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

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

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 decoloration 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 and 25°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 primary biodegradation and hydrolysis at biologically or use-relevant pH’s, 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.

No effects were seen in acute toxicity studies in fish up to 500 mg/L. Studies with a structural analogue showed no effects in an acute toxicity study in daphnia magna and only algistatic effects due to the light-absorption of the dyestuff in a more generation study in algae.

Reactive Blue 220 proved to be not genotoxic in in-vitro and in-vivo genotoxicity tests. No effects on reproduction were observed in a limit test for developmental toxicity with Reactive Blue 220. In addition, during its decades of use, no evidence of tumorigenic or proliferative effects were noted from use of Reactive Blue 220.

No evidence for chronic toxicity or specific target organ toxicity relevant for humans have been revealed during a 28-day oral gavage study in rats with a structural analogue.