2-tert-butylhydroquinone

PBT assessment

PBT assessment: overall result

Reference

Name:

t-Butylhydroquinone \ 1948-33-0 \ 217-752-2

Type of composition:

legal entity composition of the substance

State / form:

solid: particulate/powder

Reference substance:

t-Butylhydroquinone \ 1948-33-0 \ 217-752-2

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of 2-tert-butylbenzene-1,4-diolfor effects in the environment:

 

The chemical 2-tert-butylbenzene-1,4-diol (CAS no. 1948-33-0) is used as an antioxidant, stabilizer, preservative for foods, pharmaceuticals. Also used as an antioxidant in cosmetics etc..The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for2-tert-butylbenzene-1,4-diol.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

35-days Closed Bottle test following the OECD guideline 301 D was performed to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentartion 10E7 to 10E8 CFU/ml. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 78.31 %. Degradation of Sodium Benzoate exceeds 49.39 % on 7 days & 75.3 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.27 mgO2/mg. ThOD was calculated as 2.4 mgO2/mg. Accordingly, the % degradation of the test item after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 52.91 %. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

 

Thus, based on the available information, it indicates thatchemical2-tert-butylbenzene-1,4-diolcan be considered to be 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 87.4%). In soil,2-tert-butylbenzene-1,4-diolwas expected to have rapid mobility based upon a Log KOC value of 1.415. 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, 11.58 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 2% i.e reported as 1.09% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded thatchemical2-tert-butylbenzene-1,4-diolis 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 24 dimensionless, respectively and theoctanol water partition coefficient of the test chemical ranges was determined to be 1.521, 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 mutagenicity in ‘Category 2’ as per theCLP Regulation.

 

The tested chemical is regarded to be not classified for carcinogenicity 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 fish, invertebrates and algae for the substance2-tert-butylbenzene-1,4-diol indicates the LC50/EC50 value to be in the range 0.15 mg/l to 9.3 mg/L, respectively. On the basis ofthelong term eco-toxicity data for fish, the NOEC value was estimated to be 0.0004 mg/l andon the basis of the various experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach,the LC50/EC50 value for long term aq. invertebrateof the test chemicalcan be determined to be in the range 0.116 – 0.895 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 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 T criterion, but does not fulfil the P and B criterion and has therefore not been classified as a PBT compound within Annex XIII.