Biomarkers of chronic fluoride exposure in groundwater in a highly exposed population

摘要

This study examined the relation between fluoride (F一）concentrations in fingernail clippings and urine and the prevalence and severity of enamel fluorosis (EF) among Ethiopian Rift Valley populations exposed to high levels of F- in drinking water. The utility of fingernail clippings as a biomarker for F一 exposure and EF was also assessed for the first time in a high-F一 region. The study recorded the EF status of386 individuals (10 to 50 years old), who consume naturally contaminated groundwater with widely varying F- concentration (0.6-15 mg/L). The mean F- concentrations among residents of communities with primary reliance on groundwater were 5.1 mg/kg (range: 0.5-34 mg/kg) in fingernails and 8.9 mg/L (range: 0.44-34 mg/l) in urine. We show strong positive correlations between F~ in drinking water and 12-hour urinary excretion (r = 0.74, ρ < 0.001, η = 287), fingernail F~ content (r = 0.6, ρ < 0.001, n = 258), and mean individual measures of EF severity as measured using the Thylstrup and Fejerskov (TF) Index (r = 0.42’ ρ < 0.001, n = 316). The data indicate that both fingernail and urine measures are good biomarkers for F- exposure and EF outcomes, the latter being slightly more sensitive. Cases of moderate/severe EF were significantly more common among younger subjects (10 to 15 years old)