Linalyl acetate

Short-term toxicity to aquatic invertebrates

Description of key information

In a study with the read across substance linalool according to OECD Guideline 202, the 48-h EC50 was determined to be 59 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

59 mg/L

Additional information

Three studies on toxicity of the target substance linalyl acetate to aquatic invertebrates are available. Additionally, since linalyl acetate hydrolyses in water to linalool, alpha-terpineol, geraniol and acetic acid, all relevant studies have been investigated for the assessment (see Read-across justification).

In a non-GLP compliant and static immobilization test with the target substance according to the German standard method DIN 38412, Daphnia magna was exposed for 48 hours to nominal test item concentrations of 10, 18, 32, 58, 100 mg/L (4 replicates per concentration, 5 animals per vessel). A concentrated stock solution of the test substance (nominal 1000 mg/L) was prepared using Cremophor (100 mg/L) as a solvent and ultrasonic treatment. Then, this stock solution was serially diluted with culture medium to obtain the desired test concentrations. In addition, a blank control and a solvent control (10 mg/L) were tested in parallel (4 replicates per control, 5 daphnids per vessel).  The maximum solvent concentration in the test was 10 mg/L. The mobility of the daphnids was measured after 3, 6, 24 and 48 hours. In result, the 48-h EC50 of the target substance was determined to be 41 mg/L. The 48 h NOEC was 32 mg/L (BASF AG, 1990 a).

In another 48-h acute immobilization test with the target substance according to the German standard method DIN 38412, using the same set-up and test concentrations (BASF AG, 1990 b), the 48-h EC50 was determined to be 45 mg/L. The 48-h NOEC was 32 mg/L (BASF AG, 1990 b).

Both studies (BASF AG, 1990 a; BASF AG 1990 b) were disregarded since test media were prepared using Cremophor (100 mg/L) as a solvent. Furthermore, a static set-up was chosen despite the fact that linalyl acetate rapidly hydrolyses in aqueous media. Finally, test item concentrations were not analysed and thus, effect concentrations are based on nominal concentrations. Hence, these tests are not regarded reliable.

The acute toxicity of the target substance on Daphnia magna was also assessed in a static test according to OECD guideline 202 (F. Hoffmann-La Roche, 1994). The 48-h EC50 and NOEC of linalyl acetate were determined to be 15 mg/L and 10 mg/L, respectively. This study was disregarded as the test concentration could not be maintained throughout the 48 h of exposure. No test substance was detectable at the end of the exposure in all but the highest test concentrations. However, since linalyl acetate quickly hydrolyses in water, the test might have integrated parent substance as well as all hydrolysation products during exposure period. Thus, the revealed EC50 value is likely to reflect a realistic exposure scenario.

Key study with Linalool:

The toxicity of the source substance linalool towards Daphnia magna was assessed in a static test according to OECD Guideline 202 and GLP principles (DSM nutritional Products, 1991). Daphnids were exposed over 48 hours to nominal test item concentrations of 10, 18, 32, 58 and 100 mg/L (4 replicates per concentration, 5 daphnids per vessel). The test item was homogeneously distributed in the test vessels at all test times and concentrations. A blank control with reconstituted water was performed in parallel (4 replicates, 5 daphnids per vessel), but no positive control. Test item concentrations were measured by GC/FID to be 7, 15, 25, 46 and 75 mg/L (arithmetic mean). Immobility of daphnids was checked after 24 and 48 hours of exposure. Based on arithmetic mean measured concentrations the 48-h EC50 of the test item was determined to be 59 mg/L (95%C.L 53 -65 mg/L). The 24h-EC50 was found to be 71 mg/L. The NOEC was 25 mg/L. The test is regarded to be valid as no mortality was observed in blank controls and the dissolved oxygen concentration was > 3mg/L during the test.

No study reports were available for source substance alpha-terpineol. However, an information summary could be collected from the ECHA disseminated dossier for CAS 98-55-5 on the ECHA website. The following description of key information regarding short-term toxicity to aquatic invertebrates was provided: A GLP-compliant OECD Guideline 202 study with Daphnia magna is available for Terpineol multi (a multi-constituent substance with alpha-Terpineol as its main constituent and gamma-Terpineol as the minor constituent). Daphnids (20/dose) were exposed to nominal concentrations of 40, 48, 58, 69, 83 and 100 mg/L Terpineol multi under static conditions for 48 hours. The 69 and 100 mg/L test concentrations were analytically verified at t=0 and t=48 -h. At t=0 about 70% of nominal was detected. Concentrations remained constant throughout the test. From a concentration of 48 mg/L immobilisation was noted in 3/20 daphnids which increased to 15/20 animals at the highest concentration tested. Based on these findings the 48-h EC50 value is 73 mg/L (based on nominal concentrations). Based on the available data, the study is considered valid.

Data on the acute toxicity of geraniol to daphnids are not available. The evaluation is based on a GLP study with reaction mass of geraniol and nerol. In a static test system set up according to OECD guideline 202 the nominal concentrations of 0 (control), 4.6, 10, 22, 46 and 100 mg/L have been tested and analytically verified by HPLC. For preparation of the stock solution, the test substance was dissolved in acetone. However, the solvent was completely evaporated and subsequently test medium was added. The solution was stirred for ca. 24 hours at 60 °C. The test solutions were prepared by dilution of the stock solution. An EC50 of 10.8 mg/l was determined after 48 hours. The result is based on mean measured concentrations (BASF SE, 2010).

Conclusion:

Based on the fact, that linalyl acetate hydrolyses rapidly to the corresponding alcohol linalool, alpha-terpineol, geraniol and acetic acid, a similar fate and ecotoxicological profile is expected for the target and the source substances. This hypothesis is supported by comparable effect concentrations established for linalyl acetate and its products ranging between 10 and 100 mg/L. In conclusion, the most sensitive study results have been revealed by the testing with the source substance geraniol. However, since this substance is formed by hydrolysis to 4.3 % after 64 hours at relevant conditions (pH 7, 20°C), the contribution of geraniol to the assessment of linalyl acetate is expected to be low. Thus, the above-mentioned study with the source substance (DSM Nutritional Products, 1991) and the study using alpha-terpineol (ECHA disseminated dossier) represent the most relevant hydrolysation products with linalool revealing the most conservative EC50 value of 59 mg/L. It can be concluded, that based on all findings and the results from the fish studies, that all results range between 10-100 mg/L and fish turned out to be the more sensitive species compared to invertebrates.