Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Algal inhibition study conducted on boric acid, the hydrolysis product of the reference substance, which is applicable to use in the evaluation of the reference substances ecotoxicological properties. The 3 day EC50 (growth rate) was 52.5 mg B/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
52.5 mg/L
EC10 or NOEC for freshwater algae:
17.5 mg/L

Additional information

The reference substance (BAGE) hydrolyses within less than an hour to its hydrolysis products: Boric acid and glycerol. Therefore, conducting an algal inhibition study on the reference substance itself was considered not to be feasible. If a study was conducted on the reference substance, it would give a result representative of the hydrolysis products mentioned above.

An assessment of boric acid has therefore been made based on available algal study data.

Boric acid

Hanstveit and Oldersma (2000):

An algal inhibition study was conducted on Boric acid according to OECD Guideline 201/EU Method C.3.

Selenastrum capricornutum was exposed for 74.5 hours to the following concentrations of test substance.

0, 32, 56, 100, 181, 321, 562 mg/L boric acid, equivalent to 0, 5.6, 9.8, 17.5, 31.7, 56.2, 98.4 mg B/L.

Measured concentrations were found to be 95.4 -94.7% of the nominal concentrations.

The following results were obtained (concentration based on boron element):

3 day NOEC (growth rate): 17.5 mg/L

3 day EC50 (growth rate): 52.5 mg/L

3 day EC50 (biomass): 40 mg/L

Glycerol

Glycerol is the other hydrolysis product of the reference substance, BAGE. It is not classified for the environment according to CLP or DSD.

Available data (see section 13) suggests that glycerol is of low toxicity to algae.

Refer to section 13, Ecotoxicological expert report (BAGE: Evaluation of Environmental Fate and Ecotoxicity Properties) for further details of the evalaution of ecotoxicological properties of the reference substance and its hydrolysis products, especially for additional information on glycerol.

Supporting data

As the reference substance hydrolyses within less than an hour to its hydrolysis products; Boric acid and glycerol it was not feasible to conduct an algal inhibition study on the reference substance, as the result will be representative of the hydrolysis products Boric acid and glycerol.

A QSAR prediction has therefore been made for the reference substance (BAGE), using EPIWIN program ECOSAR (v0.99h).

The predicted 96 hour EC50 of green algae was predicted to be 4.07 x 1010mg/l. This value is greater than the predicted water solubility of the reference substance.