Iodine pentafluoride

Endpoint summary

Additional information

Stability/degradation:

No studies on the environmental fate and pathways of iodine pentafluoride are available or can be performed as in contact with water iodine pentafluoride reacts instantly and violently under 'hydrolytic' formation of hydrogen fluoride and iodate. Hydrogen fluoride will further react to fluoride whereas iodate in water forms an equilibrium with iodide. Biodegradation data are not available as this endpoint does not apply to inorganic substances.

Bioaccumulation:

Iodine species have been shown to bioaccumulate in different aquatic species. Aquatic bioaccumulation factors for iodine in fresh water are 40 (algae), 5 (invertebrates), and 15 (fish); in salt water, these factors are 4,000–10,000 (algae), 50–100 (invertebrates), and 10–20 (fish). High iodine levels in certain seaweeds levels are usually associated with the relatively high levels of iodine in seawater (50μg/kg) (US-DHHS, 2004). Reported values should be treated with caution, since they are not acquired from bioaccumulation studies, but are merely a comparison of iodine content in the source and in the organism. High intracellular iodine concentrations may have other explanations, e.g. physiological processes like active transport and intracellular enzymatic reactions (CAR draft april 2011). Based on the available data it may be concluded that species-dependent concentration of iodine species by aquatic organisms from the surrounding water takes place. However, in view of the decreasing BCF values with increasing trophic level in the food web (BCF algae > BCF invertebrates > BCFfish), it is further concluded that biomagnification will be of little significance.

As regards fluoride, in aquatic organisms fluoride accumulates primarily in the exoskeleton of crustacea and in the bones of fish. No fluoride accumulation was reported in edible tissues. In fish, BCF-values of 53-58 (d.w.) and <2 (w.w.) were found. In crustacea BCF-values based on whole body fluoride content are found to be <1 (d.w.). The highest reported BCF-value for Mollusca and aquatic macrophyta were 3.2 and 7.5 (w.w.), respectively. In an experimental marine ecosystem with fish, crustaceans and plants, fluoride was found to accumulate in all species. The highest value, 149, was found in fish. BCF-values for crustacea range from 27 to 62. Fluoride concentrations up to 30 mg F/kg were found in consumption fish.

Adsorption-desorption behaviour:

As regards the sorption properties of iodine pentafluoride decomposition products, Koc values for iodide and iodate are determined at 74 and 377 L/kg, respectively based on a study in a 10 different soils. For the sorption characteristics of fluoride only qualitative data are available. Altogether, the immobile character of fluoride in soil is likely to be due mainly to formation of complexes with aluminium, iron or calcium and dependent on the pH and the availability of these counter ions. Although some true adsorption processes are described (e.g. displacement of hydroxide from clay surfaces) these processes are probably of lesser significance.For pragmatic reasons, for environmental exposure assessment a Koc is calculated based on a log Kow of -1 in EUSES (in the EU-RAR for hydrogen fluoride a log Kow of -1.4 is suggested). When using the QSAR for non-hydrophobics (default QSAR), a Koc of 3.16 is determined.