Registration Dossier

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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Environmental Fate

It should be noted that the test substance is not considered as posing a hazard to the aquatic environment.

 

The test substance, T-9601, is a solid under all environmental conditions and is insoluble in water (water solubility value of 0.0017 mg/l). It has a low volatility (based on a vapour pressure result of 1x10E-07 hPa at 25 °C) and a high affinity for soil / sediment (based on the soil adsorption value of Log Koc = 4.2). As such, any environmental release will result in virtually all of the substance accumulating to soil/sediment, with little release directly to atmosphere or within surface water.

 

Any potential exposure to the environment is predicted to result in rapid redistribution to soil / sediment; due to its low volatility, water insolubility and partitioning values indicates that the majority of the substance would eventually partition to soil and sediment rather than to water should it be released to the environment. 

 

A Level III fugacity model was conducted in the US EPA EPISUITE (Mackay,) which assumes steady-state but not equilibrium conditions. The Level III model in EPI Suite predicts partitioning between air, soil, sediment and water using a combination of default parameters and various input parameters. This model has been used to calculate the theoretical distribution of the highest % component substance between four environmental compartments (air, water, soil, sediment) at steady state in a unit world.

 

Partitioning is detailed to be:

-         Air            0.253%

-         Water       5.45%

-         Soil           0.111 %

-         Sediment  94.2 %

 

It is proposed that although the majority of the substance distributes to the soil and sediment compartments within the model, the insolubility in water indicates that the substance is more likely to distribute to soil / sediment. T-9601 displays a low ready biodegradability in that it achieved 1% biodegradation in a 28-day study closed bottle test, indicating that it is unlikely to achieve a half life of less than 40 or 60 days within fresh water attributed to ready biodegradation alone. Given the insolubility in water, it was not possible to assess effects of hydrolysis on the substance, however information on equivalent analogues indicates that some hydrolysis may occur under normal environmental conditions. Studies on direct phototransformation in water are not available but it is assumed on the basis of chemical structure and nature of use that the substance is not degraded by direct photolysis. It is concluded, therefore, that abiotic processes may contribute to the depletion of the substance within the environment on the basis of information known on other analogues; however this is not likely to be rapid. 

 

T-9601 has a measured log Pow of 4.3, indicating a potential concern for bioaccumulation. However, a bioaccumulation study performed in carp produced BCF at high exposure level (0.1 ppm) of 15 – 58 and at low level exposure (0.01 ppm) of 61 – 124 indicating that the substance is not bioaccumulative. 

 

Dispersion via dissolution in water is not predicted, based on the low water solubility, which indicates that the substance will be more likely to bind to soils and sediments. As such, significant exposure related effects to water dwelling organisms are considered to be minimised.

 

 Based on its water insolubility and partition coefficient value it can be concluded that it is likely that T-9601 could be persistent within the environment. Abiotic effects within the environment will not contribute significantly to eventual removal, however as the substance is not bioaccumulative significant contact with the organisms in the food chain can considered to be minimised. 

Finally, T-9601 demonstrates low acute toxicity in mammalian studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.

 

Reliability.

The studies have all been ranked reliability 1 according to the Klimish et al system. This ranking was deemed appropriate because the studies were all conducted to GLP in compliance with recognised guidelines.

 

Justification for classification or non classification

The above results triggered no classification under the Dangerous Substance Directive (67/548/EEC) and the CLP Regulation (EC No 1272/2008).