In the
coal-burning fluorosis areas of China, over 10 million people suffer from
dental fluorosis caused by multiple pathways of
fluoride intake. However, the link between
dental fluorosis prevalence, the geochemical distribution of
fluoride, and contributions of different exposure pathways remain unclear. Here, we aimed to quantify the various
fluoride exposure pathways and establish the association between
dental fluorosis and
fluoride intake in Southwest China. Epidemiological data on the peak time of fluorosis prevalence were combined with geochemical analyses of the
fluoride content in
coal and
clay over a large scale, the amounts and ratios of
fluoride intake through different exposure pathways were calculated, and the association between the total daily
fluoride intake (TDFI) and
dental fluorosis severity was analyzed. The prevalence of
dental fluorosis was not significantly correlated with the
fluoride geo-background of
coal and
clay on a large scale (P > 0.05). The co-combustion of
coal and
clay contained in hand-made briquettes is the main pathway of
fluoride contamination, which occurs through the inhalation of polluted air and consumption of contaminated roasted products. Furthermore, the TDFI per person ranged from 2.78 to 17.32 mg, and it was significantly positively correlated with the prevalence of
dental fluorosis (P < 0.05). The TDFI from breathing and eating was 1.1-3.2 mg and 1.1-15.1 mg, which accounted for 9%-54% and 40%-90% of the total TDFI, respectively. The combination of living habits and soil geochemical
fluoride anomalies resulted in the higher prevalence of fluorosis in rural areas of Southwest China.