"The contaminated areas have been identified and the need for comprehensive monitoring and study, as well as toxicological and epidemiological studies in affected communities, is imperative," Mariette Liefferink from the Federation for a Sustainable Environment told The New Age.
This means the health of some of Johannesburg's residents and many communities living downstream and upwind of the ciTY's mine dumps could be under threat from potentially dangerous levels of uranium in some water supplies, windblown radioactive dust and radon gas.
Water supplies from the Upper Wonderfonteinspruit catchment area, stretching from Johannesburg to Potchefstroom, and including the West Rand Goldfield, are contaminated with potentially dangerous levels of uranium.
So said the National Nuclear Regulator in a 2007 report, Radiological Impacts of the Mining Activities to the Public in the Wonderfonteinspruit Catchment Area.
Uranium is chemically toxic and uranium in drinking water has been identified as an important source of risk to the public. People have been using the contaminated water in households, agriculture, recreation and fishing.
For more than a century, major gold mining activities, with the potential for pollution of surface and ground waters, have been carried out in the West Rand.
The gold ores contain appreciable concentrations of uranium and its radioactive progeny. Mining has resulted in the dispersal of radioactive material into the environment.
Sources of radioactivity in the West Rand include large active gold mines, old and abandoned mine workings and deposits of mining and milling residues, especially the so-called slimes dams in the area.
Elevated levels of radioactivity have been recorded over urban areas of the Johannesburg CBD according to a 2008 report, Draft Regional Mine Closure Strategy for the West Rand Goldfield, released by the Department of Mineral Resources.
The use of contaminated material and mine residues in construction has also been identified as a means of dispersal of radioactive material into the environment.
"Tailings dams (containing toxic mining residue) must be vegetated and seepage of water from tailings dams must be controlled to prevent the pollution of ground and surface water. Contaminated soil must be removed and replaced with uncontaminated soil,"Â says Liefferink.
The Department of Water and Environmental Affairs would investigate and promised to respond in due course.