Human: Subjects were selected based only on residential area. Areas were determined to be historically high or normal fluoride according to the annual surveillance data from Tianjin Center for Disease Control and Prevention, the Baodi district in Tianjin, and fluoride concentrations in this district have kept stable over the past decades. However, individual data were available on the select children. Spot urine samples were collected from each child and drinking water samples from each family were collected in pre-cleaned, labelled polythene tubes. Fluoride concentration was analyzed using ion selective electrode methods.There is no information provided to indicate that the study accounted for possible differences in urine dilution. No information was provided on QC. Detection limit was noted to be 0.0001 mg/L.

Zhou 2019

Risk of bias

Epidemiological study populations

HAWC