Sodium 3-[(1,5-dihydroxy-2-naphthyl)azo]-4-hydroxybenzenesulphonate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.01 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.015 mg/kg sediment dw

Extrapolation method:

sensitivity distribution

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.001 mg/kg sediment dw

Extrapolation method:

sensitivity distribution

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.007 mg/kg soil dw

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

33.3 mg/kg food

Assessment factor:

300

Additional information

A study was performed to assess the acute toxicity of Mordant Black 9 to Danio rerio under semi static conditions.

Observations were made on the number of dead fish and the incidence of sub-lethal effects after 2, 24, 48, 72 and 96 hours of exposure. All results are expressed in terms of nominal concentrations. Effective concentrations ranged from 102.1 % to104.4 % of nominal values in the freshly prepared media and from 100.0 % to 101.2 % of nominal values in the media after 24 hours of exposure.

No toxic effects against fish were observed at a limit test concentration of 100 mg/L.

Acute toxicity on Daphnia magna was assessed in an Acute Immobilisation Test, over an exposure period of 48 hours. Based on the results of this study, the test item had no toxic effect on daphnids at up to at least 100 mg/L nominal.

The effect of the test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata (Selenastrum capricornutum), over an exposure period of 72 hours.

However, Mordant Black 9 is a complex forming dye. The dye is stabilised on the fabric by adding chromium after applying the dye to the fabric to form a chromium complex. Due to this property as strong sequestrant, it is also conceivable that Mordant Black 9 forms complexes with the various metal ions contained in the algae growth medium such as Fe3+, Mn2+, Zn2+, Co2+, Cu2+. This is particularly critical with the trace elements, which are essential for the growth of the algae.

This is effect is proven by the results of the substance concentration analysis. The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 48.8 % to 80.0 % of nominal values at 0 hours (after 24 hours of stirring), from 7.6 % to 10.8 % of nominal values at 24 hours, and from to 0.1 % to 3.2 % of nominal values at 48 hours and correspond to 0.7 % of nominal values at 72 hours. After 72 hours only the highest test item concentration was analysed, all other concentrations were below the quantification limit (0.0292 mg/L).

That this effect is due to a complex formation has been shown by the evaluation of the IR spectrum of the original test item Mordant Black 9, the test item dissolved in millipore water and the test item dissolved in algae growth medium. The IR spectrum of the original test item Mordant Black 9 and of the test item dissolved in millipore water are identical, whereas the IR spectrum of Mordant Black 9 dissolved in algae growth medium differs distinctly from the former two.

Any growth inhibition of algae observed is therefore most likely due to the lack of essential elements and not due to a direct toxic effect of Mordant Black 9. This situation would not occur in the environment, where those trace elements are abundantly available.

Furthermore, if this complex forming feature of Mordant Black 9 takes place in the OECD medium, it is technically not possible to test just the chemical toxicity of the test substance on algae growth according to OECD 201.

Conclusion on classification

The environmental studies conducted on the substance have all been ranked reliability 1 according to the Klimisch et al system. This ranking was deemed appropriate because the studies were conducted to GLP and in compliance with agreed protocols. Sufficient dose ranges and numbers are detailed; hence it is appropriate for use based on reliability and animal welfare grounds.

The results triggered no classification under the Dangerous Substance Directive (67/548/EEC) and the CLP Regulation (EC No 1272/2008). No classification for environmental effects is therefore required.

 

The substance is therefore proposed to be “not classified” and appropriate comments are detailed within Section 2 of the registration dossier.