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PBT assessment

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PBT assessment: overall result

Reference
Name:
4,4'-methylenedi-2,6-xylenol
Type of composition:
boundary composition of the substance
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB
Justification:

Classification of 4,4'-methylenebis(2,6-dimethylphenol) for effects in the environment:

 

The chemical 4,4'-methylenebis(2,6-dimethylphenol) (CAS no. 5384-21-4) is used in synthesis of organic chemicals. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 4,4'-methylenebis(2,6-dimethylphenol). 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 using the Estimation Programs Interface Suite (2018) was run to predict the biodegradation potential of the test chemical4,4'-methylenebis(2,6-dimethylphenol)(CAS no. 5384-21-4)in the presence of mixed populations of environmental microorganisms. 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'-methylenebis(2,6-dimethylphenol)is expected to be not readily biodegradable.

 

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

 

Thus, based on the available information, it indicates that chemical 4,4'-methylenebis(2,6-dimethylphenol) can be expected to be not readily biodegradable in water and thus likely to be persistent (P) 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 61.8%). In soil,4,4'-methylenebis(2,6-dimethylphenol)was expected to have negligible to slow mobility based upon a Log KOC value of 3.9 to 5.03, respectively. 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, 32.4% of the chemical will partition into sediment according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). However, the half-life (337.5 days estimated by EPI suite) indicates that the substance is persistent in sediment andthe exposure risk to sediment animals is moderate to high.

 

If released in to the environment, 5.86% 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 substance is not persistent in water andthe exposure risk to aquatic animals is moderate to low.

 

Thus, based on the available information, it has been concluded that 4,4'-methylenebis(2,6-dimethylphenol) is considered 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 databases was determined to beranges from 1 to 1765, respectively and the octanol water partition coefficient of the test chemical was estimated to be 3.75, respectively, 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:

 

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 data for aq. algae for the substance4,4'-methylenebis(2,6-dimethylphenol)indicates the LC50/EC50 value to be > 18.05 mg/L, respectively and on the basis ofthe various experimental studies ofshort term eco-toxicity data for fish and aq. invertebratesof the structurally and functionally similar read across chemical (including the biodegradability of read across chemical) and applying the weight of evidence approach, the LC50/EC50 value was determined to be ranges from > 0.01 to 5 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’ as per the CLP regulation.

 

Based on the long-term eco-toxicity data for fish for the substance4,4'-methylenebis(2,6-dimethylphenol)indicates the NOEC value to be 0.036 mg/L and on the basis ofthe various experimental studies oflong term eco-toxicity data for aq. Invertebratesof the structurally and functionally similar read across chemical (including the biodegradability of read across chemical) and applying the weight of evidence approach, the NOEC value was determined to be ranges from > 0.0057 to 0.044 mg/l and EC50 value was determined to be 0.02 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 Chronic Category 1’ as per the CLP regulation.

 

By speculation, long-term NOEC for aquatic organisms were 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.

 

Conclusion

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