Tetrasodium 4-amino-6-[[2,5-dimethoxy-4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]-5-hydroxy-3-[[4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonate

Endpoint summary

Additional information

Reactive Blue 203 and its structural analogues have a very high water solubility. Screening tests for biodegradation in water showed that the test substance is not readily or inherently biodegradable. However, it is rapidly hydrolysed with a half-life of 2 to 6 days at pH 7. When Reactive Black 5 was applied to sediment/water at a final concentration of 1 mg/kg in the test system, it was rapidly degraded to its bis-vinyl form and further to its hydroxyl form. The DT50 of Reactive Black 5 was 2 days. After 3 to 6 days, only 10% of the applied Reactive Black 5 could be found. All metabolites decreased at the end of the test period to levels around the lower level of quantification. Consequently, an accumulation of metabolites could be excluded. The majority of the metabolites of Reactive Black 5 were deposited in form of non-extractable residues in sediment during test phase. After about 1 month, mineralization of the metabolites started.

A bioaccumulation study in the carp revealed bioconcentration factors < 11 for 0.2 mg/L and < 1.1 for 2 mg/L for Reactive Black 5. Hence, Reactive Black 5 either as bis-ester, or as bis-vinyl does not bioaccumulate in the aquatic compartment. Based on data from kinetic and metabolism studies in rats (oral and intravenous administration), Reactive Black 5 does not have any bioaccumulation potential in animals. These results can also be applied to Reactive Blue 203 based on its very close structural similarity.

Due to the very low toxicity, rapid degradation and lack of bioaccumulative properties, secondary poisoning can be excluded for Reactive Blue 203.