Demographic study of fluoride excretion vs intake: Influence of variables

Abstract

Urinary fluoride is a widely used biomarker in public health and epidemiological studies, globally. The present study investigates fluoride exposure and compares the effect of different variables on the sampled population of the Rohtak district, Haryana, India. The relation between fluoride intake, excretion, and retention of fluoride across different age groups is unveiled. Cross-sectional study of urine samples of 207 inhabitants between the ages 5- to 96 years and of 83 drinking water samples were analyzed to determine fluoride using an ion selective fluoride electrode (potentiometric method). Drinking water was sourced from supply water (n = 28), hand-pumped water (n = 45), well water (n = 3) and RO water (n = 7). Urine samples were categorized based on three different generations: Grandfather (GF), Father (F), and Son (S) from the 71 villages covered in the study. Mean urinary fluoride excretion was significantly correlated to age with values 4.50 ± 2.56, 3.42 ± 2.00 and 2.44 ± 1.30 mg/L, in declining order of these age groups, respectively. The percent increase in fluoride excretion in the urine over that consumed in the intake water was 83.67, 48.05 and 5.62% for GF, F and S respectively, indicating that other sources of fluoride intake were responsible for the increment. The eigenvalues of PCA are 1.36, 1.25, 1.19 and 1.18 for PC1, PC2, PC3 and PC4, respectively. In all plots p-values show statistical significance (p<0.05), except for those abstaining from alcohol in the father (FA) category. Sons in the smoking category (R2 = 0.30, P<0.001) exhibited higher fluoride excretion than non-smokers. Linear regression, PCA, Tukey's test, and radar chart methods were used to examine the relation between fluoride exposure and other variables like the water source (hand-pump, well, supply, reverse osmosis), diet (vegetarian/non-vegetarian), habits (smokers/non-smokers, alcohol consumers/non-consumers, regular/irregular brushing). Study concluded that age is the most significant variable which influences the retention and excretion of fluoride.