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PBT assessment

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PBT assessment: overall result

Reference
Name:
tert-butyl-4-methoxyphenol
Type of composition:
boundary composition of the substance
State / form:
solid: bulk
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB
Justification:

Classification of Tert-butyl-4-methoxyphenol for effects in the environment:

 

The chemical Tert-butyl-4-methoxyphenol (CAS no. 25013-16-5) isused as a food and cosmetic preservative. It is used as an antioxidant in many foods. Also used in cosmetics such as lipstick and eye shadow etc. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Tert-butyl-4-methoxyphenol. 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

Although one study indicates that the chemical Tert-butyl-4-methoxyphenol is not readily biodegradable, but on the basis of experimental result of guideline study for the test chemical Tert-butyl-4-methoxyphenol (CAS no. 25013 -16 -5) from study report, it indicates that chemical Tert-butyl-4-methoxyphenol can be considered to be primary inherently biodegradable in water and thus likely to be not persistent (not 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 80.5%). In soil,Tert-butyl-4-methoxyphenolwas expected to have slow mobility based upon a Log KOC value of 3.145. 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, 18.3 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 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% i.e reported as 0.854% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded that chemical Tert-butyl-4-methoxyphenol 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:

 

Theestimated BCF value from authoritative database was determined to be ranges from 8.1 to 57, respectively and theoctanol water partition coefficient of the test chemical was determined to be 2.82, 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 classified for carcinogenicity in Category 2 and reprotoxicity in Reprotox Category 2 as per theSelf classification - Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation).

The tested chemical is regarded to be not classified for mutagenicity. 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 fish, invertebrates and algae for the substanceTert-butyl-4-methoxyphenolindicates the LC50/EC50 value to be in the range 1.5 mg/l to 65 mg/L, respectively and on the basis ofthelong term eco-toxicity data for fish and aq. invertebrates, the NOEC value was determined to be ranges from 0.619 to 0.761 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 2’ as per the CLP regulation.

 

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.

 

Conclusion

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.