The fallout of volcanic ash over parts of Iceland could jeopardise the safety of drinking water, health authorities warned Friday, but said the greatest health risk was to livestock.
"It is important to prevent the ash from reaching water supplies, both for public and animal health reasons and for safe milk production," Halldor Runolfsson of the Icelandic Food and Veterinary Authority told AFP.
His colleague Guthjon Gunnarsson said the agency was evaluating the quality of drinking water, which was mostly protected because it came from under ground.
"Here in Iceland the (drinking) water is mostly groundwater so it is rather difficult for ash to heavily pollute it," he said.
But Runolfsson said the blast -- which covered large areas in a thin layer of volcanic ash -- mostly posed a health risk to Livestock because the ash contained high levels of fluoride.
"Farmers are advised to keep their livestock indoors," he said. "Intake of fluoride is known to cause problems in bones and teeth, Especially in growing animals. The ash can also ... cause problems in (animal's) respiratory and digestive systems," he said.
"We are first and foremost looking at the quantity of the fluoride," Gunnarsson said.
The concentration of fluoride near the volcano was of 23 to 35 milligrams per kilogramme of ash.
Iceland's second volcanic eruption in less than a month began under the Eyjafjallajokull glacier in the south of the country at around 1:00 am (GMT) Wednesday.
It has since then continuously spewed a 6.0-kilometer (3.7-mile) plume of volcano ash into the sky, sending a giant cloud of ash towards Europe and prompting the continent's biggest air travel shutdown since World War II.