H112323

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 Navy H112323, 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 < -5 and an adsorption coefficient log Koc of 2.5). This was confirmed for sandy loam test soils (Kenny Hill) with a Koc value increasing over time from 180 to 320 (log Koc 2.3 to 2.5), but not for silty clay loam test soils (Nebo). With the Nebo soil 98% of Reactive Navy H112323 was adsorbed within 2 hours with virtually all the test substance having been adsorbed after 16 hours, resulting in Koc values of 15000 to >160000 (log Koc 4.2 to 5.2). As such, for sandy loan, 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. Whereas for clay loam almost all of the test substance will be adsorbed without subsequent desorption.

Reactive Navy H112323 displayed low ready or inherent biodegradability. This indicates that it is unlikely to achieve a half-life of less than 40 or 60 days within freshwater or marine water, respectively, attributed to ready biodegradation alone. However, the substance showed hydrolysis at environmentally relevant pH (pH 4: t½ = 8.4 d at 50°C), indicating the potential for significant removal by hydrolysis. As such, degradation is anticipated via this route.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 Navy H112323 has a measured log Kow of <-5. This value indicates that possible bioaccumulation in the food chain is not anticipated. In a bioaccumulation study in carps, the level of accumulation was below the limit of quantification for both test concentrations. 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.

Finally, Reactive Navy H112323 demonstrates low toxicity in ecotoxicological and toxicological studies therefore in the event of exposure to environmental organisms, effects due to secondary poisoning can be excluded.