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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Reactive Orange107 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 0% biodegradation in a Zahn-Wellens test. Evaluation for elimination via adsorption showed that ca 30% of the dye adsorbs to activated sludge. Elimination of the dyestuff via flocculation with iron-oxides showed an 80% reduction of Reactive Orange 107.

The substance is expected to hydrolyse under normal environmental conditions. Experimental studies on hydrolytic effects of a structural analogue demonstrated that the substance does undergo rapid hydrolysis at environmentally relevant pH’s, (t1/2 = 87 hours at pH7 and 1 hour at pH9), indicating the potential for significant removal by hydrolysis. At use conditions during dyeing (pH > 10 at ≥ 60°C) the substance is hydrolytically unstable; from the hydrolysis study conducted on the read-across substance, decomposition at pH 9 was demonstrated as 17 min at 37°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 abiotic processes would contribute significantly to the depletion of the substance within the environment.

Reactive Orange 107 has an estimated log Kow of -4.52. This value indicates that possible bioaccumulation in the food chain is not anticipated. Given the fact that the substance is subject to hydrolysis at biologically 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. 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 Orange 107 could potentially be persistent within the environment.

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 Orange 107 and its structural analogue proved to be not genotoxic in in-vitro and in-vivo genotoxicity tests. No effects on reproduction were observed in a developmental screening test with the structural analogue. In addition, during its decades of use, no evidence of tumorigenic or proliferative effects were noted from use of Reactive Orange 107.

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 which was included in the developmental screening study with a structural analogue.

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