it is also david ncale's home. he plants vegetables here. t his produce is tainted by heavy metals and radioactive substances. this is because david's dwelling sits atop a heap of mining waste. >> i grow my own vegetables because i have no choice. i can't afford to buy food. i want to move as soon as possible. >> this entire area is polluted with waste from the gold mining boom -- uranium, toxic metals, and corrosive acids. environmental activist mariette liefferink has been visiting the area for years to inform its residents of the dangers of mining waste. today, geologist frank winde joins her. he is going to measure radioactivity with a geiger counter. levels of radioactivity around david ncale's home have risen, increasing his risk of cancer. >> the problem is that people live here permanently and so are exposed over a long period. but besides being exposed to radiation, there are others dangers. >> risks come from breathing in pollutants or ingesting them after they have polluted the ground. this is a major health threat -- one that mari