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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

Classification of N-(2-ethylhexyl)-1-[[2-methyl-4-[(4-methylphenyl)azo]phenyl]azo]naphthalen-2-amine for effects in the environment:


The chemical N-(2-ethylhexyl)-1-[[2-methyl-4-[(4-methylphenyl)azo]phenyl]azo]naphthalen-2-amine (CAS no. 93964-07-9) is used as a colorant in petroleum, pigment, rubber and ink industries. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for N-(2 -ethylhexyl)-1 -[[2 -methyl-4 -[(4 -methylphenyl)azo]phenyl] azo]naphthalen-2 -amine. 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

Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound N-(2 -ethylhexyl)-1 -[[2 -methyl-4 -[(4 -methylphenyl)azo]phenyl] azo]naphthalen-2 -amine (CAS no. 93964 -07 -9) 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical  N-(2 -ethylhexyl)-1 -[[2 -methyl-4 -[(4 -methylphenyl)azo]phenyl]azo] naphthalen-2 -amine is expected to be not readily biodegradable.


Experimental results from the read across substances (CAS: 5160-02-1 and 3618-58-4) also indicate that they are not readily biodegradable.


As the half-life value of chemical N-(2-ethylhexyl)-1-[[2-methyl-4-[(4-methylphenyl)azo]phenyl]azo]naphthalen-2-amine is not known and only predicted data is available for the substance, it has been concluded that N-(2-ethylhexyl)-1-[[2-methyl-4-[(4-methylphenyl)azo]phenyl]azo]naphthalen-2-amine is likely to be persistent (P) in nature.


Bioaccumulation assessment

The tested substance fulfils 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 130991 to 4219679, respectively and the octanol water partition coefficient of the test chemical was estimated to be 11.89, which is greater than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a high risk for the chemical to bioaccumulate in fish and food chains.


Although the BCF value indicate the chemical to be Very bioaccumulative (vB), since only predicted data is available for the substance, it has been concluded that chemical N-(2 -ethylhexyl)-1 -[[2 -methyl-4 -[(4 -methylphenyl)azo]phenyl]azo]naphthalen-2 -amine is bioaccumulative (B) 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

As per Column 2 (Annex VIII) of the REACH regulation,testing for this end point is considered scientifically unjustified since there are mitigating factors indicating that aquatic toxicity is unlikely to occur as the substance is highly insoluble in water (solubility: 0.0191 mg/L at 25° C). The chemical N-(2 -ethylhexyl)-1 -[[2 -methyl-4 -[(4 -methylphenyl)azo]phenyl]azo] naphthalen-2 -amine 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 and B criterion but does not fulfil the T criterion and has therefore not been classified as a PBT compound within Annex XIII.