ABSTRACT
The incidence of fluorosis, believed to arise from the burning of coal, has been frequently reported in the highlands in the southern part of China. With a lot of rain and a climate of low temperature, the hilly region produces coal and inhabitants use it as a fuel for cooking and heating. The fossil fuel used by them is mostly powdery. It is mixed with dirt and rolled up into bolls. In that way,the people make the briquettes that burn a long time.Ordinary houses have no chimneys to belch forth smoke, so that it stagnates indoors for a while. Soot and smoke, before flowing out via the openings in the roof shingle of the loft, spoils farm produce stored there. Because the smoke contains high concentrations of fluoride derived from coal and dirt, it is believed that eating farm produce exposed to the smoke is one of the major factors for fluoride poisoning. Many researchers have thus far analyzed farm products for fluoride content and confirmed that high levels of fluoride were contained in their samples.In the present study, we measured fluoride concentrations in some samples of corn and capsicum produced in a rural area of Sichuan, China on one hand and on the other examined the water-solubility of fluoride. Furthermore, screening tests for chronic endemic dental fluorosis were performed on students to survey the fluoride contamination in the past as compared with the present state.Incidentally, indoor air-borne fluoride concentrations in this area averaged out at0.047mg F/m3 (15 times as high as the mean in a community that was free of fluoride contamination). The fluoride content of the drinking water from a spring in the nearby hill, measured with use of a fluoride-specific electrode method,was within the range from 0.2 to 0.3μg/ml.