4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one for effects in the environment:

 

The chemical 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one (CAS no. 127-41-3) is used as a fragrance agent. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one. 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 fate

Biodegradation study was conducted according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) for 28 days for evaluating the percentage biodegradability of test substance alpha-Ionone. The percentage degradation of test substance was determined to be 75.4% by CO2 evolution after 28 days. Thus, the substance alpha-Ionone was evaluated to be readily biodegradable in water.

 

In addition, the biodegradation studies reported for read across substances (CAS: 14901-07-6 and 1335-46-2) also indicate the substances to be readily degradable 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 85.5%). In soil, 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one was expected to have negligible to slow mobility based upon log Koc in the range 2.82 – 3.47. 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 14 % of the chemical will partition into water according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (37.5 days estimated by EPI suite) indicates that 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% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded that 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one 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:

 

The estimated BCF value from authoritative databases was determined to be in the range 161 – 507 and the octanol water partition coefficient of the test chemical is in the range 3.85 – 4.29 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

Most of the available short-term eco-toxicity estimation for fish, invertebrates and algae for the substance as well as its read-across substances indicates that the substance is classified as ‘Aquatic chronic category 2’ as per the CLP criteria. But the substance is determined to be readily biodegradable and hencethe classification for aquatic toxicity will not be applicable for all of the tropic levels.

 

There are no available long-term toxicity evaluations for 4-(2,6,6-trimethylcyclohex-2-ene-1-yl)-but-3-ene-2-one. By speculation, long-term NOEC for aquatic organisms cannot be 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.