Potassium trifluorozincate

Bioaccumulation: aquatic / sediment

Description of key information

Bioaccumulation for potassium trifluorozincate is not to be expected as the substance instantly dissociates into potassium, zinc and fluor ions. Data available on these ions indicates that bioaccumulation and/or secondary poisoning is unlikely to occur.

Additional information

Bioaccumulation for potassium trifluorozincate as such is not to be expected as the substance dissociates rapidly into various ions. Data is available on uptake of zinc and fluoride ions. The availability of inorganic substances for uptake may vary depending on factors such as pH, hardness, temperature and redox conditions, all of which may affect speciation. The following information is available on bioaccumulation of zinc and fluoride ions:

Zinc:

In an integrated criteria document on zinc by the RIVM (1993) a range of bioaccumulation studies in aquatic organisms is summarized. According to this document: “The BCF values reported for aquatic plants, including algae and macrophytes, range from <100 to 50.000. The majority of BCF values for invertebrates and fish lie between 100 and 1.000, those for fish generally being lower than those for invertebrates. The highest BCFs for invertebrates, ranging between 10.000 and 100.000, have been reported for benthic organisms such as crabs, oysters and insect larvae. The highest BCF reported in fish is 2.000. It should be noted that these values were taken from reviews, which usually do not report whether the BCFs are based on fresh weight or dry weight of the organisms, and whether or not the values have been corrected for the background concentration of zinc in the organisms. Furthermore, the wide range of values observed may be partly attributable to differences in exposure concentration; so caution is required in interpreting these values. In spite of these limitations, it is concluded that zinc is concentrated by aquatic organisms from the surrounding water, and that the degree of concentration is species-dependent, varying from insignificant in fish and most invertebrates to highly significant in algae and benthic organisms. In view of the decreasing BCF values with increasing trophic level in the food web (BCF algae > BCFinvertebrates > BCFfish), it is further concluded that biomagnification is of little significance. The results of both field and laboratory studies, in which zinc concentrations were measured in a wide variety of organisms, confirm this conclusion.”

Furthermore, as regards to secondary poisoning, in the EU risk assessment report on zinc (ECB, 2010) it is concluded that:“[…] secondary poisoning is considered to be not relevant in the effect assessment of zinc” as “the accumulation of zinc, an essential element, is regulated in animals of several taxonomic groups, for example in molluscs, crustaceans, fish and mammals. In mammals, one of the two target species for secondary poisoning, both the absorption of zinc from the diet and the excretion of zinc, are regulated. This allows mammals, within certain limits, to maintain their total body zinc level (whole body homeostasis) and to maintain physiologically required levels of zinc in their various tissues, both at low and high dietary zinc intakes. The results of field studies, in which relatively small differences were found in the zinc levels of small mammals from control and polluted sites, are in accordance with the homeostatic mechanism. These data indicate that the bioaccumulation potential of zinc in both herbivorous and carnivorous mammals will be low."

Fluoride:

In the EU-RAR (ECB, 2001) on hydrogen fluoride bioaccumulation of fluoride in freshwater and marine organisms is summarized “In aquatic organisms fluoride accumulates primarily in the exoskeleton of crustacea and in the bones of fish. No F 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, F 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”.

 

As extensive data is available for the dissolved ions that are potentially available for direct uptake, and these data do not indicate that potassium trifluorozincate dissociation products would be bioaccumulative or lead to secondary poisoning, bioaccumulation testing with potassium trifluorozincate itself is considered unnecessary.