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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

Classification of (4-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochloride for effects in the environment:


The chemical(4-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochloride(CAS no. 632-99-5) is used as a dyestuff agent and as a biological stain. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for4-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochloride.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

In an experimental study from J-check databases 2017 for the target chemical (4-(4-aminophenyl)(4-imino -cyclohexa-2,5-dienylidene) methyl)-2-methylaniline hydrochloride, biodegradation experiment was conducted for evaluating the percentage biodegradability. Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance (4-(4-aminophenyl)(4-imino -cyclohexa-2,5-dienylidene) methyl)-2-methylaniline hydrochloride. (CAS no. 632-99-5). Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of test substance was determined to 0, 13 and 2% by BOD, TOC, and HPLC parameter in 28 days. Thus, based on percentage degradation, (4-(4-aminophenyl)(4-imino -cyclohexa-2,5-dienylidene) methyl)-2-methylaniline hydrochloride is considered to be not readily biodegradable in water.


In a prediction using the Estimation Programs Interface Suite (EPI suite, 2017) the biodegradation potential of the test compound (4-(4-aminophenyl) (4-iminocyclohexa-2, 5-dienylidene)methyl) -2-methylaniline hydrochloride (632 -99 -5) 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-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochloride is expected to be not readily biodegradable.


Experimental results for the similar substances (CAS: 2465-27-2 and 1100-88-5) 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 and sediment (i.e. estimated to 54.4 and 42.5%). The half-life (120 days in soil and 541.6 days in sediment as estimated by EPI suite) indicates that the chemical is persistent in sediment but not persistent in soil.


If released in to the environment, 3.02% of the chemical will partition into water according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). However, the half-life (60 days estimated by EPI suite) indicates that the exposure risk to aquatic animals is moderate to high.


Although the half-life values indicate that the substance is likely to be very persistent (vP), since only estimated values are available, it is classified as persistent (P).


Hence it has been concluded that4-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochlorideis 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:


Theestimated BCF value from authoritative databases was determined to be in the range 1 – 21.8 and theoctanol water partition coefficient of the test chemical is 1.36 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 in the range 4.3 - 1187 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 not classified as per the CLP regulation for acute toxicity.


Long-term toxicity evaluation are available for4-(4-aminophenyl)(4-iminocyclohexa-2,5-dienylidene)methyl)-2-methylaniline hydrochloride. Long-term NOEC for fish is determined to be 3.12 mg/L for a 60 day exposure. Since this value is much above 0.01 mg/L, the chemical was therefore considered as non-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.