REACTIVE BLUE FC 75311

Endpoint summary

Additional information

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

The test substance, Reactive Blue FC 75311, is a solid under all environmental conditions and is highly soluble in water. It has a low volatility (based on the high melting / boiling point and high molecular weight) and a low affinity for soil / sediment (based on the partition coefficient value of Log Pow < -2.7). 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) 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.

Table20. Partitioning model Reactive Blue 75311

Compartment	Distribution [%]		Half-life [h]
	A	B	A	B
Air	4.13E-5	2.92E-5	1.04	1.12
Water	0.554	0.552	4.32E3	4.32E3
Soil	52	52.1	8.64E3	8.64E3
Sediment	47.4	47.4	3.89E4	3.89E4

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. Reactive Blue FC 75311 displays a low ready biodegradability in that it achieved 0% biodegradation in a 28-day study closed bottle test and was not inherently biodegradable, achieving 0% biodegradation in a modified Zahn-Wellens test. This indicates that the substance 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 slowly under normal environmental conditions. Experimental studies on hydrolytic effects demonstrated that the substance does undergo some hydrolysis at environmentally relevant pH’s, with a half life of 3, 379, and 34 days at pH 4, 7 and 9, respectively, at 25 °C. At use conditions during dyeing (pH > 10 at ≥ 60°C) the substance is hydrolytically unstable (t_½< 7 hours).As such, degradation is anticipated via this route, albeit slowly. Studies on direct phototransformation in water are not available but it was found that the sulfonated azo dyes can be destroyed by UV photooxidation process (Saliha 2005). The kinetics of the degradation depends on the azo, benzene and naphthalene groups of the dyes. It was found that the first step of the degradation is related to cleavage of azo bond of the molecule and naphthalene ring which leads to further degradation until complete mineralization. It is concluded therefore, that abiotic processes would contribute significantly to the depletion of the substance within the environment.

Reactive Blue FC 75311 has a measured log Pow of <-2.7. 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 < 0.003 mg in 100 g fat at 37°C) indicate that bioaccumulation within body tissues is unlikely. Given the fact that the substance is subject to hydrolysis at biologically relevant pH’s (4 and 9), 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 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 it can be concluded that it is unlikely that Reactive Blue FC 75311 could potentially be persistent within the environment in its registered form. 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, Reactive Blue FC 75311 demonstrates low acute toxicity in mammalian studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.