Oxacycloheptadec-10-en-2-one

PBT assessment

PBT assessment: overall result

Reference

Name:

oxacycloheptadec-10-en-2-one

Type of composition:

boundary composition of the substance

State / form:

liquid

Reference substance:

oxacycloheptadec-10-en-2-one

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Oxacycloheptadec-10-en-2-one for effects in the environment:

 

The chemical Oxacycloheptadec-10-en-2-one (CAS no. 28645-51-4) is used in perfumery for fine fragrances etc. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Oxacycloheptadec-10-en-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 degradation

On the basis of various experimental results of biodegradation studies for the test chemical Oxacycloheptadec-10-en-2-one (CAS no. 28645-51-4), it indicates that chemical Oxacycloheptadec-10-en-2-one is considered to be readily biodegradable in water and thus likely to be not persistent (not P) in nature.

 

Environmental fate

Primary biodegradation in surface water from a Danish stream was determined by compound specified analysis. The study was performed following the modified OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) under aerobic conditions. Natural water (stream of good ecological quality and without known point sources close to sampling point) sampled from Gudenåen (DK) 16th of June 2020. WGS84: 56°6'23.2"N 9°43'17.4"E at a dept of 5 -20 cm below surface was used as a surface water. The water was quite clear with a slight light brown hint. Total suspended solids was 2.0 mg/L, total dissolved solids was 210 mg/L. No pre-treatment was done of the natural water. Water kept at 20 ± 1.5°C during transport to lab (4 hours), then stored at 12°C until test setup within 30 hours of sampling. The temperature and pH at the time of collection of the sample was 20.0°C and 6.5 pH. Biomass i.e., plate count at 24 and 72 hr was 36 CFU/ml and 1281 CFU/ml, respectively. Water was not filtered. Dissolved non-volatile organic carbon (NVOC) was measured instead of DOC/TOC and was 4.4 mg/L. Study was performed using 20 mL amber headspace closed vials. A large no. of biotic test systems (15 -18 replicates) consisting of 14.5 ml surface water and 0.5 ml stock solution was prepared test vials. Stock solution was prepared in water by equilibrium partioning from a pre-loaded silicone rod (passive dosing). This method for preparing stock solutions avoids the need for solvents for spiking. A similar number of abiotic control test systems were prepared using 14.5 ml MilliQ water and 0.5 ml stock solution. Blanks were prepared with 15 ml MilliQ water. Aerobic conditions created by using aerobic natural water (initial oxygen content 9.0 mg/L at 20 °C)  and incubating using a headspace of 5 mL with a low test substance concentration of 0.002 mg/l. Test was conducted at a temperature of 12°C and pH of 6.5 under continuous darkness with conductivity of 334 µS/cm while rolling. pH of the test medium (natural water) was not adjusted. No aeration was provided during the study. Suspended solid concentrations uded in the study was 2.0 mg/l. At 5 -6 time-points, 3 biotic and 3 abiotic test systems were sacrificed for analysis (day 2, 6, 9, 14 and 21). Tests systems were put directly on the autosampler of the GCMS without storage. Blank test systems were prepared and incubated with biotic and abiotic test systems and analyzed at each time-point (signal well below the 3% dilution of initial test concentration). Analysis was carried out using direct immersion solid phase microextraction coupled to GC-MS. Carryover was < 1.0% and since test systems were analyzed alternating biotic and abiotic test systems this constitutes the detection limit in this test. Biodegradation was then evaluated by the ratio between peak areas in the biotic and abiotic test systems. Triplicate ratios of biotic/abiotic test system peak areas were calculated for each time point and used in Graph-pad Prism 8.4.3 to fit the first order degradation model with lag phase. The (pseudo-)first order (= half-life) (DT50) of the test chemical was evaluated to be 0.6 days at 12°C. Primary percentage degradation of the test chemical was determined to be >99% at 7 days. Thus, on the basis of results, test chemical was considered to be not persistent in surface water.

 

Bioaccumulation assessment

The tested substance fulfils the B criterion within Annex XIII based on the assessment that here follows:

 

The octanol water partition coefficient of the test chemical was determined to be ranges from 5.51 to 6.7, respectively, which is greater than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a high 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 aq. invertebrate and algae for the substance Oxacycloheptadec-10-en-2-one indicates the LC50/EC50 value to be in the range 1.7 to >16.6 mg/L, respectively. These value suggest that the substance is likely to be hazardous to aquatic organisms at environmentally relevant concentrations. Since, the test chemical is readily biodegradable in water, chemical can be considered as non-toxic to aquatic organisms and thus can be considered to be ‘not classified’ as per the CLP classification criteria.

 

In addition to the above information, as per column 2 (Annex VII and VIII) of the REACH regulation, testing for the aquatic toxicity end points is considered scientifically unjustified since there are mitigating factors indicating that aquatic toxicity is unlikely to occur as the substance is highly insoluble in water.

 

There are no available long-term aq. toxicity evaluations for chemical Oxacycloheptadec-10-en-2-one. 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 B criterion but does not fulfil the P and T criterion and has therefore not been classified as a PBT compound within Annex XIII.