1,2,4-Oxadiazole, 3-phenyl-5-(2-thienyl)-

Bioaccumulation: aquatic / sediment

Description of key information

The steady state BCF for PH label were 169 and 223 for the mean measured concentrations of 0.38 and 4.4 μg/L, while for the TH label were 201 and 307 for the mean measured concentrations of 0.34 and 4.3 μg/L. Chromatographic profiles of fish tissue extracts indicated that the test substance was rapidly metabolized to a complex mixture of metabolites. Significant amounts of radioactivity in fish tissues were non-extractable, indicating formation of bound residues.

Key value for chemical safety assessment

BCF (aquatic species):

307 L/kg ww

Additional information

A study was conducted to assess the potential of the test substance for bioaccumulation according to OECD Guideline 305 and US EPA OPPTS 850.1730, in compliance with GLP. The test was divided into two phases: uptake (for 28 d) and depuration (for 35 d). During the uptake phase, bluegill sunfish were exposed to two nominal test concentrations (0.6 and 6 μg a.i. /L) of each of two radiolabeled forms of the test substance (phenyl (PH)- and thiophene (TH)-labeled). During both phases of the test, test organisms and water samples were collected and analyzed for total 14C radioactivity. Test organisms and water samples were analyzed for parent compound during the uptake phase and for one interval of the depuration phase. The determinations of the concentrations of the radiolabeled test substances and/or metabolites in freshwater and fish tissue were performed using LSC. These values were used to determine the substance-specific half-life (t1/2), the kinetic bioconcentration factor (BCFK) and the steady-state bioconcentration factor (BCFSS) in fish, as well as lipid-normalized and growth-corrected kinetic and steady-state bioconcentration factors (BCFSSL, BCFKL, BCFKg and BCFKLG). Selected tissue samples were also extracted and analyzed by HPLC in order to investigate the metabolism of the test substance in fish. The mean measured (total radioactivity in tissues of fish) concentrations for PH-labeled were 0.53 and 5.5 μg/L, and for TH-labeled were 0.52 and 5.4 μg/L. Mean measured (in terms of parent compound in tissues of fish) concentrations for PH-labeled were 0.38 and 4.4 μg/L, and for TH-labeled were 0.34 and 4.3 μg/L. The steady state BCF for PH-labeled were 169 and 223 L/kg, respectively, for the mean measured concentrations of 0.38 and 4.4 μg/L, while for the TH-labeled were 201 and 307 L/kg, respectively, for the mean measured concentrations of 0.34 and 4.3 μg/L. Chromatographic profiles of fish tissue extracts indicated that the test substance was rapidly metabolized to a complex mixture of metabolites. Significant amounts of radioactivity in fish tissues were non-extractable, indicating formation of bound residues (Schneider SZ, 2014).