Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Water treatments alone not enough to combat fluorosis in Ethiopia

27.04.2012
Increased intake of dietary calcium may be key to addressing widespread dental health problems faced by millions of rural residents in Ethiopia's remote, poverty-stricken Main Rift Valley, according to a new Duke University-led study.

As many as 8 million people living in the valley are estimated to be at risk of dental and skeletal fluorosis as a result of their long-term exposure to high levels of naturally occurring fluoride in the region's groundwater.

Fluoride is essential for healthy tooth enamel development, but consuming too much of it can damage enamel and bones, particularly in children between the ages of 3 months and 8 years.

Mild to moderate fluorosis typically results in permanent discoloring and disfiguration of tooth enamel. Severe fluorosis can cause chronic pain and lead to tooth and bone loss.

Most efforts to combat fluorosis in the region have focused primarily on treating drinking water to reduce its fluoride content.

The new Duke-led study, published online in the journal Environment International (www.sciencedirect.com/science/article/pii/S0160412012000530), finds that these efforts "may not be sufficient on their own, because of the region's geology and the low threshold of exposure at which we found fluorosis was likely to occur," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment.

Increasing the amount of calcium in villagers' diets, or finding alternative sources of drinking water may be necessary in addition to these fluoride-reducing treatments.

By systematically analyzing groundwater quality in the valley, Vengosh and his colleagues found that as water flows from the surrounding mountains into the rift, it interacts with volcanic rock, which contributes fluoride to the water while also removing most of its calcium. That's important, he explained, because "calcium is essential for mineral formation that can capture fluoride in a groundwater system."

Water samples from 48 of 50 wells tested in the valley contained fluoride levels above World Health Organization safe guidelines. The average daily fluoride intake of people drinking from the wells was six times higher than the current no-observed-adverse-effects-level (NOAEL) – the highest known level of exposure that can occur before adverse biological effects are detected.

The researchers also conducted clinical examinations of 200 villagers' teeth to see if differences in fluoride levels in drinking water supplies affected the severity and prevalence of fluorosis in a community's population.

"The idea was to test the hypothesis that higher fluoride in the water correlates to more common and severe cases of fluorosis in the people who drink it. But we found no linear correlation above a certain point," said Tewodros Rango, a postdoctoral researcher at Duke's Nicholas School of the Environment who was lead author of the study. "Essentially, our examinations showed that once you reach a low threshold of fluoride exposure, fluorosis is likely to happen."

In some of the communities, the fluoride levels in well water were so high you could treat the water to cut the fluoride content by half and it still wouldn't drop below the critical threshold, he said.

In villages where people had access to milk, severe fluorosis was about 10 percent less likely to occur, Rango's clinical examinations found. Further research is needed to explain this anomaly, he said, but it may be possible that by drinking milk -- which is not a common staple in the rural Ethiopian diet -- these people take in enough calcium to retard fluorosis development.

"Future mitigation strategies may want to include increased calcium intake in diets, particularly for children," he said.

The research team's tests also found high levels of naturally occurring toxic elements, including arsenic and uranium, in the groundwater samples.

"The combined impact of these elements on human health may be higher than the sum of the effects from each specific contaminant," said study co-author Dr. Julia Kravchenko, a researcher at the Duke Cancer Institute. "For example, it could result in aggravated toxicity of fluoride as well as increased risk of damaged kidney function. This phenomenon is very important for evaluating region-specific safety limits for water contaminants."

Increased numbers of fluorosis cases have been reported in recent years in many parts of the world, including Mexico, Brazil, China, Vietnam and Thailand. Devising mitigation strategies that take into account each region's geology and water quality is critical, the researchers noted, because global warming could worsen the quality of drinking water in these regions in coming years.

Other co-authors on the study were Marc Jeuland of Duke's Sanford School of Public Policy; Nicholas School PhD student Brittany Merola; Behailu Atlaw of Jimma University in Ethiopia, and Peter G. McCornick of the International Water Management Institute in Sri Lanka. Support came from the Duke Global Health Institute and Duke's Nicholas Institute for Environmental Policy Solutions.

Tim Lucas | EurekAlert!
Further information:
http://www.duke.edu

More articles from Ecology, The Environment and Conservation:

nachricht Seabird SOS
01.09.2015 | University of California - Santa Barbara

nachricht Northern bald ibises fit for their journey to Tuscany
21.08.2015 | Veterinärmedizinische Universität Wien

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Starke, aber zeitlich begrenzte Temperaturabkühlungen unter der Lupe

Grosse Vulkanausbrüche schleudern beträchtliche Mengen an Schwefeldioxid in die Atmosphäre, die sich in Aerosole umwandeln, in der Stratosphäre verteilen, dort einen Teil der Sonneneinstrahlung blockieren und so die Erdoberfläche für einige Jahre abkühlen.

Ein internationales Forscherteam mit Berner Beteiligung hat nun dank der Kombination von Jahrringuntersuchungen an Bäumen und Klimamodellen einen Ansatz...

Im Focus: Elektrofahrzeuge kabellos laden und entladen

Über ein kabelloses Ladesystem können Elektroautos künftig nicht nur tanken, sondern die Energie ins Stromnetz zurückspeisen. Auf diese Weise helfen sie das Netz zu stabilisieren. Das kostengünstige Ladesystem erreicht hohe Wirkungsgrade – über den vollen Leistungsbereich von 400 Watt bis 3,6 Kilowatt. Die Abstände zwischen Auto und Ladespule können bis zu 20 Zentimeter be- tragen. Auf der Internationalen Automobil Ausstellung IAA in Frankfurt stellen Fraunhofer-Forscher den Prototyp vom 15. bis 18. September 2015 vor (Halle 4, Stand D33).

Es regnet in Strömen. Wer jetzt ein dickes unhandliches Kabel zwischen Elektrofahrzeug und Ladesäule einstecken muss, wird patschnass. Doch es nützt nichts,...

Im Focus: Increasingly severe disturbances weaken world's temperate forests

Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.

"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...

Im Focus: Meeresinseln als Heimat einmaliger Pflanzenarten

Warum leben in manchen Ökosystemen auffallend viele, in anderen Ökosystemen nur wenige Pflanzenarten? Wie kommt es, dass einige Arten jeweils nur in einer bestimmten, klar abgrenzbaren Region der Erde zuhause sind? Mit diesen Fragen hat sich Dr. Manuel Steinbauer in einer Reihe wissenschaftlicher Studien an der Universität Bayreuth befasst. Für seine Forschungsarbeiten wird der Bayreuther Ökologe, der zurzeit als Postdoc an der dänischen Universität Aarhus forscht, mit dem diesjährigen Wilhelm Pfeffer-Preis der Deutschen Botanischen Gesellschaft (DBG) ausgezeichnet. Der Preis ist mit 2.500 Euro dotiert.

Wenn es darum geht, den Gründen für die Verbreitung pflanzlicher Arten auf die Spur zu kommen und theoretische Erklärungsansätze zu überprüfen, sind...

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Internationale Ökologenkonferenz zeigt Wege in eine nachhaltige Zukunft auf

01.09.2015 | Veranstaltungen

Frankfurter Hochhausfassadentage 2015: Frankfurt UAS veranstaltet Symposium und Hochhausführung

31.08.2015 | Veranstaltungen

Erreger unter Superlupen – Aufbruch in unsichtbare Welten

31.08.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Neuer Forschungsschwerpunkt zum Upgrade des Large Hadron Colliders

01.09.2015 | Förderungen Preise

„Dreh Dein Bild der Informatik“: Videopreis 2015 ausgeschrieben

01.09.2015 | Förderungen Preise

Fraunhofer IWM präsentiert Lösungen für Leichtbau auf der Composites Europe

01.09.2015 | Messenachrichten