REAKTIV-ORANGE DYPR 1410

Endpoint summary

Description of key information

The substance is a mono-constituent consisting of disodium 4-amino-3-(2-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}diazen-1-yl)naphthalene-1-sulfonate as the major constituent. In water it is rapidly hydrolysed to its vinylised form sodium 4-amino-3-{2-[4-(ethenesulfonyl)phenyl]diazen-1-yl}naphthalene-1-sulfonate, which is the active form during the dyeing process. The content of this vinyl-form in the testing material can vary largely, as its development is dependent on temperature and humidity during synthesis, storage and/or transport (see section 1.2). As these vinyl-component forms rapidly in the presence of water and under testing conditions, it has therefore been tested together with the ester form.

The reactive form of the dye, the vinyl-sulfone form, is generated in the dye bath by treatment with base. The dye-fibre adduct is formed in a subsequent reaction by Michael-type 1,4-nucleophilic addition (Weber, 1990). Competing with this reaction is hydrolysis to give the 2-hydroxyethylsulfone form (sodium 4-amino-3-{2-[4-(2-hydroxyethanesulfonyl)phenyl]diazen-1-yl}naphthalene-1-sulfonate). This reaction is the same in each dye containing the 2-sulfatoethylsulfone moiety, independently of the remaining dye-structure, therefore it is a general mechanism as described in many literature sources (Zollinger, 2003).

A common dyeing process for reactive dyeing of cellulose fiber textiles consists of two phases. In the first phase, the dyeing process takes place at 60° C for 45 - 60 minutes at a neutral range of pH. During the second process step the dyebath is adjusted to a high alkalinity (pH approx. 10-11 for 60 minutes).

For home-dyeing in the washing machine, the dye is also formulated to a basic pH to assure the hydrolysis to the vinyl-forms, which are required to form the covalent bond to the fabric. The recommend washing program for dyeing in the washer is using an easy-care wash program (ca. 2 hours) with a temperature of 60°C. Hence, as in industrial/professional dyeing, the dyeing takes place with elevated pH and temperature over a time of 2 hours and only hydrolysed substance is released into the environment.

Hence, the substance not bound to the fiber in the dyebath is completely hydrolysed sodium 4-amino-3-{2-[4-(2-hydroxyethanesulfonyl)phenyl]diazen-1-yl}naphthalene-1-sulfonate at the end of the dyeing process.

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-Orange DYPR 1410, is a solid under all environmental conditions and is highly soluble in water. It has a low volatility (based on a vapour pressure result of < 10E-05 hPa at 25 °C) and a low affinity for soil / sediment (based on the partition coefficient value of Log Kow -5.0 and calculated Koc value of0.05968 L/kg). 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                     0.0131 %

-   Water                9.1 %

-   Soil                    89.6 %

-   Sediment           1.27 %

 

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-Orange DYPR 1410 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. 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’s, with a half-life of 2.7 days at pH 7. 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-Orange DYPR 1410 has a measured log Kow of -5.0. This value indicates that possible bioaccumulation in the food chain is not anticipated. No direct information on bioaccumulation is available; however, physico-chemical properties, particularly the partition coefficient value of log Kow -5.0 indicate that bioaccumulation within body tissues is unlikely. Given the fact that the substance is subject to hydrolysis at biologically relevant pH’s (4, 7 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 and fairly rapid hydrolysis rate at environmentally relevant pH’s, it can be concluded that it is unlikely that Reaktiv-Orange DYPR 1410 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-Orange DYPR 1410 demonstrates low acute toxicity in mammalian studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.