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Classification & Labelling & PBT assessment

PBT assessment

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Administrative data

PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Classification of Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonate for effects in the environment:

 

The chemicalSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonate(CAS no. 6406-56-0) is mainly used for polyamide (70-75%) and wool (25-30%) dyeing; also used for silk and some modified acrylic fibres..The aim was to assess whether the PBT criterion within Annex XIII was fulfilled forSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)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

Based on the various experimental results and predicted data for the target chemicalSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonate(CAS no. 6406-56-0) and experimental study for itsread across substance (CAS: 2783-94-0), it indicates that the target chemicalSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonatecan be considered 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 57.6%). In soil,Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonatewas expected to have rapid mobility based upon a Log KOC value ranging from 0.3-1.317, respectively. The half-life in soil (120 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, 36.8% of the chemical will partition into sediment according to the Mackay fugacity model level III in EPI suite version 4.1 (2017).The half-life in sediment (541.66 days estimated by EPI suite) indicates that the chemical is very persistent in sediment and the exposure risk to sediment dwelling animals is moderate to high.

 

Moreover, its persistent characteristic is also observed in the water compartment according to the Mackay fugacity model level III in EPI suite version 4.1 (2017) with a half-life value of 60 days. This half-life value indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high. 

 

Although the half-life value in sediment indicate the chemical to be Very persistent (vP), since only predicted data is available for the substance, it has been concluded thatSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonateis likely to be 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 authoritative database was determined to be ranges from 1 to 21.9, respectivelyand the octanol water partition coefficient of the test chemical was 2.68, 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 estimations for invertebrates and algae for the substanceSodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonateindicates the LC50/EC50 value to be in the range 116.05 – 135.54 mg/L, respectively. These value suggest that the substance is not likely to be hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered to be ‘not classified’ as per the CLP regulation.

 

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 criterion but does not fulfil the B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.