Determination of bioavailable fluoride from sepiolite by “in vivo” digestibility assays

Safety and efficacy of a feed additive consisting of sepiolite for all animal species (Sepiol S.A and Tolsa, S.A)

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the re-evaluation of the authorisation of sepiolite as a feed additive for all animal species. The FEEDAP Panel considered that sepiolite is unlikely to be absorbed. Harmful amounts of residues of any chemical component in edible tissues/products, as a consequence of the use of sepiolite as a feed additive, are not expected. Sepiolite is not genotoxic and does not induce any toxicity effects following oral administration and, therefore, it was considered safe for the consumers. The additive was considered safe for dairy cows at the recommended use level with a safety factor of 2.5. The conclusion was extrapolated to other dairy ruminants but owing to the lack of sufficient data, no conclusions can be drawn on the safety of the additive for the other target species/categories. Based on the results of a chronic inhalation toxicity study, the additive is considered a respiratory irritant. Owing to the dusting potential of the additive and its silica content, handling the additive was considered a risk by inhalation for the users. It is not irritant or corrosive to skin or eyes. Due to the nickel content, it is considered a skin and respiratory sensitiser. The additive was considered safe for the environment. The FEEDAP Panel concluded that sepiolite was efficacious as a thickener-suspending agent, binder and anticaking agent in feed for all animal species under the proposed conditions of use.

Effects of acute fluoride exposure on the jejunum and ileum of rats: Insights from proteomic and enteric innervation analysis

Fluoride (F) is largely employed in dentistry, in therapeutic doses, to control caries. However, excessive intake may lead to adverse effects in the body. Since F is absorbed mostly from the gastrointestinal tract (GIT), gastrointestinal symptoms are the first signs following acute F exposure. Nevertheless, little is known about the mechanistic events that lead to these symptoms. Therefore, the present study evaluated changes in the proteomic profile as well as morphological changes in the jejunum and ileum of rats upon acute exposure to F. Male rats received, by gastric gavage, a single dose of F containing 0 (control) or 25 mg/Kg for 30 days. Upon exposure to F, there was a decrease in the thickness of the tunic muscularis for both segments and a decrease in the thickness of the wall only for the ileum. In addition, a decrease in the density of HuC/D-IR neurons and nNOS-IR neurons was found for the jejunum, but for the ileum only nNOS-IR neurons were decreased upon F exposure. Moreover, SP-IR varicosities were increased in both segments, while VIP-IR varicosities were increased in the jejunum and decreased in the ileum. As for the proteomic analysis, the proteins with altered expression were mostly negatively regulated and associated mainly with protein synthesis and energy metabolism. Proteomics also revealed alterations in proteins involved in oxidative/antioxidant defense, apoptosis and as well as in cytoskeletal proteins. Our results, when analyzed together, suggest that the gastrointestinal symptoms found in cases of acute F exposure might be related to the morphological alterations in the gut (decrease in the thickness of the tunica muscularis) that, at the molecular level, can be explained by alterations in the gut vipergic innervation and in proteins that regulate the cytoskeleton.