3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)- for effects in the environment:

 

The chemical Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)- (CAS no. 509-34-2) is used for dyestuff application and as a stain for biological staining. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)-. 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 fulfils the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance C.I. Solvent Red 49 (CAS no. 509 -34 -2). Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l. The percentage degradation of test substance was determined to be 0 and 1% degradation by BOD, TOC removal and HPLC in 28 days.  Thus, based on percentage degradation, C.I. Solvent Red 49 was considered to be not readily biodegradable in nature.

 

Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound C.I. Solvent Red 49 (CAS no. 509 -34 -2) in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that C.I. Solvent Red 49 is expected to be not readily biodegradable.

 

Biodegradability of C.I. Solvent Red 49 (CAS no. 509 -34 -2) is predicted using QSAR toolbox version 3.4. Test substance undergoes 15.77% degradation by CO2 evolution in 28 days. Thus, based on percentage degradation, the test chemical C.I. Solvent Red 49 was estimated to be not readily biodegradable in water.

 

Biodegradation studies available for read-across substances (CAS: 518-47-8 and 81-88-9) also indicate that they are not readily biodegradable in nature

 

Hence it has been concluded that Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)- is likely to be persistent in nature.  

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is sediment and soil (i.e.estimated to 50.4% and 48.3% respectively). In sediment and soil, the substance was expected to have slow mobility based upon a Log KOC of 2.68. The half-life in sediment and soil (1620.83 days and 360 days, respectively estimated by EPI suite) indicates that the chemical is persistent in both compartments.

 

If released in to the environment, 1.36 % 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 (180 days estimated by EPI suite) indicates that the substance is persistent in this medium.

 

Although the half-life values suggest classification as very persistent (vP), the substance is classified only as persistent (P) since only estimated half-life values are available for the same. Hence it has been concluded that Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)- is 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 partition coefficient (n-octanol/water) of test substance 3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (CAS No. 509-34-2) was determined as per the HPLC method (OECD Guideline-117). The Log Pow value was found to be 3.649 ± 0.054 at 25°C which is less than the threshold of 4.5.

The bioconcentration factor (BCF) for test substance 3',6' Bis(diethylamino)spiro[isobenzofuran1(3H),9'[9H]xanthene]3one (CAS No. 509-34-2) was determined according to OECD Guideline 305 (Bioconcentration: Flow through Fish Test). The BCF value was observed to be <= 0.91 L/kg at dose concentration 10 µg/L and <= 9.1 L/kg at dose concentration 1 µg/L on test organism Cyprinus carpio during 28 day period. If this chemical is released into the aquatic environment, there should be a moderate 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 estimation for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in the range 3.4 to 98.16 mg/L. 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.

 

There are no available long-term toxicity evaluations for Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-bis(diethylamino)-. By speculation, adverse effects at environmentally relevant concentrations in freshwater species were not expected for the substance based on the determined acute EC50 above 10 mg/L (from 3 trophic levels)

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 P criterion but does not fulfil the B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.