Registration Dossier

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, Reaktiv Rot F-66813, is a solid under all environmental conditions and is highly soluble in water. It has a low volatility (based on a presumed low vapour pressure from the physico-chemical data available) and a low affinity for soil / sediment (based on the partition coefficient value of log Kow of < 0.2 (calculated to be -3) and an adsorption coefficient of log Koc < 1.25). As such, any environmental release will result in virtually all of the substance compartmentalising into water compartments, with little release directly to atmosphere or compartmentalising to soil/sediment compartments.

 

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

 

A Level III fugacity model was conducted in the US EPA EPISUITE (Mackay et al., 1996a, 1996b; Mackay 1991) 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            7.95e-005%

-         Water      1.39%

-         Soil           63.3 %

-         Sediment 35.3 %

 

It is proposed that although the majority of the substance distributes to the soil and sediment compartments within the model, the high solubility in water indicates that the substance is more likely to distribute to water – e.g. soil pore water. Reaktiv Rot F-66813 displays a low ready biodegradability in that it achieved 7.2% biodegradation in a 28-day CO2 Evolution test, and a low inherent biodegradability of < 10% in a 28-day Zahn-Wellens Inherent Biodegradation 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. However it is expected to hydrolyse under normal environmental conditions.  Experimental studies on hydrolytic effects demonstrated that the substance does undergo hydrolysis at environmentally relevant pH, with a half life of 6 days at pH 7 and 25°C. As such, degradation is anticipated via this route. 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 would contribute significantly to the depletion of the substance within the environment. 

 

Reaktiv Rot F-66813 has a calculated log Kow of -3 (measured log Kow < 0.2). This value indicates that possible bioaccumulation in the food chain is not anticipated. No direct information on bioaccumulation is available; however the indications from the physico-chemical studies, particularly the fat solubility study (with results of < 0.01 mg in 100 g fat at 37 deg C) indicate that bioaccumulation within body tissues is unlikely. Given the fact that the substance is subject to hydrolysis at biologically relevant pH, it is anticipated that bioaccumulation of the substance itself would not occur, as hydrolytic effects in association with metabolic effects would result in removal of the substance.

 

Adsorption to soil is deemed to be low, based on the very low partition coefficient value, low soil adsorption coefficient (log Koc< 1.25) and high water solubility. Such a low potential indicates that the substance is unlikely to bind tightly to soils and sediments and instead partition almost exclusively to water. As such, significant exposure related effects to sediment and soil dwelling organisms are considered to be negligible.

 

 Based on its high water solubility, low partition coefficient and fairly rapid hydrolysis rate at environmentally relevant pH, it can be concluded that it is unlikely that Reaktiv Rot F-66813 could potentially be persistent within the environment. Abiotic effects within the environment will result in eventual removal from the environment and hence significant contact with the organisms in the food chain can considered to be minimised. 

 

Finally, Reaktiv Rot F-66813 demonstrates low acute toxicity in mammalian studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.