reaction mass of: pentasodium 4-amino-5-hydroxy-3-{(E)-4-[2-(sulfonatooxy)ethylsulfonyl]phenylazo}-6-{(E)-2-sulfonato-4-[2-(sulfonatooxy)ethylsulfonyl]phenylazo}naphthalene-2,7-disulfonate;tetrasodium 4-amino-5-hydroxy-3-{(E)-4-[2-(sulfonatooxy)ethylsulfonyl]phenylazo}-6-[(E)-2-sulfonato-4-(vinylsulfonyl)phenylazo]naphthalene-2,7-disulfonate;tetrasodium 4-amino-5-hydroxy-6-[(E)-2-sulfonato-4-[2-(sulfonatooxy)ethylsulfonyl]phenylazo}-3-[(E)-4-(vinylsulfonyl)phenylazo]naphthalene-2,7-disulfonate;trisodium 4-amino-5-hydroxy-3-[(2-hydroxyethylsulfonyl)-phenylazo]-6-[(E)-2-sulfonato-4-(vinylsulfonyl)phenylazo]naphthalene-2,7-disulfonate;trisodium 4-amino-5-hydroxy-3-[(E)-4-(vinylsulfonyl)phenylazo]-6-[(E)-2-sulfonato-4-(vinylsulfonyl)phenylazo]naphthalene-2,7-disulfonate;trisodium 4-amino-5-hydroxy-3-[(E)-4-(vinylsulfonyl)phenylazo]-6-[-2-sulfonato-4-(2-hydroxyethylsulfonyl)phenylazo]naphthalene-2,7-disulfonate

Toxicity to aquatic algae and cyanobacteria

Description of key information

ErC50 = 57 mg/l nominal concentration

NOEC = 1.1 mg/l nominal concentration

Key value for chemical safety assessment

EC50 for freshwater algae:

57 mg/L

EC10 or NOEC for freshwater algae:

1.1 mg/L

Additional information

The influence of the test item Navy MGi 1571 on the growth of the green algal species was investigated in a 72-hour static test according to the OECD Guideline No.201, 1984. However, the test method was modified to quantify the algicidal effect of the test item, but also the growth inhibition effect caused by reduced light intensities in the colored test solutions.
The nominal test concentrations were 1.1, 3.4, 11, 34 and 110 mg/L in parallel with a control (corresponding to 1.0, 3.2, 10, 32, and 100 mg/L without water content; the test concentrations were corrected for the water content of the test item of 10 %). All test media down to the lowest test concentration were slightly to strongly colored by the test item.
The analytically determined test item concentrations in the analyzed test media varied in the range from 97 to 109 % of the nominal values. Consequently, the test item was stable during the test period oÍ 72 hours under the test conditions, and the reported biological results are based on the nominal concentrations of the test item.
The growth inhibition effect of Navy MGi 1571 on Scenedesmus subspicatus was caused in a high degree by the indirect effect, the light absorption in the colored test solutions. However, at the higher test concentrations a real toxic effect of the test item on the growth of Scenedesmus subspicatus can not be excluded. Therefore, the results of this experimental part, where the algae grew in the test media with dissolved test item as in a usual algal growth inhibition test should be taken into consideration for the determination of the toxic effect of the test item on the growth of Scenedestnus subspicatus.
ln this experimental part Navy MGi 1571 had a statistically significant inhibition effect on the growth ol Scenedesmus subspicatus after the exposure period of 72 hours first at the concentration of 3.4 mg/L (= 72-hour LOEC: lowest concentration tested with toxic effects).
The72-hour NOEC (highest concentration tested without toxic effects) was 1.1 mg/L, since at this test concentration the mean growth rate r and the man biomass b of the algae was statistically not significant lower than in the control.

The EC50 value based on growth rate was found to be 57 mg/l.