Daily Archives: August 22, 2014

Pharmacokinetics of fluoride in toddlers receiving fluoride varnish

Milgrom P, Taves DM, Kim AS, Watson GE, Horst JA. Pharmacokinetics of Fluoride in Toddlers After Application of 5% Sodium Fluoride Dental Varnish. Pediatrics. 2014 Aug 18. pii: peds.2013-3501.

The prevalence of dental caries (tooth decay) among preschool children is increasing, driven partially by an earlier age of onset of carious lesions. The American Academy of Pediatrics recommends application of 5% sodium fluoride varnish at intervals increasing with caries risk status, as soon as teeth are present. However, the varnishes are marketed for treatment of tooth sensitivity and are regulated as medical devices rather than approved by the US Food and Drug Administration for prevention of dental caries (tooth decay). The objective of this research is to examine the safety of use in toddlers by characterizing the absorption and distribution profile of a currently marketed fluoride varnish. We measured urinary fluoride for 5 hours after application of fluoride varnish to teeth in 6 toddlers aged 12 to 15 months. Baseline levels were measured on a separate day. The urine was extracted from disposable diapers, measured by rapid diffusion, and extrapolated to plasma levels. The mean estimated plasma fluoride concentration was 13 μg/L (SD, 9 μg/L) during the baseline visit and 21 μg/L (SD, 8 μg/L) during the 5 hours after treatment. Mean estimated peak plasma fluoride after treatment was 57 μg/L (SD, 22 μg/L), and 20 μg/kg (SD, 4 μg/L) was retained on average. Retained fluoride was 253 times lower than the acute toxic dose of 5 mg/kg. Mean plasma fluoride after placement of varnish was within an SD of control levels. Occasional application of fluoride varnish following American Academy of Pediatrics guidance is safe for toddlers.

Click here for full paper (Open Source).

Water quality guideline for fluoride derived, unreasonably low?

From the studies I have seen published this water quality guideline for fluoride seems way overly conservative.

McPherson C, Lee D, Chapman P. Development of a fluoride chronic effects benchmark for aquatic life in freshwater. Environ Toxicol Chem. 2014 Aug 16. doi: 10.1002/etc.2724.

Canada has an interim water quality guideline (WQG) for fluoride for protection of freshwater aquatic life that dates from 2002; one Canadian province has a different interim WQG for fluoride that dates to 1995. The US does not have a national benchmark for fluoride in freshwater, only one us state has such a benchmark. There are no other national or regional benchmarks for fluoride chronic toxicity in freshwater. Available data on the acute and chronic toxicity of fluoride to freshwater aquatic life were compiled and reviewed. Acute toxicity was reported to occur at concentrations ranging from 11.5 to >800 mg/l f . The majority of chronic effects occur at concentrations between 1.8 and 195 mg/l. A total of 10 chronic studies representing 16 species (five fish, seven invertebrates, and four algae/aquatic plants) were used to derive a chronic effects benchmark of 1.94 mg/l f , applying the species sensitivity distribution approach.