Reaction Mass of 2,6-dimethyloct-7-en-2-ol and 2,6-dimethyloct-7-en-2-yl formate

Short-term toxicity to aquatic invertebrates

Description of key information

The 48h-EC50 of Dimyrcetol is calculated to be 17.9 mg/L based on the 48h-EC50 values of Dihydromyrcenol and Dihydromyrcenyl formate. For the determination of the 48-EC50 of Dihydromyrcenyl formate (3.2 mg/L), the value derived from Dihydromyrcenyl acetate (1.3 mg/L) was corrected for molecular weight and log Kow (Log EC50 target (mmol) = Log EC50 source (mmol) x log Kow source/Log Kow target). A weighted average (0.426*38 + 0.528*3.2) between the 48h-EC50 of Dihydromyrcenol and Dihydromyrcenyl formate was used to determine the 48h-EC50 of Dimyrcetol (17.9 mg/L).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

17.9 mg/L

Additional information

No data on acute aquatic toxicity data is available for Dimyrcetol, however an acute daphnia study with Dihydromyrcenol and with the structural analogue of Dihydromyrcenyl formate: Dihydromyrcenyl acetate is available.

Dihydromyrcenol (Acute Daphnia)

The acute toxicity of Dihydromyrcenol to Daphnia magna was studied, according to OECD TG 202 and in compliance with GLP criteria,under static conditions. Daphnids were exposed to test chemical at nominal concentrations of 0, 10, 18, 32, 56 and 100 mg/l (confirmed by analysis to have represent achieved concentrations) for 48 hours. Immobility of daphnids was recorded after 24 and 48 hours exposure. The test was considered to be valid. Based on the findings, the 48-h EC50 value was determined to be 38 mg/L.

Dihydromyrcenyl Acetate (Acute Daphnia)

The acute toxicity of Dihydromyrcenyl Acetate to Daphnia magna was determined in a 48-hour semi-static test according to OECD 202 and following GLP. The test was conducted using glass tubes completely filled with test medium and tightened/sealed with glass stoppers to avoid losses of test item (closed system). The test item was added into test water in a requisite amount to obtain a solution with a loading rate of 100 mg/L and subsequently stirred for 96 hours. After stirring, the lower aqueous and equilibrated phase was carefully separated from the non-dissolved upper test item phase and diluted with test water to obtain the following test item dilutions 1:320, 1:100, 1:32, 1:10 and 1:3.2. Additionally, a control (test water without test item) was tested in parallel. At the start of the two test medium renewal periods, the analytically measured test item concentrations in the dilutions 1:32, 1:10 and 1:3.2 were 0.40, 1.8, 4.9 mg/L and 0.50, 1.6 and 5.2, respectively. At the end of the test medium renewal periods, 73 to 114% of the initially measured values were found. The 48 -hour EC50 was determined to be 1.3 mg/L (95% CI: 1.04 – 1.5) based on mean measured concentrations.