1,1,1"((methylsilanetriyl)tris)(oxy))tris(2-methylpropan-2-amine)

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of 1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine) for effects in the environment:

 

The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for test chemical1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine)(CAS no. 28911-48-0). 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

The target test item was investigated for it’s readily biodegradability test by following OECD 301D guideline. The test item was exposed to activated sludge (supernatant) from the aeration tank ofa domestic wastewater treatment plant for 28 days. The activated sludge was collected from SMS municipal sewage treatment plant (130 MLD STP) in a thoroughly cleansed container. The sampling depth was 1-2 feet from the aeration tank. The temperature of the activated sludge was measured (38±1º C) at the site of collection. Oxygen concentration of the activated sludge sample was 2.9 mg/L. The sample was transported to the test facility within 3 hours from collection and kept it aerobic during transport. Inoculum was pre-conditioned for 1-2 days to the experimental conditions. The supernatant solution of the activated sludge was used in the study. 125 mL BOD vessels were used in the study. The test system includes an inoculum blank control group, a procedure control group, and a test item group a toxicity control group, each maintained in replicates. The biodegradation was determined by following the BOD, oxygen consumption of the test item in the incubation BOD vessels during exposure. Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. All test vessels were incubated at BOD incubator at a constant temperature of 20±1° C. Sampling of 0th h test vessels from each test group concentration were collected for analysis at zerotime (immediately after set-up). Samples were removed at regular intervals i.e., 7th, 14th, 21st, 28th, 35th and 42nd day which were measured for D.O and pH. The theoretical oxygen demand (ThOD) was calculated based on the chemical identifier. The procedure control Sodium benzoate was sufficiently degraded to 65.87% after 14 days, and to 74.85% after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the procedure control sodium benzoate, 32.28% biodegradation was noted within 14 days and 48.58% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory to the activated sludge microorganisms. Under the test conditions the percentage biodegradation of test item reached 45.45.5% after 28 days of incubation based on BOD consumption. As the final biodegradation is less than 70% in this test and all validity criteria were met, test item can be considered to be Not biodegradable in nature.

 

In a prediction done using the Estimation Programs Interface Suite, the biodegradation potential of the test compound1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine)(CAS no. 28911-48-0)in the presence of mixed populations of environmental microorganisms was estimated. 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine)is expected to be not readily biodegradable.

 

Experimental results from the read across substances also indicate that they are not readily biodegradable.

 

Thus, based on the available information, it indicates thatchemical1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine)(CAS no. 28911-48-0)wasconsidered to be notreadily biodegradablein water and thus likely to be persistent (P) in nature.

 

Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:

 

Theoctanol water partition coefficient of the test chemical was determined to be 2.028±0.010 at 25°C as per OECD TG 117, 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 substance1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine)(CAS no. 28911-48-0) indicates the LC50/EC50 value to be in the range 2.047 to 126.8 mg/L, respectively. Thus, test chemical is likely to be hazardous to aquatic organisms at environmentally relevant concentrations and hence, considered to be classified in ‘aquatic chronic category 2’ as per the CLP regulation.

 

There are no available long-term toxicity evaluations forchemical1,1',1''-((Methylsilanetriyl)tris(oxy))tris(2-methylpropan-2- amine). 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 P criterion but does not fulfil the B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.