Three premature cancer deaths in two years. Total annual damage to society €1.7 million. That is the price of radioactive groundwater.
People of Harju county, West and East Viru counties, and the Nõmme and Pirita boroughs in Tallinn mostly drink groundwater from the Vend-Cambrian aquifer. It is the deepest groundwater reservoir that covers most of mainland Estonia. The water lies at a depth of 60-70 meters in Northern Estonia and goes deeper the further south one travels.
The aquifer is rich and protected from the outside environment. However, the water has a high radionuclides content caused by a bottom layer containing uranium and thorium and a layer of clay surrounding the water.
Groundwater does not contain uranium and thorium as conditions underground do not facilitate its dissolution. However, the oxygen-deprived groundwater layer is suitable for the dissolution of radioactive radium in the water. Decades ago, radium was used to manufacture glowing watch hands for example.
Senior researcher at the University of Tartu Laboratory of Environmental Physics Madis Kiisk and his colleagues have spent the past six years looking for a solution to the problem of radioactive groundwater in Northern Estonia.
The fact that the water has a higher than normal radioactive content has been known for a few decades.
The first step to extract the radioactive radium from groundwater was taken in 2012 when a new water treatment plant in Viimsi adopted a special technology for the separation of radium. The method worked, and radium content was reduced. However, this immediately created a new problem: the radium started accumulating in the filters of water treatment facilities that became radioactive in turn and had to be treated as sources of serious danger.
Social minister Eiki Nestor laid down limit values for radioactive particles in drinking water in 2002.
“There are two kinds of parameters. First, limits the radioactivity of drinking water absolutely must not exceed. Secondly, we have indicative values exceeding of which does not necessarily mean the water is unsuitable,” Kiisk said. He said that in the latter case it needs to be considered whether it is possible to improve the quality of water and whether it would be cost-effective.
“In that case we can say that the water is drinkable, that shutting the taps would not reduce risks,” Kiisk explained.
However, all manner of ionizing radiation is a source of risk that Kiisk and his team summed up last year.
Research fellow of environmental technology Taavi Vaasma said that radium builds up just like magnesium or potassium in the human body.
The half-life of the two radium isotopes found in groundwater is 1,600 and 5.8 years. Radium particles in people’s bones are constantly emitting radiation.
“People have a constant supply of radioactive matter in their bodies,” Vaasma said.
A major study looked at results of several narrower cancer studies in 2011 and found that high radium content in groundwater is most closely associated with bone, bladder, blood, breast, and lung cancer.
A study from 2009 showed that the radium content of groundwater in Northern Estonia is on average three times higher than recommended.
There are some water companies the wells of which produce water the radium content of which is just a few dozen percentage points higher than the norm. At the same time, radium content is seven to eight times higher than recommended in Kunda. Recommendations to use water closer to the ground are usually unfeasible as corresponding reserves are modest.
Lives and healthy years lost due to cases of cancer caused by high radium content in drinking water cost Estonia €1.7 million every year, University of Tartu environmental technicians found in a study.
Water quality requirements are the domain of the Health Board that has not laid down limits for radioactive content so far. The agency lacked methodology with which to assess risks tied to radioactivity and determine when something should be done to clean water of radioactive particles.
“We need to weigh the risks and consider the cost of managing them,” Kiisk said.
One year of life lost to radioactive water costs €60,000.
Looking at the figures, it turns out that water companies with over one thousand consumers should take steps to reduce radium content in drinking water.
Radium has been separated from the water by accident so far and has accumulated in filters, turning the latter into sources of radiation. Workers charged with cleaning the filers are doing hazardous work.
A new solution exists and has been tested in Viimsi. Radium is extracted in a process that first sees oxygen added to the water. This causes iron and manganese to oxidize. Oxidized manganese complexes radium, and the resulting sediment can be rinsed into waste water without creating radioactive filters.
“Unfortunately, the separated radium is not a vein of gold; rather it is still a problem,” Kiisk said.
The new purification method might not hike the price of water as it is possible to use ordinary quartz sand instead of more expensive filtration sand in the process.
University of Tartu and Tallinn University of Technology researchers are now working on a joint project with Spanish scientists to find a way to filter out uranium and radium particles while wasting as little water as possible. Unlike Estonia, Spain is short on freshwater reserves.