Civilian populations have suffered significant health impacts from mining and the associated conflicts. A 2009 study in Katanga Province found "substantial exposure to several metals, especially in children. The urinary Co concentrations found in this population are the highest ever reported for a general population." In 2016, researchers discovered extensive metal contamination in the fish in Katanga's Lake Tshangalele, near mining and other metallurgical operations in Likasi, in species commonly eaten by the local population. A study of coltan miners in North Kivu Province also found very high levels of exposure. Workers at the Ruashi mine reported headaches and musculoskeletal and respiratory disorders. Environmental contamination in soils has been shown to correlate with proximity to former mining sites: "These values are much higher than the sediment guidelines for the protection of aquatic life and international soil clean-up standards. Enrichment factor and geoaccumulation index results indicated important contribution of mining activities to the study sites pollution in addition to natural background."