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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 1,4-Bis(ethenyl)benzene for effects in the environment:

 

The chemical 1,4-Bis(ethenyl)benzene (CAS no. 105-06-6) is used as a polymer intermediate.The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 1,4-Bis(ethenyl)benzene. 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 key study from authoritative database (J-CHECK, 2018) and secondary source, biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance1,4-Bis(ethenyl)benzene (CAS no. 105-06-6). Activated sludge was used as a test inoculums for the study. 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 1,4-Bis(ethenyl)benzene was determined to be 0 and 3% by BOD and GC parameter in 28 days. Thus, based on percentage degradation, 1,4-Bis(ethenyl)benzene is considered to be not readily biodegradable in nature.

 

In a prediction using the Estimation Programs Interface Suite (2018), the biodegradation potential of the test compound 1,4-Bis(ethenyl)benzene (CAS no. 105 -06 -6) 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 1,4-Bis(ethenyl)benzene is expected to be not readily biodegradable.

                                                                 

Experimental results from the read across substances also indicate that they are not readily biodegradable.

 

Hence, it has been concluded that chemical 1,4-Bis(ethenyl)benzene is likely to be persistent (P) 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 authoritative database was determined to be ranges from 148.7 to 402, respectively and the octanol water partition coefficient of the test chemical is 4.46 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

As per Column 2 (Annex VIII) of the REACH regulation,testing for this end point is considered scientifically unjustified since there are mitigating factors indicating that aquatic toxicity is unlikely to occur as the substance is highly insoluble in water (solubility: <0.001 mg/L at 25° C). The chemical 1,4-Bis(ethenyl)benzene 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 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.