In many countries, radon is the second leading cause of lung cancer after smoking. Radon is a chemically inert, naturally occurring radioactive gas without odor, color or taste.
It is formed during the natural radioactive decay of uranium that is found in rocks and soil.
Radon can also be present in the water.
In many countries, drinking water obtained from underground sources such as springs, wells and boreholes.
Water from these sources usually contain higher concentrations of radon than surface water from rivers, lakes and streams.
In have been measured in many countries the level of radon concentration in individual water was 20 Bq / l, and in some cases more than 100 Bq / liter.
As a result of research conducted to date, the link between radon in drinking water and cancer of the digestive and other systems have not been established.
"WHO Guidelines for Drinking-Water Quality," recommends repeat measurements if the level of radon in public drinking water supplies exceeds 100 Bq / liter.