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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

For the purposes of classification and labelling, data on the whole substance is used. A study performed on Citrathal Concentrated S TW gave an ErL50 of 3.58 mg/L and an ErL10 of 2.68 mg/L based on WAF loading rates.

 

For the purposes of the environmental risk assessment, two assessment entities have been defined. To derive appropriate PNECs, experimental fish data available for Citral was used for the C10 -C12 oxygenated group, while daphnia was identified as the most sensitive species for the C7 -C9 hydrocarbon group (see aquatic toxicity endpoint summary for details).

Key value for chemical safety assessment

EC50 for freshwater algae:
3.58 mg/L
EC10 or NOEC for freshwater algae:
2.68 mg/L

Additional information

A study was performed to assess the effect of the registered UVCB substance on the growth of the green alga, Pseudokirchneriella subcapitata. Since the substance is a complex mixture composed of components with different water solubility, the test item was prepared as Water Accomodated Fractions (WAFs). As components of the test item were suspected to be volatile, the test was conducted in closed bottles without headspace. Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 0.3, 0.949, 3.0, 9.49 and 30 mg/L for 72 hours. Specific chemical analysis was performed to demonstrate consistent preparation of the WAFs and stability during the test. Quantification of the exposure concentrations was based on 16 signals divided into two analyte groups (monoterpene hydrocarbons and oxygenated C10/12 organic compounds). The measured concentrations of CITRATHAL CONCENTRATE S TW in the fresh media (0 h) ranged from 0.0886 to 8.01 mg/L for the component monoterpene hydrocarbons and from 0.0435 to 5.92 mg/L for the component oxygenated C10/C12 organic compounds. The measured concentrations in the media after 72 hours were >85% of the initial measured values for the component monoterpene hydrocarbons and >91% of the initial values for the component oxygenated C10/C12 organic compounds, thereby indicating that the test item was stable over the test period.

Given that the toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole, the results were based on nominal loading rates only. The 72h ErL50 and ErL10 were determined to be 3.58 and 2.68mg/L respectively. Both values have been considered in the environmental classification of the registered substance.