Linalyl acetate

Biodegradation in water: screening tests

Description of key information

In a Manometric Respirometry Test following OECD Guideline 301 F linalyl actetate was determined to be readily biodegradable (according to OECD criteria).

All hydrolysation products revealed readily biodegradability in OECD guideline studies, too.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

One study investigating the ready biodegradability of linalyl acetate is available. In addition, one ready biodegradability test is available for each of the source substances linalyl acetate, alpha-terpineol and geraniol (see Read-across justification).

Key study with linalyl acetate:

The test on the ready biodegradability of linalyl acetate was set up according to OECD Guideline 301 F using domestic activated sludge (adaptation not specified). The initial test substance concentration based on test material was 81 mg/L (corresponding to 30 mg/L DOC). Due to its high volatility, the test substance was added directly into the test system (7 replicates). Biodegradation was followed by oxygen consumption expressed as % ThOD (sampled daily). In result, the target substance reached the pass level for ready biodegradability of 60% ThOD after 11 days. On day 28 a biodegradation of 76% ThOD was determined. In conclusion, linalyl acetate was found to be readily biodegradable in a 10-day-window and after 28 days (BASF SE, 1989).

There is one ready biodegradability test according to OECD TG 301 D (DSM Nutritional Products, 1991) available for the source substance linalool. Its biodegradability was assessed at an initial concentration of 2 mg/L (based on test material). In addition, an inoculum blank control was performed along with a positive control using the reference substance sodium benzoate (2.94 mg/L). Biodegradation was followed by O2 consumption (expressed as % BOD/ThOD) and sampled after 5, 15 and 28 days. In result, the oxygen depletion in the inoculum blank was about 1.1 mg O2/L in average. According to the version of the test guideline used, this is a deviation as the oxygen demand in the blank with inoculum should not be higher than 0.6 mg O2/L. However according to the newer guideline (1992) the maximum is 1.5 mg O2/L. The difference between treatments was <20%. Moreover, degradation of the reference substance was >60% BOD/ThOD after 15 days confirming the suitability of the test system and the residual oxygen concentration was above 0.5 mg/L in all solutions. Therefore, the test is regarded to be valid. The biodegradation for linalool was calculated as 40.9% BOD/ThOD on day 5, 60% BOD/ThOD on day 15 and 64.2% BOD/ThOD in 28 days passing the level for ready biodegradability as given in the guideline. In sum, the total number and spacing of measuring points does not allow a determination of the 10 days window. But since the degradation started immediately and the curve was steep, linalool is considered to be readily biodegradable in this test.

There was no study available on the degradation on the source substance alpha-terpineol. However, information was available in a disseminated dossier on the ECHA site for registered substances referring to CAS 98-55-5. However, the information given seems sufficiently detailed to assess the biodegradability of this source substance:

In a ready biodegradation study performed according to OECD Guideline 310 and GLP, Terpineol multi, of which alpha-Terpineol is the main constituent, was tested at concentrations of 25.7 mg/L and the inoculum was activated sewage sludge, domestic. The degradation of the test material was assessed by the determination of the inorganic carbon concentration. The test treatments, inoculum blank and reference (sodium acetate) were measured in triplicates. At 25.7 mg/L test concentration, greater than 10% biodegradation of the test substance was reached on Day 5 and greater than 60% biodegradation was reached on Day 12. Hence, the test material met the 10-day window requirement for ready biodegradability. On Days 28, the biodegradation was 80% (ECHA disseminated dossier; CAS 98-55-5).

Regarding the source substance geraniol there are two ready biodegradability tests available according to OECD 301A or 301F, respectively. In a GLP guideline study conducted in compliance with OECD 301A the ready biodegradability was tested using domestic activated sludge (adaptation not specified). The initial test substance concentration based on test material was 12.2 mg/L (corresponding to 10 mg/L DOC). Biodegradation was followed by measuring the DOC removal as %. In result, the source substance reached the pass level for ready biodegradability of 60% DOC removal already at day 3 (= 91%). On day 7 a biodegradation of 100% DOC removal was determined. Based on the determined DOC removal, a degradation rate of 90 - 100 % within 3 days was detected (BASF AG, 1994). To further support these findings, a second study set up according to OECD guideline 301F was used for assessment. The O2 consumption of non-adapted, activated sludge was recorded for 28 days with an initial substance concentration of 100 mg/L based on test material after pH adjustment. A final degradation rate after 28 days of 94 % was determined (Givaudan-Roure SA, 1994).

Conclusion:

Based on available data it can be concluded that both the target substance as well as all relevant source substances are readily biodegradable in water.