Disodium benzene-1,3-disulphonate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Disodium benzene-1,3-disulphonate for effects in the environment:

 

The chemical Disodium benzene-1,3-disulphonate (CAS no. 831-59-4) is used as a pharma intermediate, for chemical synthesis as well as a laboratory reagent. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Disodium benzene-1,3-disulphonate. The PBT criterion was herein assessed based on experimental data in conjunction with standardized environmental fate models. Here follows a description of the PBT assessment.

 

 

Persistence assessment

The tested substance does not fulfil the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

 

Various experimental studies for the target compoundDisodium benzene-1,3-disulphonate (CAS no. 831-59-4) were reviewed for the biodegradation end point which are summarized as below:

 

In a study from authoritative database (GSBL, 2017) for the target chemical disodium benzene-1,3-disulfonate(CAS No. 831-59-4), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance disodium benzene-1,3 –disulfonate. The study was performed according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test). The activated sludge was used as a test inoculum obtained from the biological purification plant. Concentration of inoculum i.e, sludge used was 1100 mg/l and initial test substance conc. used in the study was 50 - 400 mg/l based on DOC concentration and 200 – 1000 mg/l based on COD concentration, respectively. Mineral medium was used for the study. Duration of acclimatization phase was 7 – 10 days and duration of logarithmic degradation was 7 – 9 days. The percentage degradation of test substance was determined to be 88 and 97% degradation by DOC removal parameter in 21 and 28 days, respectively. Thus, based on percentage degradation, disodium benzene-1,3 -disulfonate is considered to be readily biodegradable in nature.

 

In an another study, biodegradation experiment was carried out for 19 days for evaluating the percentage biodegradability of test substance disodium benzene-1,3 -disulfonate (CAS no. 831 -59 -4) (GSBL, 2017) . The study was performed according to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test). The mixed culture was used as a test inoculum obtained from sewage treatment plant. Initial test substance conc. used in the study was 5 - 20 mg/l based on DOC concentration. Mineral medium was used for the study. The percentage degradation of test substance was determined to be 19.8% by DOC removal parameter in 19 days. Thus, based on percentage degradation, disodium benzene-1,3 -disulfonate is considered to be inherently biodegradable in nature.

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with log Kow as the primary descriptor, percentage biodegradability of test chemical disodium benzene-1,3-disulfonate(CAS No. 831-59-4) was estimated. Test substance undergoes 79.16% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical disodium benzene-1,3-disulfonate was estimated to be readily biodegradable in water.

 

Further, various supporting studies for read across substances (CAS: 98-11-3; 868-18-8 and 98-48-6), also indicate that the substances are readily biodegradable in nature.

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 79.3%).Thehalf-life in soil (30 days estimated by EPI suite) indicates that the chemical is not persistent in soil and the exposure risk to soil dwelling animals is moderate to low.

 

If released in to the environment, 20.6 % of the chemical will partition into water according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (15 days estimated by EPI suite) indicates that the exposure risk to aquatic animals is moderate to low.

 

Moreover, its persistent characteristic is only observed in the sediment compartment but Fugacity modelling shows that sediment is not an important environmental fate (less than 1% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded that Disodium benzene-1,3-disulphonate is not persistent in nature.

 

 

Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:

 

The estimated BCF value from various databases was determined to be in the range 3.2 L/kg wet wt. and theestimatedoctanol water partition coefficient of the test chemical is -4.69 which is less than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a low risk for the chemical to bioaccumulate in fish and food chains.

 

Toxicity assessment

The tested substance does not fulfil the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

The tested chemical is regarded to be not classified for carcinogenicity, mutagenicity and reprotoxicity, Further, there is no evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure), category 1(oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume) or category 2 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume).

 

Aquatic organisms

All of the available short-term eco-toxicity estimation for invertebrates and algae for the substance indicates the LC50/EC50 value to be >100 mg/L. These value suggest that the substance is likely to be non-hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered to be not classified as per the CLP regulation.

 

There are no available long-term toxicity evaluations for Disodium benzene-1,3-disulphonate. By speculation, long-term NOEC for aquatic organisms were not expected for the substance at concentration below 0.01 mg/L based on the data mentioned above.

 

The chemical was therefore not considered as hazardous to aquatic environments as per the criteria set out in Annex XIII.

 

Conclusion

Based on critical, independent and collective evaluation of information summarized herein, the tested compound does not fulfil the P, B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.