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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-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride for effects in the environment:


The chemical4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride(CAS no. 3248-91-7) is usedas a non-reactive hair colouring agent (“direct” dye) in semi-permanent hair dye formulations at a maximum concentration of 0.5% in the finished cosmetic product.The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride. 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 4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride (CAS no. 3248-91-7) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 22.375% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloridewas estimated to be not readily biodegradable in water.


Another prediction done by using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride(CAS no. 3248-91-7) in the presence of mixed populations of environmental microorganisms was estimated. 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-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochlorideis expected to be not readily biodegradable.


Experimental results from the similar substances (CAS: 90-41-5 and 101-77-9) 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 sediment (i.e.estimated to 49.8%). The half-life in sediment (541.66 days estimated by EPI suite) indicates that the chemical is very persistent in sediment.


If released in to the environment, 48.1% of the chemical will partition into soil according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). In soil,4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloridewas expected to have rapid to moderate mobility based upon a Log KOC value ranging from 0 to 3.00, respectively. However, the half-life (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.


Moreover, its persistent characteristic is also observed in the water compartment with a half-life of 60 days (estimated by EPI Suite version 4.1).


Although the half-life value in sediment compartment indicate the chemical to be Very Persistent (vP), since only predicted data is available for the substance, it has been concluded thatsubstance4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochlorideis considered 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 database was determined to be in the range from 1 to 37.4, respectively and theoctanol water partition coefficient of the test chemical is 1.5366 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 fulfils the T criterion within Annex XIII based on the assessment that here follows:



The tested chemical is regarded to be classified for Reprotoxicity as ‘Category 2’ as per the Regulation (EC) No 1272/2008 (CLP Regulation).

Further, the tested chemical is regarded to be not classified for carcinogenicity and mutagenicity.


Aquatic organisms

All of the available short-term eco-toxicity estimations for invertebrates and algae for the substance4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochlorideindicates the LC50/EC50 value to be in the range 240.314– 508.66 mg/L. 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.

There are no available long-term toxicity evaluations for4-[(4-amino-m-tolyl)(4-imino-3-methylcyclohexa-2,5-dien-1-ylidene)methyl]-o-toluidine monohydrochloride. 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 and T criterion but does not fulfil the B criterion and has therefore not been classified as a PBT compound within Annex XIII.