Cassava crop toxins threaten food security

Cassava, a staple crop of southeast Africa, contains more toxins, including cyanide, than are safe for people to eat, say researchers. Scientists found levels of toxins in excess of World Health Organization standards in the leaves and tuberous roots of cassava plants being grown in regions of Mozambique with drier climates. Tim Cavagnaro led the study, funded by AusAID, with his team from the School of Biological Sciences and Australian Centre for Biodiversity at Monash University, working in collaboration with scientists in Mozambique. In sufficient quantities, the compounds can cause poisoning and death in humans and animals when consumed. The low concentrations generally found in cassava to help protect it from pests are considered harmless. In regions where cassava is a primary part of the diet, Cavagnaro says appropriate processing procedures were required to eradicate toxins in the crop. “The study examined the cyanide levels and nutritional value of cassava, which are important to the overall quality of this crop and therefore its sustainability as a staple part of the diet in African communities,” Cavagnaro says. “These findings highlight the need for adequate processing of cassava-based foods prior to consumption, and education of new growers about the risks associated with cassava. “If developed further, cyanide testing kits used in this study could significantly reduce the risk of cyanide poisoning in existing and new cassava growing areas.” The study, published in the Journal of Agricultural and Food Chemistry, tested the toxicity levels in cassava from different locations in rural Mozambique. Staple food for more than 500 million people throughout tropical Africa, Latin America, and parts of Asia, the carbohydrate-rich but low-protein plant is an important energy source.