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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

Classification of 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid for effects in the environment:


The chemical 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid (CAS no. 25251-42-7) is used as an intermediate for chemical synthesis. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid. 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

Biodegradability of test chemical 4-hydroxy-6-[(3-sulfophenyl)amino]naphthalene-2-sulfonic acid (CAS No: 25251-42-7) is predicted using OECD QSAR tool box v.3.3 using log Kow as primary descriptor. The test chemical 4-hydroxy-6-[(3-sulfophenyl)amino]naphthalene-2-sulfonic acid showed 4.48 % biodegradability by considering BOD as parameter and microorganisms as inoculum in 28 days. Since percent biodegradability is very low it is concluded that this test chemical is not readily biodegradable.


Another prediction done by using Estimation Programs Interface Suite (EPI suite, 2017) to estimate the biodegradation potential of the test chemical 4-hydroxy-6-[(3-sulfophenyl)amino]naphthalene-2-sulfonic acid (CAS No: 25251-42-7) in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 4-hydroxy-6-[(3-sulfophenyl)amino]naphthalene-2-sulfonic acid is not readily biodegradable.


Experimental results from the similar substances (CAS: 119-40-4 and 90-51-7) also indicate that they are not readily biodegradable.


Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 80.5%). In soil, 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid was expected to have rapid to moderate mobility based upon a LogKOC in the range 0-1.98. Thehalf-life in soil (75 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, 9.59 % and 9.96 of the chemical will partition into water and sediment respectively, according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). The half-life (37.5 days in water and 337.5 days in sediment as estimated by EPI suite) chemical is not persistent in water but persistent in sediment.


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 that 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid 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:


Theestimated BCF value from authoritative database was determined to be in the range 1.0 – 3.162 and theoctanol water partition coefficient of the test chemical is -0.12 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:



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 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 4-hydroxy-6-(3-sulphoanilino)naphthalene-2-sulphonic acid. 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.



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.