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Ecotoxicological information

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Description of key information

Short-term toxicity

Fish: LC50 (96 h) > 100 mg/l

Aquatic invertebrates: EC50 (48h)> 100 mg/l

Algae: ErC50 (72hrs) = 82.5 (77.2 – 88.6) mg/l (nominal); NOEC (72hrs, growth rate and yield) = 11.7 mg/l (nominal)

Long-term toxicity

Fish: NOEC (fry length) < 0.625 mg/l (nominal)

Aquatic invertebrates: NOEC (21d, mortality) = 5.63 mg/l

Additional information

Aquatic toxicity-testing on the substance presents a number of critical issues because of factors like:

- strong influence of pH on solubility

- strong adsorption to organic fraction

- influence of cation on solubility under customary test conditions (flocculation can occur)

- increase of toxicity for speciates like calcium

Based on a dissertation [1]:

- the substance forms strong ion-pairs with calcium ions in water

- the octanol-water partition coefficients of the ion-pairs are two orders of magnitude higher than the partitioning coefficient of the native substance

- the strongly decreased hydrophilicity due to ion-pair formation decreases the water solubility

The mentioned experimental results suggest precipitation of ion-pairs/complexes (the medium for the daphnia test contains Ca2++). During a test performed in Bayer facilities (report not more available) microscopic pictures of daphnia antennas were taken that showed crystalline deposits, which were interpreted as calcium complexes of same brightener. The test was then stopped.

The solubility and ionic interaction effects in the laboratory testing on the substance is an artefact and it is not representing a realistic environmental situation, as the concentrations of the substance hardly exceed 2 μg/l. Under environmental conditions, it can be expected an almost complete dissociation [2].

In well conducted short-term tests on Fish and Daphnia no effect were reported until more than 100 mg/l. For Algae, during the study performed according to the OECD Guideline 201 the ErC50 (72hrs) was determined as 82.5 (77.2 – 88.6) mg/l (based on nominal concentrations). In conclusion, based on the short-term toxicity studies and the effect levels obtaines, algae seems to be the most sensitive species.

Regarding long-term studies, a long-term toxicity study on fish and on aquatic invertebrates are present, performed according to the OECD Guideline 210 and 211, respectively and under GLP conditions.

The test item caused significant effects on Zebrafish in an early life stage test, 30 days post hatch. For the parameter hatch, the NOEC was 10.0 mg/l. Therefore, the respective LOEC was determined to be > 10.0 mg/l. For the parameters post hatch survival and overall survival, the NOECs were 1.25 and 2.50 mg/l, respectively. Therefore, the respective LOECs were determined to be 2.50 and 5.00 mg/l. For the parameter fry growth (expressed as length and fresh weight) the NOECs were < 0.625 mg/l (length) and 0.625 mg/l (weight). Therefore, the LOECs for length and weight were determined to be 0.625 and 1.25 mg/l, respectively.

The effects on reproduction of daphnia were evaluated based on the reproduction per introduced parent animal, since this parameter is the ecologically most relevant response variable and is required by the OECD test guideline 211 (2012), when a significant trend in mortality is detected. The overall effect threshold for effects of the test item on daphnid reproduction under the test conditions was 11.3 mg/l (NOEC) and 22.5 mg/l (LOEC) based on the nominal concentrations of the test item. NOEC for adult mortality was determined as 5.63 mg/l based on nominal concentrations.

Considering the available data on the three trophic levels, fish is considered to be the most sensitive species as the effect level during the fish early-life stage toxicity was the lowest obtained.

Therefore, SELECTED NOEC for aquatic toxicity: 0.625 mg/l from the fish early-life stage toxicity on the substance.

The study conducted on the substance is used for the chemical safety assessment, following a conservative approach. More information on the results of the substances of the category are found on the document attached under "Ecotoxicological information".

REFERENCE

[1]“Poiger, T.: Behavior and Fate of Detergent-derived Fluorescent Whitening Agents in SewageTreatment. Swiss Federal Institute of Technology, Zürich,1994. ”

[2]HERA Report 2004: Substance: Fluorescent Brightener FWA-1