APPROACH JUSTIFICATION
C20-24 calcium sulfonate and Sulfonic acids, petroleum, calcium salts (CAS 61789-86-4) are UVCB substances that are produced using similar manufacturing process and raw materials and are manufactured in mineral oil. They are members of a category of chemicals described as alkaryl sulfonates, which was established as part of the U.S. Environmental Protection Agency High Production Volume (HPV) Challenge Program. These substances are similar in that they have a common functional group, the salt of aryl sulfonic acid. TOXMATCH and OECD Toolbox QSAR structure similarity assessments using Tanimoto distance fingerprint, Hellinger distance atom environment, Euclidian distance and Dice calculations indicate that these substances are only similar to a certain extent. However, a certain difference can be expected due to the presence of additional benzene rings and a significantly increased amount of secondary alkylations. They have similar physicochemical properties, similar environmental fate characteristics, and similar ecotoxicity and mammalian toxicity profiles. For example, these substances can dissociate only in the presence of strong acids such as in the stomach but are not expected to dissociate under environmental conditions. For further details on this, please refer to the separate Read-Across Statement (Chemservice S.A., 2017). The similar toxicity profiles indicate that they have a similar MOA. C20-24 calcium sulfonate and Sulfonic acids, petroleum, calcium salts (CAS 61789-86-4) are both not classified for environmental toxicity.
The similar findings (refer to data matrix outlined below and the separate Read-Across Statement) for both substances support the conclusion that similar molecules are expected to be formed from both substances, and in consequence, similar effects can be reasonably expected. Hence, the analogue may serve in a worst case approach as a read-across substance for the C20-24 calcium sulfonate. So, based on the WOE of these data, the available data on CAS 61789-86-4 can be used to cover the systemic endpoints currently lacking for C20-24 calcium sulfonate and read across is scientifically justified, making further testing obsolete.

4. DATA MATRIX
There is mainly data available on the toxicological properties of the analogues CAS 61789-86-4 / its overbased version CAS 68783-96-0 and for CAS 70024-69-0 / its overbased version CAS 70024-71-4. Data on Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts covers merely the physico chemical properties. Hence, the identification and discussion of common properties of the analogues and the C20-24 calcium sulfonate will be mainly based on this physicochemical data.
The available data for the following physico-chemical properties, which are relevant for absorption into living organisms, are very similar. The substances are rather huge molecules and have a similar molecular weight range, which triggers already similarities in their absorption/adsorption and desorption behaviour. Furthermore, the physico-chemical properties like their partition coefficient, water solubility and vapour pressure are similar. Regarding the application of these substances, the substances are usually solved in an inert mineral oil to enable handling. The C20-24 calcium sulfonate and all analogous substances are hydrolytically stable in the natural environment, as they do not contain hydrolysable groups. In addition, at least CAS 70024-69-0 and CAS 61789-86-4 are not readily biodegradable, and the available data suggests this to apply also for C20-24 calcium sulfonate. Taking into account the vast amount of data available for partition coefficient data on various calcium sulfonates it can be concluded that they do not have a significant potential for bioaccumulation in aquatic and terrestrial organisms. However, they are expected to be adsorbed to a significant extent to the sediment and soil and to be thereby not bioavailable, which was confirmed by the results of short-term toxicity tests to fish, daphnia and algae for CAS 70024-71-4; CAS 115733-09-0 and CAS 61789-64-4, in which the lowest LL50 was already > 100 mg/L WAF.
For the following toxicological endpoints there is data available derived from CAS 70024-69-0/ CAS 70024-71-4, Analogue of CAS 70024-69-0, CAS 115733-09-0, CAS 61789-86-4/ CAS 68783-96-0 and CAS 75975-85-8: Acute toxicity, Skin irritation / corrosion, Eye irritation /corrosion, Skin sensitization, Repeated dose toxicity, Genetic toxicity in vitro and in vivo and Toxicity to reproduction (fertility / developmental toxicity). Furthermore a rather extensive data package is available concerning the human sensitization potential of numerous analogous substances. For the acute oral toxicity, the values for all read across substances are very high, all LD50 values being above 2000 mg/kg (reaching in older tests up to greater than 20,000 mg/kg) and the values for the substances can be considered as similar within normal biological variations. The substances are also not toxic via the inhalation or the dermal route of exposure. Regarding Skin/Eye Irritation, the available data on CAS 70024-69-0 and CAS 61789-86-4 shows both substances to be not irritating to the skin or the eyes. The skin sensitization data in animals and humans (for CAS 75975-85-8; CAS 61789-86-4 and EC 939-141-6) evaluated in a weight-of-evidence approach indicates that low TBN calcium sulfonates (TBN < 300) are skin sensitizers with a specific concentration limit (SCL) of 10% and that high TBN calcium sulfonates (TBN ≥ 300) are not skin sensitizers. Last but not least, the available genetic toxicity data for Analogue of CAS 70024-69-0, CAS 61789-86-4 and its overbased version CAS 68783-96-0 prove all of these substances to be not mutagenic. The NOAELs derived for the endpoints Repeated dose toxicity (Analogue of CAS 70024-69-0 and CAS 61789-86-4) and Toxicity to reproduction (fertility / developmental toxicity for CAS 115733-09-0)) have been also found to be in a similar range.
For further details please refer to the separate Read-Across Statement (Chemservice S.A., 2017) and/or the robust study summaries of the respective studies in this IUCLID file.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF loading rate

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF loading rate

Basis for effect:

mobility

Details on results:

No immobilisation was observed in any daphnids at 100 mg/L nominal WAF loading rate

Results with reference substance (positive control):

24 hour EC50 = 1.5 mg/L (95 % CL = 1.4-1.7 mg/L)
48 hour EC50 = 1.2 mg/L (95 % CL = 1.0-1.3 mg/L)

Reported statistics and error estimates:

The EC50s and associated confidence limits for the reference substance were calculated using the Spearman-Karber method.

Validity criteria fulfilled:

yes

Remarks:

Scientifically validity criteria are fulfilled.

Conclusions:

The report represents a valid guideline study with GLP compliance. The calcium sulfonate Read-Across substance (CAS 61789 -86 -4) was not toxic to Daphnia magna at a loading rate up to 100 mg/L nominal WAF, therefore the EL50 is considered to be > 100 mg/L. These results can be used to fulfill the information requirements for the chemical substance Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, due to the high structural similarity of these substances. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement (Chemservice S.A., 2017).

Executive summary:

Sulphonic acids, petroleum, calcium salts (CAS 61789-86-4) was used as test substance in an experiment according to OECD 202 to Waterfleas (Daphnia magna) under static conditions (Goodband, 2005). Water Accommodated Fractions (WAFs) were prepared due to the intrinsic properties of the test substance. Daphnids were exposed to control and test chemical at a nominal concentration of 100 mg/L WAF for 48 hours. Immobilisation and sublethal effects were observed daily. Water temperature was recorded daily throughout the test. Dissolved oxygen and pH were recorded at the start and termination of the test. No immobilisation was observed in any daphnids at 100 mg/L nominal WAF loading rate. Spearman-Karber method was used as statistical method. The EL50(48h) is considered as > 100 mg/L.

These results can be used to fulfill the information requirements for the chemical substance Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, due to the high structural similarity of these substances. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement (Chemservice S.A., 2017).

Description of key information

No toxicity observed even at highest concentration level tested.
RA_CAS115733-09-0_OECD 202_Daphnia magna: EC50 (48h) > 1000 mg/L WAF,
RA_CAS61789-86-4_OECD 202_Daphnia magna: EC50 (48h) > 100 mg/L WAF

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L

Additional information

General considerations

For the substance itself, no experimental data are available. The following read-across substances were used to fulfil the endpoint of short-term toxicity to Daphnia magna: Calcium sulfonate read-across substance (CAS 115733-09-0) and calcium sulfonate read across substance (CAS 61789-86-4). Investigations concerning toxicity in marine invertebrates were not performed. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement attached to this Chemical Safety Report (Chemservice S.A., 2017).

Acute toxicity to freshwater invertebrates

Two key studies are available to characterise acute toxic effects of the test substance towards aquatic invertebrates. Based on the intrinsic properties of the used substances, Water Accommodated Fractions (WAFs) were prepared for testing. Daphnia magna was exposed to the test substance for a duration of 48 h, whereby mortality, immobilisation as well as sublethal effects were recorded daily.

In the first key study, the toxicity of the calcium sulfonate read-across substance (CAS 115733-09-0) under static conditions was investigated by Ward (1993) in accordance to US EPA Guideline OTS 797 -1300. Daphnids were exposed to control and test chemical at nominal concentrations of 100, 300 and 1000 mg/L WAF for 48 hours. After 24 h, no immobilised or dead organisms were observed. At the end of the experiment, 5 %, 0 %, 20 % and 5 % immobilisation were reported for the control, 100, 300 and 1000 mg/L WAF, respectively. Therefore, the test substance is considered as non-toxic to daphnids at WAF loading rates up to 1000 mg/L. The EC50 (48h) is > 1000 mg/L WAF.

In the second key study, performed with Sulphonic acids, petroleum, calcium salts (CAS 61789-86-4), Daphnia magna were exposed also under static conditions for 48 hours (Goodband, 2005b). Beside control, daphnids were exposed to a single nominal test substance concentration of 100 mg/L WAF for 48 hours. Immobilisation and sublethal effects were observed daily. No immobilisation was observed in any daphnids at 100 mg/L nominal WAF loading rate. The EL50(48h) is considered as > 100 mg/L.

Conclusion:

No toxic effects observed in both acute studies with daphnids even at the highest concentration levels tested.