Trihydrogen trifluoro[phosphato(3-)-O]borate(3-)

Toxicity to aquatic algae and cyanobacteria

Additional information

No study data is available for the test substance. Similar to all coordination complexes of boron trifluoride with organic and inorganic species (like alcohols, ethers, amines, sulfuric acid, sulfuric dioxide, etc) the complex of boron trifluoride and phosphoric acid is extremely water sensitive and reacts even with moist air. In the instantaneous reaction with water as a first step phosphoric acid and boron trifluoride dihydrates are formed. The latter undergoes further rapid hydrolysis to boric acid, fluoboric acid and tetrafluoroborate. Effects on aquatic algae were studied using the read across substances boric acid (CAS No 10043-35-3), phosphoric acid (CAS No 7664 -38 -2) and tetrafluoroborate.

WoA (phosphoric acid; study report 2010)
In a 96 -hour toxicity study, cultures of green algae (Desmodesmus subspicatus) were exposed to the read across substance phosphoric acid (CAS No 7664 -38 -2) a nominal concentration of 100 mg/L under static conditions according to OECD guideline 201. The concentration used for the main test was based on a preliminary test conducted with nominal concentrations of 0.10, 1.0, 10 and 100 mg/L. No effects on growths were observed up to 10 mg/L. The growth was slightly reduced at 100 mg/L.
In the main test the pH value of the test concentration was adjusted to 7.5 and six replicates were tested. No growth inhibition was observed in any of the replicates. Furthermore no abnormalities were observed. The NOEC and EC50 values based on algae growth were 100 mg/L and > 100 mg/L.

WoA (Public references I and II from 1965 to 1990 and from 1980 to 2002; focus on boron) 
NOEC(4d) values, obtained for the fresh water algae Chlorella pyrenoidosa (10 mg B/L), Anacystis nidulans (50 mg B/L) and EC10(3d) values obtained from fresh water algae Selenastrum capricornutum (24.5 mg B/L, biomass; 35 mg B/L; growth rate) are reported and applicable assessing the read across substance boric acid (CAS No 10043-35-3).  Another non published data according to OECD 201 with Selenastrum capricornutum (Hanstveit and Oldersma 2000) reported a NOEC concentration of 17.5 mg B/L. The lowest NOEC value was found in the fresh water algae Chlorella pyrenoidosa (0.4 mg B/L) after 14 days study duration which does not meet the standard procedure. Finally, the EC50(4d) value obtained for the fresh water algae Selenastrum capricornutum of 3.3 mg B/L (growth rate) is regarded as worst case result.

WoE (tetrafluoroborate)
In the present study, the toxic effects of imidazolium-based ILs (1-butyl-3-methylimidazolium cation associated with bromide [BMiM][Br] and tetrafluoroborate [BMIM][BF4]) to the freshwater green alga Selenastrum capricornutum were investigated. Two approaches were followed to quantify toxicity of these compounds: Analyses of photosynthetic activity and cell proliferation. The obtained data showed that the relative declines of growth rates generally were more pronounced than those of photosynthetic activity. The ecotoxicity of a range of common organic solvents also was examined. It was revealed that both imidazolium-based ILs studied were some orders of magnitude more toxic than methanol, isopropanol, and dimethylformamide ([BMIM][BF4 ]EC50 was estimated 3467µM resulting in approx. 784 mg/L). In addition, with respect to incorporating perfluorinated anion, EC50 values of the previously prepared stock solution were significantly lower compared to those of the freshly made one. This might be due to hydrolytic effects of [BMIM][BF4] leading to fluoride formation. which was confirmed by ion chromatography analysis.

Based on the results of the acute ecotoxicity tests using freshwater algae, the EC50(96h) of  > 100 mg/L for phosphoric acid does not indicate toxicity triggering classification and labelling.  Boric acid reveals NOEC(4d) and EC10(3d) values of about 10 to 50 mg B/L. The EC50(4d) value with boric acid obtained for the fresh water algae Selenastrum capricornutum  of 3.3 mg B/L (growth rate) is regarded as worst case result (considering the molecular weight ratio of boron trifluoride phosphoric acid complex versus boron, the EC50/(4d) would be 50 mg  boron trifluoride phosphoric acid complex/L) but would not trigger classification and labelling for boric acid as all (chronic) NOEC values are > 1 mg/L and the substance has no potential to bioaccumulate.  With respect to aquatic toxicity, boric acid is not classified according to Dangerous Substance Directive 1272/2008 (CLP). In conclusion, the substance boron trifluoride phosphoric acid complex needs not to be classified and labelled as under Regulation (EC) No 1272/2008, as amended for the sixth time in Regulation EC No 605/2014.