Urinary fluoride parameters in spot urine samples associated with exposure to systemic fluoride through

Worldwide fluoridation schemes are designed to achieve optimal fluoride (F) ingestion for participants with customary F intake from diet and toothbrushing at a community level. However, even short-term excessive systemic F ingestion during tooth formation can potentially increase the risk of development of dental fluorosis. Since urine is the main elimination route for systemically absorbed F (i.e. bioavailable F) from the body, 24-hour urine has been suggested as a good biomarker for short-term F exposure. Collection of 24-hour urine samples from children, particularly those who are not toilet trained, is quite challenging. Spot urine collection could be a simpler alternative to 24-hour urine sample collection. However, urinary F concentrations vary throughout the day, and therefore the F concentration in a spot urine sample may not be representative of its 24-hour urinary excretion. The common way of compensating for daily variation in urinary dilution of analytes is to adjust for parameters (such as urinary creatinine and/or urine specific gravity), which may have low variability or fairly constant excretion over time and are not notably influenced by exogenous factors.
The aim of this randomised cross-over multi-centre study is to assess the validity of urinary F concentration, urinary F/specific-gravity ratio and urinary F/creatinine ratio in spot urine samples for monitoring F exposure in children ingesting F through toothpaste, community water, milk and salt in different geographical locations.

The project is led by Teesside University in collaboration with Newcastle University (Centre for Oral Health Research, School of Dental Sciences), University of São Paulo/Bauru School of Dentistry/Brazil, Universidad El Bosque/Bogotá/Colombia and University of Talca/Faculty of Health Sciences/Chile.

Principal Investigator: Prof V Zohoori, Teesside University
Co Investigators:
Prof Anne Maguire and Roy Sanderson, Newcastle University
Prof Marilia Buzalaf, University of São Paulo
Dr Edgar Beltran and Dr Stefania Martignon, Universidad El Bosque
Dr Rodrigo A Giacaman, University of Talca