2-(4-tert-butylbenzyl)propionaldehyde

Long-term toxicity to fish

Description of key information

According to the hazard assessment performed on the basis of available acute toxicity data, biodegradation rate as well as bioaccumulation potential, no chronic studies on fish have been proposed for this substance. Within the scope of a substance evaluation under the CoRAP process of REACH, however, an OECD 229 was requested to address a potential endocrine disrupting activity of the substance. To meet these requirements, a Fish Short Term Reproduction Assay has been performed using the fathead minnow as a test organism in a flow-through system. Several technical measurements have been set up to avoid rapid oxidation of the test substance to the corresponding acid. Nevertheless, analytical results revealed, that the oxidation of the test substance was unavoidable. Accordingly, both the aldehyde as well as the acid have been measured throughout the experiment. As the sum of aldehyde and acid concentration are within 20 % of the nominal test concentration of the parent compound, derived effect levels refer to the nominal concentration of the parent test substance. During 21 days of exposure, no adverse effects on population relevant endpoints have been observed up to the highest nominal test concentration of 200 µg/L (= 10% of the LC50 value for fish). These endpoints were: adult mortality, reproduction (fecundity, fertilization rate), growth (length and weight) and gonadal histopathology. Secondary sexual characteristics determined by tubercle assessment where not affected either. As a biomarker response, the blood level of vitellogenin (VTG) were significantly elevated in the two highest test concentrations in male fish. However, this biomarker level did not adversely affect male fish in terms of reduced reproductive fitness or other population relevant endpoints within the scope of this Short Term Reproduction Assay. Based on the results of the OECD 229, the derived adverse effect NOEC for fish is >200 µg/L.