Evaluation of vascular and kidney injury biomarkers in Mexican children exposed to inorganic fluoride

Exposure to inorganic fluoride (F) has been implicated in cardiovascular and kidney dysfunction mainly in adult populations. However, limited epidemiological information from susceptible populations, such as children, is available. In this study we evaluated the relationship of F exposure with some vascular and kidney injury biomarkers in children. A cross-sectional study was conducted in 374 Mexican schoolchildren. Dental fluorosis and F concentrations in the water and urine were evaluated. The glomerular filtration rate (eGFR) and the urinary concentrations of kidney injury molecule 1 (KIM-1) and cystatin-C (uCys-C) were examined to assess kidney injury. The carotid intima media thickness (cIMT) and serum concentrations of vascular adhesion molecule 1 (VCAM-1), intracellular adhesion molecule 1 (ICAM-1), endothelin 1(ET-1) and cystatin-C (sCys-C) were measured to assess vascular alterations. High proportions of children exposed to F were observed (79.7% above 1.2 ppm F in urine) even in the low water F exposure regions, which suggested additional sources of F exposure. In robust multiple linear regression models, urinary F was positively associated with eGFR (β = 1.3, p = 0.015), uCys-C (β = −8.5, p = 0.043), VCAM-1 (β = 111.1, p = 0.019), ICAM-1 (β = 57, p = 0.032) and cIMT (β = 0.01, p = 0.032). An inverse association was observed with uCys-C (β = −8.5, p = 0.043) and sCys-C (β = −9.6, p = 0.021), and no significant associations with ET-1 (β = 0.069, p = 0.074) and KIM-1 (β = 29.1, p = 0.212) were found. Our findings revealed inconclusive results regarding F exposure and kidney injury. However, these results suggest that F exposure is related to early vascular alterations, which may increase the susceptibility of cardiovascular diseases in adult life.