The effect of non-fluoride factors on risk of dental fluorosis: evidence from rural populations of the Main Ethiopian Rift.
Elevated level of fluoride (F(-)) in drinking water is a well-recognized risk factor of dental fluorosis (DF). While considering optimization of region-specific standards for F(-), it is reasonable, however, to consider how local diet, water sourcing practices, and non-F(-) elements in water may be related to health outcomes. In this study, we hypothesized that non-F(-) elements in groundwater and lifestyle and demographic characteristics may be independent predictors or modifiers of the effects of F(-) on teeth. Dental examinations were conducted among 1094 inhabitants from 399 randomly-selected households of 20 rural communities of the Ziway-Shala lake basin of the Main Ethiopian Rift. DF severity was evaluated using the Thylstrup-Fejerskov Index (TFI). Household surveys were performed and water samples were collected from community water sources. To consider interrelations between the teeth within individual (in terms of DF severity) and between F(-) and non-F(-) elements in groundwater, the statistical methods of regression analysis, mixed models, and principal component analysis were used. About 90% of study participants consumed water from wells with F(-) levels above the WHO recommended standard of 1.5mg/l. More than 62% of the study population had DF. F(-) levels were a major factor associated with DF. Age, sex, and milk consumption (both cow's and breastfed) were also statistically significantly (p<0.05) associated with DF severity; these associations appear both independently and as modifiers of those identified between F(-) concentration and DF severity. Among 35 examined elements in groundwater, Ca, Al, Cu, and Rb were found to be significantly correlated with dental health outcomes among the residents exposed to water with excessive F(-) concentrations. Quantitative estimates obtained in our study can be used to explore new water treatment strategies, water safety and quality regulations, and lifestyle recommendations which may be more appropriate for this highly populated region.
Duke University Medical Center, Department of Surgery, Division of Surgical Science, DUMC, Box #3850, Duke University, Durham, NC 27710, United States. Electronic address: julia.krauchanka@duke.edu.
Julia
J
Kravchenko
Division of Earth and Ocean Sciences, Box #90227, Nicholas School of the Environment, Duke University, Durham, NC 27708, United States.
Tewodros
T
Rango
Center for Population Health and Aging, Duke University, Box #900408, Durham, NC, 27708, United States.
Igor
I
Akushevich
Jimma University, College of Public Health and Medical Sciences, Ethiopia.
Behailu
B
Atlaw
International Water Management Institute, PO Box 2075, Colombo, Sri Lanka.
Peter G
PG
McCornick
Division of Earth and Ocean Sciences, Box #90227, Nicholas School of the Environment, Duke University, Durham, NC 27708, United States.
R Brittany
RB
Merola
Division of Earth and Ocean Sciences, Box #90227, Nicholas School of the Environment, Duke University, Durham, NC 27708, United States.
Christopher
C
Paul
Nicholas School of the Environment, Box #90328, A135 LSRC, Durham, NC 27708, United States.
Erika
E
Weinthal
Nicholas Institute for Environmental Policy Solutions, Duke University, Box #90335, Durham, NC 27708, United States.
Courtney
C
Harrison
Division of Earth and Ocean Sciences, Box #90227, Nicholas School of the Environment, Duke University, Durham, NC 27708, United States.
Avner
A
Vengosh
Sanford School of Public Policy, Duke University, Box #90239, Durham, NC 27708, United States; Duke Global Health Institute, Duke University, Box #90239, Durham, NC 27708, United States.
Marc
M
Jeuland
D000818:Animals; D002417:Cattle; D004032:Diet; D060766:Drinking Water / Q000737:chemistry; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis*; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D005459:Fluorides / Q000032:analysis*; D009050:Fluorosis, Dental / Q000453:epidemiology*; D060587:Groundwater / Q000737:chemistry; D006801:Humans; D008297:Male; D008892:Milk; D012424:Rural Population / Q000706:statistics & numerical data; D014881:Water Supply / Q000706:statistics & numerical data
D060766:Drinking Water; D004785:Environmental Pollutants; D005459:Fluorides
Dental fluorosis; Ethiopia; Fluoride; Milk; Multiple contaminants approach; Water quality