Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride for effects in the environment:

 

The chemical Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (CAS no. 27668-52-6) is used for as an intermediate in chemical synthesis and as an Agrochemical Microbiocide. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride. 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

Estimation Programs Interface Suite (EPI suite, 2016) was run to predict the biodegradation potential of the test compound (3-(Trimethoxysilyl)propyl) dimethyloctadecylammonium chloride (CAS no. 27668 -52 -6) 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 (3-(Trimethoxysilyl)propyl)dimethyloctadecylammonium chloride is not expected to be readily biodegradable.

 

Various experimental studies on read across substances (CAS: 61789-80-8, 57-09-0 and 7173-51-5) also indicate the substances to be not readily biodegradable.

 

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 66.2% and 32.1% respectively). In sediment and soil, the substance was expected to have low mobility based upon a Log KOC of 7.68. The half-life in sediment and soil (337.5 days and 75 days, respectively estimated by EPI suite) indicates that the chemical is persistent in sediment but not persistent in soil.

 

If released in to the environment, 1.69 % 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 low.

 

Hence it has been concluded that Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is persistent in nature.  

 

Although the half-life values reported suggest classification of the substance as very Persistent (vP), it is classified only as Persistent (P) due to lack of experimental data since only estimated values are available.

 

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 (EPI Suite, 2016) was determined to 70.79 L/kg wet wt. 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 estimation for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in the range 0.51 to 13.54 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 acute category 1 and aquatic chronic category 1 as per the CLP regulation.

There are no available long-term toxicity evaluations for Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride. Short term NOEL for invertebrates is reported as 0.3 mg/L in a 48 hr study and LOEC in algae was reported as 10000 mg/L in a 100 hr study based on effects on cell viability.

By speculation, long-term NOEC for aquatic organisms were not expected for Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride 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.