Fusel oil

Toxicity to aquatic algae and cyanobacteria

Description of key information

EC50 = 275 mg/L based on growth rate

Additional information

Studies on the acute toxicity to aquatic algae are available for two of the four main constituents of Fusel oil.

The key study available for 2 -Methylbutanol (CAS No. 137-32-6) was conducted according to the OECD Guideline 201 under GLP conditions (BASF, 2011). Therefore, green algae (Pseudokirchneriella subcapitata) were exposed for 72 h under static conditions to nominal test concentrations of 0, 3.2, 10, 32, 100 and 320 mg/L in a limit test. The test concentration was analytically verified, resulting in mean measured test concentrations of < 2 (control), 2.2, 9.6, 29, 120 and 353 mg/L. No sublethal effects could be observed at the end of the exposure period. Therefore, an EC50 value could not be calculated and it is considered to be > 353 mg/L (mean measured) based on growth rate. The NOEC was reported to be 29 mg/L (mean measured) based on growth rate.

The key study carried out with Ethanol (CAS No. 64-17-5), was performed by using a method equivalent to the OECD Guideline 201 under non-GLP conditions (El Jay, 1996). Green algae (Chlorella vulgaris) were exposed in a static system over a period of 5 d to different concentrations in a dose-response test. The EC50 and EC10-values were determined to be 275 mg/L (nominal) and 11.5 mg/L (nominal), respectively, based on growth rate.

Further supporting studies are available for Ethanol (CAS No. 64-17-5) on different freshwater and marine algae species, and all indicate low toxicity of the substances to algae.

As no experimental results on the acute toxicity to aquatic algae are available for 3-Methylbutanol (CAS No. 123-51-3) and 2-Methylpropanol (CAS No. 78-83-1) QSAR-calculations were performed for these constituents as well as for the remaining two major ones. The EC50 (72 h) values determined by using ECOSAR v1.00 as well as the experimental results are presented in the following table.

 

Constituent of Fusel oil	CAS-No.	EC50 [mg/L]	Reference
Ethanol	64-17-5	275	El Jay, 1996
		209.25	ECOSAR v1.00
2 -Methylpropanol	78-83-1	90.65	ECOSAR v1.00
3 -Methylbutanol	123-51-3	53.05	ECOSAR v1.00
2 -Methylbutanol	137-32-6	>353	BASF SE 2011
		53.05	ECOSAR v1.00

 

The QSAR data indicate low toxicity of all main constituents to algae. They also demonstrate the similarity of the toxic potential between the two isomers 3 -Methylbutanol and 2 -Methylbutanol, and that 2-methylpropanol is expected to be even less toxic. The available data is thus considered to adequately describe the toxicity of all main constituents.

Concluding from the results reported for the main constituents Ethanol, 2-Methylpropanol, 2-Methylbutanol and 3-Methylbutanol, the short-term effects of Fusel oil are expected to be in the range between 50 mg/L and > 100 mg/L.