N-tert-butylacrylamide

PBT assessment

PBT assessment: overall result

Reference

Name:

N-tert-butylacrylamide

Type of composition:

boundary composition of the substance

State / form:

solid: bulk

Reference substance:

N-tert-butylacrylamide

PBT status:

the substance is not PBT / vPvB

Justification:

Classification ofN-tert-Butylacrylamidefor effects in the environment:

 

The chemicalN-tert-Butylacrylamide(CAS no. 107-58-4)is used as a paint and coating additive. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for N-tert-Butylacrylamide. 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

42-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 concentration 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 42.16  % on 7 days &  63.25 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 0.8 mgO2/mg. ThOD was calculated as 2.26 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 35.39 %. Based on the results, the test item, under the test conditions, was considered to be primary inherently biodegradable in nature.

 

Thus, based on the available information, it indicates thatchemicalN-tert-Butylacrylamidecan beconsidered to be inherently biodegradablein 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 70.7%). In soil,N-tert-Butylacrylamidewas expected to have moderate mobility based upon a Log KOC value of 1.869, 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, 29% 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 0.0916% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded thatN-tert-Butylacrylamideis 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 authoritative databases was determined to beranges from 2.19 L/Kg, respectively and the octanol water partition coefficient of the test chemical was determined to 1.45, 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 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 data for fish, invertebrates and algae for the substanceN-tert-Butylacrylamideindicates the LC50/EC50 value to be > 100 mg/L. These value suggest that the substance is likely to be not hazardous to aquatic organisms at environmentally relevant concentrations and can be considered to be ‘not classified’ as per the CLP regulation.

 

On the basis ofthelong term eco-toxicity data for fish and aq. invertebrates, the 30 d and 21 d NOEC value was determined to be 10 mg/l (for fish as per OECD TG 210) and >10 mg/l (for aq. Invertebrates as per OECD TG 211), respectively. 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 does not fulfil the P, B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.