Dihydrogen hexafluorotitanate(2-)

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.02 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.123 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.002 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1.67 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

27.36 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

5.47 mg/kg sediment dw

Assessment factor:

50

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

21.33 mg/kg soil dw

Assessment factor:

10

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential to cause toxic effects if accumulated (in higher organisms) via the food chain

Additional information

Dihydrogen hexafluorotitanate is an inorganic substance which will rapidly dissociate into fluoride, hydrogen and titanium ions upon dissolution in the environment. However, hydrogen and titanium ions do not remain as such in solution, only fluoride ions do. The hydrogen ion attaches to a hydroxide ion to form a water molecule. The analysis of dissolved titanium levels in aquatic toxicity test solutions for algae, daphnia and fish according to OECD 201, 202 and 203 (Schlechtriem, 2013a, b; Teigeler, 2013) indicates that up to a loading of 100 mg/L dipotassium hexafluorotitanate, very low levels of titanium (often < 10% or even 5%) remain in solution at environmentally relevant pH while nearly all of the fluoride (often more than 95 %) could be recovered.

Indeed, under almost all environmental conditions (except the most acid conditions,i.e.,below pH 2), titanium displays a very low mobility, mainly due to the low solubility of the oxide TiO2. This limits the concentration of dissolved Ti in most natural solutions (fresh water, seawater as well as soil and sediment porewater) to <3 μg/L. Titanium only exists in a fully hydrated form, TiO(OH)2, in water above pH 2, and is, therefore, transported in a colloidal state rather than as a dissolved ion. Concentrations of ‘dissolved’ Ti generally decrease with increasing salinity. However, higher concentrations in organic rich water provide further evidence of colloidal transport. Titanium may be removed from water by flocculation of colloidal material, adsorption and scavenging by precipitation of Mn and Fe oxides. (http://www.gtk.fi/publ/foregsatlas, accessed on 12.03.2013). Thus, regarding the environmental fate and toxicity of dihydrogen hexafluorotitanate, it can be assumed that toxicity (if any) will be driven by the fluoride anion. Therefore, full read-across to potassium fluoride (CAS #7789-23-3) and other fluorides based upon a molecular weight conversion is justified.

 

Based on available substance-specific aquatic toxicity data from read-across substances it can be assumed that the aquatic toxicity potential of dihydrogen hexafluorotitanate (marketed and used only as an aqueous solution of ≤ 61% (w/w)) is low and below relevant classification criteria of Directive 67/548 EEC and CLP Regulation (EC) No 1272/2008.

Conclusion on classification

According to Directive 67/548 EEC and CLP Regulation (EC) No 1272/2008, a classification and labelling for aquatic toxicity of dihydrogen hexafluorotitanate (marketed and used only as an aqueous solution of ≤ 61% (w/w)) is not required.