6 Severe bone deformities, resulting from endemic ﬂuoro- sis, have also been identiﬁed in children who live in India. In a recent study, skeletal signs of SF, including Genu valgum, Genu varum, and anterior bowing of legs, were identiﬁed in children ages 1–18 years, who resided in endemic ﬂuorosis villages of the Bihar State, India [16]. Study investigators concluded that high rates of SF among children/adolescents in this region are due to overexposure to high ﬂuoride levels coupled with serious vitamin and mineral deﬁciencies, especially calcium and vitamin D deﬁciencies [16]. One limitation of the present study is that we did not measure vitamin and mineral intake among our children. It is possible that the severity of skeletal ﬂuorosis cases among children in Zhijin may vary due to other factors that could include the child’s diet and intake of vitamins and minerals necessary for proper bone growth and development. Further investigation is necessary to assess all the potential factors that contribute to SF incidence and severity among children and adolescents in China. While excess ﬂuoride exposure is necessary to cause SF, we expect that SF severity in pediatric populations is related to other contributing factors such as dietary intake, exercise, concurrent diseases, and general overall health. A staggering 97% of children from our sample had some clinical signs of DF. Furthermore, nearly 84% of these chil- dren had signs of moderate-to-severe ﬂuorosis on at least one tooth. DF prevalence among Zhijin children/adolescents in our sample is similar to the prevalence among children, aged 10–15 years, in Pengsui County, Sichuan Province, where 99.5% of children present with signs of DF [4]. Extremely high prevalence of DF among children/adolescents suggests that exposure to high ﬂuorine levels in these areas of southwestern China has been occurring in the recent past (as tooth development occurs early in a child’s lifespan). Animal studies suggest that teeth may be good biomarkers for skeletal ﬂuoride exposure in humans exposed to greater than optimal levels of ﬂuoride [22]. Hence, children and adolescent populations with high DF incidence rates may represent at risk populations for SF in adulthood and further highlights the need for ﬂuorosis control measures and de- ﬂuoridation projects in southwestern regions of China. The present study is one of very few to report percentage of SF among children living in a severely endemic ﬂuorosis region of China. Often excluded, or under-sampled, in epidemiological reports of endemic ﬂuorosis, prevalence of SF in children and adolescents closely represents the incidence of SF in a population and can be used to assess the successfulness of control measures at the population level. China recognized ﬂuorosis as a major endemic disease in 1977 and the Chinese Government has attached great importance to controlling ﬂuorosis [23]. Pilot schemes designed to improve domestic stoves were launched in the 1980’s and a campaign to adapt stoves in Guizhou Province was conducted in the 1990’s [23]. During the campaign, open stoves were converted into closed stoves by the addition of a chimney. Despite improved household stoves, populations in Guizhou Province still suﬀer from high exposure to indoor air pollution, and adverse eﬀects from overexposure to ﬂuoride [22]. Recent studies have indicated that limiting inhalation of stove emissions by using a chimney-style stove Journal of Environmental and Public Health would only result in a minor reduction in ﬂuoride exposure [4]. New fuel sources or other methods of drying foodstuﬀ would have a greater impact on ﬂuoride exposure levels in this region of China. Other methods of ﬂuoride exposure control need to be designed if ﬂuorosis prevalence among residents of coal- burning endemic ﬂuorosis areas is to be reduced. 5. Conclusions Indoor burning of ﬂuoride-rich coal is believed to cause endemic ﬂuorosis cases among children in the Guizhou Province of China. The present study illuminates the extent of endemic SF among children and adolescents living in a heavily polluted neighborhood of Guizhou Province, Zhijin County. In our sample, 7.5% of the children were diagnosed radio graphically with SF. Peasants in many regions of China depend upon coal as a fuel source because it is cheap and abundant. 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