RESUMO
Objective:To study the relationship between adult fluoride exposure and grip strength in rural areas of China with fluorosis, as well as the roles of basal metabolic rate (BMR) and body fat percentage (BFP) in the association between fluoride exposure and grip strength.Methods:From April to May 2017, a cluster sampling method was used to conduct a questionnaire survey, physical examination, and biological sample collection on residents aged 18 - 60 in Tongxu County, Kaifeng City, Henan Province (epidemic areas of drinking-water-borne fluorosis). A total of 1 168 subjects were included in the study, including 427 males and 741 females. The fluoride ion selective electrode method and the picric acid method were used to determine the concentrations of urine fluoride and urine creatinine, and the adjusted urine fluoride concentration (CUF) was calculated. BMR and BFP were measured by a bioelectrical impendence method, and the grip strength was measured by a Jamar grip dynamometer. The relationship between CUF, BMR, BFP and grip strength were analyzed using a generalized linear model regression. The mediation effect model was used to assess the mediating effect of BMR and BFP on the association between CUF and grip strength.Results:Female grip strength decreased by 0.28 kg ( P = 0.043) for every 1.00 mg/L increment in CUF. No similar association was found between the two in males ( P = 0.744). Regardless of gender stratification, BMR was positively correlated with grip strength ( P < 0.001). For every 1.00% increase in BFP, female grip strength decreased by 0.18 kg ( P = 0.043). The mediation effect model analysis results showed that the mediation effect ratios of BMR and BFP in the association between CUF and grip strength in female were 65.1% ( P < 0.001) and 8.4% ( P = 0.111), respectively. Conclusion:Fluoride exposure is associated with changes in female grip strength, and BMR changes play a partial mediating role in the association between fluoride exposure and female grip strength.