RESUMEN
Objective:To understand the current situation of children's fluorosis in the coal-burning-borne endemic fluorosis areas (abbreviated as coal-burning fluorosis) in Suojia Miao, Yi and Hui Township (Suojia Township for short) in Liuzhi Tequ, Guizhou Province, and to provide scientific basis for formulating prevention and control strategies and measures.Methods:In 2019, the cluster sampling method was adopted to select children aged 8-12 years old from 6 primary schools in Suojia Township, Liuzhi Tequ, Guizhou Province to conduct a questionnaire survey to collect basic information, and perform dental fluorosis examination and indexing in accordance with the "Diagnosis of Dental Fluorosis" standards. Immediate urine samples were collected from children in April and October, and urinary fluoride content was determined by ion selective electrode method.Results:A total of 1 381 children aged 8-12 years old were investigated, aged (9.84 ± 1.38) years old, including 679 boys and 702 girls. A total of 625 children with dental fluorosis were detected, and the detection rate was 45.26%; the dental fluorosis index was 1.00, and the prevalence intensity was moderate; the main score of dental fluorosis was extremely mild, accounting for 37.00% (511/1 381). The detection rates of dental fluorosis in children aged 8 to 12 years old were 35.10% (106/302), 35.83% (115/321), 47.96% (129/269), 55.23% (153/277), and 57.55% (122/212), respectively; the difference between different ages was statistically significant (χ 2 = 48.949, P < 0.01), and the detection rate of dental fluorosis in children increased with age(χ 2trend = 45.254, P < 0.01).The detection rates of dental fluorosis in boys and girls were 43.59% (296/679) and 46.87% (329/702), respectively, and there was no significant difference between different genders (χ 2 = 1.492, P > 0.05). In April and October, 123 and 107 urine samples of children aged 8-12 years old were tested. The geometric mean of urinary fluoride was 1.55 and 0.47 mg/L, respectively. The urinary fluoride level in April was higher than the normal range (< 1.40 mg/L). Conclusions:Suojia Township in Liuzhi Tequ of Guizhou Province is still a fluorosis area, and there is a big difference in urinary fluorine level in different months, which indicates that the residents in this area may have intermittent high fluorine intake, and prevention and control of endemic fluorosis should be further strengthened.