A mixture of: tetrasodium-phosphonoethane-1,2-dicarboxylate; hexasodium-phosphonobutane-1,2,3,4-tetracarboxylate

Long-term toxicity to aquatic invertebrates

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

Two data are available.

In the first one (Safepharm, 1998), the assessment of the effect of ITC 288/S on the reproduction of Daphnia magna was performedover a 21 day period. The method followed that described in the draft OECD GL 211 and the GLP.

Daphnia magna were exposed (10 replicates of 1 daphnid per replicate) to an aqueous dispersion of the test material over a range of test concentrations of 10, 32, 100, 320 and 1000 mg/L for a period of 21 days. The test solutions were renewed 3 times per week. The numbers of live and dead adult Daphnia were determined daily. The numbers of young Daphnia (live and dead) were determined at each test media renewal. The Daphnia were fed daily with a mixed algal suspension. The test was performed using dechlorinated tap water with the hardness adjusted to approximately 80 mg/L as CaCO3.

Analysis of the freshly prepared test media on day 0 and expired test media on days 2, 5, 7, 9, 12, 14, 16, 19 and 21 showed the measured test concentrations to be in excess of the required 80% of nominal. It was therefore considered justifiable to calculate the EC50 values in terms of the nominal test concentrations only.

Mortality (immobilisation) occurred within the first 24 hours of exposure at the highest test concentration of 1000 mg/L. Significant mortality (immobilisation) also occurred during the study in the 320 mg/L test group resulting in 100% mortality by day 18.

No mortality occurred at the 10, 32 and 100 mg/L test concentrations throughout the study.

After 21 days, there were no statistically significant differences (P>=0.05) between the control and the 10, 32 and 100 mg/L test groups in terms of the number of young produced per adult alive.

Consequently, the following effects concentration were determined:

21 -Day EC50 (immobilisation) = 180 mg/L (95% CL 100 -320 mg/L) (based on nominal test concentrations, for the parental Daphnia generation (P1))

21 -Day EC50 (reproduction) = 180 mg/L (95% CL 100 -320 mg/L) (based on nominal test concentrations)

21 -Day NOEC (immobilisation and reproduction) = 100 mg/L.

The validity criteria of the OECD FGL 211 were fulfilled.

As the method followed the OECD TG and GLP, this study is considered as reliable and is selected as key study.

The second information available (Safepharm, 1997) is a preliminary study of the key study described above. It aimed at the determination of the effect of the water hardness on reproduction to Daphnia magna. For this, diluents of different hardness (i.e. 80, 150 and 250 mg/L as CaCO3) were used. The results were that exposure of Daphnia magna to the test material of a test concentration of 10 mg/L showed no effect on reproduction over a water hardness range of 80-250 mg/L as CaCO3. These results being consistent with the results of the key study, it has been selected as supporting study.