During the closing stages of the conflict, the Rhodesian government resorted to biological warfare. Watercourses at several sites close to the Mozambique border were deliberately contaminated with cholera and the toxin Sodium Coumadin, an anti-coagulant commonly used as the active ingredient in rat poison. Food stocks in the area were contaminated with anthrax spores. These biological attacks had little impact on the fighting capability of ZANLA, but caused considerable distress to the local population. Over 10,000 people contracted anthrax in the period 1978 to 1980, of whom 200 died. The facts about this episode became known during the hearings of the South African Truth and Reconciliation Commission during the late 1990s.