Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Short-term toxicity to fish

In a 96-h acute toxicity study performed according to the OECD guideline No. 203, 1992, Carps (Cyprinus carpio, Teleostei, Cyprinidae) were exposed to styrene oxide at nominal concentrations of 4.6, 10, 22, 46 and 100 % (% of the WSF prepared at a loading rate of 100 mg/L) under semi-static conditions. The total test period was 96 hours and samples for analytical confirmation of actual test concentrations were taken at the start and the end of the first and the last refreshment period. Initial concentrations slightly decreased during the renewal periods (67-82 % of initial). Given these results, effect parameters were based on the average exposure concentrations that were calculated to be 1.9, 4.7, 10, 22 and 52 mg/L.

The 96-h LC50 was 6.9 mg/L based on average exposure concentrations (95 % confidence interval between 4.7 and 10 mg/L)and was already reached after 72 hours of exposure.

The NOEC value, based on mortality effects, was 4.7 mg/L. At the end of the test all fish exposed to the three highest test concentrations had died, while all fish exposed to the two lowest concentrations survived without showing any clinical effects.

 

Short-term toxicity to aquatic invertebrates

In the study performed according to the OECD Guideline 202 (April 13, 2004) the 48h acute toxicity of styrene oxide to Daphnia magna was studied under semi-static conditions. Daphnids were exposed to control, reference control, and test substance for 24 and 48 hours. Initial concentrations at 10, 22, 46 and 100% of the WSF slightly decreased during the renewal periods (58-89 % of initial). Given these results, effect parameters were based on the average exposure concentrations that were calculated to be 4.3, 11, 20 and 47 mg/L.

Immobilization was observed at test termination. The 48h-EC50 of styrene oxide was 13 mg/L based on average exposure concentrations (95 % confidence interval between 12 and 16 mg/L).

 

Long-term toxicity to fish and aquatic invertebrates

In accordance with REACH Annex IX, 9.1.6, column 2, long-term toxicity testing on fish and aquatic invertebrates does not need to be conducted. A test for long-term toxicity on fish is only required if the chemical safety assessment, according to Annex I, indicates the need to investigate further the effects on aquatic organisms. The choice of the appropriate test(s) depends on the results of the chemical safety assessment. The registration substance does not need to be classified with regard to environmental effects. The long-term exposure of aquatic organisms is unlikely as the substance is processed under strictly controlled condition and is proved to be readily biodegradable.

 

Toxicity to aquatic algae and cyanobacteria

In a 96 hour acute toxicity study conducted similar to the OECD guideline 201, the cultures of Scenedesmus subspicatus (new name:Desmodesmus subspicatus) were exposed to Styrene oxide under static conditions.  The 96h EbC10and EbC50values based on cell density were 12 and 32 mg a.i./L, respectively. There were no compound related phytotoxic effects.

 

Toxicity to microorganisms

According to REACH regulation (Annex IX, 9.4.2 column 2), short-term toxicity testing to soil microorganisms does not need to be conducted. The direct and indirect exposure of soilcompartments is unlikely as the substance is processed under strictly controlled condition and is proved to be readily biodegradable.