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Summary on aquatic toxicity:

Due to the low water solubility of the substance (0.007 mg/l), a dispersant-solubilizer system (DMF/Castor oil HCO-40, 3/1 (w/w)) was used in all toxicity tests and stability of the test substance was monitored using GC-MS. A homogenous solution could be attained only at (and below) the nominal concentration of 5.0 mg/l with the maximum allowable dispersant concentration of 100 mg/l. No precipitations or emulsions were observed at this nominal concentration. The analytical results show stability of the test substance during each experiment and a recovery rate greater than 80 % of the nominal test concentrations. Thus it is shown that the dispersant-solubilizer system significantly increases the solubility of 6,6’-di-tert-butyl-2,2’-methylenedi-p-cresol in water. All measured test concentrations used in the aquatic toxicity tests were far exceeding the water solubility of the substance, representing unrealistic environmental conditions. Consequently, the effects observed in the aquatic toxicity tests are also at levels higher than the water solubility.

Trophic Level              Enpoint              result (mg/L)

Algae                         72h-EC50                  >5

Algae                      72h-NOEC                  1.3

Daphnia                     48h-EC50                  >4.8

Daphnia                     21d-NOEC                 0.34

Fish                            96h-LC50                  >5

Furthermore, no effects have been seen in a study in microorganisms up to 10000 mg/L.

As all effects were above the water solubility, no PNECs can be derived. No classification for the environment is required.

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