Sodium 3-(p-anilinophenylazo)benzenesulphonate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Sodium 3-(p-anilinophenylazo)benzenesulphonate for effects in the environment:

 

The chemical Sodium 3-(p-anilinophenylazo)benzenesulphonate (CAS no. 587-98-4) is used in the dyestuff industry and as a laboratory chemical. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Sodium 3-(p-anilinophenylazo)benzenesulphonate. 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 fulfils the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

 

Various experimental studies for the target compound sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate (CAS No. 587-98-4) were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental study from peer reviewed journal (Rais Ahmad et. al, 2010), the biodegradation of sodium 3-[(4-anilinophenyl) diazenyl] benzenesulfonate is carried out by using anaerobic (UASFB bioreactor)/aerobic (aerobic bioreactor) processes. Methanogenic granular sludge/Aerobic sludge were used as inoculum. Study period for the biodegradation is 150 days and the parameter used for the study is % Biodegradation. Two aromatic amines 4-ABS and p-ADPA are the biodegradation products of sodium 3-[(4-anilinophenyl) diazenyl] benzenesulfonate, potentially formed by the anaerobic reduction of test chemical. Further 4-ABS was biodegraded aerobically, but degradation of p-ADPA doesn’t take place. Biodegradation products were confirmed with the help of HPLC and UV spectroscopic methods. The given test chemical was considered to be not readily biodegradable under aerobic conditions but this dye readily decolorized in anaerobic conditions. As per the results obtained sodium 3-[(4-anilinophenyl) diazenyl] benzenesulfonate shows 98% biodegradation in 150 days, which confirms the test chemicalsodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonateis inherently biodegradable.

 

Another biodegradation experiment under anaerobic conditions was performed for chemical sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate at 35oC and initial concentration of chemical taken was 100mg/L for 7 days (D. Brown and B. Hamburger, 1987). By spectrophotometric analysis 97% degradation was observed in 7 days. The metabolite formed after degradation of sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate are 3-aminobenzenesul phonic acid and N-phenyl- I ,4-diaminobenzene. From these metabolites 3-aminobenzenesul phonic acid was again subjected to biodegradation but aerobically and it showed more than 75 % degradation in 8 days. So it is concluded that sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate is readily biodegradable.

 

In a supporting study from peer reviewed journal (U. Pagga and O. Brown, 1986), the aerobic biodegradation experiment was performed for chemical sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate (CAS no.587-98-4) using activated sludge at concentration 0.5 g/L dry material as inoculums and initial concentration of chemical taken was 100mg/L for 42 days. By considering DOC removal parameter test chemical showed 11% degradation in 7 days. This percentage value is very less So it is concluded that sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate (CAS no. 587-98-4) is not readily biodegradable.

 

It is clear that sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate is not degradable under aerobic conditions but it undergoes degradation under anaerobic conditions. Thus, based on the experimental study from peer reviewed journal (2010), it can be concluded that the chemical sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate can be expected to be inherently 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 84.8%). In soil, Sodium 3-(p-anilinophenylazo)benzenesulphonate was expected to have moderate mobility based upon an experimental Log KOCof 1.69. Thehalf-life in soil (120 days estimated by EPI suite) indicates that the chemical is not persistent in soil.

 

If released in to the environment, 13.8 and 1.36 % of the chemical will partition into water and sediment, respectively according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (60 days in water and 541.6 days in sediment as estimated by EPI suite) indicates that the substance is persistent in both compartments.

 

Although the half-life values in sediment suggest classification as very persistent (vP), the substance is classified only as persistent (P) since only estimated values are available and as the percentage release of test chemical into the sediment is less than 2% (i.e., reported as 1.36%), for the same.

 

Hence it has been concluded that the substance Sodium 3-(p-anilinophenylazo)benzenesulphonate is 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 was determined to be 8.87 and the octanol water partition coefficient of the test chemical is 0.137 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 fulfils the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

The substance is self-classified as toxic for reproduction (category 2) according to CLP (Regulation (EC) No 1272/2008).

The tested chemical is regarded to be not classified for carcinogenicity and mutagenicity. 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 estimations for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be 1.5 - 25 mg/L. These value suggest that the substance is likely to be hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered to be classified in “Aquatic chronic category 2”as per the CLP regulation.

 

There are no available long-term toxicity evaluations for Sodium 3-(p-anilinophenylazo)benzenesulphonate. 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 fulfils the P and T criterion but does not fulfil the B criterion and has therefore not been classified as a PBT compound within Annex XIII.