Sample taking. Researcher supported by a safety cable taking samples of moss from a fast flowing river. He is storing the moss in a pouch for subsequent checking of its radioactivity levels. Radioactive pollution may arise from nearby nuclear power stations or natural sources. Regardless of their source, radioactive materials can cause severe health problems during prolonged exposure, the most obvious being the dramatically increased risk of cancer. This work is being done by the French government agency, l'Insitut de Protection et de Secrete Nucleaire (IPSN). Photographed on the Tinee River, France.