(E)-3-methyl-5-cyclopentadecen-1-one

Endpoint summary

Description of key information

Acute and chronic data available are summarised in the table below.

Level of exposure / trophic levels	Test substance	Organism	EC50/LC50 (mg/L)	EC10/NOEC (mg/L)	Flag / reliability	Performing laboratory	Reference in IUCLID
Acute / Aquatic invertebrates	Registered substance	Daphnia magna	48h: 0.39	Not relevant	K/2	SafePharm	Short-term toxicity to aquatic invertebrates, Safepharm, 1995, K
Acute / Fish	Registered substance	Oncorhynchus mykiss	96h: 0.22	Not relevant	K/2	SafePharm	Short-term toxicity to fish, Safepharm, 1995, K
Acute / Aquatic algae	Registered substance	Scenedesmus subspicatus	72h: > solubility limit	72h: ≥ solubility limit	K/1	SafePharm	Toxicity to aquatic algae and cyanobacteria, Safepharm, 1995, K
Chronic / Aquatic invertebrates	Registered substance	Daphnia magna	Not relevant	21d: 0.011	D/3	SafePharm	Long-term toxicity to aquatic invertebrates, Safepharm, 2003, D
Chronic / Aquatic invertebrates	Supporting substance	Daphnia magna	Not relevant	21d: 0.121	K/1	Fraunhofer	RA Source, Long-term toxicity to aquatic invertebrates, Fraunhofer, 2009, K
Chronic / Fish	Registered substance	Pimephales promelas	Not relevant	33d: 0.00098	D/3	SafePharm	Long-term toxicity to fish, Safepharm, 2003, D
Chronic / Fish	Registered substance	Pimephales promelas	Not relevant	10d: 0.18	K/1	Harlan (formerly SafePharm)	Long-term toxicity to fish, Harlan, 2013, K

Acute and chronic data are available for the three trophic levels: Algae, Invertebrates and Fish.

Among all species tested, toxic effects were found for aquatic invertebrates and fish.

For the aquatic invertebrates Daphnia magna, the acute toxicity of the registered substance was assessed for 48 hours under static test conditions. The 48h-EC50 was 0.39 mg/L. For the chronic toxicity, a read-across approach was used under semi-static test conditions with a read-across substance as the study performed on the registered substance is considered invalid. This read-across substance is considered adequate for read-across purposes (see IUCLID section 13 for justification). Indeed, this substance is one of the constituents of the registered substance, together with isomers. The read-across substance is a mono-constituent, individual optical isomer, while the registered substance is defined as a multi-constituent, with three pairs of racemate. The 21d-EC10 (Daphnia magna) was determined at 0.121 mg/L based on intrinsic rate of population increase. This result is in accordance with the expected result on the registered substance.

 

For the fish, the acute toxicity of the registered substance to Oncorhynchus mykiss was assessed for a period of 96 hours under semi-static conditions. The 96h-LC50 was 0.22 mg/L. For the chronic toxicity, a study was performed to assess the effects of the registered substance on freshly hatched larvae of the fathead minnow Pimephales promelas, for a period of 10 days under flow-through conditions. This was a compromise and a decision based on the technical challenges to maintain constant concentrations of the test substance in solution. Those Dosing Trials and Range Finding tests lasted 10 months and led to the conclusion that three concentrations could be maintained over a short period of time.  A special test design was constructed in order to dose the test substance (concentration generators and metallic splitters) that was implemented in the laboratory.  The 10d-EC10 was 0.18 mg/L based on survival. Given the inadequacies of the previous invalid fish ELS study (2003), conducted on the registered substance, it is considered that the above result provides a more reliable assessment of the chronic effects of the registered substance on the early life stages of fish. Indeed, even if the study period is shorter (10 days) than a real chronic study, the substance was well maintained at stable aqueous concentrations during the test and therefore the study provide a more reliable exposure system. In addition, as the substance has a non-specific narcotic mode of action, smaller differences in sensitivity between this study and the full early-life stage test (OECD Guideline 210) is expected, as mentionned in the OECD Guideline 212 (1998).

For the algae Scenedesmus subspicatus, the effect of the registered substance on the growth of the green alga was assessed for 72h. Exposure of algae to the substance gave EC50 and NOEC values greater than the highest attainable test concentration of 30 mg/L. The test concentration of 30 mg/L was the highest attainable test concentration that could be prepared due to the limited solubility of the test material in water (corresponding to 0.69 mg/L in aquatic medium) and auxiliary solvent and having due regard to the amount of auxiliary solvent permitted in the test under the OECD guidelines.

For the microorganisms and in accordance with column 2 of REACH Annex VIII, the activated sludge respiration inhibition test does not need to be conducted because the substance is readily biodegradable and the applied test concentrations are in the range of concentrations that can be expected in the influent of a sewage treatment plant.