Linalyl acetate

Short-term toxicity to fish

Description of key information

In a study according to OECD Guideline 203 the 96-h LC50 of lynalyl actetate was determined to be 11 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

11 mg/L

Additional information

Two studies investigating the short-term toxicity of the target substance linalyl acetate are available. Since linalyl acetate hydrolyses in aqueous media rapidly, the short-term toxicity to fish was also evaluated by considering data of the hydrolysation products linalool, alpha-terpineol and geraniol. As mentioned above, acetic acid is not considered to contribute to the short-term toxicity to fish, corrected LC50 values derived by a weight-of-evidence approach are well above 300 mg/L (see Read-across justification).

Key study with linalyl acetate:

In one study with linalyl acetate the toxicity to fish was assessed in a 96-hour test according to OECD Guideline 203 and GLP principles (F. Hoffmann-La Roche AG, 1998). Cyprinus carpio was exposed in a flow-through system to nominal test item concentrations of 0 (blank control), 10, 18, 32, 56 and 100 mg/L (1 vessel per concentration, 7 animals per vessel). The renewal rate of test solution was 12 L/h. Test item concentrations were measured by GC/FID to be 0 (blank control), 7.9, 12.3, 20.1, 27.3, 27.2 mg/L in average. The acceptance criteria of the guideline were fulfilled as no mortality was observed in the control group and all test conditions remained within the ranges prescribed by the protocol. Further, the experimental design was optimized to expose the fish to the original substance linalyl acetate including a continuous dosing of the test solutions in a flow-through system. The measured concentrations in the test solutions where some or all fish survived the test period (nominal 10 and 18 mg/L) remained stable within a 20% window during the test. Hence, the toxicity parameters could be determined using the average exposure concentrations. Under the conditions of the present test, linalyl acetate induced no lethal effects in carp at an exposure concentration of 7.9 mg/L under flow-through conditions. In result, the 96-h LC50 was already reached after 20 hours of exposure and was 11 mg/L with a 95% confidence interval between 10 and 14 mg/L.

A higher LC50 for the target substance was reported by a guideline study conducted in compliance with German standard DIN 38412, part L15 on Leuciscus idus (BASF AG, 1989). The test fish were exposed to linalyl acetate at nominal concentrations of 0 (blank control), 10.0, 21.5, 46.4 and 100.0 mg/L for 96 hours in a static test system (1 vessel per concentration, 10 animals per vessel; biomass loading rate: 3.6 g fish/L test water). The 96-h LC50 of the test item was determined to be 68.12 mg/L based on nominal test concentrations.

The toxicity of the source substance linalool to Oncorhynchus mykiss was assessed in a static test according to OECD Guideline 203 under GLP conditions (DSM Nutritional Products Ltd., 1991). Fish were exposed for 96 hours to nominal test item concentrations of 10, 18, 32, 58 and 100 mg/L (2 replicates per concentration and control, 5 fish per vessel; Biomass loading rate = 0.71 g/L). The stock solution contained 5 g of the test item mixed with 5 g of the vehicle dimethylformamide (DMF). The test item concentrations were analysed by Gas Chromatography and measured to be 3.5, 6.4, 10.3, 19.9 and 38.8 mg/L (arithmetic mean, t=0/t=96). As the concentration could not be maintained within 20% of the nominal levels, toxicity values are based on measured concentrations. In result, the 96-h LC50 was found to be 27.8 mg/L. The LC0 was 19.9 mg/L. All validity criteria of the guideline were fulfilled.

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 fish was provided: In a 96-h acute fish toxicity study with Danio rerio were exposed to Terpineol multi at concentrations of 0 (test medium control), 28, 36, 47, 62 and 80 mg/L under semi-static conditions. The 96-h LC50 was between 62 and 80 mg/L. Sublethal effects were observed at the concentration of 62 mg terpineol mix/L: abnormal behaviour, the fish stayed on the side, at the bottom of the aquarium and showed a shortness of breath. At 80 mg/l 100% mortality was seen. For estimating the LC50 the geometric mean between 62 and 80 mg/l is used = 70 mg/l.

One study report is available regarding short-term toxicity to fish for source substance geraniol. The acute toxicity of geraniol to fish was tested in a GLP guideline study performed according to OECD guideline 203. The analytically determined test concentrations were 2.0, 4.0, 8.4, 19.3 and 47.4 mg/L. Mortality occurred in the highest test concentrations. Since analytic verified test concentrations ranged within a 20% of the nominal concentrations, the derived LC50 value refers to the nominal test concentration. Brachydanio rerio were exposed to the substance for 96 hours in a static test system. A LC50 of 22 mg/l was determined based on nominal concentrations (BASF AG, 1996).

Conclusion:

In conclusion, the differences in the LC50 of both studies with linalyl acetate are likely due to the different test regimes: While the study with Leuciscus idus (BASF AG, 1989) was performed in a static system lacking analytical verification of the test concentration, the study using Cyprinus carpio (F. Hoffmann-La Roche AG, 1998) was performed in a flow-through system with test substance analytic. Accordingly, the results refer to the measured test concentrations and are considered to be more reliable. The 96-h LC50 determined for the hydrolysis product Linalool (DSM Nutritional Products Ltd., 1991) lies above the more reliable LC50 value established for the target substance. The higher water solubility and the lower logPow of the hydrolysation product supports this finding. Nevertheless, both LC50 values lay within the same range of 10-100 mg/L. The information that was available for alpha-terpineol gives no information on whether the derived values refer to the analytically verified test concentrations or to the nominal concentrations. Since a semi-static system was applied, the LC50 value of 70 mg/L may be realistic and is again in the range of 10-100 mg/L. However, since there are uncertainties regarding the study design, the LC50 was not considered for assessing the short-term toxicity to fish. Geraniol plays only a minor role in the composition of formed hydrolysation products, even though the results on short-term toxicity to fish are reliable. A static test design was used but the test substance was proven to be stable throughout the exposure time. Thus, the LC50 of 22 mg/L is considered relevant, however, does only account for a minor fraction of the hydrolysation products.

Taken together, the target substance and the source substances showed similar toxic effects to fish (range of 10-100 mg/L) regardless of the study design and the used test species. Based on available data and composition of hydrolysation products, the LC50 values of linalyl acetate and linalool are considered most relevant for the assessment. As a conservative approach, the LC50 of linalyl acetate itself (= 11.0 mg/L) is used for assessment. Accordingly, the assessed target substance is acutely harmful for aquatic organisms.