Exposure assessment of fluoride in drinking water in Qingpu District， Shanghai from 2016 to 2021

Objective The monitoring of fluoride in drinking water in Qingpu District was conducted to evaluate the external exposure of residents through drinking water， and to provide data support for the continuous improvement of drinking water quality in the area and the health level of residents.

Methods From 2016 to 2021， the pipe network water was collected from 42 monitoring points in Qingpu District， every month， and the fluoride concentration in the pipe network water was detected by ion chromatography.

Results The fluctuation range of fluoride concentration in drinking water in Qingpu District from 2016 to 2021 was between 0.10 and 0.96 mg·L^-1. The fluoride in drinking water did not exceed the standard， which was lower than the lower limit of the WHO recommended range. The median fluoride concentration in drinking water in the Qingcaosha water source area was 0.20 mg·L^-1， and the median fluoride concentration in drinking water in the Dianshan lake water source area was 0.44 mg·L^-1， and the difference between the two was statistically significant （Z=20.260， P<0.001）. The fluoride concentration in drinking water had a decreasing trend year by year， especially in the water supply area of Dianshan lake water system. The fluoride concentration in drinking water in Qingcaosha water source water supply area decreased relatively gently， from 0.25 mg·L^-1 in 2017 to 0.20 mg·L^-1 gradually. According to the "Chinese Residents' Dietary Nutrient Reference Intake 2013 Edition"， the requirement of 1.5 mg·d^-1 of suitable fluoride intake （AI） for adults. About 50% of the residents in the water supply area of Dianshan lake would consume less than 0.75 mg·d^-1， fluoride through drinking water， which was lower than 1/2 of the AI value. The fluoride content in the water supply area of Qingcaosha water source was relatively low， and 75% of the residents ingested fluoride through drinking water was lower than 0.37 mg·d^-1， which was lower than the 1/4 of the AI value.

Conclusion The concentration of fluoride in drinking water in Qingpu District is lower than the sanitary standard of drinking water in China，and the risk of excessive fluoride exposure is very low. However， the fluoride concentration in drinking water has a decreasing trend year by year， and intervention measures should be used rationally to reduce the health risks caused by insufficient fluoride intake.