2-pentylcyclopentan-1-one

Short-term toxicity to fish

Description of key information

Read-across, EU Method C.1, OECD Guideline 203, GLP, key study, validity 2:
96h-LC50 = 13 mg/L (95% CI: 7.5-23 mg/L)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

13 mg/L

Additional information

To assess the short-term toxicity of the registered substance, 2 -pentylcyclopentan-1-one, to fish, one valid experimental study is available.

 

This GLP study, assessed as a key study, was performed on a read-across substance, 2 -pentylcyclopentan-1-ol, according to EU Method C.1 and OECD Guideline 203. Both compounds (the registered substance and the read-across substance) acting with a non-polar narcotic MOA (Class 1) are structurally related, in that each has an alkyl chain with five carbon (pentyl) with a cyclopentane ring. Both compounds contain a 2 -pentylcyclopentane skeleton. The cyclopentane ring is associated with a ketone functional group for the registered substance and with an alcohol functional group for the read-across substance.

In this study, zebra fish (Brachydanio rerio, now Danio rerio) were exposed to the test substance (nominal concentrations: 4.6, 10, 22, 46 and 100 mg/L) in a semi-static condition during 96 hours. The recorded effects were mortality and visible abnormalities of the test fish. Additionally, a control group was tested in parallel. Since the test substance was determined to be volatile, the test was performed in a closed system to avoid losses of the volatile substance. In the analysed test medium samples the measured test substance concentrations ranged between 64 and 122% of the nominal values. The mean measured test substance concentrations (calculated as the average overall measurements per test concentration) varied in the range of 75 to 119% of the nominal values. Therefore, the reported biological results are related to the mean measured test substance concentrations, corresponding to 5.0, 7.5, 23, 55 and 110 mg/L.

All validity criteria were fulfilled but the measured no effect and 100% effect concentrations were adjacent with a difference of more than a factor of three. The 96h-LC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% mortality, at 13 mg/L (95% confidence interval: 7.5 -23 mg/L).

This supporting substance is considered adequate for read-across purposes based on structural similarity, on similar basic physico-chemical properties and similar environmental profile, as well as the same mode of action, between the registered substance and the analogue material used. In addition, as the log Kow value of the analogue material is slightly greater than the registered substance, the read-across approach is considered as a worst case scenario (see IUCLID section 13 for justification).