Cuprate(4-), [2-[[[[2-hydroxy-3-sulfo-5-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]phenylmethyl]azo]-4-sulfobenzoato(6-)]-, sodium

Endpoint summary

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, Reactive Blue 220, 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 Kow < -6). 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 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               6.28E-9%

-Water          3.32%

-Soil              88.1%

-Sediment     8.56%

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 220 displays a low ready biodegradability in that it achieved < 10% biodegradation in a 56-day test for ultimate biodegradability of organic compounds (ISO 11734) and was not inherently biodegradable, achieving < 20% biodegradation in a modified Zahn-Wellens test. Evaluation for primary degradation via light-absorption of filtrated samples showed an almost complete decolouration of the test medium. Therefore, a good primary biologic degradation is shown; more than 70% of the dye has been metabolized; however, less than 20% has been completely degraded to CO₂.

The substance is expected to hydrolyse slowly under normal environmental conditions. Experimental studies on hydrolytic effects of a structural analogue demonstrated that the substance does undergo some hydrolysis at environmentally relevant pH’s, with a half life of > 1 year (379 days) at pH 7 and25°C,based on a pseudo first order rate constant as calculated from the Arrhenius equation.At use conditions during dyeing (pH > 10 at ≥ 60°C) the substance is likely to be hydrolytically unstable; from the hydrolysis study conducted on the substance, decomposition at pH 9 was demonstrated as 2.1 hours at 75°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 primary biologic degradation and abiotic processes would contribute to the eventual depletion of the substance within the environment as a mechanism for removal.

Reactive Blue 220 has an estimated log Kow of <-6. This value indicates that possible bioaccumulation in the food chain is not anticipated. No direct information on bioaccumulation is available; however data from the physico-chemical studies indicate that bioaccumulation within body tissues is unlikely. Given the fact that the substance is subject to hydrolysis at biologically and use 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 and low partition coefficient it can be concluded that it is unlikely that Reactive Blue 220 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 220 demonstrates low acute toxicity in mammalian studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.

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).