Cyclohexanone oxime

Short-term toxicity to fish

Description of key information

The submission substance cyclohexanone oxime was tested in a reliable, well documented flow through study for acute fish toxicity using fathead minnows (Pimephales promelas) by Geiger et al. (1990). The study was performed similar and equivalent to OECD 203.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

208 mg/L

Additional information

The submission substance cyclohexanone oxime was tested in a reliable, well documented flow through study for acute fish toxicity using fathead minnows (Pimephales promelas) by Geiger et al. (1990). The study was performed similar and equivalent to OECD 203. 20 fish were tested for each of 5 concentration groups plus the control. All nominal concentrations were analytically verified at day 0, day 1, day 2 and day 3. Effect concentrations are based on mean measured concentrations corrected by recovery. Also behavioural effects were reported: Affected fish were hypoactive and underreactive to external stimuli, were darkly colored and hemorrhaging. Equilibirum loss was observed prior to death. The following effect concentrations were determined:

LC50 (96 hours; flow through, measured): 208 mg/L; 95% CI: 189-230;

EC50 (96 hours; flow through, measured; loss of equilibrium): 208 mg/L; 95% CI: 188-230.

This is supported by a study summary on an acute toxicity test of cyclohexanoneoxime to Oryzias latipes (study owner: Environment Agency Japan) available from J-Check, an internet resource from National Institute of Technology and Evaluation (NITE) Japan (RL4, as no original study report available). The study was conducted according to OECD 203 and compliant to GLP. The study design was semi-static (renewal after 48 hours) with analytical verification of test item concentration (measurement frequency: start of exposure, before renewal of test solution). The test was performed as a limit test at 100 mg/L. 10 animals were used for the treatment and control group, distributed over 2 replicates, each (5 animals per test basin). The determined 96 hour 50% lethal concentration for Oryzias latipes is: LC50 (96 h; semistatic) > 100 mg/L (nominal; analytically verified).

A further, non-reliable study is available supporting the low toxicity of cyclohexanone oxime towards freshwater fish: In an acute toxicity test on fresh water fish with 24 hour exposure period and 5 mg/L test item concentration (no further concentrations tested), no effects were observed with the following species (2 fish per concentration group; endpoints: death or obvious distsress): Larvae of Sea lamprey (Petromyzon marinus) 3-5 inches long; Rainbow trout (Salmo gairdnerii), fingerling size (4 inches or slightly less); Bluegill sunfish (Lepomis macrochirus): fingerling size (4 inches or slightly less). The test was part of a large testing programme covering 4346 chemicals published in 1957 (Applegate et al.).