Acid Catalysed Reaction Products of 3,7-dimethyl-2,6-octadienal in the presence of ethanol

Short-term toxicity to fish

Description of key information

For the purposes of the environmental risk assessment, two assessment entities have been defined. For the C10 -C12 oxygenated group, experimental data available for Citral was consider the most appropriate for derivation of PNECaquatic (see aquatic toxicity endpoint summary for details). The most sensitive species in acute tests was fish with a determined LC50 of 4.1mg/L (OECD SIDS, 2004). This value is within the predicted EC/LC50 range (2.98 to 13.8 mg/l) for all other known constituents belonging to this group. Thus it was considered reasonable to use the lowest measured LC50 value of 4.1 mg/L to derive PNEC (aquatic) for this group using an assessment factor of 1000. In the OECD SIDS assessment a PNEC of 0.01 mg/L was calculated for Citral from the NOEC (daphnia, 21d, Repro) of 1mg/L using an assessment factor of 100. This PNEC has not been applied to the "C10-C12 oxygenated constituents" because, to the best of the registrants knowledge, there is no chronic data available for the other constituents.

For the purposes of classification and labelling, data on the whole substance is used. A limit test performed on Citrathal Concentrate S TW showed no effect on the vitality of zebrafish at the loading rate of 4 mg/L.

Additional information

A study was performed to assess the acute toxicity of the registered UVCB substance to fish (zebrafish). 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). A limit test was performed at a nominal loading level of 4.00 mg/L. This threshold concentration was based on toxicity data of the test item in an acute daphnia test (EL50 = 10.7mg/L) and an algae toxicity test (ErL50 = 3.58mgh/L, EyL50 = 2.98 mg/L). A semi-static test with daily renewal of the test media was performed over a period of 96 hours. Due to the volatile nature of components in the test item, the test aquaria were covered with a floating lid (i.e. aluminium foil) to reduce the loss of test item via the surface.

Specific chemical analysis via GC-MS was performed to demonstrate consistent preparation of the WAF and stability during the test. Quantification was based on 16 signals divided into two analyte groups (monoterpene hydrocarbons and oxygenated C10/12 organic compounds). In fresh media (0 and 72 hours) the measured concentrations for the monoterpene hydrocarbons were 1.15 and 0.85 mg/L and the measured concentrations for the oxygenated C10/12 organic compounds 0.813 and 0.606 mg/L, indicating consistent preparation of the WAF. After 24 hours the measured concentrations were 62 to 74% initial (monoterpene hydrocarbons) and 76 to 82% initial (oxygenated C10/12 organic compounds), indicating that the dissolved test item concentration had been 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 limit loading of the test item was found to have no effect on the vitality of zebrafish. In conclusion, the LL0 corresponds to the nominal limit loading 4.00 mg/L. The LL50 and the LL100 correspond to the nominal limit loading > 4.00 mg/L.