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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

For the purposes of the environmental risk assessment, two assessment entities have been defined. For the C7-C10 hydrocarbon group, the daphnia endpoint was identified as the most sensitive species (see aquatic toxicity endpoint summary for details). The daphnia 48h LC50 value was predicted for all known constituents in this group using ECOSAR v2 and the lowest value of 0.22 mg/L selected to derive PNECaquatic for the C7-C10 hydrocarbon assessment entity.

For the purposes of classification and labelling, data on the whole substance is used. A study performed on Citrathal Concentrate S TW gave an acute 48h EL50 of 10.7 mg/L based on WAF loading rates.

 

Key value for chemical safety assessment

Additional information

A study was performed to assess the acute toxicity of the registered UVCB substance to Daphnia Magna. The test item is a complex mixture composed of constituents with different water solubility and therefore the test item was prepared as Water Accommodated Fractions (WAFs). Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 0.5, 1.0, 2.0, 4.0, 8.0 and 16 mg/L for 48 hours at a temperature of 18 -22 °C under semi-static test conditions. The study was conducted in a closed system without headspace, due to the volatile nature of the test item, to reduce contact with air and losses of test item by evaporation. The number of immobilized Daphnia and any adverse reactions to exposure were recorded after 24 and 48 hours.

Specific chemical analysis via GC-MS was performed to demonstrate consistent preparation of the WAFs and stability during the test. Quantification was based on 16 signals divided into two analyte groups (monoterpene hydrocarbons and oxygenated C10/12 organic compounds). At the start of exposure (0h) and at renewal (24h), the expected increasing trend with increasing loading rate was observed. The measured concentrations for the monoterpene hydrocarbons were in the range of 0.0927 to 3.17 mg/L (0 hours) and 0.0784 to 3.98 mg/L (24 hours). The measured concentrations for the oxygenated C10/12 organic compounds were in the range of 0.0736 to 2.96 mg/L (0 hours) and 0.0547 to 3.04 mg/L (24 hours). In the old media the measured concentrations were 51 to 89% initial (24h, hydrocarbons), 78 to 113% initial (48h, hydrocarbons), 74 to 86% initial (24h, oxygentated C10/12) and 85 to 120% initial (48h, oxygenated C10/12) indicating that the dissolved test item concentration was reasonably maintained throughout the exposure period.

Per definition of the WAF, all terms related to concentration levels were given as loading levels because partly dissolved compounds and mixtures cannot be related to concentrations. The determined 48h EL50 was 10.7 mg/L. This value has been used for classification of the registered substance.