1,3,6-Naphthalenetrisulfonic acid, 7-[2-[2-[(aminocarbonyl)amino]-4-[[4-chloro-6-[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]amino]-1,3,5-triazin-2-yl]amino]phenyl]diazenyl]-, sodium salt

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 Yellow 176 Ester, 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 8.9 x 10^-14hPa at 25°C and a low affinity for soil / sediment (based on the soil adsorption value 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,) 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              0.00538%

-        Water         0.731%

-        Soil            38.9 %

-        Sediment    60.3 %

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. Gelb Sulfato displays a low ready biodegradability in that it achieved 5% biodegradation in a 28-day study closed bottle test (by read across to a structural analogue), 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 slowly 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 18.9 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. 

Reactive Yellow 176 Ester has a measured log Pow of -6.4. 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 < 0.002 mg in 100 g fat at 37 deg C (by read across to a structural analogue) indicate that bioaccumulation within body tissues is unlikely. Given the fact that the substance is subject to hydrolysis at biologically relevant pH’s (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 Reactive Yellow 176 Ester 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.

The results of a study OECD TG 309 study (pelagic test option) show a fast degradation of the test item in aerobic natural water. Transformation of Reactive Yellow 176 Ester started directly after application. About 55 % transformation was reached within 3 days, after 14 days the detected concentration was < 10 % of the applied concentration. The test item was degraded to only one metabolite. This metabolite was formed by an elimination of the terminal alkyl sulfate moiety. This metabolite was also formed in the abiotic controls at the end of the study in equal quantities. This result indicates that the degradation is driven by an abiotic process. The DTx values of Reactive Red 239 from this study are given in Table 1:

Table 1. DTx Values of Reactive Yellow 176 Ester 

	DTx values in days [30µg/L]	DTx values in days [100µg/L]
DT50	1.91	2.05
DT90	6.34	6.82

The DT50 and DT90 test results underline a rapid abiotic degradation of the substance in the water compartment and can therefore not be classified as a persistent pollutant for the environment.

Finally, Reactive Yellow 176 Ester 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).