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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Classification of N-hydroxyphthalimide for effects in the environment:

 

The chemical N-hydroxyphthalimide (CAS no. 524-38-9) is used as a laboratory chemical and as an intermediate for chemical synthesis. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for N-hydroxyphthalimide. 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 fulfils the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

In an experimental key study, biodegradation experiment was conducted according to CO2 generation amount method for evaluating the percentage biodegradability of test substance 2 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS no. 524 -38 -9) (Scifinder, American Chemical Society, 2017). The final aerobic percentage degradation rate of test substance was determined to be 95.80% degradation by CO2 evolution parameter in a 14 day period. Thus, based on percentage degradation, 2 -hydroxy-1H-isoindole-1,3(2H)-dione is considered to be readily biodegradable in nature.

 

In a supporting study from secondary source (Scifinder, American Chemical Society, 2017), biodegradation experiment was performed according to the shaking cultivation method for evaluating the percentage biodegradability of test substance 2 -hydroxy-1H-isoindole-1,3(2H)-dione (CAS no. 524 -38 -9). The primary aerobic percentage degradation rate of test substance was determined to be 93.60% degradation in a 5 day period. Thus, based on percentage degradation, 2 -hydroxy-1H-isoindole-1,3(2H)-dione is considered to be readily biodegradable in nature.

 

For target chemical 2-hydroxy-1H-isoindole-1,3(2H)-dione(CAS No. 524-38-9), biodegradability of2-hydroxy-1H-isoindole-1,3(2H)-dioneis predicted using OECD QSAR toolbox version 3.4 with logKow as the primary descriptor (2017).Test substance undergoes 73.63% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 2-hydroxy-1H-iso indole-1,3(2H)-dione was estimated to be readily biodegradable in water.

 

In addition to the above studies, the information for read across chemicals (CAS: 85-41-6 and 85-44-9) also indicate that they are readily biodegradable in nature.

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 69.2%). In soil, N-hydroxyphthalimidewas expected to have rapid to moderate mobility based upon an estimated Log KOC in the range 1 – 2.11. Thehalf-life in soil (30 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, 30.7% 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 (15 days estimated by EPI suite) indicates that the 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 that N-hydroxyphthalimide is 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:

 

The estimated BCF value from various databases was determined to be in the range 1-6.4 L/kg wet wt. and the estimated octanol water partition coefficient of the test chemical is 0.14 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:

 

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 estimation for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be >100 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.

 

There are no available long-term toxicity evaluations for N-hydroxyphthalimide. By speculation, long-term NOEC for aquatic organisms were not expected for N-hydroxyphthalimide 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.

 

Conclusion

Based on critical, independent and collective evaluation of information summarized herein, the tested compound does not fulfil the P, B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.

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