Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Valid data on the short-term toxicity to fish, crustacea and algae are available as tabulated below. The data indicate that the toxicity is moderate to each of the tested aquatic organisms.






96 hr LC50


Leuciscus idus melanotus; Golden orfe



96 hr LC50


Pimephales promelas;

Fathead minnow



48 hr EC50


Daphnia magna



72 h EC50


Scenedesmus subspicatus.



growth rate: 16.6


Aquatic toxicity of 2-ethylhexanol was determined in acute tests for all three trophic levels algae, aquatic invertebrates (Daphnia) and fish (several species).

Acute toxicity towards algae and fish is essentially equivalent, with the exact value determined in the available key study on algae (Scenedesmus subspicatus) being only slightly lower compared to the LC50 determined for Leuciscus idus. Also acute toxicity toward aquatic invertebrates is of the same order of magnitude compared to the other trophic levels. However, Daphnia magna was of somewhat less sensitivity compared to fish and algae.

While the 72 hours EC10 (growth rate) for algae of 5.3 mg/L may be taken as chronic toxicity for freshwater algae, chronic toxicity tests for fish and aquatic invertebrates are not available. Due to the ready biodegradability of 2-ethylhexanol these data are not regarded to be necessary. Thus, for derivation of a PNEC for freshwater, the 72 hour EC50 determined based on the growth rate of freshwater alga Scenedesmus subspicatus of 16.6 mg/L is used.

For sewage treatment plants microorganisms according to "column 2" in Annex VIII of REGULATION (EC) No 1907/2006 a study on its own is not required as the submission substance has been shown to be readily biodegradable. In the reliable test on ready biodegradability (MITI-I Test equivalent to OECD TG 301-C, reliability 1) an initial test item concentration of 100 mg/L had been applied. This concentration is more than 500 times higher than the concentrations that may be expected in the influent of a sewage treatment plant, based on PEC STP values obtained under Chapter 9 for each exposure scenario. The NOEC derived from the ready biodegradability test is supported by a not assignable study (RL 4) on microorganism toxicity (ETAD fermentation tube method, Wellens 1980). In this test a NOEC (24 hours) of >300 mg/L had been determined.