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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The 72h ErL50 for Lime Oxide was 15mg/L based on loading rates. These value can be used directly for classification but is unsuitable for derivation of PNEC since partitioning in the environment of the two groups of components present in Lime oxide will make comparison with PEC meaningless. In order to derive appropriate PNECs, acute daphnia information for the two assessment entities has been used since the daphnia endpoint was identified as the most sensitive species for both groups (see aquatic toxicity endpoint summary for details).

For the purposes of classification and labelling, data on the whole substance is used. A study performed on Lime oxide gave an ErL50 of 15mg/L and an ErL10 of 11mg/L based on WAF loading rates.

Key value for chemical safety assessment

EC50 for freshwater algae:
15 mg/L
EC10 or NOEC for freshwater algae:
11 mg/L

Additional information

A study was performed to assess the effect of the registered substance on the growth of the green alga, Pseudokirchneriella subcapitata. Since the substance is a complex mixture composed of components with different water solubility (i.e. unsaturated monoterpene hydrocarbons and oxygen-containing monoterpenes), 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 completely filled, stoppered vessels to minimise possible losses due to volatilization. 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 10, 18, 32, 56 and 100 mg/L (three replicate flasks per concentration) for 72 hours. GC analysis using the total peak area associated with the test item, showed measured test concentrations at 0h of 0.918, 1.81, 4.2, 10.1 and 22.5 mg/L. Measured test concentrations after 72 hours were 84 to 96% of initial, indicating that the dissolved test item concentration had been maintained throughout the exposure 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 15 and 11mg/L respectively. Both values have been considered in the environmental classification of the registered substance.

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