Objective:By exploring the source of children's total fluoride intake and the relationship between children's total fluoride intake and dental fluorosis prevalence, to calculate the benchmark dose (BMD) of children's total fluoride intake and its 95% confidence lower limit (BMDL), and to provide the basis for revision of "Total Fluoride Intake for Inhabitants" (WS/T 87-2016).Methods:The villages that had water improvement for 5 years and more in 6 provinces of Jiangsu, Shandong, Hebei, Anhui, Henan and Shaanxi were selected as survey sites in April 2014. The water fluoride content of these villages was 0.3 - 3.0 mg/L, tap water samples from the centralized water supply were collected, and fluoride content was detected by ion selective electrode method. Children aged 8 to 12 years were selected, children's dental fluorosis was checked by Dean's method. Children's dietary and drinking water volume were surveyed by duplicate portion study (measurement for 3 d), and dietary fluoride content was detected according to the "Method for Determination of Fluorine in Foods". The mean and standard deviation of drinking water fluoride intake, dietary fluoride intake, and total fluoride intake were measured. According to the dose-response relationship between children's total fluoride intake and the detection rate of dental fluorosis, BMD and BMDL were calculated, and the reference dose (RfD) was calculated based on BMDL.Results:The mean of water fluoride of all 29 villages was 1.26 mg/L (from 0.41 to 2.85 mg/L). Totally 3 043 children aged 8 to 12 years were checked, and the detection rate of dental fluorosis was 30.2% (919/3 034). The lowest detection rate of dental fluorosis was 2.0% (2/100) and the highest was 71.4% (30/42) in the 29 villages. The children's dietary and drinking water volume of 769 person-time aged 8 to 12 years were surveyed, the children's daily drinking water fluoride intake, dietary fluoride intake, and total fluoride intake were (0.83 ± 0.66), (1.13 ± 0.61) and (1.96 ± 0.89) mg/d, respectively. The BMD of children's daily total fluoride intake was 2.43 mg, the BMDL was 2.21 mg, and the RfD was 2.21 mg.Conclusion:The BMD of 8 to 12 years old children's daily total fluoride intake is the same as the allowable limit (2.4 mg) of the national standard "Total Fluoride Intake for Inhabitants" (WS/T 87-2016).

Objective To understand the implementation effects of control measures and the dynamic prevalence of drinking water-borne endemic fluorosis in Shandong Province.Methods From 2013 to 2017 in Shandong Province drinking water-borne endemic fluorosis areas,in accordance with the method of simple random sampling,10 monitored counties were selected,10 water fluorine decreasing projects were investigated of its running effect,and water fluoride was detected.In each monitored county,3 villages in the diseased areas were selected as fixed monitored villages.If the monitored village had changed its water,the operation of the project would be investigated.If the monitored village had not changed the water,one water sample would be collected according to 5 directions of east,west,south,north and middle to determine the water fluorine.All children aged from 8 to 12 in the village were also examined for dental fluorosis.X-ray fluorosis and urinary fluorosis in adults aged over 25 were detected in 2013 and 2017.Results From 2013 to 2017,in monitored counties,the normal operation rate of improved-water defluoridation projects was 99.19％ (368/371),the qualified rate of water fluoride content was 66.85％ (248/371).In 128 improved water projects,the normal operation rate was 100.00％ (128/128),the qualified rate of water fluoride content was 67.19％ (86/128).The average detection rate of dental fluorosis and community fluorosis index (CFI) in children aged 8-12 were 33.92％ (2 608/7 689) and 0.68 in all monitored counties from 2013 to 2017.The detection rate presented a declining trend year by year (x2 =152.47 P ＜ 0.01).The average detection rate and CFI in the villages with normal operation projects and qualified fluoride content were 26.10％ (1 311/5 023) and 0.47.The detection rate presented a declining trend year by year (x2 =207.67 P ＜ 0.01).The detection rate and CFI in the villages with water improvement projects under abnormal operation or excessive fluoride were 48.65％ (1 297/2 666) and 0.90.The detection rate of dental fluorosis in the villages with normal operation projects and qualified fluoride content was lower than the rate of the villages with water improvement projects under abnormal operation or excessive fluoride (x2 =193.98,P ＜ 0.01).In 2013 and 2017,X-ray detection rates of skeletal fluorosis in adults aged over 25 were 8.04％ (119/1 481) and 6.04％ (81/1 342),respectively.The adult urinary fluoride geometric mean values (1.24,1.49 mg/L) were lower than the normal limit of 1.6 mg/L both in qualified villages of water ffuoride content and exceeding-standard villages in 2017.Conclusions In Shandong Province,the effective water improvement has acquired some effects in control of drinking water-borne endemic fluorosis.But the water fluoride content of improved water defluoridation projects exceeds the national standard seriously and fluorosis has not been effectively controlled.

Objective To grasp the current situation of drinking water-borne endemic fluorosis in Shandong Province,and provide a scientific basis for formulating preventive strategies.Methods In 2016,according to the "National Surveillance Scheme of Drinking Water-Borne Endemic Fluorosis" and "Shandong Provincial Surveillance Scheme of Drinking Water-Borne Endemic Fluorosis",10 counties (cities,districts) were selected in Shandong Province,3-5 villages were selected in each county (city,district),to investigate the operation of water improvement and fluorine reduction project and the water fluorine,and 1 tap water sample in each village was collected to detect water fluorine.At the same time,dental fluorosis examination was performed on all children aged 8-12 years old and fluorosis X-ray examination was performed on adults aged ≥25 years old.Water fluorine was detected by ion selective electrode method;the water fluorine was determined according to "Standards for Drinking Water Quality" (GB 5749-2006);criteria for diagnosis,grading and epidemic intensity of dental fluorosis were based on "Diagnosis of Dental Fluorosis" (WS/T 208-2011);the diagnostic and grading criteria for skeletal fluorosis were based on the "Diagnostic Criteria for Endemic Skeletal Fluorosis" (WS 192-2008).Results All the 32 villages in 10 counties (cities,districts) changed water,water improvement and fluorine reduction project ran normally,24 villages had qualified water fluorine (≤ 1.20 mg/L),and 8 villages had water fluorine exceeding the standard.The detection rate of dental fluorosis in children was 25.75％ (419/1 627),and the difference between 10 counties (cities,districts) was statistically significant (x2 =288.55,P ＜ 0.01);the dental fluorosis index was 0.48,and the defect rate was 2.77％ (45/1 627).The detection rate of skeletal fluorosis in adults was 4.72％ (72/1 525),and the difference between 10 counties (cities,districts) was statistically significant (x2 =18.83,P ＜ 0.01).Conclusions The problem of water fluorine exceeding the standard in water improvement and fluorine reduction project in Shandong Province is still serious.The condition of fluorosis has not been fully controlled,and the prevention and treatment measures need to be further strengthened.