Zimbabwe: Poisonous panning

“Mercury contamination is persistent in the ecosystem as the chemical is widely used by the gold panners,” Mr Katanga said. “People get affected after eating fish from the contaminated rivers. The symptoms may...present as nervous breakdown and loss of hair.”
Studies by various government and independent agencies, including the Zimbabwe National Water Authority (ZINWA), have revealed that the country’s major rivers—the Mazowe, Zambezi, Save, Runde, Sanyati, Umzingwane, Manyame, Gwayi and Shashe, which spread through eight of Zimbabwe’s ten provinces—are silting, twisting and dying because of these chemicals and other practices related to mining.
http://gga.org/stories/editions/aif-19-in-the-balance-development-vs.-conservation/poisonous-panning