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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-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid for effects in the environment:


The chemical 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid (CAS no. 12239-15-5) is used as a dye for coloring leather, silk, nylon, wool, cotton and fur etc.The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic 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 does not fulfil the P criterion within Annex XIII based on the assessment that here follows:


Biotic degradation

Biodegradability of test chemical 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid (Acid yellow 49) was determined by analyzing percent recovery of test material (Glenn M Shaul, et. al; 1991). This test material is dye and inoculums used for biodegradation was obtained from Screened raw waste water from greater Cincinnati Mill Creek sewage treatment plant was used as influent (INF) to three pilot scale activated sludge biological treatment systems (Two experimental and one control). Each system consists of primary clarifier, complete mix aeration basin and secondary clarifier. Influent was spiked with test material at concentration of1 mg/L and 5 mg/L. Then Dye analytical studies were conducted by purified dye compound in organic free influent waste water and mixed liquor. Then influent, primary influent filtrate was passed through column packed with resin. The filter paper and resin were soaked in an ammonia – acetonitrile solution and then soxhlet extracted with ammonia – acetonitrile. The extract was concentrated and brought upto 50 ml volume with methanol/dimethyl formamaide solution. All extracted samples were analyzed by HPLC with ultraviolet detector. Percent recovery from mass balance data determined was 75 % in low spiked and 68 % in high spiked. On the basis of percent recovery value biodegradation of 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was 25% and 32 %by test material analysis by HPLC parameter. On the basis of percent degradation it is concluded that this test material is inherently biodegradable. 


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 16.8, respectivelyand the octanol water partition coefficient of the test chemical was 1.702, 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 substance4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acidindicates the LC50/EC50 value to be in the range 121.927 – 215.3 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.



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.