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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 Bis(4-hydroxy-N-methylanilinium) sulphate for effects in the environment:


The chemicalBis(4-hydroxy-N-methylanilinium) sulphate(CAS no. 55-55-0) is used as a developing agent in photography and as an intermediate in hair dyes/colors. Also used for dyeing furs. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled forBis(4-hydroxy-N-methylanilinium) sulphate. 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

Biodegradation experiment was performed in batch system using adapted activated sludge as inoculums. Activated sludge was obtained from sewage plant then it is adapted for 20 days with the test chemical Bis(4-hydroxy-N-methylanilinium) sulphate (CAS no. 55-55-0) in biological medium containing Glucose peptone etc. After activated sludge get adapted concentration of test chemical was increased upto 200 mg/L and then biodegradation was observed for test chemical. Test chemical was the only source of organic carbon. All adaption process and degradation process was taken place in dark room at 20°C. Experiment was carried out till there is no decrease of COD. Inoculum blank flask was also set up simultaneously. Sampling was done at definite time interval 50-80 mL sample was taken for analyzing COD. The experiment is carried out till there is no decrease of COD. After that time the total percentage of COD removed (% degradation) and the rate of degradation are evaluated. Percent biodegradability of test chemical Bis(4-hydroxy-N-methylanilinium) sulphate observed to be 59.4 % by COD (Organic Carbon ) and rate of degradation was 0.8 mg COD /g/L per hour. If the degradation rate being over 15 mg of COD g /L/h), the substance tested can be considered to be biologically readily decomposable but for test chemical it was only 0.8mg COD g/L/h. Thus it is concluded that test chemical Bis(4-hydroxy-N-methylanilinium) sulphate is inherently biodegradable in water.


Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 87.5%). The half-life in soil (75 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% 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 (37.5 days estimated by EPI suite) indicates that the chemical is not persistent in water and exposure risk to aquatic animals is moderate to low.


Moreover, its persistent characteristic is only observed in the sediment compartment but Fugacity modelling shows that sediment is not an important environmental fate (less than 1% when estimated by EPI Suite version 4.1).


Hence it has been concluded thatBis(4-hydroxy-N-methylanilinium) sulphateis not 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 16.26 L/kg and theoctanol water partition coefficient of the test chemical is 0.79 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 forSTOT (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)as per theHarmonized classification - Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation).

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


Aquatic organisms

All of the available short-term eco-toxicity estimations for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in the range 0.25 – 0.724 mg/L and on the basis of long term eco-toxicity data for invertebrates, the LC50 value was determined to be 0.019 mg/l, respectively. These value suggest that the substance is likely to be hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered to be classified in ‘Aquatic Acute Category 1’ and ‘Aquatic Chronic Category 1’ as per the CLP regulation.


By speculation, long-term NOEC for aquatic organisms can be expected for the substance at concentration below 0.01 mg/L based on the data mentioned above


The chemical was therefore 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 T criterion but does not fulfil the P and B criterion and has therefore not been classified as a PBT compound within Annex XIII.