Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The substance will dissociate and hydrolyse in the environment to form fluoride and silicate ions. Inorganic silicate is environmentally ubiquitous and of low toxicity, is not of concern and therefore will not be considered further with regard to bioaccumulation. Fluoride is also environmentally ubiquitous but is present at lower background levels and is of greater toxicity. The availabe data on the bioaccumulation of fluoride is summarised below:

Summary of fluoride bioaccumulation

A correlation between fluoride levels in earthworms and elevated soil fluoride levels from polluted sites has been demonstrated, however levels were due to the soil content of the worm gut.  Elevated fluoride content in woodlice collected from the vicinity of an Al-reduction plant has been demonstrated (Janssen et al, 1989). Sloof et al(1989) note that uptake of fluoride into plants from soil is low as a consequence of the low bioavailability of fluoride in the soil and that atmospheric uptake is generally the most important route of exposure. A relatively high rate of fluoride uptake is noted for grass species, and the consumption of fluoride containing plants may lead to elevated fluoride levels in animals and humans. Sloof et al(1989) conclude that the limited data indicate that fluoride biomagnification in the aquatic environment is of little significance. Fluoride accumulates in aquatic organisms predominantly in the exoskeleton of crustacea and in the skeleton of fish; no accumulation was reported for edible tissues.

In the terrestrial environment, fluoride accumulates in the skeleton of vertebrates and invertebrates. The EU Risk Assessmnet Report for hydrogen fluoride (2001) notes that the lowest fluoride levels are found in herbivores, with higher levels in omnivores and highest levels in predators, scavengers and pollinators; the findings indicate a moderate degree of biomagnification. Vertebrate species store most of the fluoride in the bones and (to a lesser extent) the teeth; elevated levels of fluoride in the bones and teeth have been shown in animals from polluted areas.