N,N-diethyl-p-(phenylazo)aniline

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of N,N-diethyl-p-(phenylazo)aniline for effects in the environment:

 

The chemical N,N-diethyl-p-(phenylazo)aniline (CAS no. 2481-94-9) is used in as a dye for plastics and inks. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for N,N-diethyl-p-(phenylazo)aniline. 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 a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with log Kow as the primary descriptor, percentage biodegradability of test chemical4-(Diethylamino)azobenzene (CAS No. 2481-94-9) was estimated. Test substance undergoes 14% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 4-(Diethylamino)azobenzene was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound4-(Diethylamino)azobenzene(CAS No. 2481-94-9) 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-(Diethylamino)azobenzene is expected to be not readily biodegradable.

 

Experimental results from the similar substances (CAS: 119-93-7; 834-12-8 and 2095-06-9) 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 soil (i.e.estimated to 80.4%). In soil, N,N-diethyl-p-(phenylazo)aniline was expected to have negligible to slow mobility based upon a LogKOC in the range 1.9-4.4. Thehalf-life in soil (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.

 

If released in to the environment, 12.6% and 6.93% of the chemical will partition into water and sediment according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). However, the half-life (60 days in water and 541.6 days in sediment as estimated by EPI suite) indicates that the substance is persistent in both the compartments.

 

Although the half-life values indicate the chemical to be Very persistent (vP), since only predicted data is available for the substance, it has been concluded that N,N-diethyl-p-(phenylazo)aniline is not persistent in nature.

 

 

Bioaccumulation assessment

The tested substance fulfils the B criterion within Annex XIII based on the assessment that here follows:

 

Theestimated BCF value from authoritative database was determined to be 31.2 - 9730 and theoctanol water partition coefficient of the test chemical is 5.27 which is more than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a moderate to 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 and the octanol water partition coefficient is also just above the threshold, it has been concluded that N,N-diethyl-p-(phenylazo)aniline is bioaccumulative infish and food chains.

 

Toxicity assessment

The tested substance does not fulfil the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

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 11.1 – 12.8 mg/L. These value suggest that the substance is likely to be hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered as classified in Aquatic chronic category 3 as per the CLP regulation.

 

There are no available long-term toxicity evaluations for N,N-diethyl-p-(phenylazo)aniline. 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.

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Conclusion

Based on critical, independent and collective evaluation of information summarized herein, the tested compound fulfil 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.