Registration Dossier

Ecotoxicological information

Long-term toxicity to fish

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

No aquatic toxicity data are available for trimethyl borate since the compound rapidly hydrolyzes in water with a half-life of less than 1 second to form methanol and boric acid. Methanol is much less toxic to aquatic organisms compared to boric acid. Therefore, aquatic toxicity data for boric acid was used.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
53.82 mg/L

Additional information

The study is not technically feasible because the test substance hydrolyzes in water with a half-life of less than 1 second to form methanol and boric acid. Methanol is much less toxic to aquatic organisms compared to boric acid. Thus, PNEC values derived for boric acid are protective of the environment for the stoichiometric contribution of methanol.Therefore, toxicity data compiled on boric acid was used. The endpoints included in the dossier under environmental hazard assessment were reported from studies on the ecotoxicity of boron and various compounds, such as boric acid (H3BO3), anhydrous sodium tetraborate (Na2B4O7), and hydrated sodium tetraborates (Na2B4O7. xH2O). All endpoints were converted to concentrations of elemental boron (B) using the relative molar mass and then converted to Trimethyl borate for this IUCLID.

The lowest value taken from the key study with zebrafish was a 34 -day NOEC for growth determined as length. The NOEC was 5.6 mg B/L which was converted to 53.82 mg C3H9BO3/L and used for the freshwater PNEC derivation. A lower value was reported from this study for dry weight but due to the presence of an outlier and an indiscrpency between the results and summary sections within the report, the NOEC for growth as length was chosen. This value is seen as conservative due to the large number of studies with fish (~174).